For what it's worth I can tell you what I think... absolutely the best
Based on listening to many amps over the years
Hi Mooly,
Mr. Borbely says the same and I am beginning to think the same too. Because this I asked to PMA about what he feel on lateral mosfets at output instead bipolar transistors no ragarding price, SOA, etc.....only SOUND QUALITY !
I know this question could belongs to another thread but I wonder if there is a chance to upgrade the sound in his new amplifier.
Thanks
eD
Last edited:
About Bode plots again
Quote from PMA webpage:
"It is a loop-gain, not open-loop gain"
Plots are the same as these in ansfer for my request.
These plots looks as open loop plots, so v(out1)/(R58/R10+1).
In that case amplifier has about 26db feedback at 20kHz.
And at 400kHz there is zero crossing, so about 60deg
phase margin. And little above 1MHz 10dB gain margin.
Then why plots labels says v(out1)?
Is there just 6dB feedback at 20kHz and so on?
I am just little confused
Quote from PMA webpage:
"It is a loop-gain, not open-loop gain"
Plots are the same as these in ansfer for my request.
These plots looks as open loop plots, so v(out1)/(R58/R10+1).
In that case amplifier has about 26db feedback at 20kHz.
And at 400kHz there is zero crossing, so about 60deg
phase margin. And little above 1MHz 10dB gain margin.
Then why plots labels says v(out1)?
Is there just 6dB feedback at 20kHz and so on?
I am just little confused
Last edited:
Just to steal
PMA's design I post a modified design.The main change is the lost of the input differential.
This way the amplifier becomes (IMHO) a current feedback amplifier.
I have not simulated nor built such amplifier.
Is there anybody who tried this amplifier?
Which are the main advantages (and drawbacks) of this different topology?
Attachments
Just to steal
That's funny as i had quite the same idea, inspired from F5.
Attachments
Bobodioulasso and diy_audio_fo that type of circuit has been done quite long ago by the french and japanese, not sure who was first but long before the F5. The F5 is virtually a copy of the french Profet class A amp except the Profet uses lateral mosfets and doesnt have dual feedback like the F5.
Hi all, I am back from my ‚holiday‘.
I would like to thank to stinius, BV, John Curl, Sendy and danhard for clarification of some technical issues and for posting images and links; and also thanks to many others for their support.
I have already answered some of the questions in my website
PA2 power amplifier
especially that concerning open-loop gain and confusion with loopgain. Both only simulated, so not necessarily same as in the real amplifier.
As you can see, I have built a functional prototype and performed some measurements.
During my holiday week, I have been listening to the amplifier. I would describe the sound as:
- overall lack of smear,
- transparent, and detailed soundstage,
- free of unnatural grain,
- the bottom end well depicted,
- bass not overdamped, not overly constrained,
- combination of speed, liquidity, transparency, and creamy purity,
- tonally neutral, detailed in the midrange,
- excellent resolution of subtle, low-level dynamic detail,
- very good imaging and space.
Solid-state amps are usually too bright and hard on top, or too soft and unfocused. This one is just about right, neither etched nor softened, but just far enough on the right side of "silky-smooth" to sound tonally natural.
I have borrowed these audio review terms from MF, many thanks
Several words on topology of this amplifier. The topology was definitely invented by John Curl, as I indicated in the first post of the thread. As posted here, it can be absolutely safely used with any speaker complex load (even 2 ohm) with supply rails 2 x 30V. Increasing rails to 2 x 50V restricts speaker complex load to 4 ohm and more. The power would be 2 x 200W / 4 ohm at 2 x 50V rails. Resistive load 2 ohm is not any issue, but complex load with real component of 2 ohm is.
It would be easy to build a ‘Big Brother’ version of this amplifier. I would suggest six pairs of output devices, and supply rails 2 x 80V. Then one can expect 2 x 400W / 4 ohm output rms power, and no worries about load type.
MJL21193/4 are extremely rugged devices, and their 1 sec, 150°C Tj(pk) SOA is amazing. The use of laterals, as proposed in this thread, would not be any sound improvement IMO, and would result in much less robust amplifier.
I would like to thank to stinius, BV, John Curl, Sendy and danhard for clarification of some technical issues and for posting images and links; and also thanks to many others for their support.
I have already answered some of the questions in my website
PA2 power amplifier
especially that concerning open-loop gain and confusion with loopgain. Both only simulated, so not necessarily same as in the real amplifier.
As you can see, I have built a functional prototype and performed some measurements.
During my holiday week, I have been listening to the amplifier. I would describe the sound as:
- overall lack of smear,
- transparent, and detailed soundstage,
- free of unnatural grain,
- the bottom end well depicted,
- bass not overdamped, not overly constrained,
- combination of speed, liquidity, transparency, and creamy purity,
- tonally neutral, detailed in the midrange,
- excellent resolution of subtle, low-level dynamic detail,
- very good imaging and space.
Solid-state amps are usually too bright and hard on top, or too soft and unfocused. This one is just about right, neither etched nor softened, but just far enough on the right side of "silky-smooth" to sound tonally natural.
I have borrowed these audio review terms from MF, many thanks
Several words on topology of this amplifier. The topology was definitely invented by John Curl, as I indicated in the first post of the thread. As posted here, it can be absolutely safely used with any speaker complex load (even 2 ohm) with supply rails 2 x 30V. Increasing rails to 2 x 50V restricts speaker complex load to 4 ohm and more. The power would be 2 x 200W / 4 ohm at 2 x 50V rails. Resistive load 2 ohm is not any issue, but complex load with real component of 2 ohm is.
It would be easy to build a ‘Big Brother’ version of this amplifier. I would suggest six pairs of output devices, and supply rails 2 x 80V. Then one can expect 2 x 400W / 4 ohm output rms power, and no worries about load type.
MJL21193/4 are extremely rugged devices, and their 1 sec, 150°C Tj(pk) SOA is amazing. The use of laterals, as proposed in this thread, would not be any sound improvement IMO, and would result in much less robust amplifier.
Personally, I do not prefer a triple follower output.
I like CFP output, but only for class A amplifiers, and this is not the case here.
Regarding mosfet drivers, this might be considered, provided that supply rails for input stage and VAS would be increased above output stage supply rails.
I have rechecked datasheets, I guess that A1294/C3263 is an overkill as a driver, I would recommend something smaller and faster.
How about A1668/C4382 ?
Last edited:
Regarding VAS transistors mentioned some time ago, the VAS collector current is set quite high. This might be an explanation why the slew rate is high even with the mosfet types used.
Please recheck my webpage, time after time I am updating the images and text.
PA2 power amplifier
Please recheck my webpage, time after time I am updating the images and text.
PA2 power amplifier
I had a question. And not the other reasons?PMA said:
And the show's on again... PMA don't go again for another tour de vacation in the 'sunny bin'!..
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.