Hotrodding the UCD modules

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#781
Chris,

Are you using split foil's?
4 ports?

Where did you get them?

I'm toying with a new power supply scheme using a transformer with two secondaries and using a bridge on each.

Using a 4 port would be ideal for each rail, then tying the grounds right at the UcD amp ground.

Advantage would be very low ground noise, at the cost of an extra bridge. I suspect slightly worse regulation, but not major, and of coarse an extra diode drop.

I'm interested in this just based on my experience with how distructive ground noise is to the stage.

Mike
 
#783
Portlandmike said:
Chris,

Are you using split foil's?
4 ports?

Where did you get them?

I'm toying with a new power supply scheme using a transformer with two secondaries and using a bridge on each.

Using a 4 port would be ideal for each rail, then tying the grounds right at the UcD amp ground.

Advantage would be very low ground noise, at the cost of an extra bridge. I suspect slightly worse regulation, but not major, and of coarse an extra diode drop.

I'm interested in this just based on my experience with how distructive ground noise is to the stage.

Mike
Click to expand...

Slit foil, no that's unique to BHC. I'm using T networks from Jensen, available at partsconnexion. I do have a pair of the BHC slit foil /T networks, got them from LC audio.
 

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#785
JoshK said:
the auricap output filters are up on Kevin's site. Only $45/ea. 😱
Click to expand...

Thats crazy😡 I'll stick with my normal Auricap axial ones.
It would be interesting if anybody who happens to have both could let us know how the new cheap ones:clown: compare against the older ones, I'd expect a massive improvement for that price difference!
I've been doing some more listening, the Auricaps are better than the standard polyesters but the difference is not huge IMHO, infact I still think the CRD mod has made one of the biggest differences in my system
 
#786
maxlorenz said:
Hi Chris:
You tied TX's center tap to safety ground?

Regards
Mauricio
Click to expand...


No, what you see tied to ground is the static shield from the transformer, and of course the enable switch.

The supply is fully floating. There really is no center tap at all, only the common point which floats from chassis and serves as power ground for the modules.

Signal input is also tied to chassis. Can highly recommend this kind of supply.
 
#787
classd4sure said:


Slit foil, no that's unique to BHC. I'm using T networks from Jensen, available at partsconnexion. I do have a pair of the BHC slit foil /T networks, got them from LC audio.
Click to expand...


I think you did what I was thinking about. I assume from what I can tell that you have the 4 ports in parallel.
A bridge for each rail, correct?

So you like the jensens better than the BHC split Foil T networks?
I assume you've tried the T networks, right?



thanks

Mike
 
#788
t. said:


Thats crazy😡 I'll stick with my normal Auricap axial ones.
It would be interesting if anybody who happens to have both could let us know how the new cheap ones:clown: compare against the older ones, I'd expect a massive improvement for that price difference!
I've been doing some more listening, the Auricaps are better than the standard polyesters but the difference is not huge IMHO, infact I still think the CRD mod has made one of the biggest differences in my system
Click to expand...


I'm sure it's a typo and they meant $4.5 :clown:
I'm equally sure they'll be available elsewhere so we can benefit from competitive pricing. :clown:
It should be interesting to see how fast they come down in price, or disappear.

The cap I used, selected for the application by specs, something I guess 45$ namebrand caps don't seem to have, made a difference that was nothing short of astounding.

Conversely, the CRD's made a difference but a very subtle one.

I'd encourage you to try a cap that's right for the job, leave the overpriced names to those who'd chose a name over performance.
 
#789
Portlandmike said:



I think you did what I was thinking about. I assume from what I can tell that you have the 4 ports in parallel.
A bridge for each rail, correct?

So you like the jensens better than the BHC split Foil T networks?
I assume you've tried the T networks, right?



thanks

Mike
Click to expand...


Yeah it's a standard high end supply, not a new concept, but you're right to go that route for sure.

I have two 4 pole caps in // per rail.

I didn't have enough of the BHC's to make a direct comparison, but they are what sold me on the 4 pole technology, and so I got the Jensen caps since they're close to home.

They haven't let me down at all, and I"m very happy with them. It's a sure path to an ultra revealing amplifier with very fast response. Really can't say enough good about either of them, simply must be tried to be believed!

The only complaint I hear from people is they're so expensive but.... they're a steal for what they are. Compare the cost to black gates, or the new auricap.
 
#790
classd4sure said:



Yeah it's a standard high end supply, not a new concept, but you're right to go that route for sure.

I have two 4 pole caps in // per rail.

I didn't have enough of the BHC's to make a direct comparison, but they are what sold me on the 4 pole technology, and so I got the Jensen caps since they're close to home.

They haven't let me down at all, and I"m very happy with them. It's a sure path to an ultra revealing amplifier with very fast response. Really can't say enough good about either of them, simply must be tried to be believed!

The only complaint I hear from people is they're so expensive but.... they're a steal for what they are. Compare the cost to black gates, or the new auricap.
Click to expand...


Its a shame that Hypex doesn't do this in there high end supplies.
For the cost, it seems crazy not to.
Or do they?

Mike
 
#793
Quickie UCD 180 Question

I am about to construct a dual mono UCD 180 and have a choice on the power caps... the Hypex Instructions recommends a 4700uF cap..

Anyway, I have a set of Mallory 4800uF 75V (CGS series) and I also have a set of Nichicon 10000uF 63V...

The Mallory's are huge compared to the Nichicons...

I am running dual 28.6 VAC secondaries on the trannies giving around 40VDC/side, so 63V or 75V is just fine...

Anyone out there have any opinion?
 
#794
Re: Quickie UCD 180 Question

john65b said:
I am about to construct a dual mono UCD 180 and have a choice on the power caps... the Hypex Instructions recommends a 4700uF cap..

Anyway, I have a set of Mallory 4800uF 75V (CGS series) and I also have a set of Nichicon 10000uF 63V...

The Mallory's are huge compared to the Nichicons...

I am running dual 28.6 VAC secondaries on the trannies giving around 40VDC/side, so 63V or 75V is just fine...

Anyone out there have any opinion?
Click to expand...


Even 50V will be fine, and I'd go for at least 10,000uF.
Do you have split secondaries or center taps?

Mike
 
#795
DC offset in standby?

Today I put my UCD400s into a case adding an Elma switch
to connect the /ON switch to supply ground as recommended
in the specs. However, when the /ON switch is not connected
to ground (module is off), I see about 0,5V DC at the speaker outputs!
When the modules are on, DC offset is under 20mV.
Huh? Has anyone experienced this? I tried it on a pair of old 4 Ohm
speakers and the amps work, no popping cones or smoking woofers.
Maybe it's a little bit late now and my brain needs recovery 🙂
Is there anything wrong? I always used to have the ON switch
connected to ground so I could never really measure this before.

My setup is dual-mono with UCD1.1 modules, 2x800VA,
PSU completely floating. Only Pin 1 of the XLR input is connected
to the chassis. Everything else is floating.

Any ideas as to what could cause the weird DC? It's measurable
on both speaker terminals.

Thanks,

Mike (sleepy...)
 
#798
Hi,

Thought I'd add this here.

I made a post in another thread about the UCD180 I have sounding somewhat compressed while near clipping levels. The sound would thin out and become higher pitched at the onset of clipping, but I couldn't put a finger on the mechanism to blame for this.

Since having upgraded the caps on it, this no longer occurs at all. It even behaves somewhat differently while clipping. Where it used to snap/crackle a faint whine can be heard. Thus it seems less severe, and certainly better behaved as the sound retains proper tonal characteristics at full power, with deep and rich bass.

So perhaps the new theory on that phenomena is the stock decoupling caps running out of steam.

In addition in case anyone is interested, I have replaced the FC's with the stock decoupling caps in order to try them with my new filter cap as that's a combination I previously left untested.

Results are pretty much the same as before. It plays the exact same bass but there is no power at all behind it, while the midrange becomes much more upfront, seemingly less colored than the FC's leave them, and the high's have more air as they're moved upfront as well.

All the same, the FC's are still the preferance as I prefer an amp with a sense of power that provides some punch in the bass that you can truly feel, sadly they leave something to be desired in the midrange and highs, which the upgraded output cap cannot fully compensate for.

Regards,
Chris
 
#799
Thanks Chris 🙂

Anyone suspect the "low voltage decoupling caps"? I have a nasty HF piercing noise that I previously thought was due to one of the many tweaks to my other components. Yesterday I discovered that the base of one of the little caps (wich I think but I'm not sure is decoupling cap) of my UCD180ST V2 has oxide. I didn't had the time to check the rest of the caps. I may put some BG there.

It would be nice to see some diagrams showing the parts from the different UCD versions. I know my UCD400 but my older UCD180 are a mistery to me 🙁

Thanks
Mauricio
 
#800
maxlorenz said:
Thanks Chris 🙂

Anyone suspect the "low voltage decoupling caps"? I have a nasty HF piercing noise that I previously thought was due to one of the many tweaks to my other components. Yesterday I discovered that the base of one of the little caps (wich I think but I'm not sure is decoupling cap) of my UCD180ST V2 has oxide. I didn't had the time to check the rest of the caps. I may put some BG there.

It would be nice to see some diagrams showing the parts from the different UCD versions. I know my UCD400 but my older UCD180 are a mistery to me 🙁

Thanks
Mauricio
Click to expand...


Welcome, BTW I should fairly state that I can't say for certainty whether or not it's the decoupling caps or the stacked film (stock) filter cap that's responsible for the phenomena I experienced near clipping, and due to some bad luck won't be able to tell you.

So you changed the decouplling caps for the input stage to BG's?

That spot uses high ESR coupling caps for damping HF oscillations... might want to change them back.

Also, this could be a direct result of having floated your signal grounds, if they still are.

Regards,
Chris
 
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