I guess I'm a little late but when stuff that relates to you is going on in another universe or a tenth planet or a "joke" conscience then whenever you participate is not too late. Sorry for the long sentence from now. And hope I'm not too late
The ZCA has an extensive following, how big, I'm not sure. Almost weekly someone from some forum sends me an e-mail to ask about the ZCA. Everyone who builds one (if the stays true to the ZCA formula) is extremely pleased with and often shocked by, how good they sound.
The joke is on the builder who builds a ZCA to prove the amp is no good. But the pain is quickly forgotten as they listen to and appreciate the sound of this very simple amp. Especially when driven by a tube preamp. Excellent combo!!
It is very low powered, about 5W, it may not tolerate low impedance speakers, it will not work with low efficiency drivers, its bass may not be the tightest heard. The mid range though will shock you, think of a simple SET amp, treble smooth and extended. It has extreme transparency, good sound stage and stereo image but it runs as hot as the devils own amp.
These days I build SET amps. The ZCA introduced me to simple 0NF amps that made all acoustic instruments and voice sound good. I had an idea (in the ZCA) and I went for it. Others and myself are glad I did. Prove me wrong.
The ZCA has an extensive following, how big, I'm not sure. Almost weekly someone from some forum sends me an e-mail to ask about the ZCA. Everyone who builds one (if the stays true to the ZCA formula) is extremely pleased with and often shocked by, how good they sound.
The joke is on the builder who builds a ZCA to prove the amp is no good. But the pain is quickly forgotten as they listen to and appreciate the sound of this very simple amp. Especially when driven by a tube preamp. Excellent combo!!
It is very low powered, about 5W, it may not tolerate low impedance speakers, it will not work with low efficiency drivers, its bass may not be the tightest heard. The mid range though will shock you, think of a simple SET amp, treble smooth and extended. It has extreme transparency, good sound stage and stereo image but it runs as hot as the devils own amp.
These days I build SET amps. The ZCA introduced me to simple 0NF amps that made all acoustic instruments and voice sound good. I had an idea (in the ZCA) and I went for it. Others and myself are glad I did. Prove me wrong.
well ...Mark yes your amplifier is more or less what you describe... generally though i belive that you get all those emails cause the title ZCA and the concept arround it is CATCHY !!!!!!
other than that yes the amp is what you say ...under the specific set up it can really play very well .. though consuming this power for this result is an issue , preamp demands is an issue , choise of speakers is an issue ...and goes on and on ...
Dont be surprized of what i say i even had to answer to some kid in a Greek forum that constructed something that was based on the ZCA idea ( after copying your articles)he liked it only the problem was that he was looking for a list of mods to upgrade it to a 200W version
Look how many times forum members had to put back on the right track people ( unfortunatelly me also ) that constructed the smoking machine and sorry excuse for an amplifier from John Fisher ( indeed a very nice guy ) just because it had a CATCHY title
SIMPLE 150W AMPLIFIER
happy regards sakis
other than that yes the amp is what you say ...under the specific set up it can really play very well .. though consuming this power for this result is an issue , preamp demands is an issue , choise of speakers is an issue ...and goes on and on ...
Dont be surprized of what i say i even had to answer to some kid in a Greek forum that constructed something that was based on the ZCA idea ( after copying your articles)he liked it only the problem was that he was looking for a list of mods to upgrade it to a 200W version
Look how many times forum members had to put back on the right track people ( unfortunatelly me also ) that constructed the smoking machine and sorry excuse for an amplifier from John Fisher ( indeed a very nice guy ) just because it had a CATCHY title
SIMPLE 150W AMPLIFIER
happy regards sakis
small but musical...
My lil ZCA amp playing music passionately. Does cough with my 94dB 4Ohm speakers at louder volumes, but great for late night listening. Super deep bass is present but offers less control compared to my other amps (P3A and Aussie Amps nxv200). Midrange is special for vocals and piano.
My lil ZCA amp playing music passionately. Does cough with my 94dB 4Ohm speakers at louder volumes, but great for late night listening. Super deep bass is present but offers less control compared to my other amps (P3A and Aussie Amps nxv200). Midrange is special for vocals and piano.
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The ZCA is a rare beast. Yes all 5W of it. I’m yet to hear from anyone who has built one (to the ZCA formula) and are not extreme pleased with the result. Please let us know how it goes.
Take the Zen, and move a step backwards in sophistication by replacing the current source with a 30W space heater .. er.. resistor, and you have the ZCA.
"but I wanted to go beyond Zen"
Well, you ended up behind it. Back to its roots if you like.
Conceptually the big brother of the Szekeres headphone amplifier.
Primary virtue is extreme foolproof-ness. Will not oscillate, will not blow your speakers, no need to match parts or do any tricks whatsoever. It will also sound perfectly fine if used within the power envelope. Which for 0.8 A bias as shown, into 6 ohms, is about 1 W at best. Last but not least they are cheap and easy to build.
Downside is the extreme inefficiency. About 45-50 W all told, for 1 W+1 W output. Also has a large, persistent 2nd harmonic as a result of the very high loading. Pleasant but unrealistically 'fat' sound, exacerbated by the enormous output coupling cap needed. Finally, lousy PSRR.
Personally I think these types of designs are better down-scaled as headphone amplifiers. The same benefits for fewer headaches, thermal or otherwise. As a desktop amplifier / coffee mug warmer however, it might also hold promise...
"but I wanted to go beyond Zen"
Well, you ended up behind it. Back to its roots if you like.
Conceptually the big brother of the Szekeres headphone amplifier.
Primary virtue is extreme foolproof-ness. Will not oscillate, will not blow your speakers, no need to match parts or do any tricks whatsoever. It will also sound perfectly fine if used within the power envelope. Which for 0.8 A bias as shown, into 6 ohms, is about 1 W at best. Last but not least they are cheap and easy to build.
Downside is the extreme inefficiency. About 45-50 W all told, for 1 W+1 W output. Also has a large, persistent 2nd harmonic as a result of the very high loading. Pleasant but unrealistically 'fat' sound, exacerbated by the enormous output coupling cap needed. Finally, lousy PSRR.
Personally I think these types of designs are better down-scaled as headphone amplifiers. The same benefits for fewer headaches, thermal or otherwise. As a desktop amplifier / coffee mug warmer however, it might also hold promise...
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Ziggy has done it and reports that it sounds like a ZCA on steroids.
See here.
The ZCA loves a fairly benign impedance curve and an overdamped bass alignment. Very pleasing to listen to.
Very quick and dirty ltspice sim, with the IRF510 subbing for the 2SK1056.
My earlier guestimate was pretty much on the money - there is about 1 watt of reasonably clean output, with a 6dB or so of 'soft clipping' headroom above that before things get horribly distorted. 2nd harmonic is high, but as is typical for these circuits there are relatively few higher order components.
My earlier guestimate was pretty much on the money - there is about 1 watt of reasonably clean output, with a 6dB or so of 'soft clipping' headroom above that before things get horribly distorted. 2nd harmonic is high, but as is typical for these circuits there are relatively few higher order components.
Just an update to this thread (which I only stumbled across) try reducing the input cap to something like 0.1uf. Use a quality metal film of course. I developed the next ZCA called the MCA - Minimal component amp. I wanted to use a bipolar as the power device and get away from FETs.
What I tried and luckily worked was using a jFet, 2SK170, driving a 2N3055 in a darlington pair configuration. The PS and bias setup is exactly same so you could even build the ZCA and MCA in the one case and have switch to chose which amp you want play.
What I did discover when prototyping the MCA is that the input cap only needs to be 0.1uf. When made bigger the square wave at 1KhZ rounded heavily on the leading edge. No one has built a stereo MCA as of yet. If anyone is interested I will post the schematic. You could be the very first to build a MCA. Under the CRO the MCA way outperformed the ZCA and sounded punchy. It did only produce a watt or so, so bare that in mind.
I hope to go back to the MCA because I think I may be able to get about 2W from it.
What I tried and luckily worked was using a jFet, 2SK170, driving a 2N3055 in a darlington pair configuration. The PS and bias setup is exactly same so you could even build the ZCA and MCA in the one case and have switch to chose which amp you want play.
What I did discover when prototyping the MCA is that the input cap only needs to be 0.1uf. When made bigger the square wave at 1KhZ rounded heavily on the leading edge. No one has built a stereo MCA as of yet. If anyone is interested I will post the schematic. You could be the very first to build a MCA. Under the CRO the MCA way outperformed the ZCA and sounded punchy. It did only produce a watt or so, so bare that in mind.
I hope to go back to the MCA because I think I may be able to get about 2W from it.
If you like SE class A with super sound quality, give this one a try..... It is NOT my design, it's a modification of the Nelson Pass Amp Camp Amp. I changed the input Jfet to P-cannel, so it can be fed with symmetrical supply, and entirely DC coupled (well except the low freq. limit introduced by C1). It is dead stable (running without any readjustment for 3 months). Idle current should be set to about 1A with R9, power supplies must be well filtered (now mine is using 2x33.000 uf + a simple darlington based capacitance multiplier). Its output with +/- 12V is around 5 Watts , and let me tell you, this must be cleanest 5Watts I've ever heard..... In the past I tried , (built, listened) at least a dozen similar SE amps, but this one beats them all.
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