Hi,
Aksa is right about many views and he might also be right about where to put the comp.
Play it safe and put in the tracks to allow either form of local feedback. They are quite close to each other and should be easy to swap over the cap lead. Cap values will be similar but aim to find the MINIMUM to ensure stability in either set up. Then compare sound quality.
Aksa is right about many views and he might also be right about where to put the comp.
Play it safe and put in the tracks to allow either form of local feedback. They are quite close to each other and should be easy to swap over the cap lead. Cap values will be similar but aim to find the MINIMUM to ensure stability in either set up. Then compare sound quality.
Hi Brion,
Sorry I've been busy. A few suggestions have been mistranslated.
The emitter resistors of the Vas and it's current source need to be transposed i.e. 56<->100.
The Vas Ccb needs to be 15pF, no feedback C, and 47pF from Vas collector to input feedback (base) point.
Some input stage emitter degen, say, 100R each leg would be good. I doubt there's any need for the 2 diodes in the multiplier.
Hugh,
I only suggested the RC on the Vas current source as a dethump -not for filtering.
Cheers,
Greg
Sorry I've been busy. A few suggestions have been mistranslated.
The emitter resistors of the Vas and it's current source need to be transposed i.e. 56<->100.
The Vas Ccb needs to be 15pF, no feedback C, and 47pF from Vas collector to input feedback (base) point.
Some input stage emitter degen, say, 100R each leg would be good. I doubt there's any need for the 2 diodes in the multiplier.
Hugh,
I only suggested the RC on the Vas current source as a dethump -not for filtering.
Cheers,
Greg
Hi thanh,
I would consider 10K a bare minimum value for input impedance as it is the load on the previous equipment - preamp or CD player many of which are specified into 10K or more. A lower input impedance for the power amplifier will load these more heavily ( i.e. draw more current ) and may cause an increase in distortion or limiting.
Of course, if your source equipment is buffered you may well be OK with 4K7!
Cheers,
Greg 😉
I would consider 10K a bare minimum value for input impedance as it is the load on the previous equipment - preamp or CD player many of which are specified into 10K or more. A lower input impedance for the power amplifier will load these more heavily ( i.e. draw more current ) and may cause an increase in distortion or limiting.
Of course, if your source equipment is buffered you may well be OK with 4K7!
Cheers,
Greg 😉
See the thread about GM's new GEM amplifier for some comments about low input impedance... the GEM is 600 ohm.
> I own a 100 Watt rack mount Traynor (PA system) amp ... building two just like it for a project.
Traynor, like many tube-amp companies, stumbled going into the Brave New World of transistors. This isn't the worst amp I've seen, but it sure is over-complicated, as if they had to keep hacking at it to make it "work". (Traynor built some sweet 2x6BQ5 tube bass amps, with none of this tomfoolery.)
You can buy perfectly-good lightly-dented second-hand PA amps, mostly of much better design than this old beast, for less than you can buy the DIY parts. You can buy new-in-box warranteed 2X100W amps for not much more than parts-cost, unless you are very clever in shopping surplus. My DIY power-amps always smoke a few parts before I get the big bugs out; new-in-box amps usually won't smoke on the bench or in the nightclub, even when abused.
Random examples:
Gem Sound XP-350 Stereo Power Amp Sale Price: $99.99 100W @ 8 ohms stereo, and 175W @ 4 ohms stereo. (Fan may be loud)
Nady XA-900 Pro Stereo Power Amp Sale Price: $179.99 400W/ch @ 2 ohms, 300W @ 4 ohms, 200W @ 8 ohms
Crown XLS 202 2-Space Custom Amp Sale Price: $269.00 delivers 250W/ch @ 2 ohms, 200W @ 4 ohms, 145W @ 8 ohms, 500W bridge mono @ 4 ohms.
I am not affiliated with these companies (never even heard of Gem Sound), nor with Musician's Friend except as an occasional mostly-satisfied customer. These "sales" are nothing special; all the mega-box-stores will have similar prices on similar boxes, and occasional move-em-out sales like that $99 price.
I like DIY, but yet-another-power-amp, with nothing special about it, is IMHO too much work, too much smoke, and at best it "just works". I like DIY when I get something unique, or save a bunch of cash.... Traynor-cloning isn't my cup of tea.
Traynor, like many tube-amp companies, stumbled going into the Brave New World of transistors. This isn't the worst amp I've seen, but it sure is over-complicated, as if they had to keep hacking at it to make it "work". (Traynor built some sweet 2x6BQ5 tube bass amps, with none of this tomfoolery.)
You can buy perfectly-good lightly-dented second-hand PA amps, mostly of much better design than this old beast, for less than you can buy the DIY parts. You can buy new-in-box warranteed 2X100W amps for not much more than parts-cost, unless you are very clever in shopping surplus. My DIY power-amps always smoke a few parts before I get the big bugs out; new-in-box amps usually won't smoke on the bench or in the nightclub, even when abused.
Random examples:
Gem Sound XP-350 Stereo Power Amp Sale Price: $99.99 100W @ 8 ohms stereo, and 175W @ 4 ohms stereo. (Fan may be loud)
Nady XA-900 Pro Stereo Power Amp Sale Price: $179.99 400W/ch @ 2 ohms, 300W @ 4 ohms, 200W @ 8 ohms
Crown XLS 202 2-Space Custom Amp Sale Price: $269.00 delivers 250W/ch @ 2 ohms, 200W @ 4 ohms, 145W @ 8 ohms, 500W bridge mono @ 4 ohms.
I am not affiliated with these companies (never even heard of Gem Sound), nor with Musician's Friend except as an occasional mostly-satisfied customer. These "sales" are nothing special; all the mega-box-stores will have similar prices on similar boxes, and occasional move-em-out sales like that $99 price.
I like DIY, but yet-another-power-amp, with nothing special about it, is IMHO too much work, too much smoke, and at best it "just works". I like DIY when I get something unique, or save a bunch of cash.... Traynor-cloning isn't my cup of tea.
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