Tipps für Vorstufe gesucht

Trinnov
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Beiträge: 971
Registriert: 13.11.2009, 19:02

Beitrag von Trinnov »

Hallo Thomas,

ich stimme auch dir voll zu.
Röhre ist so eine Sache. Je nach Setup kann eine zusätzlich dazwischen geschaltete Röhrenstufe das Ergebnis auch verschlechtern.
Ich hatte diesbezüglich vor ca. einem halben Jahr ein Schlüsserlebnis.
Da ich für einen Freund eine gebrauchte Octave HP500SE Vorstufe verkaufte, hatte ich sie dem Käufer in meinem Setup vorgeführt um zu zeigen dass alles in Ordnung ist.
http://www.octave.de/htdocs/verstaerker/hp500mk3_se.php
Die Vorstufe wurde mit hochwertigen Signal-Kabeln zwischen DAC und Endstufe geschaltet.
Normalerweise verwende ich keine Vorstufe.
Der Käufer war sehr zufrieden mit dem Klang.
Da ich aber mein Setup ohne dazwischengeschaltete Vorstufe sehr gut kenne, ist mir aufgefallen, dass die Octave Vorstufe obwohl im Internet hoch gelobt, mir im Klangbild bei allen von mir geliebten Vorzügen meines Setups jeweils ein kleines bisschen wegnahm. Zum Beispiel Dynamik, Auflösung, Basspräzision, räumliche Abbildungsmöglichkeiten usw.

Trotzdem bin ich der Meinung dass ein sehr guter Röhren-VV statt Transistor-VV in vielen Setups den Zugang zur Musik erheblich verbessern kann. Eine allgemein gültige Empfehlung kann man aber nicht geben. Jedes Setup ist anders.
Der andere Weg ist das generelle Hinterfragen eines Vorverstärkers, wenn man nur mit einer Line-Level-Quelle zuspielt und diese zudem noch eine genügend potente Ausgangsstufe besitzt. Das Regeln der Lautstärke müsste dann natürlich in der Quelle erfolgen.

@Andi
Sorry wenn ich etwas vom eigentlichen Thema abgewichen bin.
Vielleicht interessiert es ja trotzdem.

Viele Grüße,
Horst
Bild
shakti
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Registriert: 18.01.2010, 16:20
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Beitrag von shakti »

wenn Geld keine Rolle spielen wuerde, waere aktuell eine Robert Koda Takumi Vorstufe mein naechstes Ziel,
ich kopiere den Test mal hier hinein, da man an der Beschreibung und dem Vergleich mit anderes "grossen" Pres erkennen kann, welche Unterschiedes es selbst bei "cost no object" Vorstufen noch geben kann:
Wojciech Pacula hat geschrieben:
Robert Koda Takumi K-15 Preamplifier
text by Wojciech Pacula, imahes by Wojciech Pacuła and Robert Koda LLC, translation by Andrzej Dziadowiec

The list of Japanese audio companies that are not—and probably will not be for a long time—represented in Poland is longer than the one listing the companies we have already "touched." A cursory glance at the latest issue of the "Stereo Sound" quarterly, the bible of Japanese audio lunatics, that is music lovers and audiophiles (each country has its own madmen), immediately returns such names as: Technical Brain, Kiso Acoustic, Uesugi (U-Bros), AET, Zonotone, TAOC, Aracraft (Tedius), Ikeda Sound Labs, Fundamental, ORB, or Nanotec Systems. These are only the names I have found featured in large commercials and reviews, without going into the smaller classified ads. It is a completely unknown to us, infinite universe. Even supposedly well-known brands like Esoteric, Fostex or Audio-Technica are rather familiar to us by their names as their products are nowhere to be found on the shelves of audio stores. The reason for all that is that although we seem to know quite a bit about Japan and its perfectionist audio market, the truth is much more prosaic. We only catch a faint glimpse of the dazzling wealth that surrounds the Japanese audiophiles every day. All the more we need to grasp and to hang on to any refined audio products from the manufacturers that we come across for the first time.

About the time of this review, the two top items in the news section of the Robert Koda website were about the newest distributor, SoundClub from Poland, and about the launch of a new flagship preamplifier, the Takumi K-15. At the same exact time, I received information that the F-15 was sent to me for a review. True global village, this time.

Robert Koda LLC was founded in Tokyo in 2008. The company grew out of the passion and experience of Robert Koch, a self-taught music lover and audiophile who for years had worked for Audio Note Japan (Kondo), one of the highest rated Japanese audio brands. After the death of Mr. Hiroyasu Kondo in 2006, he decided to work independently and taking the maiden name of his wife he went out into the world. But first he had to be born somewhere. This happened to be in South Africa, in a family "infected" with audiophilism. His father was an avid lover of high-end sound. His parents' first concern when looking for a new home would be living room acoustics.

Before he decided to realize his dream of life and create his own audio system, Robert was gaining experience working in the audio industry for 16 years. He was selling and servicing audio equipment from many manufacturers, which also led him to the conclusion that he could design better and more durable components. After learning about Kondo products, he naively decided to send his resume to Japan, asking for a job. As one might expect, nothing came out of that. During a prolonged leave that he spent in the UK, he managed to get a job in Audio Note UK. It was there that he was noticed by Hiroyasu Kondo, during one of his visits, and brought to Japan.

As we read in the Audiotechnique magazine, published in Hong Kong (April 2012, No. 367), the work in a small Japanese family business was difficult to bear for a man born under the big skies of Africa. He parted ways with Kondo three times only to come back each time, being driven by thirst for knowledge. He participated, among others, in designing the M1000 preamplifier. After the death of Kondo-san, he teamed up with his successor, Mr. Masaki Ashizawa, his close friend. It was then that he designed the MkII version of the M1000 and a DAC. His thoughts, however, were already preoccupied with his own design. The decision to cut the umbilical cord was sealed by the fact that Kondo was changing its address and moving from Meguro to Kanagawa, far from Robert's home. It was THAT moment.

The first product that made the new brand known in the circles of advanced seekers of the audio absolute was the K-70 power amplifier. Once seen, it sunk for a long time in memory, not only through its perfect workmanship and sense of proportion, but also a rather unusual design. This "tri-chassis" power amplifier consists of two monoblocks and a power supply housed in a separate chassis, for a single-ended hybrid design employing over 30 power transistors and a pair of 5842 triodes in each monoblock and 6X5 rectifier tubes in the power supply. Hi-Fi News & Record Review quotes Mr. Koch saying that the K-70 is his "vision of amplification's ultimate form" (John Bamford, Paul Miller, Robert Koda Takumi K-70 (£ 35,000), Hi-Fi News & Record Review, April 2011, see HERE). Due to its triple chassis configuration, the total amplifier weight is a hefty 80 kg (!). The K-70 delivers 70 watts in pure class A.

Each amplifier is hand crafted by Mr. Koch and manufacturing is limited to just 20 units a year. Its fascia in champagne gold finish, reminiscent of a few other Japanese brands, was used again in the K-10 preamplifier that was created in 2011, at the explicit request of Robert Koda distributors. Music lovers simply wanted to have a complete audio system. The preamplifier proved to be a solid state design, just like the third product in the company's history, the Takumi K-15 preamplifier under review today, announced as Robert Koda flagship product. The unit is beautiful. Its champagne gold finish of the fascia is further emphasized by golden details including the logo, looking very similar to the logo of Eric S. Design from Poland, the rings around control knobs and the large nameplate on the rear panel, with the unit's serial number and other information. I am sure that you can also order a nameplate with your own name.

Although from the outside the new preamplifier looks similar to the K-10, its design is more sophisticated. The manufacturer claims dynamic range of 148dB, which—if confirmed—would be an amazing achievement. It beats even the top Soulution designs by a few dB. The K-15 sports five line inputs, each one both single ended, on beautiful Furutech RCA connectors, and balanced on XLRs. Volume control is handled by a 32-step L-pad attenuator, with only two resistors in the signal path at any given step. The heart of the unit is the proprietary ITC MKII circuit, Robert Koch's original invention. The power transformer and mains switch are housed in a Mu-metal shield. A characteristic detail is the power indicator light hidden behind a large ruby. The preamplifier has no remote control.

A few simple words with…

ROBERT KOCH, Robert Koda's owner, designer

Wojciech Pacuła: Why didn't you use tubes in the K-15?

Robert Koch: Well, I am very fond of tubes but with the K-10 we managed to develop a preamplifier that could outperform tubes yet not leave a solid-state flavor. The K-15 is very much built from the basics we learned while developing K-10. I shall reserve my use of tubes for applications where they are most suited.

What is ITC MKII and how does it differ from the older one?

ITC is a simple and elegant, unique circuit I developed specifically for preamplifier use. It is an arrangement of semi-conductors that specifically addresses distortion issues that do not show up in conventional testing procedure but may be of much greater (sonic) importance than measurements like THD and the like.

ITC MKII is simply an improvement on the original. Mark II includes an extra stage of buffering, has a lower distortion and an even higher dynamic range. These improvements come from both better parts and the use of schematic refinements. It took quite some effort for us to see beyond the original ITC but we were able to make a significant leap.

Who makes this gorgeous attenuator for you?

It is built for us in Tokyo by a famous audio company. We were very lucky to have them do it for us but we do work with them quite a bit in terms of supply of highly specialized parts.

What is your current home audio system?

Well we recently moved and built a music room out of two existing rooms. Only problem is we are having quite a bit of water coming in during the strong typhoons that we have here. We are trying to solve that problem and once solved I can complete the room.

In terms of electronics, well, I use K-15, K-70, my own custom DAC/Master clock and Kondo cables mostly. I bought a pair of Vivid Audio G2s the other day and they have a nice transparency.

Sound

Albums auditioned during this review

• Music For A While. Improvisations on Purcell, Christina Pluhar, L'Arpeggiata, Erato 4636203, CD + DVD (2014).

• Show Band, Punkt styku, GAD Records GAD CD 013, CD (2014).

• Jim Hall, Concierto, CTI/Mobile Fidelity UDSACD 2012 SACD/CD (1975/2003).

• Karl Bartos, Off The Record, Bureau CD 974282 BB079, CD (2013).

• Martyna Jakubowicz, Burzliwy błękit Joanny, Universal Music Polska 376 131 8, CD (2013); reviewed HERE.

• Miles Davis, The Complete Birth of the Cool, Capitol Jazz/EMI 4945502, CD ([1957] 1998).

• Miles Davis, The Original Mono Recordings, Columbia Records/Sony Music Japan SICP 30521-9, Blu Spec CD2 x 9 (1957-1964/2013)

• Porcupine Tree, Deadwing, Lava 93437, CD (2005).

• Portishead, Dummy, Go! Disc Limited/Universal Music Company [Japan], UICY-20164, SHM-CD (1994/2011).

• Sohn, Tremors, 4AD/Hostess CAD3403CDJ, CD (2014).

• The Modern Jazz Quartet, Pyramid, Atlantic Records/Warner Music Japan WPCR-25125, "Atlantic 60th", CD (1960/2006).

• Wes Montgomery & Wynton Kelly Trio, Smokin' At The Half Note, Verve 2103476, "Verve Master Edition", CD (1965/2005).

It's hard to believe it's been already almost two years since we published the High Fidelity issue entirely dedicated to preamplifiers. The August 2012 issue No. 99 was intended as a look through the audio market for the most interesting, most promising preamps in the high-end category (see the ARCHIVE and scroll down for the August issue). I had no chance to reach all designs, not even a representative part of the market. This did not matter, however, because I meant it to be a representative sample of what can be achieved in this area. I would later add to the list more designs that struck me as worthy of interest, such as Jeff Rowland Aeris or, recently, Dan D'Agostino Momentum Preamplifier. Combined with the previously reviewed Ayon Audio Spheris II and Convergent Audio Technology SL1 Legend, it gives us a pretty solid overview of the top line preamplifiers.

However, regardless of how many products I quote and what kind of prices I throw at you, first we need to ask ourselves a fundamental question: is the preamp at all needed? Since each time I try to present another interesting version of the same answer and I am slowly running out of ideas, this time I will say briefly: YES, in 99.99% of cases. The remaining 0.01% covers the cases where the audio system is designed, built and adjusted for a direct coupling of source and power amplifier. Like the flagship system from Ancient Audio, for example. Except that in this particular case the preamp is absent "on the outside", as volume control is the fundamental, and sometimes sole, function of the preamplifier.

The preamplifier is therefore essential from a technical point of view, even if just for volume control. In my opinion, it is preferable as an active audio component. It brings to the system dynamics, fullness and bass which passive systems are usually lacking, and a sort of "density". If anyone should still think that the top components are all equally great and, hence, sound similar to each other (as there is only one natural sound), they need to think again. My point is that audio products are designed and made by concrete people, and are a manifestation of their views on how the home audio should look like. There is no agreement on that, and even though we share a broad consensus as to what does and what does not constitute a good sound, there remains a wide margin of discretion.

It therefore comes as no surprise that Robert Koch has his own idea of the sound of audio system. Knowing his story, it is not difficult to guess that one of his sources of inspiration was the sound of components from Kondo. Rich, warm, thick, putting emotion before calculation. How he managed to do it using solid state technology seems absolutely unique to me, and hence very interesting.

The reviews of the K-70 power amplifier that I have read share a common conclusion that runs as follows: a hybrid amplifier with solid state output stage that sounds like a pure-bred tube amp. The same relates to the K-15, provided that "tube amp sound" denotes something other than warm, plump, rounded. It is true that top audio products show a similar sonic character, maintaining the signature features of their individual designers, and it makes less difference which components or what kind of design ideas are used. Indeed, certain characteristics of tube technology are still not repeatable in solid state designs, but the same can be said the other way round. They have, however, no bearing on the product rating but only on its description, as a whole "package" that we either "buy" or not.

The "tube character" of the preamplifier under review today, for example, manifested itself as the absence of any sharpness. The sound was silky smooth. And as colorful as silk Japanese kimonos. The machine did a sort of "remastering" of poorly produced albums. Maybe even not quite poorly but simply those exhibiting some problems. The new album from Martyna Jakubowicz shows a fair amount of compression, intelligent but manifested as bringing vocals and guitars forward, with a simultaneous dulling of their "head" and veiling of their texture. It may also happen that sibilants get somewhat "separated" from vocals. They are not overly bright or sharp, but simply not always are part of vocal emission. The K-15 put it all together into one sensible whole. I was listening to this album for a long time because it was an interesting experience. One moment there was something "not quite right" and the next moment it was gone. The effect of this treatment was very clear. Much less was the fact that it was a "treatment" superimposed on the sonic texture. It was something "underneath" the surface, some kind of mechanics hidden beneath the music layer, which operated without leaving any fingerprints. Of course, the fingerprint manifested as the change of sound, but the print itself was not visible.

For some time, I suspected that the machine was simply rounding over attacks and withdrawing treble. But it was not so; the highs were better built than on my Polaris III and only the Dan D'Agostino preamplifier had showed something similar. As a result, I had a presentation that was fuller and closer to reality, in terms of the amount of information. When Alan Grant announces the band accompanying Wes Montgomery on the full version of his album Smoking'…, tape and microphone noise is audible. It is not particularly disturbing and does not sound like a hiss; it is simply there and we know that it is an inherent part of the recording. It is all good. But the moment the whole band starts to play, the K-15 showed a rise in noise level, as if the instrument microphones had been earlier turned down or the intro had undergone additional processing during the remastering. Normally, the noise is masked by louder sounds. During a live performance, we know that it is there but—just like on vinyl—we do not interpret it as distortion as much as part of the "whole package," alongside the music. The same was true here—the low frequency noise did not disappear, as it does with almost all other preamps I know, but simply was quieter.

It does not mean, of course, that I was listening to noise. All I am saying is that it is simply part of the recording, which allows to figure out many things and which shapes the sound at the same time. The K-15 did not emphasize this aspect; I would even say that it was blended into the presentation in an extremely refined way. It made sense and was significant because Mr. Koch's preamplifier is exceptionally resolving. I would mostly call it smooth, thick and full, and right after that resolving. It was capable of showing things in the recording which I rarely ever hear, even on magnetostatic headphones, like delicate bass harmonics in the starting passage of Złe sny ("Bad dreams") from the new Martyna Jakubowicz's album (with Marcin Pospieszalski on bass), or the change of timbre of the low bass on the opening track Tempest from Sohn's album Tremoros. These were subtle changes but they made the sound even more alive and gave it deeper musical meaning, making it simply more interesting.

The Octave Jubilee preamplifier is very similar sonically, except that in its case it actually results from a slight warming of the sound. It shows slightly better three-dimensionality and depth, but at the expense of clarity. In turn, the Convergent Audio Technology SL1 Legend sounded warmer than either of these two units, presenting a true tube sound in the full sense of the word. Its density and fleshiness were simply phenomenal. Very close to the American Legend would be another American preamp, the Aeris from Jeff Rowland. However, the resolution and differentiation of both the Jubilee and K-15 are on a completely different level.

The closest sonic match to the component that is the result of Mr. Koch's love for music were two different design preamplifiers, the solid-state Momentum Preamplifier from Dan D'Agostino and my Ayon Audio Spheris II (I'm still waiting for the version III). They both sound lower and meatier than the K-15. Their soundstage presentation is different, too. The flagship Robert Koda's sound is somewhat recessed behind the speakers, slightly more distant, closer to the live presentation. In turn, the Ayon and Dan sound meaty, showing the foreground closer up and more palpable than what one hears in the concert hall.

Which one is true and which is not? Here we get to the heart of the preamplifier dispute. It all depends on what we define as "true." If the live sound is the "absolute sound", then Robert Koch is right and other preamps of this type, like the Accuphase C-3800 (I apologize for forgetting about it earlier on). On the other hand, if what is true is the sound on the physical medium, recorded in the studio or live in concert, the other preamplifiers take the prize. I dare not publically declare myself in favor of either "truth". If we were sitting over a beer and having fun, and someone asked my personal opinion, I would say that I don't care about truth and that I choose what I like better, which is the sound of the Momentum, Legend and Spheris. That is, however, only my personal opinion and I do not want it to be binding. For I cannot help thinking that it is Mr. Koch who might be right. Maybe one needs to put together a matching system and stick to this particular presentation. Since all recordings are presented in this manner, it is not an aberration but rather a conscious and consistent pursuit of top quality sound.

But perhaps this is an unnecessary, purely academic discussion, because the K-15 is such an outstanding piece of equipment that even with its different vision of home audio reproduction I cannot but admit that I have yet to hear a better implemented vision of sound.

Conclusion

As I said, each of the top preamplifiers sounds different and brings in a different package of features. There is no component that does everything on an equally good level at the same time, or even one that simply sounds "neutral." That can only be guaranteed by a live sound. Therefore, one needs to pick and choose, like in a buffet. Luckily, the shelves are full.

The K-15 sounds very soft. It is a good kind of softness. It does not seem rounded on transient attacks or recessed in the upper midrange. I would rather say that its outstanding resolution allows it to steer clear of the problems of most other products that contour the sound to achieve better clarity, selectivity and dynamics, at the same losing its natural "velvet". Resolution and differentiation are exceptional; I have only heard something similar from the Ancient Audio Lektor Grand SE CD player and Vivaldi dCS system coupled directly to the power amplifier. The Takumi K-15 is warm but extremely disciplined. At the same time, it shows soundstage layers at a distance from the listener, which is a break from what other companies have made us used to, that is if the sound is warm and velvety it is also close, at hand's reach. Such a unique combination of different features gives the Japanese preamplifier a distinct personality and makes it easy to find out if that is what we are looking for. Its design is flawless, watched over by Mr. Koch's spirit. The sound is similar; it is absolute top high-end that maintains its own sonic characteristics, distinguishing it from other flagship components of this type.

Design

The Takumi K-15 is a balanced line preamplifier, without a remote control. Gain is 8dB (V). Its dimensions are slightly different from the traditional "full-size" audio components because it is narrower and taller, which makes it look a bit like a sumo wrestler. The enclosure is made of anodized aluminum panels, finished in champagne gold. The bolts that hold the panels together are gold plated, just like several other details, including the logo on the front panel, the rings around the volume and input selector knobs, and the large nameplate on the rear panel. A very characteristic detail is the large ruby with the power indicator light underneath. The unit is powered on with a little knob like those used in Kondo components.

The rear panel is just as beautiful as the front. You can see rows of great rhodium plated RCA connectors from Furutech, a newer version of those used in my Lektor AIR V-edition CD player. There are five pairs of inputs and two pairs of outputs, each additionally on balanced XLRs manufactured by Neutrik in Liechtenstein. Their pins are gold plated. Adjacent to them is a small toggle switch to select either balanced or single ended. Below you will find a ground lift switch to disconnect the ground from the chassis.

There is also a large, rhodium plated ground terminal (from Furutech). The IEC power socket is more of a classic affair, this time not from Furutech. However, the preamplifier comes equipped with a quality Furutech power cord, model FI-E11 (G).

The enclosure turns out to consist of two layers, an outer aluminum body and inside shell of lacquered thick copper plates. It is the latter that add to the considerable weight of the K-15. The interior looks phenomenal and reminds of tube designs. On the right side is the largest attenuator I have ever seen, with four separate rotary switches and multiple ultra-precision resistors designed solely for audio. It looks to be hand assembled to order and sports lots of copper and gold. The whole assembly is housed in a transparent acrylic box. Sensitive components, including the ITC gain stage, are shielded by "double encapsulation" – a copper shell and a Mu-metal capsule within. I was unable to remove the mu-metal cover. A long shaft couples the front panel knob to rotary input selector switch at the rear panel. An R-core power transformer and power switch are housed in a large sealed Mu-metal enclosure. Adjacent to it is the power supply board, with large Elna capacitors and voltage regulators. An incredible device!

Technical Specification (according to the manufacturer)

S/N Ratio: 114dB A weighted at 1V

Dynamic Range: > 148dB (A)

Gain: +8dB

Input Impedance (RCA/XLR): 50k ohm/100k ohm

Output Impedance (RCA/XLR): 30ohm/60ohm

THD: < 0.00003% at 2V

Price: 180,000 PLN

Robert Koda
392-1 Ookawa Higashi-Izu-machi
Kamo-Gun Shizuoka-Ken | 413-0301 Japan
tel.: +81 (0)557-23-2882
sales@robert-koda.com
robert-koda.com

MADE IN JAPAN[/i]


http://robert-koda.com/file/rk/bro_k15.pdf


Robert Koda • Takumi K-10 Preamplifier

Poised, natural, tube-like sound from "an extraordinary new solid-state preamp."

by Marc Mickelson | May 25, 2012

f you ever have the chance to review these, I would love to hear your impressions. I'm told they are amazing!" This is the entire text of an e-mail I received from Kevin Tellekamp, the head of Silent Running Audio, more than two years ago. He pointed me to the website for a brand of electronics I'd never heard of: Robert Koda. Kevin was referring to a peculiar pair of mono amplifiers, the Takumi K-70s. The amps' unusual physical layout -- two amps that share a power supply, for a total of three chassis -- was the first sign of a highly original design. The K-70s are actually referred to as a single amplifier, one that operates single ended but offers an un-single-ended-like 70Wpc in "class A1." The K-70 is a hybrid, using solid-state output devices along with a pair of 5842 triode tubes at each input.

Price: $31,000.
Warranty: Two years parts and labor.

Robert Koda
1-9-4 Azusawa Itabashi Ku Tokyo 174-0051 Japan
http://www.robert-koda.com

In a follow-up message, Kevin revealed that he had made a few sets of his Ohio Class XL+ isolation bases for the Robert Koda amps -- make that, amp -- and this was what brought the K-70 to his attention. Curious, I wrote the company and received a quick reply from Robert Koch, who does all of the design work in addition to running the entire enterprise. After a bit of e-chit-chat, we discussed a review of the K-70, the only Robert Koda product at that point in time. Koch told me that he was working on a preamp and that he would be more apt to offer it for review, as it would be brand new and in need of some exposure.

So here we are two years later and the subject of this review is that preamp -- the Takumi K-10. After researching the K-70, I would have wagered that the K-10 would have tubes lurking somewhere within its single, hefty chassis. It only stood to reason, given that the K-70 was a hybrid, and, frankly, the preamp's $31,000 price is a neighborhood where tubes are pretty much de rigueur in audio electronics. But the K-10 turns de rigueur on its head -- it's solid state from input to output, though with a few interesting wrinkles that are in keeping with a maxim that strongly informs both Robert Koda products: eschewing conventional thinking in favor of the best circuit for the purpose.

"Best," in Robert Koch's words, means "dynamic simplicity" and "total freedom from power-supply sound." Koch has been working in the audio industry for many years, his entry being like that of so many manufacturers: following his father into the ever-deepening waters of audiophilia, a preoccupation from his childhood in South Africa onward. Beginning in his teens, Koch worked in audio retail, mixing this with formal study of electronic engineering with an emphasis on addressing the big issues: "I spent most of my time studying AES journals and the like and concentrated on equating subjective performance with measurable electrical performance."

"Then I went over to the UK, worked for Audio Note UK a bit -- I wanted to find out more about the other side of products (i.e., production) as it had been my childhood dream to have my own high-end audio brand." Infected with the sound of low-power single-ended amplifiers, Koch gutted a pair of van den Hul amps he owned and used the chassis to house his electronics. "There were several more moves between South Africa and Japan. Several comings and goings from Audio Note Japan, where I helped engineer the M1000, the M1000 Mk II and various other items before I finally said goodbye to them and started Robert Koda," which launched in 2008.

An intriguing question for me, given Koch's globe-trekking, is whether his design philosophy grew out of his vast and varied experience in the audio industry, or if that experience was directed by his maturing design philosophy. In other words, was nature or nurture responsible for the making of this audio engineer and his products? Koch provided some insight during e-discussion: "I had realized at a very early stage that circuits with great specifications would more often than not not yield high-fidelity music reproduction." Nature it is, but with a twist, one that doesn't elevate "great specifications," such as they are understood today, above "music reproduction." In other words, Koch listens as much to music as he does his own ideas about designing audio electronics, what my experience tells me is the highest of approaches and the one most likely to succeed.

Which brings us back to "dynamic simplicity" and "total freedom from power-supply sound." For Koch, these tenets don't simply coexist in his amp and preamp, they enable each other. The former is the product of some well-known design ideals, including eschewing feedback and ensuring low output impedance, but the larger notion, as Koch expressed, is removing "uncontrollable variables." These include the local bypass capacitor in the power supplies of his amp and preamp, which, according to Koch, has a tremendous effect on the sound. To overcome this, the K-10 "runs two loops through the power supply, each modulation being of the same intensity but mirror-imaged. The result is that there is almost no audio signal flowing through the power supply and related regulators, bypass capacitors, etc. due to a near-perfect cancellation effect." Koch also uses a very good bypass capacitor "in any event" along with a Japanese-made R-core transformer and four chokes.

While most designers who cite the power supply as a particular concern house it in a second chassis, Koch discovered through trial and error that this led to no sonic gains. But the implementation of the K-10's power supply inside the chassis is anything but usual, housed as it is within 2mm of soft iron plate. "We tie the problem up at every end and then tie it up again," Koch says.

The K-10's fully balanced audio circuit is the product of a clean-sheet design process focusing on new circuit concepts. Koch's ITC (Inverted Transconductance Coupler) solid-state circuit uses all of ten transistors and no integrated circuits. There are no relays and minimal circuit boards, which are connected with silver wire. There is also no remote control, which, given the K-10's volume control and input selector, would have required motors, logic circuits, and extra power supplies. The K-10's volume attenuator uses resistors created for sound reproduction and its source selector is a rotary switch built specifically for audio use.

Functionally, the K-10 is as bare bones as a preamp can be. Only the volume control, input selector, on/off indicator and a bit of explanatory script adorn the faceplate. There's no balance control, so if you adjust channel balance often (I don't), you'll want to look elsewhere. There are four inputs: three single ended and one balanced. Outputs are both single ended and balanced, their use determined by a rear-panel switch. The other rear-panel feature is a grounding post, which Koch includes because "ground noise can be very destructive to sound quality." Perhaps to prove his commitment, all K-10's available now have two grounding posts on the back panel: one each for chassis earth and signal earth, a configuration that gives more flexibility than the single post. The K-10's chassis is as deep -- 15" -- as it is wide, and it weighs a lot -- nearly 60 pounds. The weight is centered within the chassis, giving the K-10 a cannonball-like feel when you pick it up.

Although the K-10 is all solid state, Robert Koch doesn't recommend keeping it on at all times. I suspect this is due to heat, which is minor on the exterior but possibly major within the tight quarters of the fully sealed chassis. Twenty minutes of warm-up are recommended, and I would consider that a minimum, as the K-10 sounded even better -- more liquid and dynamic -- after 45 minutes. I was never anal about the on/off status of the K-10. I left it on a few times over the course of a couple of days, and there were no issues, even here in toasty Arizona.

was able to use the K-10 with a lineup of amplifiers that embodies the phrase "a wealth of riches": Lamm M1.2 Reference and ML2.2, Atma-Sphere MA-2 Mk 3.1 and Audio Research Reference 250, all monoblocks. I used all but one of them extensively. Because the K-10 has extremely low voltage gain -- a mere 6dB -- it didn't work well with the Lamm ML2.2s, which also have rather low gain, creating a situation with some phono stages where there wasn't enough gain for analog playback to sound anything but dynamically limp. The Lamm M1.2s, on the other hand, have very high gain, with the MA-2 Mk 3.1s and Reference 250s occupying the middle ground. All were very good matches with the K-10 in this respect -- and in sonic terms as well. While I often discover that a certain amp simply sounds best with a preamp I'm reviewing, that wasn't the case here, as all three combined for stellar outcomes, with some sonic differences of course. This went hand in hand with my initial feelings about the K-10 -- that its performance made the act of reviewing it a challenge. While it sounded tight and polite right out of its box, it broke in quickly, and in short order I was listening for hours on end without thinking -- or remembering -- that I was supposed to be dissecting what I heard.

The K-10's performance was immediately explained by what it didn't achieve -- that well-worn audiophile concept, hi-fi sound. Hi-fi sound can be initially impressive, hitting the marks for resolution, dynamics, speed and spaciousness, but never resembling anything more than competent reproduction. While I agree with Brother Roy Gregory that audio systems, no matter how exceptional, fall far short of reality, they can nonetheless display many of the earmarks of live music, and this is why they are compelling to us. In the terms of another well-worn audiophile concept, they suspend disbelief, even if we know that's all they are doing, and they achieve this through a preponderance of those live-music earmarks.

The K-10's sound was abundant with qualities that suspend disbelief, all presented in a manner that never called into question their hi-fi credentials. The K-10 was about poise more than fireworks, even as its finely drawn treble extended to nothingness and its fleet, well-defined bass plumbed whatever depths were on each recording. Its sound had weight, both in the traditional sense of producing substantial images and in terms of the musical consequences and meaning conveyed. It made me lean into the music, becoming engrossed in it and forgetting the equipment that put me there. If there's a higher audio ideal, I'm not aware of it.

The K-10 displayed a skillful balance in perspective and especially tone. It was neither forward nor recessed, and it cannily combined the inherent linearity of solid state with a touch of golden glow, giving the mids and treble an endearing approachability. There was none of the arid leanness that can often color solid-state sound (though some audio reviewers inexplicably call this "neutrality"), none of the exaggerated speed that gives transients an artificial snap that obscures decay. From this you might be thinking, just as I was, that the K-10 sounds as though there are tubes within it. Like a great tube preamp, the K-10 managed to sound beautiful and honest at the same time, though never cloying or ruthless. It resolved with grace, disappearing into the music it made better than any preamp I've heard.

Along with this, its sheer resolving power was evident but subordinate to its holistic approach to music-making. It was particularly useful at revealing the differences among source components. The reality of being a busy audio reviewer is that you are often listening to more than one product at a time -- not added to your system simultaneously, of course, but one after another, in order to determine what one can bring out in the other. Such was the case with the K-10 and, coincidentally, the K-01, a characteristically stalwart CD/SACD player that is Esoteric's top single-box source at this point in time. I have a great deal of experience with Esoteric digital gear, but that didn't prepare me for the K-01, which abounds with features that affect its sonic performance. The K-01's musical power -- a term I'll explain in my forthcoming review -- was never subordinate to the K-10's naturalness, and the sophisticated sound of the best SACDs extant, the Japanese SHM SACDs, was laid bare. In fact, that the K-10 possessed much of what makes those SHM SACDs special: a relaxed yet highly detailed view of the music, silky treble, adept communication of space, an inherent honesty, an elegant musical flow.

A sense of evenness permeated the K-10's sound from one frequency extreme to the other, the bass displaying the same delineation as the mids and treble. "Supreme coherence" my listening notes called it in the thrill of the moment of discovery. It was a trait that meshed especially well with analog. I had to send my Dynavector XV-1s back to Japan for a check-up, which led to my buying a Denon DV-103R to use as a backup. An Audio-Technica AT33EV had occupied that role, because it impressed me when it was mounted on the VPI Classic I reviewed over two years ago. More recently, mounted on my Tri-Planar tonearm and TW-Acustic Raven AC turntable, it sounded so mushy and blurred that I decided to give the Denon a go. Even before the '103R was completely optimized, it laid waste to the AT33EV, sounding faster and more open, yet harmonically rich and tonally sweet. While it didn't possess the airiness and sheer resolving power of my Dynavector, nor its bass definition and power, the '103R had no glaring flaws. There is an inherent effortlessness to analog that the K-10 also possesses, a free-flowing naturalness that, again, urged forgetting about the hardware.

How much you value the K-10 will depend on how much you value this sense of oblivion -- and the qualities responsible for it. I can imagine that some listeners will prefer a more forward, hard-charging sound, finding the K-10 to be too mannered. Those who fixate on the bass region may find the K-10's more integrated portrayal lacking in one way or another. Those who need a balance control, preferably on the unit's remote, will definitely want to look elsewhere. However, amidst the very best preamps I've heard, the K-10 fits right in, offering a little more of this in trade for a bit less of that (as they all do). It stands equal with units that are its price and performance peers -- and use tubes.

The limited-edition Audio Research Reference Anniversary ($25,000) inhabits the high ground in terms of sonic performance, its stature actually growing somewhat now that it's no longer available. Putting aside the obvious differences like its two-chassis configuration, vacuum-fluorescent display and remote control, wherever the Reference Anniversary excels sonically, the K-10 is not far behind. Contemporary Audio Research electronics -- amps as well as preamps -- always portray space with a side-to-side, front-to-back enormity that's both immediately impressive and addictive over the long term. Some will argue, I'm sure, that this is where tubes exert their greatest influence. While the K-10 doesn't sound as immediately big, the sense of space it conveys is still vast and, moreover, appropriate to the recording, even if it doesn't achieve quite the panoramic spread that the Reference Anniversary does. Likewise with the bass, which is a bona fide strength of the Reference Anniversary (and unusual for a tube preamp). The K-10 has nimble, well-defined lows that don't equal the sock of the Reference Anniversary's bass but never lack for weight and power.

Where the solid-state K-10 surprises -- to the point of stupefying -- is in the mids and treble, which are the domain of tubes. Its treble extension and refinement along with its midrange texture and dimensionality impart fine detail that, depending on the recording, equals or surpasses the Reference Anniversary, making for a presentation that's more sophisticated at the micro end of the dynamic scale, where low-level harmonics complete the musical picture. Small gestures -- breath through a woodwind, the pull of a finger on a string -- are more naturally rendered and intelligible. The K-10's resolution seems to come from a deeper place, where space is subordinate to the performers that occupy it.

Audio Research electronics also display very adept macrodynamic capabilities, scaling from soft to very loud dexterously and realistically. Perhaps because the K-10 doesn't sound as overtly big as the Reference Anniversary, it also doesn't put its dynamic foot forward first. It is as proficient at both ends of the dynamic scale, however, and ramps up and down gracefully -- as it does everything else.

Whether you would choose the Reference Anniversary over the K-10, or vice versa, may well come down more to the difference in features than sound. There is also the fact that the Reference Anniversary is discontinued, so buying secondhand is a requirement. Before the K-10 arrived, and knowing that it had no tubes, I wouldn't have expected that it would go toe-to-toe with the Audio Research preamp, but so it did.

he design of so much audio equipment, especially those products that occupy the uppermost strata in terms of price and performance, begins with an assumption about what technology will be used. This is natural, as designers come at their task with different belief systems in place, each dictating an approach before even the first part is chosen. This fact, along with his use of tubes in his K-70 amp, makes Robert Koch's design work for the K-10 preamp all the more curious. If anything, audio designers will use tubes in preamps and solid-state devices in amps, in order to make use of conventional advantages of each. Koch's approach was 180 degrees out of phase to "conventional"; his analysis of the product's purpose, from which the K-10's circuit grew, had making music at the very top.

It's hard to disagree with the outcome. Koch's K-10 bridges many audio chasms: between detail and coherence, vividness and ease, truth and beauty, solid state and tubes. This final one is not a matter of the K-10's parts, of course, but rather its performance, and that makes it all the more surprising. Tube electronics more often attain certain characteristics of solid state than the other way around, and when a solid-state preamp blurs its origins in a price range dominated by tubed competition, that's not just unusual but consequential.

Kevin Tellekamp wrote me about an intriguing hybrid amp, but it led to discovery of an extraordinary new solid-state preamp. My impression of the K-10? I loved it.

Wenn ich bei der Suche nach einer Komponente einen offensichtlichen Kompromiss einzugehen habe, beschaeftige ich mich erst einmal mit dem maximal moeglichen, damit ich verstehe, was ueberhaupt moeglich ist.

Dann ueberlege ich mir, in welchen Bereichen ich einen Kompromiss einzugehen in der Lage bin, bzw was in meiner Kette als Kompromiss moeglich ist.

Bei dieser Herangehensweise laufe ich auch nicht in den Irrtum, dass mit einem Funk Vorverstaerker das maximal moegliche erreicht ist..., der Funk ist schlicht und ergreifend ein Kompromiss in eine bestimmte Richtung. Dieser kann, muss aber nicht zu dem eigenen Anforderungsprofil passen.

Und ich glaube Andi hat bereits klar gemacht, dass der von Funk gewaehlte Kompromiss nicht derjenige ist, den er fuer seine Kette sucht.

Deshalb mal der Hinweis auf die Koda Geraete...

Gruss
Juergen
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Bernd Peter
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Beitrag von Bernd Peter »

Hallo Thomas,
music is my escape schrieb
der dann aber (Überraschung!) zumeist kein Röhrenklang mehr sondern eine wunderbar entspannt-transparente Neutralität
aktuelle Röhrendesigns, die ich in letzter Zeit hören durfte, haben dieses qualitative Hauptmerkmal:

Klangfarben Klangfarben Klangfarben

Gruß

Bernd Peter
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music is my escape
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Beitrag von music is my escape »

Hallo Jürgen,

da hast Du ja ganz schön viel zum Überscrollen hier einkopiert....
shakti hat geschrieben:
Bei dieser Herangehensweise laufe ich auch nicht in den Irrtum, dass mit einem Funk Vorverstaerker das maximal moegliche erreicht ist..., der Funk ist schlicht und ergreifend ein Kompromiss in eine bestimmte Richtung. Dieser kann, muss aber nicht zu dem eigenen Anforderungsprofil passen.

Und ich glaube Andi hat bereits klar gemacht, dass der von Funk gewaehlte Kompromiss nicht derjenige ist, den er fuer seine Kette sucht.
Meiner Wahrnehmung nach ist allein der öffentlich vom TE Andi hier im Forum dokumentierte Weg (zu was auch immer) geradezu gezeichnet von Inkonsequenz, Wirrungen und Irrtümern, so dass es auf einen Test mit dem Funk nun wirklich nicht mehr ankäme... :wink:

Wenn Du aber schon vorher weißt, was dabei herauskommt: dann auch gut.

Viel Freude Euch weiterhin beim Komponententausch!

Thomas

:cheers:
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music is my escape
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Beitrag von music is my escape »

Bernd Peter hat geschrieben:Hallo Thomas,
music is my escape schrieb
der dann aber (Überraschung!) zumeist kein Röhrenklang mehr sondern eine wunderbar entspannt-transparente Neutralität
aktuelle Röhrendesigns, die ich in letzter Zeit hören durfte, haben dieses qualitative Hauptmerkmal:

Klangfarben Klangfarben Klangfarben

Gruß

Bernd Peter
Hallo Bernd Peter,

das klingt bestimmt nicht schlecht... :D

Grüße,
Thomas
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Bernd Peter
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Beitrag von Bernd Peter »

Hallo Thomas,

klingt wie es aussieht. :wink:

Macht gute Laune und manchen Forenten hier zum Parsifal.

Gruß

Bernd Peter
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Hans-Martin
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Beitrag von Hans-Martin »

Salvador hat geschrieben:IViele Vorstufen haben aber leider recht hohe Ausgangsimpedanzen, bei der Audio Research Reference 5 SE sind es gar 600 Ohm per XLR, bei der MFE Tube One SE sind es 127 Ohm.
Welche klanglichen Konsequenzen hat es denn, solch hohe Ausgangsimpedanzen mit einer recht niedrigen Eingangsimpedanz von 10 kOhm zu verbandeln.
Hallo Andi
ob die AGM sich von den 10k auf einen höheren Abschlusswiderstand umstellen lassen, könnte vom Hersteller leicht geklärt werden, ich denke: ja.
Ich habe zur Zeit meiner Röhrenbastelei festgestellt, dass mindestens der 10-fache, besser 100-fache Abschlusswiderstand gegenüber der Quelle vorhanden sein sollte, damit der Bass locker bleibt und nicht weggequetscht wird.
Der Musical Fidelity X10D hat vor 20 Jahren vorgemacht, wie man aus einer Röhre auf eine niedrige Ausgangsimpedanz kommt, messtechnisch war fast kein Unterschied ob 100k oder nur 1kOhm Last. Wie es gehörmäßig klingt, ist ein anderes Thema.
http://www.stereophile.com/content/musi ... rpyo6Vg.97
Durch eine Überallesgegenkopplung gibt es einen Ausgangswiderstand nahe 20 Ohm, einen Wert, den ich sonst kaum für möglich gehalten hätte, wenn nicht die Messung es aufzeigen würde.
Bei 2V vom DAC müsste bei 20 Ohm der Ausgang 100mA hergeben, das ist jenseits dessen, was die Röhre kann. Aber 1k wollen nur 2mA, da liegen wir im unteren Bereich der ECC88. Der Anodenwiderstand der Ausgangsröhre beträgt 10k, umso mehr überraschen die Messungen, und man muss sich von pauschal angewandter Theorie frei machen. Gegenkopplung macht was.
Es werden 2 Röhren in Anodenschaltung betrieben, somit die Polarität nicht gewendet (anders als beim Funk, der das unerklärterweise tut).
Grüße Hans-Martin
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Salvador
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Beitrag von Salvador »

music is my escape hat geschrieben:
Meiner Wahrnehmung nach ist allein der öffentlich vom TE Andi hier im Forum dokumentierte Weg (zu was auch immer) geradezu gezeichnet von Inkonsequenz, Wirrungen und Irrtümern, so dass es auf einen Test mit dem Funk nun wirklich nicht mehr ankäme... :wink:
Lustig,
wie manche Leute ein systematisches, empirisches, fleissiges und konsequentes Vorgehen bewerten. Oder doch zum Kopfschütteln.

Den Funk kenne ich und weiss wie er nicht klingt, nämlich so, wie ich mir das vorstelle. Daher muss ich ihn auch gar nicht mehr testen. Ich habe ihn mir in meiner Inkonsequenz bereits angehört und eine Meinung dazu gebildet. Oder irre ich mich? Bin von den ganzen Irrtümern, die meine Anlage in den letzten Jahren immer weiter verbessert haben, schon ganz wirr im Kopf. :P

Andi
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nemu
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Beitrag von nemu »

Hallo Leute,

jetzt streitet doch bitte nicht. Es gibt halt unterschiedliche Meinungen, Ansichten und Hörpräferenzen.
Ich selbst habe sowohl schon sehr gute und stimmige Röhren-Vorverstärker, wie auch Transistor-Vorstufen in unterschiedlichen Anlagen und Hörumgebungen gehört.

Ich finde es auf jeden Fall toll, dass sich so viele hier im Thread beteiligen und über Ihre Erfahrungen mit Vorstufen berichten. Ich hoffe dies geht so noch eine Zeit weiter.

Selbst höre ich derzeit mit einem Funk Monitor MTX an meinen Geithain 901, was mir persönlich klanglich gut gefällt. Die Funk gibt halt das genau wieder, was man alles Quelle hineinschickt. Aber ich könnte mir auch Vorstellen mit einer guten Röhre zu hören, die hier ein bißchen Soundtuning in den Höhen macht, solange es im Rahmen bleibt. Ist aber auch abhängig von der Musik!

Wie sagt man so schön im Rheinland: "Jeder Jeck ist anders!"

In dem Sinne wünsche ich allen Forenten ein schönes Wochenende.

Gruß Stephan
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Hans-Martin
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Beitrag von Hans-Martin »

nemu hat geschrieben:Selbst höre ich derzeit mit einem Funk Monitor MTX an meinen Geithain 901, was mir persönlich klanglich gut gefällt. Die Funk gibt halt das genau wieder, was man alles Quelle hineinschickt.
Stephan,
von der LAP-2.V3 wissen wir, dass genau dieses nicht geschieht, wie der Hersteller auf Anfrage bestätigte:
Betreff: Vorverstärker Funk LAP-2.V3
Ist das bei bei Monitor MTX korrigiert?
Grüße Hans-Martin
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nemu
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Beitrag von nemu »

Hallo Hans-Martin,
Hans-Martin hat geschrieben:
nemu hat geschrieben:Selbst höre ich derzeit mit einem Funk Monitor MTX an meinen Geithain 901, was mir persönlich klanglich gut gefällt. Die Funk gibt halt das genau wieder, was man alles Quelle hineinschickt.
Stephan,
von der LAP-2.V3 wissen wir, dass genau dieses nicht geschieht, wie der Hersteller auf Anfrage bestätigte:
Betreff: Vorverstärker Funk LAP-2.V3
Ist das bei bei Monitor MTX korrigiert?
Grüße Hans-Martin

Das kann ich nicht sagen, da musst Du mal bei Herrn Funk nachfragen. Ich habe auch schon öfters Quellen direkt an die Aktiven angeschlossen. Jedenfalls ist mir dies beim Hören nie aufgefallen. Und bei einigen Mustickstücken hört man eigentlich eine Phasendrehumg sofort. Es gibt ja auch viele Aufnahmen, bei dem die Phase gedreht ist.

Aber wo Du mir hier schon die Frage stellst. Hast Du die Hersteller Deiner Geräte mal gefragt, ob hier eine Phasendrehung stattfindet?

Der Funk Monitor hat jedenfalls einen Phasenschalter, sowohl auf dem Gerät wie auch von der Kabelfernbedienung aus bedienbar. Also wo ist das Problem? Da interessieren mich doch andere Kriterien viel mehr!

Gruß Stephan
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shakti
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Beitrag von shakti »

eine 180grad Phasendrehung ist bei vielen Geraeten normal, somit ist es recht zufaelllig , welche Phase am LS ankommt. Da wir aber auch nicht wissen, mit welcher Phase aufgenommen wurde, sollte man diese bei jedem Stueck neu bestimmen (doch wer macht das schon)
Meine Conrad Johnson Act 2 dreht ebenfalls die Phase, dann habe ich zu einem workshop mir die muehe gemacht und habe mit der aktuell hier oft beschriebenen Coltrane/Hartman Aufnahme die Anlage gehoert und alles hat gepasst.
Nun lese ich, dass die Aufnahme mit invertierter Phase gemacht wurde...
Also haben wir diese auf meinem Workshop zumindest korrekt gehoert...
Aber womoeglich andere Aufnahmen nicht .
so what :-)
Gruss
Juergen
ps
in Stephan's Kette spielt die Funk prima, aber das ist eben nicht uebertragbar sondern muss in anderen Ketten evaluiert werden. Dies hat Andi gemacht, er sagt ja nicht, dass die Funk schlecht ist, sie passt halt nicht in seine Kette.
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snilax
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Beitrag von snilax »

Schöne Sonntagsgrüße an das Forum!
Ich habe den Beitrag über die Phasendrehung beim Funk LAP2V3 und den Kommentar von Hans-Martin zum Anlass genommen, Herrn Funk zu befragen wie es sich mit der Invertierung beim Monitor MTX und dem LAP verhält.
Hier ist seine Antwort:
"...der MTX-Monitor hat einen Phasenschalter für 1 Kanal (links). Damit kann ein Phasendreher zwischen linkem und rechten Kanal korrigiert werden. Die absolute Phase beider Kanäle eines Stereoausgangs eines Audiogerätes sollte damit nicht verändert werden können.
Prinzipiell könnte man durch das verdrehen der Pole in einem XLR-Stecker von Pin2 mit Pin3 die absolute Phase für das nachfolgende Gerät vertauschen. Das macht aber nur Sinn in einer größeren Anlage wo viele Signalquellen gleichzeitig laufen (z.B. auch innerhalb einer Abhörsituation mit mehreren Verstärkern für jeweils verschieden Übertragungsbereiche) oder gemischt werden sollen.

Sonst spiel die absolute Phase eines Audiosignals keine nennenswerte Rolle. Die absolute Phase beim LAP-2 zu drehen macht keinen Sinn solange der LAP-2 der einzige Vorverstärker ist der zum selben Zeitpunkt läuft.

Der Innenwiderstand des LAP-2 ist mit ca. 60 Ohm schon so niedrig, dass eine weitere Verringerung nur bei sehr langen und qualitativ für Audiosignale schlechten Kabeln (hohe Kapazität im Bereich 120...200 pF/m) hörmäßig Sinn machen würde. Egal was manche Redakteure hier behaupten.

Alle die von Ihnen angegeben Maßnahmen sind möglich. Es sollte da aber keine klangliche Veränderung erwartet werden.

Mit freundlichem Gruß aus Berlin

Thomas Funk"

Gruß
snilax
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music is my escape
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Beitrag von music is my escape »

Salvador hat geschrieben:
Lustig,
wie manche Leute ein systematisches, empirisches, fleissiges und konsequentes Vorgehen bewerten. Oder doch zum Kopfschütteln.
Lustig, was manche Leute als systematisches, empirisches, fleissiges und konsequentes Vorgehen bewerten. :wink:

BTW: ich habe eben erst zufällig einige Beiträge entdeckt, welche ursprünglich in diesem Thread hier gepostet, anschließend aber zu anderen Themen verschoben oder gleich ganz ins Archiv gesteckt wurden. Hätte ich eher gewusst, wie sehr Du Dich bereits gegen die Empfehlung Funk MTX Monitor zur Wehr setzen musstest, hätte ich Dich mit der neuerlichen, von meiner Seite her ausschließlich gut gemeinten Erwähnung dieses Gerätes ganz sicher verschont.

VG,
Thomas
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Salvador
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Beitrag von Salvador »

Hallo Jürgen und alle,

was ist denn von einer McIntosh C500T zu halten?

Die hat eine Ausgangsimpedanz von 220 Ohm, das müsste sehr gut gehen. Die MFE Tube one (übrigens immer noch ein heisser Kandidat) hatte sich mit den AGM 5.4 bestens vertragen und hat eine ähnliche ausgangsimpedanz, 226 Ohm glaube ich.
Hingegen schreibt Audio Research bei der Reference 5, 5SE und 6, die alle symmetrisch eine Ausgangsimpedanz von 600 Ohm habenn, dass eine Minimallast von 20 kOhm Pflicht ist. Zur Erinnerung, ich habe bei den AGMs 10 kOhm.

Also nochmal, wer mag mir hier etwas über McIntosh-Röhrenvorstufen schreiben, am besten spezielle zur C500T?

Beste Grüße,
Andi
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