one question, i recall EC8010 saying that David Hafler solve some oscillation problems by increasing the coupling capcacitors. the original issue uses a 0.25uf cap and the "revised" a 0.22uf. could i be a smart **** by putting 0.47uf?
I've been searching desperately to find the article (I think it was Hafler), but I just can't seem to find it I have a feeling that the coupling capacitors were made quite a bit bigger, perhaps 1.5uF.
EC8010 said:
Hafler and Keroes, Audio Engineering, reprinted in Audio Anthology v2, "Ultra-Linear Operation of the Williamson Amplifier".
Hacknet
Andy's suggested circuit is much better than a Williamson. That is if you want to build a modern sounding amp and not just something of historical value.
Going as far back as the sixties amp builders noticed the Williamson plays better in mono than stereo. Lots of NFB keeps the sound strictly in the speakers, kills dynamics and soundstaging and together with the excessively repetitive use of 6SN7 produces cold and boring (for a tube amp) mids.
Andy's suggested circuit is much better than a Williamson. That is if you want to build a modern sounding amp and not just something of historical value.
Going as far back as the sixties amp builders noticed the Williamson plays better in mono than stereo. Lots of NFB keeps the sound strictly in the speakers, kills dynamics and soundstaging and together with the excessively repetitive use of 6SN7 produces cold and boring (for a tube amp) mids.
Hi,
As an example:
I have a PP 2A3 amp that uses only local FB, no global loop whatsoever...
The soundstage that little amp can throw is little short of amazing.
With any decent recording you can plunk the speakers down, even only 4-5 foot apart, you just can't tell the sound comes from those speakers.
That's not to say the amp is perfect, it isn't.
For what it cost me however it's a joy to listen to.
Cheers,😉
As an example:
I have a PP 2A3 amp that uses only local FB, no global loop whatsoever...
The soundstage that little amp can throw is little short of amazing.
With any decent recording you can plunk the speakers down, even only 4-5 foot apart, you just can't tell the sound comes from those speakers.
That's not to say the amp is perfect, it isn't.
For what it cost me however it's a joy to listen to.
Cheers,😉
fdegrove said:
Hi Frank, i've been wanting to make a PP 2A3 and been contemplating on the JE Labs PP 2A3. However, I want to try one of yours. Is that at all possible? Share the schematic or is this a commercial amp?
hmm... williamson or not williamson...
i`ll have a look and see what i decide on... the rest look quite game on a williamson.
i`ll have a look and see what i decide on... the rest look quite game on a williamson.
That's not to say the amp is perfect, it isn't. For what it cost me however it's a joy to listen to.>
That's exactly my response to taking off the global feedback loop - joy! The sound just makes you like it - happy pills. Haven't got a clue how this effect measures, but I was just grinning when I heard the sound without feedback. If I'm reading the language correctly, others seem to have a similar response. Not to say that others don't grin when they add feedback - I'm sure this happens too.
That's exactly my response to taking off the global feedback loop - joy! The sound just makes you like it - happy pills. Haven't got a clue how this effect measures, but I was just grinning when I heard the sound without feedback. If I'm reading the language correctly, others seem to have a similar response. Not to say that others don't grin when they add feedback - I'm sure this happens too.
Personally, I prefer vintage iron. 6600 ohms is a pretty common value so should not be impossible to find. Acro, Brooks, and Fairchild are ones I've used with great success.
Any iron? No. The quality of your circuit will be strongly limited by the transformer choice. It's the single most critical component.
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