Solved the problem of oscillation on Pioneer A-09 output stage with a filter before the 500KHz.
I have prepared the environment for a listen test.
Both the output stages are connected by the same driver stage.
The frequency response now have a limit 238kHz at -3dB.
I have prepared the environment for a listen test.
Both the output stages are connected by the same driver stage.
The frequency response now have a limit 238kHz at -3dB.
Attachments
Nice!
Is the LP filter to avoid oscillations composed by R58/R59/C7/C8?
What is the purpouse of the diamond buffer on the left of the bias selection? Does this input typology have higher input impedance?
From the pictures I assume that the voltage stage is the same as the high power hybrid amplifier.
Thanks
Ivan
Is the LP filter to avoid oscillations composed by R58/R59/C7/C8?
What is the purpouse of the diamond buffer on the left of the bias selection? Does this input typology have higher input impedance?
From the pictures I assume that the voltage stage is the same as the high power hybrid amplifier.
Thanks
Ivan
I have use an input resistor, on the right of out3, 1k1ohm and C7/C8 to have 238KHz at -3dB.
This evening I had a listening session with a friend of mine who has considerable experience recording and hi-end playback and we agreed that the Pioneer A-09 output stage sounds much worse than the original AR D100 configuration.
I am using low bias from 5 to 100mA without any differences.
The condition of original Pioneer A-09 was 170mV on 0.44ohm so 0.386A for each final transistor but it means 0.386 * 4 = 1.54A at 90VDC => 140W (original was powered with only 28+28 so 56VDC)
This evening I had a listening session with a friend of mine who has considerable experience recording and hi-end playback and we agreed that the Pioneer A-09 output stage sounds much worse than the original AR D100 configuration.
I am using low bias from 5 to 100mA without any differences.
The condition of original Pioneer A-09 was 170mV on 0.44ohm so 0.386A for each final transistor but it means 0.386 * 4 = 1.54A at 90VDC => 140W (original was powered with only 28+28 so 56VDC)
In short, the sound of the Pioneer A-09 output stage has a much more evident and less pleasant midrange even with loudspeakers with paper cones.
The only positive factor is a greater sense of power without limits.
The idea now could be to test the complex D400 configuration.
The only positive factor is a greater sense of power without limits.
The idea now could be to test the complex D400 configuration.
Attachments
It is quite interesting that the Pioneer A-09 schematic worsen the result.
This gives value to the simpler "original" Hybrid Amplifier End circuit!
Keep us informed about what happens with the D400 topology!
This gives value to the simpler "original" Hybrid Amplifier End circuit!
Keep us informed about what happens with the D400 topology!
I have tested the performance of the D400 version
The result is good but still to test the sound result.
In this case 3 trimmer has been used
1) level of the correction
2) bias of final transistors
3) balance the current generator to compensate the mosfet P/N differences
Only few opamp are good for this use, I have used SA5230 like original and 2SK216/2SJ79.
I think that the definitive solution if we have to use such a complex circuit is to measure the current absorbed by the load and not the voltage to correct the generators.
The result is good but still to test the sound result.
In this case 3 trimmer has been used
1) level of the correction
2) bias of final transistors
3) balance the current generator to compensate the mosfet P/N differences
Only few opamp are good for this use, I have used SA5230 like original and 2SK216/2SJ79.
I think that the definitive solution if we have to use such a complex circuit is to measure the current absorbed by the load and not the voltage to correct the generators.
Attachments
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The D400 circuit have a very clean behaviour! How does it compare to the distorsion figure of the original topology (end stange only)?
Thanks for your work!
Please keep us informed about the listening sessions
Thanks for your work!
Please keep us informed about the listening sessions
Dear Andrea,
I am aware that I lack the expertise to provide technical suggestions...
Anyway,may I ask about the Voltage regulator of this end stage?
Does it affect the sound?
Is it possible that a reduced voltage drop of the capacitance multiplier (changes in R23/R24 and R28/R33) may result in an improved bass ?
Thanks
Fabrizio
I am aware that I lack the expertise to provide technical suggestions...
Anyway,may I ask about the Voltage regulator of this end stage?
Does it affect the sound?
Is it possible that a reduced voltage drop of the capacitance multiplier (changes in R23/R24 and R28/R33) may result in an improved bass ?
Thanks
Fabrizio
Hi,
I'm very corius about the performances of the last D400 circuit, compared to the original one...
Have You tested it?
Kind regards
I'm very corius about the performances of the last D400 circuit, compared to the original one...
Have You tested it?
Kind regards
hello, I am still here
the diyaudio continue to put my account in the banned state and I don't understand why
In my old post there was link to my website but now I post the complete project here without any external link
I don't get money from my audio activity, sometimes I get some special price on some component or I received sample but no money
the diyaudio continue to put my account in the banned state and I don't understand why
In my old post there was link to my website but now I post the complete project here without any external link
I don't get money from my audio activity, sometimes I get some special price on some component or I received sample but no money
If you can post here, you obviously have not been banned? Or do you mean with a different username? Surely if you were banned you must have been informed why?
PS Posting with more than one account per person is not allowed. Perhaps sending a moderator a message asking to be reinstated or reason for ban to be explained is the better path.
PS Posting with more than one account per person is not allowed. Perhaps sending a moderator a message asking to be reinstated or reason for ban to be explained is the better path.
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I guess your other name is Audiodesignguide.com?
And that's not banned.
So why did you register under a new name? That can get you into trouble, having two accounts.
Jan
And that's not banned.
So why did you register under a new name? That can get you into trouble, having two accounts.
Jan