Transformer problem...

5150ed · 27th June 2008, 03:33 PM

Hi I am about to build an invert gainclone using OPA 541. I have a problem finding a good quality transformer in my country. As we know transformer does effect the sound of the amp so much. So I decide to use an old transformer from my old class A Electrocompanient amp which shold be very good quality.

But the problem is its secondary are 35V-0 3.5A 35V-0 3.5A too high for my use I want it like 16V to 20V.
Is there any way can I reduce the voltage to 16V-0 16V-0 without trade of the sound quality???

And the primary of the transformer is 110V-0 but my country use 220V AC, anyway, in the amp has a circuit to reduce the ac input voltage to 110V. My question is is it gona reduce the sound quality if I use that circuit with my gainclone too???

Please help

Greg Erskine · 27th June 2008, 04:24 PM

hi 5150ed,

3 options:

1. rewind transformer
2. use autotransformer
3. buy proper transformer

regards

AndrewT · 27th June 2008, 04:56 PM

4th option:
refurbish the ClassA Electrocompanient.

Nuuk · 27th June 2008, 06:00 PM

5th option. Pay for me to fly out to Bangkok with a decent traffo!

5150ed · 28th June 2008, 08:08 AM

Hmmmm... Thanks you all.

From ur five options you all suggest, I may have to ask u a new question

.

Is there any online store which provide a high quality transformer and ship worldwide???

Nuuk · 28th June 2008, 08:36 AM

Try here .

5150ed · 28th June 2008, 09:34 AM

Thanks so much Nuuk.

I just went through the web and found MULTICOMP Toroidal transformer.
It quite expensive, around USD120.
Does anyone has experiences about this brand of transformer???

And what should be the voltage using with OPA541 inverted schematic?
I plan around 14V-18V coz I aim for more natural and relax sound like SET amp, Is it too low?

Nuuk · 28th June 2008, 09:46 AM

What speakers will you be driving with this amp?

5150ed · 28th June 2008, 09:57 AM

I am not sure but should be 6ohms minimun and 89db up.
May be Fostex F200A I had.

I like bass, power, soundstage but not too much dynamic and attact.
My music is 80% old jazz and vocal and the rest is classical and pop.

Nuuk · 28th June 2008, 10:05 AM

OK, I would still aim for around 27 volts using an 18VAC transformer. If you can afford it, go for two at around 120VA and build dual mono. If not, 225VA will be fine.

I run my OPA541 amps at 27 volts and they sound very much how you want yours to sound.

27th June 2008, 03:33 PM	#1
5150ed diyAudio Member Join Date: Jul 2005 Location: BKK	Transformer problem... Hi I am about to build an invert gainclone using OPA 541. I have a problem finding a good quality transformer in my country. As we know transformer does effect the sound of the amp so much. So I decide to use an old transformer from my old class A Electrocompanient amp which shold be very good quality. But the problem is its secondary are 35V-0 3.5A 35V-0 3.5A too high for my use I want it like 16V to 20V. Is there any way can I reduce the voltage to 16V-0 16V-0 without trade of the sound quality??? And the primary of the transformer is 110V-0 but my country use 220V AC, anyway, in the amp has a circuit to reduce the ac input voltage to 110V. My question is is it gona reduce the sound quality if I use that circuit with my gainclone too??? Please help

27th June 2008, 04:24 PM	#2
Greg Erskine diyAudio Member Join Date: Jan 2002 Location: Sydney/Australia	hi 5150ed, 3 options: 1. rewind transformer 2. use autotransformer 3. buy proper transformer regards __________________ Greg Erskine

27th June 2008, 04:56 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	4th option: refurbish the ClassA Electrocompanient. __________________ regards Andrew T.

27th June 2008, 06:00 PM	#4
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	5th option. Pay for me to fly out to Bangkok with a decent traffo! __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

28th June 2008, 08:36 AM	#6
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	Try here . __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.


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28th June 2008, 08:08 AM	#5
5150ed diyAudio Member Join Date: Jul 2005 Location: BKK	Hmmmm... Thanks you all. From ur five options you all suggest, I may have to ask u a new question . Is there any online store which provide a high quality transformer and ship worldwide???

28th June 2008, 09:34 AM	#7
5150ed diyAudio Member Join Date: Jul 2005 Location: BKK	Thanks so much Nuuk. I just went through the web and found MULTICOMP Toroidal transformer. It quite expensive, around USD120. Does anyone has experiences about this brand of transformer??? And what should be the voltage using with OPA541 inverted schematic? I plan around 14V-18V coz I aim for more natural and relax sound like SET amp, Is it too low?

28th June 2008, 09:46 AM	#8
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	What speakers will you be driving with this amp? __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

28th June 2008, 09:57 AM	#9
5150ed diyAudio Member Join Date: Jul 2005 Location: BKK	I am not sure but should be 6ohms minimun and 89db up. May be Fostex F200A I had. I like bass, power, soundstage but not too much dynamic and attact. My music is 80% old jazz and vocal and the rest is classical and pop.

28th June 2008, 10:05 AM	#10
Nuuk diyAudio Member Join Date: Feb 2003 Location: Somerset, SW England	OK, I would still aim for around 27 volts using an 18VAC transformer. If you can afford it, go for two at around 120VA and build dual mono. If not, 225VA will be fine. I run my OPA541 amps at 27 volts and they sound very much how you want yours to sound. __________________ The truth need not be veiled, for it veils itself from the eyes of the ignorant.

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