UcD400 Q & A

[matjans]

ackcheng: yes, all transformers are 500VA and require a softstart or else they'll blow a fuse or trip the main fuses.

[R Dijk]

4 UCD 400 is powered by this psu with slowstart and mute.

2 Transformers 400VA, 160 000uF all in 1U cab

[ghemink]

Originally posted by Al Garay
Hi Gertjan,

What speakers are you using that require so much firepower for all channels? Are you using the DEQX for crossover?

Al

I'm indeed using the DEQX crossover. I plan to use 2 UcD400 in bridge for the woofers (2 x Vistaton TIW200XLS in a dipole, or more like an U-type frame) or one UcD400 per woofer (so not bridged). For the midwoofers I use two Seas Excell W18EX001 per channel (also dipole) and the tweeters are the Vifa ringradiators. The mids and tweeters are now running with UcD180s, sounding very well. However, since the UcD400 seems to be better spec'd than the UcD180, I want to try the UcD400s also for mid and high. Using a bridged configuration for the woofers will also avoid power supply pumping effects when I uses an SMPS. Power supply pumping with an SMPS could be a problem since the SMPS uses relatively small caps in the LC filter (2x470uF per rail).

Almost finished building one SMPS, just need to get some thermal conductive paste for the power mosfets and rectifier diodes (the paste was not in the kit). I don't really want to fire it up without the transistors being thermally connected to the heatsink.

Best regards

Gertjan

[SSassen]

Gertjan,

If you're going to use two woofers that are meant to acoustically work together, e.g. in a dipole or other configuration, you MUST drive them from the same amp, driving them from two different amps will introduce harmonic distortion and loss of spl due to the cones not moving at exactly the same time.

Best regards,

Sander Sassen
http://www.hardwareanalysis.com

[R Dijk]

inside 4 ucd400

[ackcheng]

Seems like a mixture of old and new modules. Any problem?

[ghemink]

Originally posted by SSassen
Gertjan,

If you're going to use two woofers that are meant to acoustically work together, e.g. in a dipole or other configuration, you MUST drive them from the same amp, driving them from two different amps will introduce harmonic distortion and loss of spl due to the cones not moving at exactly the same time.

Best regards,

Sander Sassen
http://www.hardwareanalysis.com

Hi Sander,

Do you have experience with this?

I'm planning to bridge two UcD400s, so both woofers see the same amps. In case both have their own UcD, I don't see why it would create problems. It would mean a lighter load for each UcD and an even higher damping factor, so why would it become worse? In that case one could even iron out small differences in the efficiency of the woofers by lowering the input signal of the amp of the woofer with the highest efficiency (actual not planning to do that).

So basically, I don't see any problem by giving each driver their own amp. Do others have experience with this?

Gertjan

[wytco0]

R Dijk,
that looks interesting not much room left in that rack ;-)

What power supply are you using? is it your own design? I cant see what board (if any its using).

[wytco0]

Just noticed that there are more picture of the new power supplies on the hypex site at New Hypex Power supply pictures

[Bgt]

when testing the UCD 400 power amp. with a FM Tuner on I hear interference with certain stations. While the tuner(Sony with 2 antenna inputs, quite new) is on a cable antenna system, so there is a strong signal, another tuner(older 1 with air cap.tuner) has no problem at all. Seems the modern 1 has more trouble with EMI from the amp. than the old one. BTW the amp. is build in an Allu. case so there should be enough shielding. I mean, where does the EMI come from to disturb the tuners reception?