There is another option, which is to use a pair of single-rail SLB supplies. The 29V secondaries will give you plenty of headroom to accommodate the synchronous rectification + capacitance multiplier. Each SLB will need a pair of 15,000 uF, 50V electrolytics, and the big 20,000 uF caps you already have will go inside the VFET chassis underneath the OS boards.
I have just finished my p channel amp. Special thanks to Papa, Jason, 6L6, and all the other who worked so hard to make this special project possible. The sound is incredible as all the others have talked about. I was away from home most of last year until recently. I did not buy the chassis from DIY shop as I sourced my own chassis. The next step is to do fine tuning and adding mods that has been discussed on this thread to tailor the sound. A linear PS is already in the plan.
@KevinHeem
Take a look at this mouser part: 485-915
@TungstenAudio
I certainly would like to try the Mark J FEs, but am trying to see which one I want to try as I don't think I can afford to try all four, probably the ones without the edcor. Between the MARAUDER and the DREADNOUGHT, I am not sure which one will suit my taste better, may have to bite the bullet and get both to try.
Take a look at this mouser part: 485-915
@TungstenAudio
I certainly would like to try the Mark J FEs, but am trying to see which one I want to try as I don't think I can afford to try all four, probably the ones without the edcor. Between the MARAUDER and the DREADNOUGHT, I am not sure which one will suit my taste better, may have to bite the bullet and get both to try.
I am currently listening to a simplified version of the Marauder FE in my rebuilt M2x. Basically an OPA551 as a unity gain buffer driving the Edcor in its 1:5 autoformer configuration. It’s clean, fast and quite detailed. Prior to that I had the Mtn View cards, which are precursors to the Scourge FE.
If you want to hear what the VFET output stage sounds like as naked as possible, I recommend the Marauder FE.
The Dreadnought FE is a more complex build, and one that I modified more to get the sound the way I liked. Also interesting, as it is a transconductance amplifier, which has a subtly different sound. Well rounded and still detailed.
If you want to hear what the VFET output stage sounds like as naked as possible, I recommend the Marauder FE.
The Dreadnought FE is a more complex build, and one that I modified more to get the sound the way I liked. Also interesting, as it is a transconductance amplifier, which has a subtly different sound. Well rounded and still detailed.
Yesterday I took out the vanilla FE's because I want to try out the Edcor transformers in my SissySit. I have a Wayne line stage as preamp and together with the DAC they provide enough swing, so I listened to the amp without FE (N channel). I am giving it another go today but I was positively surprised
Provided your combination of source and preamp have enough gain and you have sufficiently efficient speakerd, is this the most naked way to listen to the VFET OS?
Anyway, I thought I'd share my experience as this gives another possibility 😉
Provided your combination of source and preamp have enough gain and you have sufficiently efficient speakerd, is this the most naked way to listen to the VFET OS?
Anyway, I thought I'd share my experience as this gives another possibility 😉
It is of course a blessing to have so many "mature" FE cards to "play" with!
Now, regarding "If you want to hear what the VFET output stage sounds like as naked as possible", there is a last and more consequent option. It costs nil and is absolutely safe / easy, one I tried without any problem: bypass the FE card, eg. no FE, sound from your source directly to the OS input.
Due to the high impedance of the OS' input, that works very well as long as you can live with the loss of some overall gain in the chain, due to no FE gain. That means usualy in a normal listening domestic environment with reasonably loud records a source capable of 2V or more output and LS with quite a good sensitivity, say from roughly 94dB/W/m upwards (but then the VFET is made anyway for high efficiency LS first place)... or any equivalent combinaison of course, for example lower voltage sources can be compensated by higher efficiency LS etc.
To find quickly out if it is OK in your case, other than just trying, an easy way is when your source is a DAC with an integrated volume control. You get a clear feel of what max loudness you would get by dialing its volume down from max (baseline) to -14dB.
Enjoy that great amp
Claude
Now, regarding "If you want to hear what the VFET output stage sounds like as naked as possible", there is a last and more consequent option. It costs nil and is absolutely safe / easy, one I tried without any problem: bypass the FE card, eg. no FE, sound from your source directly to the OS input.
Due to the high impedance of the OS' input, that works very well as long as you can live with the loss of some overall gain in the chain, due to no FE gain. That means usualy in a normal listening domestic environment with reasonably loud records a source capable of 2V or more output and LS with quite a good sensitivity, say from roughly 94dB/W/m upwards (but then the VFET is made anyway for high efficiency LS first place)... or any equivalent combinaison of course, for example lower voltage sources can be compensated by higher efficiency LS etc.
To find quickly out if it is OK in your case, other than just trying, an easy way is when your source is a DAC with an integrated volume control. You get a clear feel of what max loudness you would get by dialing its volume down from max (baseline) to -14dB.
Enjoy that great amp
Claude
Posted at the same time LOL, glad I wasn't the only one... and, yes, I was very positively surprised aswell, as posted back then.
But then how could it be different? I made provisions to tweak that little gem and have therefore quickly swapable FEs (on stand-offs, with all terminals with screws). Further, that additional (iron!)stage, it could only degrade sound, so I had bought four DPDT switches to enable quick integrated FE bypasses by a flick.
Foolish me, I should have known that 1) Papa knows how to design a gain stage (LOL), 2) he would not degrade his VFET by throwing in a non qualitative suitable FE.
As posted, bypassing entirely the FE gave me an unexpected result... so that's another FE card option: the NO card one LOL
Enjoy music
Claude
But then how could it be different? I made provisions to tweak that little gem and have therefore quickly swapable FEs (on stand-offs, with all terminals with screws). Further, that additional (iron!)stage, it could only degrade sound, so I had bought four DPDT switches to enable quick integrated FE bypasses by a flick.
Foolish me, I should have known that 1) Papa knows how to design a gain stage (LOL), 2) he would not degrade his VFET by throwing in a non qualitative suitable FE.
As posted, bypassing entirely the FE gave me an unexpected result... so that's another FE card option: the NO card one LOL
Enjoy music
Claude
I prefer a little extra gain from the FE cards in my VFET amp. The Marauder and Dreadnought cards have a default gain of 6.1, or 15.7 dB. Bulwark by default has a gain of 5 from the Edcor, but can be adjusted for higher gain. My gain adjustments may be found here.
I built two versions of the Bulwark FE – one with Edcor and one with Jensen iron. The Jensen sounds very good. It required a special mezzanine board to make the connections. Perhaps more work than many are willing to take on, but I found the effort to be worthwhile.
Listening to my new OPA551 buffer card driving the Edcor in my M2x has been a fun and informative experience. The detail and transparency have been somewhat surprising. So the Edcor is not to blame for anything lacking in the sound of either the M2x or the VFET.
I built two versions of the Bulwark FE – one with Edcor and one with Jensen iron. The Jensen sounds very good. It required a special mezzanine board to make the connections. Perhaps more work than many are willing to take on, but I found the effort to be worthwhile.
Listening to my new OPA551 buffer card driving the Edcor in my M2x has been a fun and informative experience. The detail and transparency have been somewhat surprising. So the Edcor is not to blame for anything lacking in the sound of either the M2x or the VFET.
The LPS is in operation. I would to report that the result is extremely positive. My observation is that it would take the amp from a very good one to an outstanding one. The key improvements are in the sound stage and instrument image rendering. The sound stage is deeper, and layering of an orchestra more apparent. There is more air around each instruments and the image of them are more 3D. The overall image is less dark, meaning more transparent. Micro-dynamic is also improved.
I highly recommend those who want to extract the best performance out of this beautiful amp to put the effort in to build a LPS, preferably dual mono setup.
I highly recommend those who want to extract the best performance out of this beautiful amp to put the effort in to build a LPS, preferably dual mono setup.
Is anybody interested in purchasing my round #1 lottery amp? I’m just looking to get what I paid for it ($525) and whatever it costs to ship. Honestly, it’s a superb amplifier, but I have a few superb amps and I find the Sony collecting some dust. Makes more sense to pass along to someone who’ll get more use out of it.
I have a strong preference to stick with a buyer in the US, but am open to shipping wherever - just know that you’ll be paying whatever shipping costs and assuming all the risk.
If you’re interested, please send me a PM. I’ll go based on the order I receive them. Replies in this thread won’t count.
ps. I realize a post like this makes more sense in the swap meet, but I wanted to give dibs to those in the Pass forum.
I have a strong preference to stick with a buyer in the US, but am open to shipping wherever - just know that you’ll be paying whatever shipping costs and assuming all the risk.
If you’re interested, please send me a PM. I’ll go based on the order I receive them. Replies in this thread won’t count.
ps. I realize a post like this makes more sense in the swap meet, but I wanted to give dibs to those in the Pass forum.