UcD400 Q & A

[Jan-Peter]

Henrik,

I am sorry but my answer is no. The overvoltage protection works at 68VDC........

We recommend for the highest sonic performance a voltage between 50V and 63VDC.

On the other hand a low impedance of even 1 ohm is no problem for the UcD400. Actually in our testsetup we use 1 ohm to check if the amp delivers the maximum current of +/-20A piek. In the THD versus Power curve the THD stays nice below 0.05%

Regards,

Jan-Peter

[classd4sure]

Originally posted by Jan-Peter
Henrik,

I am sorry but my answer is no. The overvoltage protection works at 68VDC........

We recommend for the highest sonic performance a voltage between 50V and 63VDC.

On the other hand a low impedance of even 1 ohm is no problem for the UcD400. Actually in our testsetup we use 1 ohm to check if the amp delivers the maximum current of +/-20A piek. In the THD versus Power curve the THD stays nice below 0.05%

Regards,

Jan-Peter

How about a graph of that if you have the time? We haven't seen one yet for a 1 ohm load. Not that I don't believe you or anything it would just be neat to see.

Or whatever graphs you posted before for the UCD400 done on the new version would be neat too. You must have some kicking around?

Thanks

[Jan-Peter]

Ok!

Tomorrow I will post some graphs.

Jan-Peter

[nyman]

I'm planning to put the amp in a box together with a xls10 and two passive radiators each with a 100g extra weight. The only thing between the ucd400 and my amplifiers sub output will be some copper and a pot. What's a good value for that pot?

[aawirth]

Hi, is there an answer to the question Brian Lewis brought up earlier on the DC offset of the UCD400 and a way of getting rid of it???

Al

[ghemink]

Originally posted by aawirth
Hi, is there an answer to the question Brian Lewis brought up earlier on the DC offset of the UCD400 and a way of getting rid of it???

Al

Of the UcD180 modules that I have, the DC offset at the output is in the order of 20-30mV or so, measured it a while ago, so may not be exactly that, guess it will be similar for the UcD400. I don't know if that is too much for certain ribbon drivers? I don't think it is that easy to get even lower offset, using DC servo circuits?

Gertjan

[Yves Smolders]

On the other hand a low impedance of even 1 ohm is no problem for the UcD400. Actually in our testsetup we use 1 ohm to check if the amp delivers the maximum current of +/-20A piek. In the THD versus Power curve the THD stays nice below 0.05%

Amazing stuff. Is 20A peak, or can it be sustained for a while?

Just think about how much $$$ you have to drop on a class AB monoblock that is stable to 1 ohms and can deliver 20A....

[ghemink]

Originally posted by Yves Smolders


Amazing stuff. Is 20A peak, or can it be sustained for a while?

Just think about how much $$$ you have to drop on a class AB monoblock that is stable to 1 ohms and can deliver 20A....

Hello Yves,

As far as I understand it, this 20A is where the protection starts to kick-in. It means you should be able to have 20A all the time, just if you ask for 21A, the protection circuit will prevent you from doing that :-)

20A peak is very good since with a 4 Ohm load and say 56V peak voltage at the output (for 400W in 4 Ohm) the module "only" has to deliver a peak current of 14A, so at 3 Ohm you could get about 530Watt. If you bridge two modules (I plan to do that for my woofers, you can just get 800W at 4 Ohm. That should be enough to rock my house without actually having an earthquake :-). However, I have dipole woofers that can use some power.

Best regards

Gertjan

[Yves Smolders]

20A peak is very good since with a 4 Ohm load and say 56V peak voltage at the output (for 400W in 4 Ohm) the module "only" has to deliver a peak current of 14A, so at 3 Ohm you could get about 530Watt

Yeah,

That's why I asked... My speakers are 8 ohm but have nasty drops to 3.

If Ucd400's can pump 530W (ideally) into each channel continously at 3 ohms, that is just amazing... No surround receiver can do such a thing (except the new denon 5.... something, but that thing is a 5000$ beast) - a huge toroid and lots of caps will take care of the rest

When I complete my amp i'm going to test it on a friends disco-setup

[Jan-Peter]

Originally posted by Bob Lewis;
Hi All,
Anyone any ideas about the best way to null the DCoffset on the UCD400AD modules as I intend to actively drive APOGEE ribbon speakers with these? The MRT ribbons are very sensitive to DC,suffering displacement in the magnet structure plus premature aging and stretching.

The best idee is to add some DC at the input of the UcD400 after the coupling caps. Supose you have 20mV DC output, the gain is 20 times, when you ad -1mV at the input you will have zero output. Ofcourse you have to decouple this DC very good because it's connected to your input.

Regards,

Jan-Peter