PS evaluation

[fdegrove]

Hi,

It's based on the WE 91 amp and it has a 6sj7 in it.

Actually it's almost an exact copy of the Japanese Anzai 300B Zaika amp which predates the one by Angela by about 20 years.

I've heard it a few times while in Paris and can't say I was impressed.

The only 300B SE amp that I liked so far was a Kondo design...

There's one small drawback though: it costs a fortune.

Brett's right though, the 300B is a lazy valve unless you grab it by the you know what...

Cheers,

[HeadSh0T]

The one I posted isn't any more complicated, and actually has the capacity to drive the 300B grid properly.

I was referring to the ones in the link. But I agree that the SV83/300B schematic is worth trying and seems easy enough.

Maybe they like the 30's mantle radio sound.

I don't.

Actually it's almost an exact copy of the Japanese Anzai 300B Zaika amp which predates the one by Angela by about 20 years.

Really? But of course, Angela has to use weird component values which only Angela seems to sell.

Brett's right though, the 300B is a lazy valve unless you grab it by the you know what...

I'm glad you guys told me this. I've only heard good things about the 300B and most designs I've seen are using 6sn7, 5687, 6sj7, etc.. I did not realize that 300B was such a tough one to drive.

I hope it turns out well.

[Saurav]

Trust Brett and Frank on this one I built a 2A3 SET design from the Angela website that had a 6SL7 SRPP driver stage. Then I took Brett's advice and changed my driver to a CCS loaded ECC99. The difference was... well, let's put it this way, that one change taught me a lot

[Brett]

Originally posted by HeadSh0T
I was referring to the ones in the link. But I agree that the SV83/300B schematic is worth trying and seems easy enough.

There's not that much more involved in the Amity amps, but they will sound a hell of a lot better than any SET. My point for linking it was to show distortion and driver design roughly the way I see it should be done.

I'm glad you guys told me this. I've only heard good things about the 300B and most designs I've seen are using 6sn7, 5687, 6sj7, etc.. I did not realize that 300B was such a tough one to drive.

I hope it turns out well.

Until you hear the difference, it's hard to describe, but not at all hard to hear.

[Positron]

I read the Lynn Olsen article for about the 4th time, and I would say some of it is utter nonsense. I would be careful about believing everything he says.

[Brett]

Originally posted by Positron
I read the Lynn Olsen article for about the 4th time, and I would say some of it is utter nonsense. I would be careful about believing everything he says.

Be specific

[Positron]

1st, I have performed alot of research, and found, in my opinion, some of what he says to be without merit. I think he needs to do alot more research before making some comments.

2nd, "(Although the familiar 6DJ8/6922/E88CC has low plate impedances, it also has relatively high third-harmonic distortion)".

Generalizations: it depends on the design and brand tube. He needs to update his page and keep it current.

3rd. "This is why I feel that linearity right at the device level is the most important quality of an amplifier; this preference comes from my background in speaker design, where driver build quality sets the upper limit on the sonic potential of the entire system. In a similar way, the amplifying elements themselves set the upper limit on the sonics of the system."

In my opinion, parts selection is more important as there are many more parts than tubes. There combined distortions are much more pronounced. With that said, the brand of tube does make a difference, but minor sonic problems can be corrected.

4th, "Matt Kamna also demonstrated a technique for zooming in on the waveform on the power-transformer secondary (about 10V/div on the scope screen). The rough appearance around the zero-crossing was very obvious with solid-state diodes. HEXFRED's gave a small improvement, but conventional tube rectifiers looked much smoother, and the TV damper diodes were by far the smoothest of all. So even in low-current preamp applications, TV damper diodes give the least noise. I know from experience in the Tektronix Spectrum Analyzer division that it's much easier to eliminate noise at the source than filter it afterward. If there was an even quieter device, I'd use that, but as far as I know, TV damper diodes are the quietest from the viewpoint of switching noise."

So, I use SS rect and don't have any noise problem affecting the sonics. Again it is the design. Making generalizations isn't necessarily good.

5th. I would never use trannies in the signal path in a preamp. Limited bandwidth, distortion, phase shift problems. My preamp doesn't use one and it "sounds" like "nothing", just like a straightwire/original sound entering it leaves it. When there is a sonic problem, I know it is elsewhere in the audio system; either the amp, speakers, source, or accessories.

6th. "None (capacitors) are as transparent as a good transformer, although the very finest caps ... Auricap, Teflon, Jupiter ... get the cap-coloration down to acceptable levels. "

That is not really true in my opinion. Transformers color sound and aren't a straight wire in sonic performance. They also cause elliptical loadlines, and greater distortion at low frequencies. And different brands sound different too. And there are caps that clearly beat the brands he mentions. But I ain't tellin which brand (s). They sound just like straightwires.

7th. "Gary Pimm, Gary Dahl, Bud Purvine and I are working together on the Aurora Mark II, an amplifier that combines features of the Amity, Raven, and the first version of the Aurora. Personal communications from John Atwood, of One Electron, indicate the triode-connected 6W6 family of tubes would also make superb PP drivers, without the hassles of hum-balancing 2A3 filaments - less power consumption too, not a bad thing in an amplifier of this size."

Why would one focus on lowering distortions and then mention trying one of the highest distortion tubes ever made, the 6W6?

8th. "The triodes that were the most popular in the Fifties (12AX7, 12AU7, 12AT7, and 6DJ8) were not in fact the most linear available."

Somewhat true. the best 6922s are much much better sounding than 6dj8s and others. In fact I use them to make one of the best preamps in the world. They also have a much better frequency response and less phase shift than the older tubes. Of course one could use negative feedback at the higher frequencies to extend the frequency response of those older tubes.

9th. Why use capacitive or transformer coupling when DC coupling sounds better than either?

10th. "Since the circuit is built around intrinsically linear devices, feedback is not required, which also sidesteps problems with phase margin and stability with complex and nonlinear loads..."

I thought phasing margin problems resulted from a lack of good frequency response and linearity reduces distortion?

11th. " Perhaps more important is adequate current and low output impedance in the driver. Much of the amplifier coloration is actually in the driver, and is a result of not enough current to properly charge the grids of the output tubes. I give Arthur Loesch credit for pointing out that the "sound" of different DHT output tubes is greatly exaggerated by not having enough current in the driver. With enough current, DHT's become more transparent sounding and begin to lose the characteristic colorations they are known for. This implies that grid current is present during much of the duty cycle and is quite nonlinear. The more current available and the lower the source impedance, the less important this grid-current nonlinearity will be."

Fine, but if 7ma isn't good enough, 70ma will only produce, maybe a 20 db improvement. For 40db improvement, one may need 700ma. Still a problem. I guess a help, but still a problem.

12th. "The capacitive load the output tube presents to the driver changes the load-line into an ellipse, which pushes the driver into it's nonlinear low-current region - once per cycle for a SE amp, twice per cycle for a PP amp."

Interesting in that IDTs have similar capacitances and nothing is mentioned about them having this problem. Frequency would have to be quite high for pf to have such an inpact. For example, a 100pf load at 100khz has 15900 ohms reactance. Only with higher Rp tubes would this be a problem.
And then why use transformers with similar problems?

13th. "There Is No Best. Get the idea out of your head. This is a pernicious and ugly myth propagated by greedy marketers and lazy magazine reviewers. The entire notion of an "Absolute Sound" is false. Absolute to who? To some self-appointed "expert" who knows how to write and publish a magazine? Don't be fooled."

"Trust what you hear; people really do hear different things, and your perceptions are unique to you. I've been in high-end audio for thirty years now, and I've only found a handful of people who hear things the same way I do. Audio perceptions are every bit as individual as food preferences or your idea of the best lover or life companion; why should you take the guidance of a stranger you've never met? Listen for yourself, get out of the stores and hi-fi shows, and hear what's going on with the more adventurous builders. You'll be surprised."

This is interesting and full of nonsense in my opinion because even though everyone listens and hears differently, a perfect system would reproduce exactly what each was concerned with at the live event.
In otherwards, if one likes the highs at the live event, a perfect system at home would produce those same exact highs. So he is satisfied.
If another concentrates on the strings, then the perfect system would reproduce those exact same strings just as he heard them at the live event. Thus he would be happy.

The perfect system would be totally "neutral" and each set of ears would hear the exact same thing from the system as they heard at the live performance. And all would be happy.

Now, you are thinking no system is perfect. BUT, there are systems that are closer to the live event than others (and some that may tie). Now, if the Near perfect system "A" doesn't emphasis one particular portion of the music the listener concentrates on, but is more accurate with all the other parameters than system "B", than "A" is clearly more accurate than "B". (If he wants system "B" no problem, that is his choice.) But since system "B" sounds better in one particular aspect does it mean that system "B" is actually better than "A". Of course not. (Remember, "there is no best system" type of talk can be used to market products too. It is a trick I have already seen done.)

There are many parameters that determine the quality of a system, not just one or two. Some systems are better, more accurate, than others about reproducing the original event, no doubt about that. So I think he is quite wrong.

All in all, I think he makes some good points and also some poor points that need correcting.