UcD400 Q & A

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#222
Hey Stefan, nice layout - love the boxes! How do they sound...?

A few people have shielded the modules on their setup. How much benefit is this worth?

Here is my first stab at a UCD400 amp. The power supply layout is pretty messy (I think). However, tucking the caps under the modules saved me a lot of space (quite neat I thought).

The power supply is as I documented in another thread "optimal power supply for UCD/Zappulse". It's just one rectifier per rail, with 4 sets of bypass caps per rectifier. No other smoothing caps though. Main caps are 10,000 BC caps from Hypex, and torroid is 1,000va

http://www.wildgooses.com/downloads/amp8.jpg
http://www.wildgooses.com/downloads/amp9.jpg

I have another two modules to build now. I would be grateful for any suggestions on how to improve on the current design?

Would dual mono PS be worth doing? (it's going to be crowded in there...) Is the extra rectifier worthwhile..? Are different caps useful?

Thanks
 
#223
ewildgoose said:
Hey Stefan, nice layout - love the boxes! How do they sound...?

A few people have shielded the modules on their setup. How much benefit is this worth?

Here is my first stab at a UCD400 amp. The power supply layout is pretty messy (I think). However, tucking the caps under the modules saved me a lot of space (quite neat I thought).

Thanks
Click to expand...

Looks great. So how is the sound quality compared to your ZAPpulse amp?
 
#224
Interesting question. I was actually saving that thought until I had managed to canvas a few thoughts on how to improve my UCD400...

I have two Zappulse amps now:

1) Single PS, dual 200va 42v toroids. Modules close together with ground planes joined. Schafner mains filter *WITH* Y caps... (Lars told me to do it). Also the "attenuation" circuit is "installed" - Lars suggests joining the +ve input with the sync input.
http://www.wildgooses.com/downloads/amp4.jpg

2) Single PS. Two sets of 15,000 80v caps. 45V 1,000va torroid. Modules on opposite sides of the case.
http://www.wildgooses.com/downloads/amp7.jpg

Amp 1) sounds pretty average. Great bass - lovely imaging. However, the treble is so harsh that I cant really bear to turn it up loud. I assume it's some kind of harmonic distortion - it's hard to describe, but basically the treble *sounds* louder/harsher than it really is. It also runs really hot - the case above the modules is actually almost too hot to hold.

I also have a lot of problems with some kind of interference through the mains supply with this amp. If I connect it up to my mains conditioner then it acquires a high pitched whine. I do wonder whether the shafner Y filter is allowing the high frequency junk on the earth connection back into the amp in some fashion?


Amp 2) is much better. It's still really hot though, but the sides of my case are alu and get rid of the heat a little better... The sound is very full, with much less harshness. I haven't tested it with my mains conditioner to see if it still has problems. On this amp though I used one of the "medical" mains filters that don't have the Y caps.

Sound on this second Zappulse is rather impressive. Absolutely stunning bass from my Proac 1.5 speakers. Previously, even with some DSP room correction and my Meridian 557 power amp I would never have believed this level of bass would come out of those speakers - in fact I have just finished an IB based sub woofer, and would probably never have bothered if I had heard this amp before...


OK, so how does the UCD400 stack up.... Well, it's very similar to the second Zappulse, but best described as "smooth". It does still have a lot of the bass kick, but it doesn't seem to have quite so much as the Zappulse. Likewise, the midrange and high frequency on the UCD seem a little "quieter", with the midrange almost a touch recessed.

However, this then raises the question of which amp is "correct". For high end reference I only have my Meridian amp to compare against. It's quite likely for example that the nice punch of the Zappulse is actually a small amount of IMD? The "quieter" midrange of the UCD seems more likely to be correct (considering the design of the UCD), than the zappulse.

So the UCD is less "punchy", and slightly more smooth than the Zappulse. I have also chosen the UCD as my main amp (the zappulse is on the sub woofer - crossover circa 120Hz...)

Also, the UCD is incredibly silent at idle!! With ear pressed against the tweeter I can only *imagine* a slight bit of hiss. Phenominal.

So basically I have two more UCD modules and I would love to try and improve on the current design. Anyone got any sensible suggestions for improvement? (I'm not really interested in tweaking for the last tiny fraction of a percent. But I suspect that there are still some sensible big changes that I could make)

...I also need to fix that first Zappulse amp so I can use it for my rear surround speakers... I suspect that removing the Schafner thing would be a good first start... However, anyone want to make me an offer on it - swap for two new UCD400?
 
#225
Oh, I should also add that the UCD400 heatsinks stay very cool on my build. In fact you could almost run them in free air I should think?

However, the output coil gets very hot... The outer casing is pretty much too hot too touch on my amps after running for a few hours at low volume. Is this reasonable?
 
#228
Ed, I don't have a good reason for this suggestion other than I don't really see the reasoning of using two transformers with a single power supply !

On the dual transformer amp have you tried disconnecting one of the transformers? you could probably try disconnecting the soft start as well the single transformer should not be a problem.

I have no idea if this would change the sound but it walked be easy to try.

I intend to rebuild my amp (2x ucd180) as dual mono blocks.
 
#229
Hi, thanks for the idea. I assume you are referring to the Zappulse 1) amp? The reason for two transformers is simply because it's the only way to get a sensible sized transformer into a 1U case. Those things are 200va each, wired in parallel and are slim enough to fit into a 40mm high position!

It's quite neat... It just doesn't sound that great...

I will try removing the Y filtering caps first, but otherwise I will rebuild it with the modules seperated. Possibly in a larger case, although the 1U sized box is convenient (I had envisaged putting all of them in such a small box)
 
#230
Ed. yes I meant Zappulse 1, but I wasnt commenting on your use of transformers for height issues rather I dont see the reason for the Predator being used with 2 transformers (other than maybe for height reasons).

My feel is that the problem is likeley to be related to having a link of some sort between tha channels, dont know what though ;-)
 
#231
5 channel amp

Hi,

I am still working on my 5 channel amp. It turned out that all the stuff will not fit in the enclosure I purchased.

So I decided to put just one power supply in. For now that means only one 500VA transformer, but if I feel after listening that that is not enough I will get a 1000VA instead. I left room for such a transformer. Two 500VA's with their rectifiers and caps simply won't fit.

So I have a spare 500VA transformer, rectifier and two BC 10.000uF caps.

I find the soldering of wires to the rectifiers not a simple task by the way. And how do you let one supply go to 5 UcD400 modules? I use things that are used in house-electricity situations, in which you stick wire that automatically gets stuck. It's probabely not high end (not even copper), but I have no alternative at the moment.

I'll try to make some pictures in the near future.

Frans
 
#233
Acheng:
What does on (internal pull up) means??
Click to expand...

The /ON signal must only be connect to GND. By an open collector transistor for example.

Ewildgoos;
Oh, I should also add that the UCD400 heatsinks stay very cool on my build. In fact you could almost run them in free air I should think?

However, the output coil gets very hot... The outer casing is pretty much too hot too touch on my amps after running for a few hours at low volume. Is this reasonable?
Click to expand...

Please don't use them without any cooling! At 60V DC the dissipation is around+/-8W, the T-shape aluminium is not sufficient. The outputcoil will be indeed +/-60oC, is no problem the coils are designed for a high temperature.

BTW, nice setup😉

Regards,

Jan-Peter
 
#237
OK, I know I am off topic, but if anyone does want the 1U zappulse amp, then please contact me offlist at: edward (at) wildgooses dot com.

It has a single LCaudio powersupply, twin 42v 200va transformers, softstart and dc filter. WBT terminals and balanced inputs. The power supply input filter has Y caps and almost certainly needs to be swapped for one without.

These are brutally powerful amp modules.
 
#238
UCD400 components

Hello everyone and Jan-Peter,

I am building my UCD400 now and need a decent PSU.
Since Schuro is very slow and not answering my emails -
does anyone have an idea where to get two high-end
transformers? I want to build my monoblocks
with 2x10.000uF 63V Jensen 4-pole caps, bridge rectifier,
Wima and Mundorf caps for HF filtering.

I would appreciate if someone could sell me PSU parts
or tell me where to get them in Europe.

Thanks,

Michael
 
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