UcD400 Q & A

[ewildgoose]

Originally posted by richie00boy

The downside is that you must be mindful of the fact that the red speaker terminal on the inverted amp will be ground and the black one signal, which can present problems if you want to feed a subwoofer from the speaker outputs, or some active DC protection modules.

I'm missing something obvious here... Why don't you invert the speaker connection inside the case as well, and then both red's are positive...?


Same question to the people who agree that inverting amplifiers make sense. No problems there, but why don't they change the labels on the speaker connections around so that red speaker output equals positive input to the amplifier?

[koldby]

Same question to the people who agree that inverting amplifiers make sense. No problems there, but why don't they change the labels on the speaker connections around so that red speaker output equals positive input to the amplifier?

That would be dangerous. People could in some aplications connect the black connector to chassis/ground and thereby shortcircuit the output.
But a clear indication on the back of inverting amplifiers is mandatory IMHO.

Koldby

[richie00boy]

Originally posted by ewildgoose
I'm missing something obvious here... Why don't you invert the speaker connection inside the case as well, and then both red's are positive...?

Because then the two speakers (left right) would be out of phase.

[ewildgoose]

Aha, I see what you mean. Are the UCD400 modules considered to be short circuit safe? Can I expect any ill effects from shorting the output to ground, or back into the other module accidently?

(Not that I plan to habitually abuse my amps like this...)

I have a stereo UCD400 which has 20,000uF per rail. It sounds really good, but I guess its slightly short on capacitance even for an 8ohm load. I need to pull the amp apart to try some things that Jan-Peter has suggested to remove my RFI problem, so I might try swapping the polarity on one module and see what effect it has... I have a zappulse stereo amp with 30,000uF per rail and that does have a little more authority in the bass region for sure, could be just the extra capacitance talking...

Thanks

[GregD]

Originally posted by ewildgoose
I have a stereo UCD400 which has 20,000uF per rail. It sounds really good, but I guess its slightly short on capacitance even for an 8ohm load. I need to pull the amp apart to try some things that Jan-Peter has suggested to remove my RFI problem, so I might try swapping the polarity on one module and see what effect it has... I have a zappulse stereo amp with 30,000uF per rail and that does have a little more authority in the bass region for sure, could be just the extra capacitance talking...

Thanks

I tried a Zappulse and UCD400 with the exact same power supply and the Zap had a little more authority in the bass region for me as well. But since everything else sounded more natural with the UCD400, I'm inclined to think that perhaps the Zap unnaturally emphasizes the bass; either that, or the extra 100 watts or so of the Zap is showing its colors. It'll be interesting to see how a UCD700/1000 sounds when it comes out.

[Jan-Peter]

All UcD modules has a constant loopgain, so the THD is a straight line from 20Hz-20kHz.

We are at all not used to listen to an amplifier with a flat THD curve. According to our 'audiophile' designer (Bruno) this seems to be the big difference at first listening between an UcD and any other amplifier with a fast rising THD curve.

What you actually hear in the beginning some slightly weak bass region. But actually this is not true, it is more detailed and more in harmonic with the higher part because of the constant loopgain.

Regards,

Jan-Peter

[patriz]

Originally posted by Jan-Peter
All UcD modules has a constant loopgain, so the THD is a straight line from 20Hz-20kHz.

We are at all not used to listen to an amplifier with a flat THD curve. According to our 'audiophile' designer (Bruno) this seems to be the big difference at first listening between an UcD and any other amplifier with a fast rising THD curve.

What you actually hear in the beginning some slightly weak bass region. But actually this is not true, it is more detailed and more in harmonic with the higher part because of the constant loopgain.

Regards,

Jan-Peter

This is my experience too, It's only two days that my ucd are running but I'm really impressed with sound . Actually I'm using them only in the bass and I'm going on putting together the ucd 180 for the others ways. I have horn bass cabinet and I put only 10.000mf per rail in each mono amp. Transient are much faster than my previous amp (Bel 1001) and overall all seem much cleaner, the upper ways too. Sometime I felt like the lowest hz are missing but them I noticed my dinner table vibrate which it never did before. I think Ucd bass are very neutral and natural.
Giorgio

[Yves Smolders]

@Jan-peter,

Now that you have the famous Bruno in-house, you can start building UcD's with double the power, let Bruno sign the PCB and name it a UcD400 Signature Edition

Ahm, no that's too... Carver like

I do have a real question though, instead of ever more powerful modules (higher wattage), will there ever be UcD's with a higher current capacity? Not that I am complaining, it drives my speakers with ease, but I believe the UcD concept is close to the really heavy Class AB amps out there.

So maybe it wouldn't be bad to make a "statement" or "signature" edition, cost no object (relatively speaking), just to show the world what Hypex is capable of.

Maybe Bruno will better his UcD concept now that he is free from the restraints of a mass-producer. Quality first now!

[classd4sure]

Bruno really has nothing to prove. I'm sure everyone would like to see modules of the highest possible caliber, but what one might consider useless excess, another may consider necessity, where all things cost more.

I do believe Bruno is rather skilled at knowing where to draw that line, and that he's already done so for the UCD.

I'd expect his R&D to be for something new, thought it would be nice to hear what Hypex's future plans actually are.

I really hope they don't plan on taking the route of the signature series, where a small mod or two and some screen print triples the price.

[Bruno Putzeys]

Originally posted by Yves Smolders
I do have a real question though, instead of ever more powerful modules (higher wattage), will there ever be UcD's with a higher current capacity?

It is quite feasible to modify the UcD400 design to support reduced supply voltage combined with increased output current. That would for example produce 400W into 2 ohms but only 200W into 4. If there is à real demand for such a UcD400LZ it could be considered. I doubt that 2 ohms is really common though.

Originally posted by Yves Smolders
Maybe Bruno will better his UcD concept now that he is free from the restraints of a mass-producer. Quality first now!

Hidden among plans of UcD700, SMPS, full-bridge amps etc is also a control loop version with 20dB more loop gain. We'll keep you posted.