I have driven the F4 into clipping and it sounds pretty clean until clipping, by which point extended listening will cause deafness. The ASR folls are not ready to face reality: THD has nothing to do with sound quality. The fact that higher order harmonics are kept low is far more important than low THD.
Back to the OP's OP: I can probably let you know in a couple months. I have a couple of Aikido 12VAC boards to build up a cute balanced front end (FE) for the F4s. One of my goals is to learn to measure things. But what are you really after? Your line of questioning appears to hint at wanting change. What is it that you are looking for?
Not sure what you are asking. To me, increasing the transparency of a piece of audio electronics would require no increase in noise or distortion. While I have no measurements to show, when I went from Dynaudio BM6 powered monitors to ACAs to F6s to balanced F6s to balanced F4s, every step resulted in less feeling like an amplifier was there.
I have no idea. I saw some posts in that thread that many of the folks deriding the performance were used to line level DAC performance measurements and what was tested was indicative of a good amplifier.
Me, personally, would do nothing to that F4. It is out of production and hand built by Mr. Pass. If you were looking to mod something, I'd buy some boards and make a clone to dink around with. Of course, this is under the assumption that I'd know what I was doing. Currently, I know enough to build a bunch of different FEs to try different flavoring (Glassware Aikido w/ 12AU7, Glassware SRPP w/ 12AU7, Iron Pre, DIY FE 2022, BA3 FE, maybe some of the M2x daughter boards.) Still working up to designing my own low powered Class A balanced amplifier of the 25W/ch variety. These F4s are nice but way overkill given they are pumping out 100W/ch and sucking down around 600W of getting more expensive electricity.
So, what is it that you are itching for?
The current (ha, punny) hypothesis is that the Aikido will be the driver of distortion in that setup. I tend to believe the Aikido will be the distortion driver because of tubes and the lack of noise I hear out of the F4s but until someone builds one and tests it out, an unknown. I'm working on it but I've got a Pearl 3 and a Halcyon Redux ahead of it. That and my Benchmark DAC3 provides plenty of gain as it is in my new (smaller) listening room (so the whole FE experiment got demoted).
Current hypothesis is no, the amplifier's distortion will not be the driver but until someone can build up the chain and test it, it is unknown.
I have not and I'm not aware of anyone that has. But much will depend on the gain circuit that the 6SN7 gets implemented in so if someone is using a preamp based on a 6SN7, sonics will vary depending on the preamp design.
Not sure what you are asking. To me, increasing the transparency of a piece of audio electronics would require no increase in noise or distortion. While I have no measurements to show, when I went from Dynaudio BM6 powered monitors to ACAs to F6s to balanced F6s to balanced F4s, every step resulted in less feeling like an amplifier was there.
I have no idea. I saw some posts in that thread that many of the folks deriding the performance were used to line level DAC performance measurements and what was tested was indicative of a good amplifier.
Me, personally, would do nothing to that F4. It is out of production and hand built by Mr. Pass. If you were looking to mod something, I'd buy some boards and make a clone to dink around with. Of course, this is under the assumption that I'd know what I was doing. Currently, I know enough to build a bunch of different FEs to try different flavoring (Glassware Aikido w/ 12AU7, Glassware SRPP w/ 12AU7, Iron Pre, DIY FE 2022, BA3 FE, maybe some of the M2x daughter boards.) Still working up to designing my own low powered Class A balanced amplifier of the 25W/ch variety. These F4s are nice but way overkill given they are pumping out 100W/ch and sucking down around 600W of getting more expensive electricity.
So, what is it that you are itching for?
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I have this combo and can tell you that 6sn7 will not have enough voltage gain in aikido preamp to drive f4 to full power.
I certainly wouldn’t think of doing any mods on the F4. It was never my intention anyway. I only wanted to confirm whether those who know the most about the amp, beyond Nelson Pass, had ever found ways to improve it. Good to know the answer is no, though I presume that you seriously wish that the F4 could be easily and safely modded to output less power when a pair of them are used in balanced mode!
For years Pierre’s loved the Aikido he built to drive his build of the Sony V-FET power amp.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764 (posts # 15,266, 15, 276).
And as my new speakers will be similar, the Aikido/6SN7, plus perhaps some tube rolling for “voicing”, seems like a very safe bet.
But I’m waiting to hear from Grovegardner, who also built the SP14 (??) preamp.
Thanks for planning to build the Aikido to drive your F4s! And the 6sn7 is often the driver of choice among the most accomplished tube amp designers like Dick Olsher, Lynn Olson, Gary Dahl, et al, though their preamp designs are no doubt very advanced and parts quality is probably prohibitive for most. But at least even new 6SN7 tubes are not crazy expensive, which should leave funds for better quality film caps and more use them in the power supply, as John Broskie recommends for better bass performance.
Grovegardner, who built the Aikido and SP14 preamps (both with 6SN7), said the Aikido does so many things so well, which accounts for its popularity. Posts # 29, 35, 38. https://www.diyaudio.com/community/...or-less-than-great-sounding-cds.408331/page-2 , while not a warm sounding preamp, like the SP14. Post #2. https://www.diyaudio.com/community/...arm-tube-preamp-to-pair-with-pass-amp.384364/
So building either preamp should make for very special aural experiences when driving the F4.
…people who routinely listen at hearing-damaging levels maybe? I dunno.
Anyway, an Aikido and F4 is going to work great.
Anyway, an Aikido and F4 is going to work great.
IMPORTANT! Here's some invaluable design tips from Jayme, post # 4. https://www.diyaudio.com/community/threads/aikido-sound.76933/
Also, after just chatting, Jayme added: I do remember my Aikido sounded best with a big iron power supply. I used CLCLC, with 100uf motor run cans for the second and third cap stage, and big 7H chokes. When i tried CRCRC with even lower ripple, it sounded duller.
🙂
Interesting. In the distant past, I built the 6SN7 based Aikido with a Janus regulator PS. I also built the 12VAC Aikido with 12AU7s. The 6SN7 one sounded more "polite". The 12VAC version had much more of a liveliness. Always made me wonder if it was the PS that made the difference, not just the tube types.
Attachments
https://www.audiosciencereview.com/...rements-of-my-diy-replica-firstwatt-f4.10647/
My F4 into 93db speakers could melt your ears on a fraction of its output. Dont need anywhere near full, 1000sq ft 8 foot ceiling. The upstairs will rumble too….
Fwiw
My F4 into 93db speakers could melt your ears on a fraction of its output. Dont need anywhere near full, 1000sq ft 8 foot ceiling. The upstairs will rumble too….
Fwiw
And it doesnt seem to give two 💩s about impedance either. I use it with a 4ohm pair that no doubt dip wayyy lower and have heard the combo play "earthquake" frequencies.
Remarkable what some people throw in the mix with old analog drum machines....
🙂
Remarkable what some people throw in the mix with old analog drum machines....
🙂
Quite possibly: A good amplifier is like a pyramid. Nine tenths of the amp is really power supply, and one tenth is the audio circuit proper. You want the power supply wagging the audio, rather than the audio wagging the power supply. Our power transformer , for example, could easily run two amplifiers. By overbuilding here, the supply voltage sags very little when large demands are put on the amplifier. http://www.dehavillandhifi.com/Q&Akara_chaffee.htm
Nothing horrible i could see with the ASR measurements. Is it possible to get lower distortion out of a highly biased PP buffer? Certainly, but perhaps difficult within the same physical form factor.
I think most measurement equipment is incapable to source a test signal with the required amplitude and source impedance in order to properly test a unity gain amplifier at full power.
I think most measurement equipment is incapable to source a test signal with the required amplitude and source impedance in order to properly test a unity gain amplifier at full power.
Nor at ~ 7 wpc, a much more common range to be used with >93db/w/m >6 ohm speakers?