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 Post subject: Pre-amp shootout
PostPosted: Tue Apr 18, 2017 9:08 pm 
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Joined: Sat Aug 15, 2015 7:22 pm
Posts: 3
Location: los altos hills, CA, US
Preamp shootout: Coincident Statement Phono Stage vs. Convergent Audio Technology Signature vs. Audible Illusions M3B vs. Doge 8 LP

I thought I would share my recent experience with attempting get the best phono sound out of a few highly regarded tube pre-amplifiers/phono stages that I could get my hands on, namely: the Coincident Statement Phono Stage, Convergent Audio Technology SL-1 Signature, Audiblie Illusions Modulus 3B and Doge 8 LP (pronounced dough-she). Most of these pre-amplifiers have been enhanced in some way- I will go into detail on each set-up after I list my associated equipment and bias. I have listened (almost) exclusively to vinyl for the last 39 years. Needless to say, the interaction among different components plays a huge part in the overall sound of a system. So while I am stating my interpretation of the results here, yours undoubtedly will vary.
Another key factor is the type, make and year of the tubes utilized. I have been tube rolling for decades and For me, one of the greatest features of tube equipment is the ability to quickly swap tubes, and, to varying degrees, change the character of your equipment.

My kit:
-Record cleaner: Ultrasonic
-Cartridge: Benz Micro LP-S
-Tonearm: VPI JMW Memorial 12.6 with silver wiring
-Turntable: VPI TNT jr.
-Turntable base: Vibraplane
-Phono cable: Transparent audio ultra
-SUT (used for CAT, AI and Doge 8): EAR MC-4, CSPP has built-in SUT
-Interconnects: Alpha-Core Goertz AG-3
-Mid/tweeter amp- Inspire Firebottle 18 watt SEP
-Woofer amp- ARC 100.2 Class A
-Speaker Cables: Alpha-Core Goertz AG-3 Divinity
-Speakers: Von Schweikert VR4SR MKlll
-Rack: Solidsteel
-Tweaks: VPI Magic Bricks, wood clothes pins, etc.

I listen to live music at least once/month, but typically closer to once/week. This helps guide my recorded music efforts, where I'm continually trying to achieve it all: soundstage, coherency, space, impact, realism, sound floor, noise floor, tonal balance, etc. My tastes range from rock to blues to Americana and some country and classical- basically everything. However, now that my system has reached a pretty discriminating (but not necessarily expensive) level, I find myself drawn almost exclusivity to the subset of well-engineered albums within that range. Some of the artists I currently use to test my systems are: The Beatles, Dire Straights, Alan Parsons, Thelma Houston, Joe Cocker, Glenn Campbell, Tracy Chapman, Bob James, Supertramp, the Crusaders, etc.
As soon as I make headway in one area, I have to go back and check the others to make sure they I haven't regressed in another. Recently I was making great advancement on air, coherency and realism on some cuts, when I put on my copy of one of my standard test cuts: Bob James' Snowbird Fantasy. For some reason the "forest of conga's" which really start to become apparent 2 minutes in was much smaller and more compressed than it used to be when I was using a pair of Magnepan 3.6r's- I hope to have this addressed by the time I finish writing this article.
Until this comparison, my music bias has led me to prefer the warm side for the mids and uppers and fast, edgy, high-definition for the bass (that is why I bi-amped with the pont-to-point wired Fire Bottle on top and a Class A solid state on the bottom). In the past, I felt as though one had to make a choice between warmth and definition. This was often presented as a choice between the "tube sound" and the "transistor sound". When that was the case, I almost always chose the warm tube sound (acknowledging its flaws and weaknesses in my then (Quicksilver, Dynaco and ARC) tube amp implementation versus the somewhat bright and edgy transistor defined sound (of my, at the time BEL, Hafler, Classe, First Watt, Sunfire, ARC and Bedini)). On a side note, the original Bedini 25/25 is the only solid state amp that I have ever been able to enjoy, for any period of time, driving the speaker mids/highs or full range.
So here are the preamps - starting with my CAT SL-1 Signature- it has been one of the constants in my system since 1994. Modifications include significant tube rolling: Amperex 6922 PQ's white label and GE 5751 triple mica black plates in the phono stage (even though CAT doesn't recommend the 5751's) with corresponding old stock tubes in the line stage. This preamp, along with my VPI table and cables, has endured for over two decades, everything else has changed numerous times. I purchased this unit used in 1994 and except for a blown resistor, which Ken Stevens, the founder of CAT fixed In 1999, it has been a tank. The CAT SL-1 Signature is over 20 years old and it's a testament to its design and implementation that it is able to compete effectively with the following three preamps which are of current vintage. Btw- the CAT has been enhanced over the years along with its price. I think this unit clocked in around $3.5k and can be had used for $2.5k while new units are north of $12k.
Next up is the new Audible Illusions Modulus 3B. This unit started out as an AI M3A which I purchased in 1989 and decided to upgrade in 2015. I traded the M3A unit in for a new M3B unit which performed well for six months until a channel went out. I was sent a new unit in the summer of 2016. This is the only unit which I tested in its stock configuration. Usually, I would substitute in NOS Amperex 6922's in almost any "6DJ8" socket, but the AI design pushes tubes so hard that they only recommend a few brands that can stand up to the punishment. I ran the test with the stock 6h23n Russian tubes- I think they are Voshkods but they might be Reflektors. One feature of the AI I like, is the dual attenuated volume controls which negate the need for a balance control. I got the unit with Moving Magnet input only, as I don't feel any of the high gain MC inputs into any of the preamps I have tried can effectively boost a LOMC cartridge without an unacceptable level of noise.
Next on the list is the new Doge 8 LP. The Doge 8 LP is an incredible value at $1.4k with a phono and line stage driven by 4-12ax7's and 4-12at7's respectively. Unlike all the other units in this test it does not have a separate power supply nor does it have balance control, but it does come with a remote control. My tubes of choice here are 1950's era triple mica black plate Sylvania 5751's subbing for the 12ax7's and 1950's GE 6201's subbing for the 12at7's. The Doge 8 LP has two switch selectable impedance and capacitance settings, the CSPS has four while the AI and CAT have zero- instead relying on external RCA pigtails. This unit is ordered on the web direct from Doge in China. It shows up well packed, 7 days to California from the date of order- you have to appreciate Internet commerce.
Last but not least is the new Coincident Statement Phono Stage (CSPS). Costing $6k, this unit is a heavy beast. Like the other preamps, except the Doge, it has a separate power supply but it is SIGNFICANTLY larger and heavier. It is a phono stage only- no line stage included like the other full-function preamps (its matching line stage, the CSLS is equally as large and costs an additional $6k) however, it does have an additional input for a non-phono source. It is driven by 4-12at7's and once again, I substituted the 1950's era Sylvania 3 mica black plate 5751's in their place. It comes with a four switch selectable capacitance settings.
Now here is where this gets tricky this shootout consisted of: 1) consideration of the preamps themselves and 2) additionally, consideration of the "hot-rodding" implementation (with two different systems) that yielded the best sound for me. I initially read about this breakthrough implementation in one of the stereo magazines (I think it was TAS, but not positive) in the 1980's when it was dubbed "hot-rodding". The authors of the implementation experimented with settings of the front-panel switches on an ARC SP-10 mkii and took the phono signal straight out from the tape outputs bypassing all knobs and switches (read pure phono signal but no volume, balance or line stage boost). I had forgotten about it until I was reviewing the phono stage recommendations from High-endaudio.com by Arthur Salvatore where he again brought it up as an option to consider.

So on to the music....... I narrowed down my test tracks to the following which I repeated over and over among the different equipment until I could confidently describe what I was hearing. Btw- this A/B testing methodology is somewhat suspect and I feel should also be complimented with a longer term (as in weeks or months- which I only did with the top two solutions) listening sessions which would much more accurately flush-out any listener fatigue issues. The Tracks: Dire Straights-Ride Across The River, Crosby, Stills, Nash- Cold Rain, In My Dreams, Gordon Lightfoot- If You Could Read My Mind, Tracy Chapman- Piles Of Things, Willkie Nelson- Georgia On My Mind, Joe Cocker- Unchain My Heart, Paul McCartney- Rough Ride, Supertramp- Crime Of The Century, Thelma Houston- I Got The Music In Me, Michael Jackson- Billie Jean, and Bob James- Snowbird Fantasy.
I find that when trying to isolate the qualities of sound, the simpler the better, which is why I have a preponderance of a single voice with guitar which I can easily connect with. But then your system has to entertain you, take you through complex passages and dynamics, and be able to let you boogie down.

Let me first say that without different units to test side by side, I think I could live fairly happily with any of the top four solutions for years to come.

6th place- Audible Illusions M3B. Don't read this as an indictment of the AI M3B, but more likely an indication of the inferiority of the Russian 6h23n tube. I had high hopes for the Modulus and the 6h23n, which are readily available and fairly cheap but it was not to be. In my setup with the phono being fed by the EAR MC-4, the AI had an incredibly low noise floor. The soundstage was good, outside the VSA speakers. Imaging was pretty good but the sound and coherency ran pretty bright and sterile in comparison. Regardless of how long I let it warm up, I just couldn't get nearly as close to it as the others. I feel that the bugger here is the tube and not the AI preamp itself. As a test, I replaced the Amperex 6922 input tubes on my beloved ARC D-115 amp with both Voshkod and Reflector 6h23n's - rebiased the amp, burned them in and warmed it up and - it was screaming bright. To me- unlistenable for any amount of time. Unfortunately for the AI, I feel the two are "tied-at-the-hip" because I wasn't about to risk destroying any of my expensive Amperex tubes to see how this amp would compare with the others armed with a comparable tube. So, the design pushes its tubes hard requiring a very rugged tube, which negates the ability to tube roll with the most highly regarded tube types.

5th- Coincident Statement Phono Stage. I know, I know, with all the great press some are going to think I'm crazy rating this fifth, but hang in here with me for a minute. The CSPS has a built-in SUT, so it is able to take the output directly from the Benz micro cutting out a number of superfluous connection colorations. The cartridge can be easily dialed in with the adjustable capacitance. The CSPS is incredibly good. Black background, pinpoint imaging, great soundstage and a fantastic blend of warmth and emotion. Then what's the problem you ask? For my system, it failed Arthur's Savatore's "Bolero Test". There just isn't enough gain in the phono stage (without an accompanying line stage) to reach a satisfactory SPL on a number of my test songs. (This is with 92db sensitive speakers, 100 watts on the low-end, 20 watts on top both dialed in at about 2.9mv sensitivity and the CSPS's attenuators on 100%). I found myself frustrated on numerous passages fiddling with my system trying to increase its output. The other preamps did not have this issue. But stay tuned for when this challenge can be solved.

3rd and 4th- TIE- 2016 Doge 8 LP and 1992 CAT SL-1. This is not a cop out. I originally ranked the CAT higher than the Doge, but after continued listening I feel I ranked the CAT higher because it was warmer, which, after two decades was what I was used to. Namely, I have preferred being on the warm side of the spectrum, but I now feel that the CAT preamp (phono combined with line stage and the Amperex 6922's) is a touch too warm while the Doge preamp could be a touch warmer (phono combined with line stage with the Sylvania 5751's). Although I haven't tried it yet, the Doge combined with a Koetsu cartridge in place of the Benz Micro LPS might be an E-ticket ride. Each of these preamps had to be fed with my EAR MC-4 SUT to reach this level, with the CAT being almost overdriven by the EAR SUT.
The CAT is an awesome piece of gear doing all things very well: great coherency, huge soundstage, lots of air around the instruments- warm bodies- it sounds like live music. But compared to the Doge and the hot-rodded systems, it is a bit slow and slightly bloated in the upper bass. (I always thought when I read reviews, how in the heck can someone hear that a unit is slightly bloated in the upper bass- but when compared to some of the better implementations noted below, I can hear it). I didn't have the time nor the luck, but I bet this CAT could move solely into third place by swapping out the wonderful Amperex 6922 tubes with some that are a tad more aggressive like NOS Telefunkens, Siemens or Tung-Sols.
The Doge 8 LP is one awesome, compact preamp (with the right tubes)- an incredible price performer. However, right out of the gate using the stock Shugang hi-fi tubes, the Doge 8 LP exhibited much the same shortcoming as the AI, something close to a (good?) solid-state preamp. But when mated with GE or better yet, the Sylvania black triple 5751s, it becomes a very rare breed of preamp. In fact, if I hadn't spent the last two decades being influenced and romanced by my CAT, I would probably rank the Doge 8 above it. It's soundstage is slightly narrower than the CAT and I feel there is just a smidgen less air around the players, but it has a unique combination of warmth and pace that delivers a real live performance. I found myself leaving it in the connected position more frequently than the CAT. The difference between the two preamps becomes evident when listening to the plucking and decay of the guitar strings on "In My Dreams" by CSN. The CAT is larger and just a touch airier, but the Doge is more linear, analytical, aggressive and coherent without losing the warmth factor. They each have strengths and weaknesses. I have a dedicated listening room so I can address imbalances pretty easily, others may find the lack of a balance control on the Doge an issue if their amp is not channel adjustable. So, my hunch is the "best" battle between these two would be, the CAT with SIemens 6922's (or equal) being fed by the Benz Micro vs the Doge with the Sylvania 5751's being fed by the Koetsu rosewood signature.

2nd- The CAT "hot-rodded" with the Doge 8 LP line stage. Ok, I like them both, one a little warm and a touch slow the other a little cool and fast, put them together - audio nirvana, almost.
On Arthur's website he states the following: "*The phono stages from this era (of the CAT's vintage) will be even better than we remember, since they were only heard with their own line stages, which were of varying quality. It's definitely possible that one (or more) of these models had an amazing phono stage, which was "sabotaged", at the time, by their own mediocre line stage. The superb line stages available today will finally allow them to shine."
Quoting Richard Pryor in Stir Crazy- "No S**T".
It is an awesome combination. The phono section of the CAT with the Amperex 6922's combined with the line stage of the Doge 8 with the GE 12at7-WA's is a combination made in Live Music Heaven. For me, It has the right amount of pretty much everything. On track after track I felt as though the performers were there with me. I got excited. I listened for hours and when I left to go on a trip, I thought about how great it was and what I was going to listen to the minute I returned. The slam, warmth, air and coherency of Unchain My Heart and I've a Got The Music In Me are thrilling. If you think it is difficult to hot-rod you are wrong- piece of cake. Worked first time - from Arthur's website:

"I have CRITICAL information for those of you who are using the phono stage section of a tube preamplifier (through its Tape Output), while also bypassing its line stage. Since I've advised using this procedure for years now, here's the latest advice I learned (from Tom Tutay) about optimizing the performance of these components. It's quite simple...
While the Selector Switch is obviously on the Phono input, you should also make certain that the Tape Monitor switch, if there is one, is always set to "Tape" or "On". When you do this, the output signal of the dedicated phono stage goes directly to the Tape Output ONLY, while none of the signal goes to its internal Line Stage, which would further load it down, thus weakening it. Keep in mind: ANY weakening of this already delicate phono signal will be detrimental to it, so this procedure is mandatory if you want to optimize the inherent capabilities of the phono stage. This procedure may also help transistor phono stages.
Also, do NOT remove the tubes in the now unused line stage. Put "junkers" in the tube sockets if you have to. Why? Because the heater voltages may otherwise become too high for the remaining tubes still in the phono stage, which may both compromise their performance and even reduce their operating life."
The CAT, hot-rodded with the Doge is about $5.5k- $2.5 for a used SL-1 signature, $1.5k for the Doge and I ran it with a $1.5k used EAR SUT. Still no balance adjustment but as I said, I'm OK with that.

1st- Coincident Statement Phono Stage connected to the Doge 8 LP line Stage. Ok, same hot-rodding as above, but the CSPS is only a phono stage in search of an equally compelling line stage. This combination is the winner, but not by much. These top 2 implementations are very, very close. I must have gone back and forth twenty times. The CAT's warmth is so damn seductive. But in the end, I was able to focus on a passage that allowed me to judge one small difference that tilted the judgement in favor of the CSPS/Doge combo. When I was a kid in elementary school, they still taught music and the students were able to play different instruments during class (I was really good at the triangle). Every classroom had an upright piano, that, when the teacher was out of the room, we students would play on. I remember vividly pressing down on the key and hearing AND FEELING the hammer make impact with the string. Especially evident in the upper octaves, you can hear the hammer impact the string before the sound of the string vibrates. Once again, on "Unchain My Heart" by Joe Cocker in the first 10 seconds there is a piano riff. With the CSPS, I could feel the impact of the hammer with the string a bit more clearly than with the CAT- it took me back to grade school. I remember saying "wow" out loud. Now, on vocals, I slightly prefer the CAT implementation but overall, I feel the CSPS/Doge combo is more accurate and truthful. The CSPS/Doge combo clocks in at $7.5k. Not chicken feed and by far the most I have ever spent on a "preamp" solution. By the way, the CSPS allows you to adjust the gain on each channel separately, at the cost of some sonic purity, so this solution also has a balance option. Synergistically, as previously mentioned, there is a matching line stage for the CSPS which might work a little better than the Doge, but then you are looking at $12k.

So that's it. I know I said before that I could live happily with any of the top four solutions presented here, but the truth is I would be happier with either of the top two. I if you are thinking of a new preamp I hope you have found this helpful.
Next up for me will be a test of the CAT and Doge with the previously outlined changes above and then shoot-outs of some amplifiers I've been going through including: Doge 9's, ARC D115's, First Watt F6, Sunfire 300, ARC 100.2, Bedini 100/100, Inspire Firebottle, and Bedini 25/25. Some full-range and some bi-amped. Then probably a quick cartridge comparison among an Accuphase AC-2, Koetsu Rosewood Signature, Denon DL-103r modified and a Benz Micro LPS. Then the success or failure of a little project modifying a pair of Magnepan 1.6r's and integrating them with a sub or the woofers on the VR4's as well as a comparison among Maggie 1.6s and 3.6rs, the VSAs and a pair of modified Sound Dynamics 300ti's.


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 Post subject: Re: Pre-amp shootout
PostPosted: Tue Apr 25, 2017 2:43 am 
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Joined: Fri Jan 28, 2005 11:09 am
Posts: 10
Location: Sault Ste. Marie, ON, CA
I enjoyed your evaluation,paid particular attention because I own the Coincident Line stage so I was interested in how the phono would compare with the other products.Big fan of Arthur Salvatore,my go to guy when contemplating an esoteric audio purchase.


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 Post subject: Re: Pre-amp shootout
PostPosted: Wed Apr 26, 2017 4:38 am 
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Joined: Sun Jun 27, 2010 7:02 pm
Posts: 3
Location: North Haven, CT, US
Check out Arthur's newest reference line stage. Nirvana for those of us on a budget. Amazing performance for the price!


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