I've found this page during a googleing session.
http://audioprana.free.fr/materiel.htm
I believed to have a heart attack.
http://audioprana.free.fr/materiel.htm
I believed to have a heart attack.
http://audioprana.free.fr/cables.htm
yep, it's cotton...
he's a tube dude, might explain something... oldskool, all the way (except for those class d modules
)
yep, it's cotton...
he's a tube dude, might explain something... oldskool, all the way (except for those class d modules
)UcD Power supply problem
Hi
I have a problem with my amplifier. The positive supply (both R and L channels), after the power on, will increase from 46V to above the admissible max. The negative supply will stay stable. The “on” signal is connected to GND. If the power supply is disconnected from UcD it remains stable, the problem appears only when the power supply is connected to the amplifier.
Could you please help me to find the mistake?
Amplifier set up:
Hypex: 2 UcD180 + 1SofStart
2 TR (30-0-30)AC 300VA (not hypex)
2 Power supply http://www.ub-audio-shop.de/downloads/ntekurzen.pdf with T-Net-Capacitors
Hi
I have a problem with my amplifier. The positive supply (both R and L channels), after the power on, will increase from 46V to above the admissible max. The negative supply will stay stable. The “on” signal is connected to GND. If the power supply is disconnected from UcD it remains stable, the problem appears only when the power supply is connected to the amplifier.
Could you please help me to find the mistake?
Amplifier set up:
Hypex: 2 UcD180 + 1SofStart
2 TR (30-0-30)AC 300VA (not hypex)
2 Power supply http://www.ub-audio-shop.de/downloads/ntekurzen.pdf with T-Net-Capacitors
Re: UcD Power supply problem
That sounds like you have DC offset. If the offset is enough, the pumping affect (transfering energy from one supply to the other, will, will cause the symtom your discribing.
Does it happen when there is no input to the amps?
Have you modified the op amps or the boards in a way that could have increased the offset?
Portland Mike
bruno3955 said:
That sounds like you have DC offset. If the offset is enough, the pumping affect (transfering energy from one supply to the other, will, will cause the symtom your discribing.
Does it happen when there is no input to the amps?
Have you modified the op amps or the boards in a way that could have increased the offset?
Portland Mike
I report back my experience after some change in my ucd 180 and 400 modules.
This is what I did:
1) I substituted ad8620 with LM4562
2) changed resistors to set the gain as in the Hypex application note
3) changed the 470mf 63v with same value but Rubycon Zl
4) changed the input caps with 10mf non polar black gate and russian teflon for the amps in the mid-high drivers
5) changed the output filter caps with a smd polypropilene caps
6)input opamp supply with jung super regulator .
After a couple of months all thinks are settled in and I can say the big job (four stereo amps were transplanted) was really worth it. Really impressive difference, the sense of reality in the attack, control, and lack of coloration is stunning.
Giorgio
This is what I did:
1) I substituted ad8620 with LM4562
2) changed resistors to set the gain as in the Hypex application note
3) changed the 470mf 63v with same value but Rubycon Zl
4) changed the input caps with 10mf non polar black gate and russian teflon for the amps in the mid-high drivers
5) changed the output filter caps with a smd polypropilene caps
6)input opamp supply with jung super regulator .
After a couple of months all thinks are settled in and I can say the big job (four stereo amps were transplanted) was really worth it. Really impressive difference, the sense of reality in the attack, control, and lack of coloration is stunning.
Giorgio
Attachments
Dear Giorgio,
Congratulations.
You went farther than myself by using SR's.
Did you address the on board opamp ceramic PS bypass caps?
Where did you get Rubycon ZL 470/63V???
I found 470/100V at referenceaudiomods.com , wich fit the UCD400, but never 63V versions.
Amazing bass they bring...
Thanks for the info.
M
Congratulations.
You went farther than myself by using SR's.
Did you address the on board opamp ceramic PS bypass caps?
Where did you get Rubycon ZL 470/63V???
I found 470/100V at referenceaudiomods.com , wich fit the UCD400, but never 63V versions.
Amazing bass they bring...
Thanks for the info.
M
maybee umm probably already the question has gone answered but here goes anyway! the fets, http://www.irf.com/product-info/datasheets/data/irli540n.pdf
how would these work or wouldnt they? maybee I just try them?
how would these work or wouldnt they? maybee I just try them?
Input caps on older UcD400AD?
Hi.
I've read through this thread and it looks like shorting or removing the DC blocking caps at the op-amp should be an easy mod that even I should be able to do. My other amp is DC coupled and I never had any problems with that.
Problem is that I can't find them(!) There are no hole-mounted capacitors near the opamp at all, and my UcDs look different fromt the current model.
They are called UcD400AD v1.1 and are dated 2004. The major visible difference between my modules and the current ones is that mine dont have any faston connectors. Everything (audio in, speaker out and power in) is done with plastic/pin connectors (molex?).
Anyone who can help? Jan-Peter?
Thanks
Hi.
I've read through this thread and it looks like shorting or removing the DC blocking caps at the op-amp should be an easy mod that even I should be able to do. My other amp is DC coupled and I never had any problems with that.
Problem is that I can't find them(!) There are no hole-mounted capacitors near the opamp at all, and my UcDs look different fromt the current model.
They are called UcD400AD v1.1 and are dated 2004. The major visible difference between my modules and the current ones is that mine dont have any faston connectors. Everything (audio in, speaker out and power in) is done with plastic/pin connectors (molex?).
Anyone who can help? Jan-Peter?
Thanks
Thanks for the quick reply Jan-Peter.
So what you're saying is that some of the older modules were DC coupled all along (I bought them new and haven't modified them myself).
I build those amplifiers with 2 big Rifa 22000uF/100V cans per channel in the powersupply 3 years ago, but the sound was never quite right. After a while I lost interest until recently. Now I tried with 4 10000uF/80V Nichicon caps I had lying around and man what a difference!
The bottom end has tightened up and the top end is much much cleaner. It used to be very hissy on S-sounds, and in that respect it has improved quite a lot.
With DC coupling not being an issue, which other low hanging fruits are there to pick? Ie. are there any other free/very cheap easy improvements that will impress as much as the power supply capacitor change? Snubbers? Better rectifier brigde (I currently use a standard rectifier with caps soldered between the diodes)?
Thanks
So what you're saying is that some of the older modules were DC coupled all along (I bought them new and haven't modified them myself).
I build those amplifiers with 2 big Rifa 22000uF/100V cans per channel in the powersupply 3 years ago, but the sound was never quite right. After a while I lost interest until recently. Now I tried with 4 10000uF/80V Nichicon caps I had lying around and man what a difference!
The bottom end has tightened up and the top end is much much cleaner. It used to be very hissy on S-sounds, and in that respect it has improved quite a lot.
With DC coupling not being an issue, which other low hanging fruits are there to pick? Ie. are there any other free/very cheap easy improvements that will impress as much as the power supply capacitor change? Snubbers? Better rectifier brigde (I currently use a standard rectifier with caps soldered between the diodes)?
Thanks
Hi Hansen,
Using Patriz own mod list I would suggest the following easy mods:
I hope it helps.
M
Using Patriz own mod list I would suggest the following easy mods:
1) substituting input opamp with LM4562.
3) changing the onboard main PS caps for 470mf/100v Rubycon Zl available at referenceaudiomods.com
Do it only if you want even deeper, weightier bass
5) changed the output filter caps with a (smd) polypropilene or polyester caps like those from Wima or Epcos brands.
6)input opamp supply tweaking or separate PS (with jung super regulator in Patriz' case)
I hope it helps.
M
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