Sjöström Audio DIY forum

Projects => Power supplies => Topic started by: rtate on April 03, 2008, 05:55:01 PM

Title: dct-01 question...
Post by: rtate on April 03, 2008, 05:55:01 PM
I have 8 mono blocks built with toroid transformers and a few of them have a hum or buzz.
I am considering the dct-01 as a possible solution and was wondering if Icould just use one dct-01 on the supply to the power bar instead of one for each amplifer??

The amps are "leach superamps" 250 watts and use 10 amp transformers with 80,000uf capacitance. 115 VAC mains
I am currently in the process of installing soft start circuits in each amp.
Title: Re: dct-01 question...
Post by: peranders on April 03, 2008, 08:44:10 PM
If you connect them to the same outlet, do them hum equally much?
Title: Re: dct-01 question...
Post by: rtate on April 03, 2008, 09:58:06 PM
The amps are fed from a dedicated 20 amp breaker run with 10 gauge wire.
There are no other devices on this circuit.
One wall recepticle feeds a power bar where the amps are plugged in.
I do not think that they all hum equally and the volume of the hum seems to rise and fall in no particular pattern.
I am wondering if this is a product of several hard starts over the 4 years that they have been in service.
The hum seems to have gotten worse over time.
I just thought that if I put the trap before the wall recepticle I could clean up the signal before it gets to the power bar.
Title: Re: dct-01 question...
Post by: peranders on April 04, 2008, 06:46:22 AM
If you have a hum that comes and goes, then it might be DC which is causing this.
Title: Re: dct-01 question...
Post by: rtate on April 04, 2008, 12:41:01 PM
So my question is, can i use one trap to clean up the mains feen or do i have to use one for each amplifer on the circuit/
Title: Re: dct-01 question...
Post by: peranders on April 04, 2008, 01:01:56 PM
The limit is set by the diodes and the size of the caps. I should recommend one trap to each amp.
Title: Re: dct-01 question...
Post by: rtate on April 04, 2008, 03:58:50 PM
If I put one in each amp should I put it before or after the softstart circuit.

Do you have suitable part numbers for the diodes, and values for the capacitors so that I can build a proto-type before i order the pcb's

THANKS.
Title: Re: dct-01 question...
Post by: peranders on April 04, 2008, 06:05:53 PM
It doesn't matter where you put it.

Diode: 6 A or more, voltage rating > 10 V

Cap: 10000 uF or more, >25 V but I should think 16 V would work. Max DC voltage is only 1-3 V.
Title: Re: dct-01 question...
Post by: rtate on April 04, 2008, 07:28:04 PM
 P-A just to confirm again:

1) If I were to use 6 diodes as per your schematic rated at 6 amp, this would be ok for  1000va transformers with 80,000uf capacitance placed before my softstart circuit.

2) In the trap circuit is there a benefit to more capacitance?

3) Which line woud you put the trap on  Hot or neutral and why?

4) Why not on both hot and neutral?

Space in my chassis is not a concern for component size.
Title: Re: dct-01 question...
Post by: peranders on April 04, 2008, 07:43:33 PM
1) Start with 2 diodes. Current flows in the diodes only at start up. The unit is intended for home use, not hard professional duty.

2) Yes

3) Doesn't matter

4) Only in series with the primary winding, that's enough.