I think the problem I'm having here is that you are dismissing single-ended amps on the same kind of evidence with which some people hear differences in cables. I don't share the same experience as you concerning the performance of SET amps.
Opinions are shaped by any number of prejudices, among the most obvious is when people read about superior equipment specifications or the technical aptitude of the designer - they are inclined to favor that equipment. The best example I can think of is the system developed by Siegfried Linkwitz. A good many people who followed his writings found it to be a great sounding set-up. I and many of my friends, despite preconceived enthusiasm, found it to be among the nastiest sounding things we've ever heard.
Perhaps the same thing may be true for something designed by the otherwise estimable Morgan Jones.
John
Opinions are shaped by any number of prejudices, among the most obvious is when people read about superior equipment specifications or the technical aptitude of the designer - they are inclined to favor that equipment. The best example I can think of is the system developed by Siegfried Linkwitz. A good many people who followed his writings found it to be a great sounding set-up. I and many of my friends, despite preconceived enthusiasm, found it to be among the nastiest sounding things we've ever heard.
Perhaps the same thing may be true for something designed by the otherwise estimable Morgan Jones.
John
I've only heard the SL speakers in one venue- wasn't impressed, but they were being driven pretty hard. SETs, on the other hand, I've heard dozens of, all sorts of price points, all sorts of output tubes, with lots of different speakers, and in lots of different places. Very consistent sound to me. You may like that sort of high coloration (that's an objective, measurable fact), many people do, but I don't. Chacun a son gout.
I'll second that as I have a pair of FE167 in half chili chang cabinets and I am definitely not a fan, and anything based on a driver like this is at least 10dB shy of the efficiency required for decent performance with a small SE amp.
Hi, I build 6528 SE last two year for my friend. It was a good sound amp.
I used 5842 as a driver and 3B22 as a rectifier tube.
Yoss, that is a very nice amp!
What operating points and opt did you use?
I may have to test both SE an PP in my test bench and decide if i do like the sound of the SE for this tube.
Alfredo
In a properly implemented SET system the amp is putting out less than .1% distortion at normal listening levels (90dB) and about 1% or 2% on 102dB peaks. If you can hear that kind of distortion compared to a push-pull amp that reduces the even-order components and is putting out .01% distortion at normal listening levels, then I salute you.
John
Oh no, not a PP/SE war again. They just sound different - like single coils pickups sound different from humbuckers in electric guitars. I don't think distortion levels is the key to understand the difference, but don't ask me what it is - I suspect it's because they have different circuits and output transformers. I love my PP triode amp and I'm not going back to SE, but I respect all opinions. Different strokes for different folks with different speakers.
I love my PP triode amp and I'm not going back to SE, but I respect all opinions. Different strokes for different folks with different speakers. I used B+ 250-260V, bias by 240 ohm cathode resistor. Cathode current is 90-95 ma ane grid voltage is 22-25V aproximately. The OPT primary impedance is 1-8-2.0K, this amp use 1.8K but another I've design is 2.0K.
Do you think using high impedence OPT (1.8K rather that typical 1K) will help damping factor? Can this 6528 SE amp drive reference speaker like B&W Matrix 810?
Yes, Higher impedance, better damping factor. I also use OPT 2.5K OPT for my ED8000 SE. I just change from 1.5K, the result is lower power but better speaker control. Please note that ED8000 has plate resistant only 250ohm but I use 2.5K OPT.
My friend use this 6528 amp with Monitor Audio BR5, it work very well. For B&W I never try but I think it will not big difference from another SET amp like 2A3 or 300B.
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This is what I am after, finding out what the right driver is. I think there may not be enough experimentation with these tubes and therefore very little information about the optimal tube choices.
Is there such thing as a quick reference list with distortion scales for different driver tubes (triode)?
Alfredo
Those curves look sweet.
From my personal experience - these types of tubes work best at high current low plate voltage, and run as class A PP (single valve per channel). This will give you about the same watts- but they are likely to be cleaner when driven beyond a watt or so. In this configuration they can beat 300B SE amps hands down. Good gain of 9, but self splitter is not the best way to go as the sides tend to be highly variable.
I might consider selling my Granny to get my hands on some lol.
Shoog
From my personal experience - these types of tubes work best at high current low plate voltage, and run as class A PP (single valve per channel). This will give you about the same watts- but they are likely to be cleaner when driven beyond a watt or so. In this configuration they can beat 300B SE amps hands down. Good gain of 9, but self splitter is not the best way to go as the sides tend to be highly variable.
I might consider selling my Granny to get my hands on some lol.
Shoog
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I prototyped the class A self splitter in my bench with a regulated power supply running B+ at 240 and the 317hvt current source at 250ma. It sets the bias point at close to -20v.I used a 25 ohm pot to balance the current in both tubes. I used a 100w power toroid transformer as opt that gives me 9800 ohm p to p. I checked the frequency response into a 8 ohm load at 1 watt. The lows are low, -3db at around 5 hertz with visible distortion, at 25 hz it is full level without visible distortion. The 3db rolloff at high frequency is at 110khz.
Also put a square wave at 1khz and the output is a perfect square wave.
I will be building the amp soon, think i will create a new thread on the build.
Alfredo
Good to hear. I like the idea of a self splitter, but prefer the reality of a LTP - just my choice.
Something to consider when using the toroidal is that they tend to have better response when the primaries are wired in one direction rather than the other. This is especially true of low frequency roll off and distortion.
In class A PP you shouldn't achieve any advantage with a regulated power supply. I would be inclined to run more current within their limits - but that just me again.
I will be very interested in how it all pans out.
Shoog
Something to consider when using the toroidal is that they tend to have better response when the primaries are wired in one direction rather than the other. This is especially true of low frequency roll off and distortion.
In class A PP you shouldn't achieve any advantage with a regulated power supply. I would be inclined to run more current within their limits - but that just me again.
I will be very interested in how it all pans out.
Shoog
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Thanks Shoog,
The reason i am trying out the self split is because i will try driving the amp directly from my preamp that puts out 10vrms. This way there are no caps and only two 6528 tubes.
I am going with a non regulated linear supply, i have a monster toroidal that i found at my local surplus, it is a 100/120/130 to 115 @ 2.75 amps in a voltage doubler configuration. Also have a 500ma choke laying around.
Alfredo
Hi Audiocarp,
Here are a couple of links.
DIY ECC802S SRPP / EL84 (6BQ5) Push-Pull Tube Amplifier
Oddwatt Push Pull Amplifier Proyects