| 5150ed |
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 :D |
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| Greg Erskine |
hi 5150ed,
3 options:
1. rewind transformer
2. use autotransformer
3. buy proper transformer
regards |
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| AndrewT |
4th option:
refurbish the ClassA Electrocompanient. |
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| Nuuk |
| 5th option. Pay for me to fly out to Bangkok with a decent traffo! ;) |
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| 5150ed |
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??? |
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| 5150ed |
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? |
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| Nuuk |
| What speakers will you be driving with this amp? |
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| 5150ed |
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. |
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| Nuuk |
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. |
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| 5150ed |
Hmmm... Money is not a problem.
I just want to know is MULTICOMP Toroidal transformer a high quality and worth the money or not.
But I do not want to have a useless pair of transformer more in my house.
I already have 5 transformer left unused. :whazzat: |
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| Nuuk |
| What is the problem with the other transformers? |
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| 5150ed |
The probles are about the quality of the transformer wound in my country.
I choose the most well known company but their transformers are very poor quality.
-Always +20% voltage to the order spec, once I order a 5V transformer for my 300B filaments and guess what I get 5.96V.
-They shake right after the switch turned on and get very hot after 10mins.
-And their price is not cheap at all USD30-80.
I am not sure if this characteristic considered poor quality by others but they are really annoying me very much.
So I decide to pay hard but just one time.
Anyway, what is the gain u set on your OPA541 amps?
Can you suggest me the resistors value???
Millions thanks :) |
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| Nuuk |
Is it possible you have DC on your mains supply?
It could be worth trying this before spending out more money on transformers. :att'n:
From memory I have a gain of 9 or 10 in my OPA541 NIGC, using something like 1K and 9K1 for the resistors. |
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| 5150ed |
Nuuk,
Your link is invalid, can you give me a new one? |
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| AndrewT |
Hi 5150,
the open circuit voltage of transformers is always higher than the loaded voltage.
The ratio between these two voltages is the regulation figure quoted in the specification.
An EI tends to have higher regulation than an equivalent VA toroid.
A small VA transformer always has a higher regulation than a larger version built to the same spec. |
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| Puffin |
| Nuuk. Interesting article. Not read anything about that before. |
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| Nuuk |
| Could be worth a try! Are Thailand and Malaysia on the same electricity sub-station? :D :D :D |
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