Re: Re: CD63 Transistor Output Stage
Hi Champi,
Thanks for your detailed comment. I think changing that cap will make some difference. That nasty hum could be 100Hz ripple from part of the PSU seeping through. If you have a scope you should check for ripple on the PSU lines. Could be something is drawing excessive current or a cap/regulator that's badly connected. It's low frequency, so it's either that or a ground-loop.
Regards,
Ray.
pantera6 said:
Hi Champi,
Thanks for your detailed comment. I think changing that cap will make some difference. That nasty hum could be 100Hz ripple from part of the PSU seeping through. If you have a scope you should check for ripple on the PSU lines. Could be something is drawing excessive current or a cap/regulator that's badly connected. It's low frequency, so it's either that or a ground-loop.
Regards,
Ray.
6h5c said:
first impression i thought it sounded a bit veiled
left on play repeat then today same thing preferred tranny's
playing different cd's most of the day and it suddenly opened up.
must been the solen breaking in, heard it once before didn't beleive
myself about a cap untill it happened
soundstage is back nicely spaced in front of speakers.
Base is same as tranny's, i think speaker restriction
i need to find an old aldum i tested bass with. (someone going berko on a Double Bass)
more detail Glasses clinking at back of room (better positioning)
really very nice unit
will think about the 2sk117 to a 2sk170 better power handling
may change caps to 10uf's just out of interest (maybe lower inductance/impedance)
need to leave it alone and get use to the sound
in a few day's i'll try the pots
allan
Ray
the tranny version has a darlington pair output.
high gain, low output impedance.
Darlington = lower input impedance
A fet has a low input, high output impedance
wonder if this affects the low frequencies (bass)
come to think of it i think the tranny has tighter bass
but not much in it.
allan
ps prefer the fet though
the tranny version has a darlington pair output.
high gain, low output impedance.
Darlington = lower input impedance
A fet has a low input, high output impedance
wonder if this affects the low frequencies (bass)
come to think of it i think the tranny has tighter bass
but not much in it.
allan
ps prefer the fet though
Discrete out PCB
Those of you who have built the excellent output stage with the help of my PCB must have an urgent look at the connections. Brent spotted a mistake (thanks Brent) concerning the correct connection of the wires.
Where the pcb says 'LO' you have to connect 'LON' and where it says 'RO' there should be the wire coming from 'RON'.
Putting it simpler: exchange LON and LO, RON and RO.
Thanks,
Jaap
Those of you who have built the excellent output stage with the help of my PCB must have an urgent look at the connections. Brent spotted a mistake (thanks Brent) concerning the correct connection of the wires.
Where the pcb says 'LO' you have to connect 'LON' and where it says 'RO' there should be the wire coming from 'RON'.
Putting it simpler: exchange LON and LO, RON and RO.
Thanks,
Jaap
Voltage reference
I had some AD780 laying around and fitted one on a small PCB. It's a very precise voltage generator, giving out exactly 2.50Vdc.
It's a common mod for high price studio gear (analog-digital converters) to have the reference voltage modified, so I wondered why not?
For this purpose I ripped out (you know me by now) R124,R125,C123 and C124. The output connects to the hot side of R125.
Please don't ask me for results as I did several mods at once. Bottom line: the fat lady sings like never before!
Regards, Jaap
I had some AD780 laying around and fitted one on a small PCB. It's a very precise voltage generator, giving out exactly 2.50Vdc.
It's a common mod for high price studio gear (analog-digital converters) to have the reference voltage modified, so I wondered why not?
For this purpose I ripped out (you know me by now) R124,R125,C123 and C124. The output connects to the hot side of R125.
Please don't ask me for results as I did several mods at once. Bottom line: the fat lady sings like never before!
Regards, Jaap
Attachments
6h5c said:
Hi Allan,
I'm glad things opened up.
You could try a mixed configuration with darlington in the output and FET's in the input stage. Maybe the tranny is a better choice as an output device. I'm curious about the effect of the pots.
Regards,
Ray.
had thought about the bc516 in the out[ut when i was biulding it, any diff in a sim?
will try the pots in a few days. (will wait for the initial impressions to pass)
allan
After some google searching I found various DIY project where the 2SK170 is used in parallel to give better noise and input capacitance (equiv to the 2SK147), this has been done mainly on MC and MM applications.
I gave it a whirl and could not tell any difference . LOL. Don't know much about the MM and MC circuits but looking at them the capacitance would affect them.
Brent
I gave it a whirl and could not tell any difference . LOL. Don't know much about the MM and MC circuits but looking at them the capacitance would affect them.
Brent