va ratings for ucd180

[snkby]

i built a powersupply for 2 ucd180 modules.

2 xformers rated @2.35a each with secondaries of 27v.

each xformer feeds a full-bridge monolithic 25a metal-case rectifier.

each rail is 27kuf and measures 40v +/-.1v

the caps are seriesed for the +/- rails.

everything is great until i start to really crank the volume.

right when it starts getting to where i think it sounds really big the amps start momentarily shutting down.

i started to think they were clipping but i heard no distortion prior to them shutting down.

they shut down during the loudest transients for only the duration of the transient.

i know i have enough capacitance but im starting to wonder if i have enough amperage.

is my psu running out of amperage ?

2.35a x 27v = 63.45va per rail right ?

ive been using an old mitsubishi 2-channel amp and it plays plenty loud for me and i think its rated at only about 60wpc.

i was hoping i would be able to go loud and keep all the great stuff that the pwm amps do.

i have a pair of hugeass 11a@27v xformers i could use but didnt want to build a larger psu if that wasnt the problem.

thanks

 

[classd4sure]

It could likely be due to very poor regulation. I use a duel secondary 500VA, 31Vac and there is no shutting down, it runs two 180's off it. I'd try a better transformer.

 

[snkby]

do you think the supply voltage is

sagging too much under the biggest loads(transients) ?

are you using regulators ?

if you are using regulators then which ones ?

thanks.

 

[snkby]

just thought of this.........the psu is

outboard and connected with a 5' cable of 14awg 3-conductor.

ive used a similar setup with other amps with no problems.

could it be a problem for the ucd180 ?

or is the low va most likely the cause ?

thanks.

 

[classd4sure]

Probably both. Nope, not using regulators.