Al Garay said:
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
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
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
SSassen said:
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
Just noticed that there are more picture of the new power supplies on the hypex site at New Hypex Power supply pictures
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?
well before the output filter there is a pwm carrier signal at (i believe) ~450khz. Despite hypex being very careful in creating a pcb that radiates as little emi as possible, some tuners are pretty sensitive to this stuff.
jp, wouldn't it be nifty if you could change the low-voltage output on the psu board with a trimpot in stead of making it 15V fixed? Looks like it'c nicely regulated..
jp, wouldn't it be nifty if you could change the low-voltage output on the psu board with a trimpot in stead of making it 15V fixed? Looks like it'c nicely regulated..
ghemink said:
I have the SMPS working. Just test drived it on a 90W lightbulb for half an hour or so, in fact it was a 60W lightbulb for 100V, but I had about 125V out (+ and - 62.5V). So the bulb was a bit overloaded and I guestimate that I delivered about 90W.
Under that load condition. I have a 100Hz signal of about 0.35V RMS sitting on the 62.5V and about 30mV RMS 75kHz switching frequency and a few harmonics.
I have nothing modified yet. I will later this week try it with more load. Had it not yet heatsinked, just the power MOSFETs and the diodes mounted on an Aluminum L profile that is meant to bolt it to a heatsink. Even after half an hour or so at 90W, this L profile did not get very warm (did not measure temperature but felt not hot, just nicely warm, 40C??).
I want to improve the regulation behavior to suppress the 100Hz more. I also want to make the slowstart slower (increasing one cap in value) since currently, when starting up with the lightbulb load in place, I get an overshoot to +- 72V before the output voltage settles at +- 62.5V. Probably the overshoot disappears when I make the slowstart slower.
Best regards
Gertjan