UCD 400 Mono's

[glt]

Re: Re: Re: UCD400's

mikela,

Below is part of an email from Jan-Peter. I have read this in the forums as well.

There are no big sonic difference between the two amplifiers. although the advantage of the UcD700 is that you need an auxiliary power supply to drive the buffer op amp. This will improve the sound.

Probably the main reason is because the 12V is derived from the power rails and it is too high in the 700, so you need an external 12V supply. However, the built-in 12V supply in the 180HG and 400HG is pretty good (I think shunt type with zener reference). This is lower noise than an LM317/337 based regulator. In addition, the LM opamp has a ps rejection ration of 100db or so. Thus I will doubt you can do better with the 700 unless you need the power.

 

[eclectic2k]

Hi Chris,

I am interested in doing this too. Can you provide details or a link?

Thanks,
Mike

Hi Mike,

For my main amp, I'm using the Hypex soft start. This makes switching and triggering fairly easy. It can operate via switch, momentary switch, or PTC.

I'm just using the switch closure input and wiring a FET in parallel with the front panel switch. So what I end up with is a simple, logical OR. I'm paranoid about ground loops from the 12v trigger (had issues once) so on my amp, the trigger input jack is isolated from the chassis, then run through an optocoupler, which in turn will control the FET. (I had originally planned a much more complicated arrangement and then got smart ;-)

For my surround amp, I'm using project39 softstart from ESP audio.
http://sound.westhost.com/project39.htm
I ordered the PCB, and I have to say they're quite nice and very small. A detail not mentioned on the public page is he added an extra transistor and some traces for a 12V trigger. It's a great little board. Of course you could easily wire it up without the PCB if you don't like the cost.

If you don't need a softstart you could easily wire up something similar with just a few transistors and a relay. It's also nice as it allows low voltage control of the AC, so that only the relay sees the high voltage.

-Chris