Harmonic profile is only one part of design. It can also indicate problems in the amp. I may be fretting over harmonic profile right now but I can't learn everything at once...
I'd be happy to listen to those amps but probably will never get to.
It's painfully obvious to me right now the affect speakers and sources have on the sound. I have no consistent way to judge the sound of anything, because I'm afraid of blowing my hi-fi speakers out with DIY projects, and all my other speakers are magnitudes worse. My soundcard is very noisy and distorts heavily at anything above 30% volume and headphones, my CD player distorts heavily into anything and is very noisy, my house has no grounded outlet, etc.
Designing an amp with .00001% THD is not practical if the signal source is not as clean. And maybe once in a blue moon you will find something with THD this low. So really, the amp's THD might be indiscernible above the source's THD. So for the moment it seems the amp's primary function is to control the speaker correctly and handle severe loads with ease. Or, perhaps, to soften up issues found in the rest of the chain...
As far as Cdom... It should have been obvious to me that Cdom refers not to a topological thing, but the function of the component.
- keantoken
I'd be happy to listen to those amps but probably will never get to.
It's painfully obvious to me right now the affect speakers and sources have on the sound. I have no consistent way to judge the sound of anything, because I'm afraid of blowing my hi-fi speakers out with DIY projects, and all my other speakers are magnitudes worse. My soundcard is very noisy and distorts heavily at anything above 30% volume and headphones, my CD player distorts heavily into anything and is very noisy, my house has no grounded outlet, etc.
Designing an amp with .00001% THD is not practical if the signal source is not as clean. And maybe once in a blue moon you will find something with THD this low. So really, the amp's THD might be indiscernible above the source's THD. So for the moment it seems the amp's primary function is to control the speaker correctly and handle severe loads with ease. Or, perhaps, to soften up issues found in the rest of the chain...
As far as Cdom... It should have been obvious to me that Cdom refers not to a topological thing, but the function of the component.
- keantoken
Keantoken thats why audio is so intriguing, when you think you have it all worked out something comes along along and unwinds everything again.
Has someone done THD figures that low, i dont think its possible as yet. I strive for the very lowest THD too but with a eye on the spectrum. With todays design ideas and components its possible having lower THD figures than self blameless amps and using less parts. Using transconductance stages I can easily manage between .0003 and .003 figures THD20 but lower i dont know,what bigun is striving for is what I will be spending some time on too when I can find it, crossover distortion, this is a big nasty and hard to overcome but vital if better figures are to be had.
Has someone done THD figures that low, i dont think its possible as yet. I strive for the very lowest THD too but with a eye on the spectrum. With todays design ideas and components its possible having lower THD figures than self blameless amps and using less parts. Using transconductance stages I can easily manage between .0003 and .003 figures THD20 but lower i dont know,what bigun is striving for is what I will be spending some time on too when I can find it, crossover distortion, this is a big nasty and hard to overcome but vital if better figures are to be had.
I was discussing privately with Bigun about that (no need for secrecy, but I don't want to clutter up the forums with ideas until someone decides to try and apply them), I have an idea which may show promise. Maybe we could work together.
- keantoken
- keantoken
I dont know what youve guys have tried to far, Im playing around with feedforward and combining classes like in high bias AB with class C which is showing the best results so far, thats spice only and will have to be built to check the results. Crossover distortion is not easy to address, I hope I have the patience for experimentation.
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Mixed class - sounds interesting - last time I looked at this was Broskie's blog, but I didn't get good results from my own efforts at sims from it. I heard Wavebourn does some good mixed class amps. What kind of topology are you playing with ?
p.s. your avatar (fly riding a bike) cracks me up !
p.s. your avatar (fly riding a bike) cracks me up !
Thats where i got the idea to explore the mixed classs, from broskie s blog problem is spice is very inaccurate, I have to make some time to build it and to make some real measurements but according to his findings it looks promising. I have adapted the feedworward idea by renardson too into a normal ef design, a third which seems promising is a buffer ive used for years now except in small signal circuits, similar to DB but the inputs are common base, it works into class a till a determined bias which you can set but and then goes class ab at higher currents, it seems to avoid by some degree gm doubling problem and crossover is cleaner, kinda works like blomleys design and is very close circuit wise.
The fly cracked me up too, thats why I couldnt resit the temptation to use it here, I found it on a site with jokes on it, some distraction from work is always welcome to me.
Wavebournes designs I dont know too well, but I built a little simple headphone amp of his which he showed here some years back which is great little amp, when I listen to classical music its my preffered choice, for rock and pop I use a current feedback type with jfets.
The fly cracked me up too, thats why I couldnt resit the temptation to use it here, I found it on a site with jokes on it, some distraction from work is always welcome to me.
Wavebournes designs I dont know too well, but I built a little simple headphone amp of his which he showed here some years back which is great little amp, when I listen to classical music its my preffered choice, for rock and pop I use a current feedback type with jfets.
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Well homemodder, sounds interesting, I'll certainly take a look at anything you want to post in more detail.
The 'tubey TGM' is not in my HT system doing a good service. I haven't the equipment to measure it but it's such a simple idea I hope somebody with the gear will try it one day and let me know how it works in the real word as a correlation against the improved sound that I hear.
Simulated, it seems to generate low order even harmonics without a detrimental increase in odd harmonics.
The 'tubey TGM' is not in my HT system doing a good service. I haven't the equipment to measure it but it's such a simple idea I hope somebody with the gear will try it one day and let me know how it works in the real word as a correlation against the improved sound that I hear.
Simulated, it seems to generate low order even harmonics without a detrimental increase in odd harmonics.
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I should have said "...is now in my HT system..." - it's been playing well. But I have also completed my first tube amp and it sounds much better 😉
Actually, I played with A+C class amps. Right combination of nested feedbacks results in more toobey sound than "properly biased" class AB amps can even dream about.
The even-order stuff looks like a bit of full (or half) wave rectified output leaking back to the input. Second harmonic is almost the same % at 16W and 44W.
It should be fairly easy to trim most of that out (or dial some in, as Bigun's doing).
This whole dial-a-distortion thing must be contagious - there's even a thread about it in the tube section now. 😀
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The real BIG surprise for me was not how easy it is to dial in even harmonics to virtually any gnf amplifier, but that my DIY tube amplifier doesn't sound 'tubey'. My no-feedback SET sounds crystal clean, simply wonderful to listen to - there's no 'tube sound' that I could describe to you and so I'm not sure anymore what I'd be trying to emulate with a SS circuit....?
Now I happen to have picked up an ancient tube radio from a junk sale to fix up, maybe this will turn out to have a tubey sound.
Now I happen to have picked up an ancient tube radio from a junk sale to fix up, maybe this will turn out to have a tubey sound.
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