Both signal and speaker cables do make a difference. The only case is to find the real reason, and no one of us seems to get it yet ... 😀
Good to know that you believe that this is not a Myth.
So...i will be more carefull when next testing were done, i will search for better cables too.
I was thinking this as a Myth, as i have tested many years ago, without something very different in sonics.
But as Pavel and you Michael, both respectable guys are telling this, i will reduce myself to my insignificance and i will try to listen what you are perceiving.
thanks.
Everyday learning something...this is good.... can be better than the shame of my own ignorance.
regards,
Carlos
So...i will be more carefull when next testing were done, i will search for better cables too.
I was thinking this as a Myth, as i have tested many years ago, without something very different in sonics.
But as Pavel and you Michael, both respectable guys are telling this, i will reduce myself to my insignificance and i will try to listen what you are perceiving.
thanks.
Everyday learning something...this is good.... can be better than the shame of my own ignorance.
regards,
Carlos
Hi all.
Congratulations MikeB. It is great amp. J have build 5.3 version in oryginal and version with two pairs output devices (supply +/-45V, bias 150mA, mpsa18 replaced by mps42). Sound is just like just to say my predecessors who build this amp - great!
Congratulations MikeB. It is great amp. J have build 5.3 version in oryginal and version with two pairs output devices (supply +/-45V, bias 150mA, mpsa18 replaced by mps42). Sound is just like just to say my predecessors who build this amp - great!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Hi Borys, thanks, and nice work !
Is there a benefit from the 2 outputpairs ? (Haven't tried myself yet)
Are you "borysgo2" on www.audiostereo.pl ?
You might get better sound if you don't use ceramic caps (if i looked correct) for the 330pF and the 10/22pf.
Mike
Is there a benefit from the 2 outputpairs ? (Haven't tried myself yet)
Are you "borysgo2" on www.audiostereo.pl ?
You might get better sound if you don't use ceramic caps (if i looked correct) for the 330pF and the 10/22pf.
Mike
Hi MikeB. Yes I'm borysgo2. (http://pszyszka.googlepages.com/)
I am waiting for silver mica's for two weeks and can't wait to collect them. Benefits, hmm, maybe higher output power and posibility to use low spl speakers, that is all I think.
One chaneel I build using only mpsa (92/42), the other one just like in 5,3 project except mps18 (I used mpsa42). I'm not sure but this with mpsa only sounds better. I must listen to it a bit longer. Maybe this is result of higher harmonic distortion level. I'll try to measure it in spectralab.
I am waiting for silver mica's for two weeks and can't wait to collect them. Benefits, hmm, maybe higher output power and posibility to use low spl speakers, that is all I think.
One chaneel I build using only mpsa (92/42), the other one just like in 5,3 project except mps18 (I used mpsa42). I'm not sure but this with mpsa only sounds better. I must listen to it a bit longer. Maybe this is result of higher harmonic distortion level. I'll try to measure it in spectralab.
Chucks comeback
Helo Mike,
my boards are finalized. And works well. I hope I can find some time to finalize whole amp.
Helo Mike,
my boards are finalized. And works well. I hope I can find some time to finalize whole amp.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Borys, do you mean mpsa42/92 instead of 2n5551/5401 ? In which way did the sound improve ? Clearer or nicer, brighter, softer ? The measurings should show the difference...
Chuck, nice collection of instruments ! Are you using 3.3pf for c14 ? (feedback cap) I ask because of the overshoot...
Mike
Chuck, nice collection of instruments ! Are you using 3.3pf for c14 ? (feedback cap) I ask because of the overshoot...
Mike
Mike: Yes 3,3p.
But 330p for C3 and C4. This can be little away from optimum and this measurement was made without load. I havent got sufficient PSU for measurement with load. Im working on PSU with DCprotection too.
But 330p for C3 and C4. This can be little away from optimum and this measurement was made without load. I havent got sufficient PSU for measurement with load. Im working on PSU with DCprotection too.
MikeB
My Engilsh isn't good enough, but I'll try.
Sound is little bit brighter and has a more of detail, specially on the bacground.
I suppose that this could be result of more harmonic distortion (2,4,6,...). If measurments do not confirm this, it will mean that mpsa realy improve the sound.
My friend have made a measurments (with souncard), amp was made with mpsa. He sed that this meas. was only to check how the program works, so it could be nothing important.
http://img394.imageshack.us/my.php?image=19v5r1khzpe7.png
http://img394.imageshack.us/my.php?image=19v5r1khzpe7.png
Load 5R, output amplitude 19V.
My Engilsh isn't good enough, but I'll try.
Sound is little bit brighter and has a more of detail, specially on the bacground.
I suppose that this could be result of more harmonic distortion (2,4,6,...). If measurments do not confirm this, it will mean that mpsa realy improve the sound.
My friend have made a measurments (with souncard), amp was made with mpsa. He sed that this meas. was only to check how the program works, so it could be nothing important.
http://img394.imageshack.us/my.php?image=19v5r1khzpe7.png
http://img394.imageshack.us/my.php?image=19v5r1khzpe7.png
Load 5R, output amplitude 19V.
I would not care about the overshoot shown, as the response is very fast. It seems that rise time (10% - 90%) is about 200ns, which indicates to F(-3dB) = 1.7 MHz. These are certainly Toshiba output devices.
Try complex load, this would answer on amplifier stability.
Try complex load, this would answer on amplifier stability.
Hi Pavel, yes, it shouldn't hurt, no ringing visible... The output devices do look like Toshibas !
Borys, something is wrong with the measuring, symasym normally does not produce these levels of 7th harmonic, but might be caused by soundcard. The even harmonics are "normal", it's caused likely by pcb layout. Brighter sound is mostly an indicator for increased distortions.
I attached one of Pavels measurings.
Mike
Borys, something is wrong with the measuring, symasym normally does not produce these levels of 7th harmonic, but might be caused by soundcard. The even harmonics are "normal", it's caused likely by pcb layout. Brighter sound is mostly an indicator for increased distortions.
I attached one of Pavels measurings.
Mike
Attachments
My friend used Thosiba's output devices. He set up bias 50mA, but he might make a mistake becouse VAS takes aprox 50mA.
(Correct me if I'm wrong - VAS).
Today I'll make a measurments.
(Correct me if I'm wrong - VAS).
Today I'll make a measurments.
Borys, i guess you mean driver stage ? (mje15030/31,U5/6) 50ma in the VAS would frie the to92 transistors immediately. Normal value for driver stage is ~36ma. 50ma here would be too much.
VAS is formed by Q3/4/5/9/12.
Mike
VAS is formed by Q3/4/5/9/12.
Mike
I mean VAS and driver stage, all whitout output devices, sory (ups).
Now is all clear. As I supposed, that is result harmonic distortion. Level of the harmonic in this print screans is not important becouse I have cheap soundcard.
As input I have temporary 2x47k.
Now is all clear. As I supposed, that is result harmonic distortion. Level of the harmonic in this print screans is not important becouse I have cheap soundcard.
As input I have temporary 2x47k.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
borys said:
It's hard to read, but it looks like version with mpsa42/92 has 20db higher distortion (factor 10). This might prove 2n5551/5401 as very suitable audio transistor. I guess that mpsa42 is also bad choice here as input transistor.
You mean sum of vas and driver stage ? On my symasym-page at the bottom is a chart of currents, you can use that as guide. It matches quite good real world measurings.
"Cheap soundcard"... You meant very cheap ? Onboard sound ? 😉 It has ~30db higher distortion than symasym...
What do you mean with input you have 2x47k ?
Mike
Infortunetly onboard sound chip is very bad 
47k I mean voltage driver - "poslog", I don't know how does it names in Engilish (variable resistor 🙂 ), I don't have 22k now.
47k I mean voltage driver - "poslog", I don't know how does it names in Engilish (variable resistor 🙂 ), I don't have 22k now.
Borys,
I can see following from your pictures:
1) bad PSU or supply wiring,
2) bad signal wiring,
3) low Iq (bias)
P.S.: the bright sound may be a result of the 50Hz multiples. Look at the pictures: 600Hz, 650Hz, 700Hz, 750Hz etc. .... everywhere upt to several kHz .....
I can see following from your pictures:
1) bad PSU or supply wiring,
2) bad signal wiring,
3) low Iq (bias)
P.S.: the bright sound may be a result of the 50Hz multiples. Look at the pictures: 600Hz, 650Hz, 700Hz, 750Hz etc. .... everywhere upt to several kHz .....
PMA
Thanks for your post.
I have bad signal wiring, with conected signal wire only I have terible noises aprox -90dB, it could be one of the reasons my poor measurments. Whitout signal wire I have -130dB nois level.
I have 150mA bias now.
Thanks for your post.
I have bad signal wiring, with conected signal wire only I have terible noises aprox -90dB, it could be one of the reasons my poor measurments. Whitout signal wire I have -130dB nois level.
I have 150mA bias now.
Borys, could you run a RMAA test for your soundcard ? It would be nuts to hunt problems with your amp if the soundcard is causing these problems.
You can download it here: http://audio.rightmark.org/download.shtml
To run the test simply connect a cable from output to input.
My last soundcard had IMD of 10%...
Mike
You can download it here: http://audio.rightmark.org/download.shtml
To run the test simply connect a cable from output to input.
My last soundcard had IMD of 10%...
Mike