Tweaking the Van Alstine Fet Valve CFR Hybrid Preamp and Vision SET 400 AmpI have been listening to the stock versions of the CFR Hybrid Preamp and Vision SET 400 Amp since August 2019, both pieces are very musical with perfect synergy. The sound is grain free and detailed with sparkling highs and subterranean bass. Imaging is better than amps I have heard in my system ranging in price from $1000-$5998 and includes previous AVA amps, nCore and PS Audio. My speakers are the excellent Salk HT2-TL.
The sound of AVA electronics is slightly warmer than neutral, but not by much. I made some cable changes a little more than a year ago with the addition of Hapa Quiescence Silver and Gold/Silver interconnects. I put together a review back then:
https://www.audiocircle.com/index.php?topic=173888.0I really like what both interconnects do, they are fast, clear with a wide soundstage and allow low level detail like room echo to be resolved. The interconnects, because of the silver wire, also moved the sound a click or two closer to a neutral/detailed presentation. I have happily lived with the Hapa/AVA sound for over a year but recently began to wonder what a few changes would sound like.
The Fet Valve CFR Hybrid Preamp has 4 tubes, 2 JJ 12AT7/ECC81 and 2 JJ 12AU7/ECC82. The JJ tubes are very reliable, readily available, affordable and sound pretty darn good. My interest in rolling tubes came from a few posts and a review, they planted a seed that slowly grew.
Dean wrote "I am using NOS Mullard M8136 (12AU7) and M8162 (12AT7) in my FET Valve CF. Before rolling I would suggest spending some time with the stock JJ's. The pre-amp is great with either set."
https://www.audiocircle.com/index.php?topic=156817.msg1678780#msg1678780The thread: Evaluation of AVA FET Valve CF Preamp by Kwebb comparing the original JJ tubes to Genalex tubes
https://www.audiocircle.com/index.php?topic=125473.msg1323021#msg1323021 The Absolute Sound's FET Valve CF Preamplifier review replaced the stock JJ tubes with Philips Miniwatt 12AU7 and Mullard M8162/CV4024 without listening to the stock tubes, real bad form in my opinion but here the Mullards show up again.
https://www.theabsolutesound.com/articles/audio-by-van-alstine-fet-valve-cf-preamplifierFrank Van Alstine was able to compare the JJ tubes to the Phillips and Mullard tubes used in the review and could not hear a difference which is a good thing since this tube set would cost $300. Other tube sets push $400.
https://www.audiocircle.com/index.php?topic=126423.msg1333845#msg1333845Re-reading the reviews a few times I concluded the change in sound would be subtle, which is exactly what I was looking for. Years ago I rolled tubes in my Hagerman Cornet2 phono preamp and the difference could be huge.
I checked out Jim McShane's tube selection and picked a pair of 12AT7 and 12AU7 tubes that fit the budget and had a good reputation. If the experiment didn't work out I could resell the tubes.
http://www.mcshanedesign.net/tubes.htmTubes I picked:CV4024/12AT7 Mullard, NOS/NIB, military boxed, the pin protectors in place, no Mullard logo on
them. With double stapled plates and copper getter ring supports, these are really fine tubes, $44.50 ea., $89.50/pair.
Beware of fakes!! A number of vendors have used/washed tubes in fake boxes and are selling them for full price! In
their defense, they may not even know they have used tubes! But I guarantee my stock is 100% new!
Genalex Gold Lion B749/ECC82/12AU7 reissues This tube has warmth and body, the noise level is very low, and microphonics
are virtually nonexistent. The track record is clear - these Genalex reissue tubes are superb, as good as most of the old stock! $44.50 ea., $89.50/pair.
The reviews are correct, tube rolling in the CFR Hybrid preamp is subtle. The change is noticeable as a slightly more relaxed presentation. The JJ tubes are more analytical with a precise quick presentation, they add excitement. Nothing is lost with the Mullard/Genalex tubes but the presentation isn't as "in your face" as it is with the JJ's. The difference is similar to, but not as extreme, as listening to the YG Acoustics speakers and the Vandersteen Model 7 at a past RMAF.
Vision SET 400 amp with the Viborg High Fidelity Audio Power CableMick Wolfe has been enthusiastically recommending the Viborg High Fidelity Audio Power Cable to our audiophile group and here on AC.
https://www.audiocircle.com/index.php?topic=180338.msg1895594#msg1895594At first I didn't believe that power cords make much, if any, difference. But...
The space behind my electronics is a rats nest of wires. Amazingly the system is very quiet and I do my best to keep it that way by running shielded cables wherever I can, including power cords. I picked up a few Volex 14 gauge shielded pc back in 2005 after reading Occam's review, they have served me well. I didn't hear any change in the sound when I replacing the stock pc on the Vision SET 400 amp with the Volex.
https://www.audiocircle.com/index.php?topic=15325.msg133273#msg133273Recently though, a low hum appeared. Through trial and error I found out it wasn't originating from any transformers or interconnects. Very annoying.
Maybe the shield on a Volex developed a ground loop so I switched to a generic pc. The hum diminished but was still present, a computer monitor and probably other stuff is spraying noise all over. Out of desperation I ordered a Viborg cable. It worked, the hum and high frequency noise is gone. The shield on the Viborg is connected to ground at only one end which lessons the chance of a ground loop. Of course the first thing I did was take apart the plug to check the connections. The cord and plug assembly was professionally done, I couldn't have done better. The second thing I checked was polarity, it was correct.
The Viborg cable with copper plugs Mick recommended was sold out, I bought the cable with the rhodium plated plugs on Amazon for $149.00 with free returns, relatively cheap by power cord standards.
MTR1501 16pcs Multiplex Copper AC Audiophile Mains Cord with Rhodium Plated US Standard Connector VM512R+VF512R PlugThe Viborg plugs are available if you want to DIY, AliExpress sells the VP1501 cable but it is cheaper to buy a completed cable. A lot of fun parts at the Viborg site:
http://www.viborgaudio.com/en/Viborg 1501 and AVA stock power cables
Viborg says the 1501 cable is 10AWG.
Yes, there definitely more low bass and space with the Viborg pc. After 2-1/2 years I can tell when the sound is different, either good or bad. Deep bass is deeper and stronger when listening to either FM or digital. The change jerks me out of casual listening to "What was that? I never heard that before." The highs and midrange doesn't change. Music with no low bass sounds the same but there is more space around the performers, the room opens up, especially on minimally recorded music that includes the recording space.
Check out the new Gillian Welch and David Rawlings album "The Good Times Are Past And Gone". A digital download is only $9.99.
"The production doesn’t attempt to produce a studio recording at home. Rather it’s a living room recording done right—or whatever room in the Welch/Rawlings house was used. A Telefunken SM2c condenser stereo microphone vividly and accurately captures the three-dimensional space and the duo in it. Rawlings used an Otari ¼” in 2 track deck recording at 15 IPS. Playback was via a Studer A820 with the signal cut directly to lacquer on a Neumann VMS80 lathe fitted with an Ortofon DSS 731 cutterhead. Also utilized: a Fairchild 670 limiter, Barry Wolifson’s (Sterling Sound’s lathe tech) M/S decoder and a P&G 1500 Series Stereo Fader. Can it get more purist?"
https://www.analogplanet.com/content/welch-rawlings-lock-down-produces-all-good-times-are-past-and-goneAnd the One Mike+ recordings of Carmen Gomes by Sound Liason
https://www.soundliaison.com/
"The advantages of the One Microphone approach to recording are obvious; phase coherence, perfect imaging, great sense of depth, superior realism. Another advantage is that it forces the band being recorded to really play. There is nowhere to hide, no fixing it in the mix. Our ears are much more sensitive to phase errors than we are aware of. The obvious solution to avoid phase errors is to record the whole band from one point. But until recently we didn't experienced a microphone that was up to the task. Drums and piano sounded too distant and the sound stage did not reflect what I heard standing in front of the band. The first thing that impressed me about the Josephson C700S was the natural sound of the mic and the sound off axis. This is what makes the difference between a good microphone and an average microphone. Secondly the microphone is quite unique, it has three capsules instead of the more common two.
So when recording with the Josephson C700S, instead of placing microphones at the instruments we now place the instruments around the microphone. Mixing is no longer possible. We have to create the complete sound stage at the spot by carefully moving each instrument closer or further away as well as left and right in relation to the microphone. The benefits of this way of working is that the result is completely free of phase errors and that the sound is very natural with a wide deep soundstage. So far all musicians have been struck by the incredible authenticity of the recordings and commented that they never heard their instrument sound so real and lively."
- Frans
The Third Part of the Preamp/Amp Tweak is the most expensive but is also the most important: a real subwoofer. Ideally fast with a sealed cabinet and the ability to go to 20 Hz. I use a REL Gibraltar G2 (discontinued) that goes down to 18 Hz. Some REL subs are -6dB at 30 hz, that is where my G2 starts. 30 Hz is great for most music but I think the recording space (i.e echo and low level room sound) is much lower. Tone Magazine has a review of the REL Carbon Limited Subwoofer
https://www.tonepublications.com/review/the-rel-carbon-limited-subwoofer/Upscale Audio's Kevin Deal describes the sound of a REL sub better than I can:
https://www.youtube.com/watch?v=pSHkpy2280QREL subs use a high level input from the amps speaker terminals, with increased low bass the main speakers and sub respond appropriately. Without a sub, if a speaker rolls off at 40 Hz like my JBL L100's then the extra low bass is wasted, it will never be heard. The fat, fire hose power cords won't make a noticeable difference. The inability of a stereo to reproduce real low bass and space is probably one reason many people think aftermarket power cords don't do anything important.
Should new AVA owners immediately change out tubes and power cords? Probably not. The changes are subtle, get to know your system first. Your money would be much better spent on room treatments, experimenting with interconnects and speaker placement. Wait a year or two, during that time your system will evolve. My stereo has been stable for quite a while so it was time for a change. These few tweaks makes me happy. Would any of my audiophile buddies notice a difference? Probably not.
But I'm having fun.
