Any advantage to make dual mono (PSU) for the gainclone (I'm ordering Brian GT's kit) - diyAudio
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Old 2nd April 2004, 07:01 AM   #1
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Default Any advantage to make dual mono (PSU) for the gainclone (I'm ordering Brian GT's kit)

Hi all,

I'm new at the gainclone. That's why for the shortcut, I order Brian GT's board+kit.

Will there be any advantage to make dual mono power supply for the gainclone kind of amp? (popular approach on the common solid state amp)

Also, currently I have an average 4-ohm load speaker (min is 3.9 ohm), what transformer voltage/power rating is the best for this load? (value before the rectifier)

What if next time I change my speaker to 8-ohm one, do I need to change the transformer, to get optimum result with this load?

Of course my questions above are for 'soundwise' decission. And I understand that 'best' and 'optimum' is subjective person-to-person.

So I would really appreciate for any opinions.

Regards,
---
David A.W.
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Old 2nd April 2004, 07:37 AM   #2
Nuuk is offline Nuuk  United Kingdom
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Selamat Pagi David,

If you spent the rest of your life reading through this part of the forum, you would still not have a definitive answer

Some like separate PSU's for each channel, some a single one.

I have tried both and can't honestly decide which I like best.

If you use transformers of at least 160VA rating, you could build two PSU's either of which would be capable of powering a Gainclone. You would then have the choice of trying one or two.

As regards the speaker impedance, if you use transformers with 18 volt secondaries they will do for both 8 and 4 ohm speakers.
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Old 2nd April 2004, 08:38 AM   #3
Ropie is offline Ropie  United Kingdom
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My ten pence worth: Dual mono psu will give a more forceful sound that will fill a big room but could get a bit harsh. One transformer will probably give you a softer sound (easier listening ) and personally I prefer that. I don't notice any difference in sound quality between having an integrated psu (in the amp case) or a separate psu connected to the amp with a cable.

My advice, similar to Nuuk's, is to start with one transformer and try that. At a later stage you can add another, in a seperate case, or the same case if it is big enough. This way you will save money initially, then if you prefer the dual mono psu sound you can keep it that way, or use the new transformer on another GC (once you build one GC, you will probably want to try another at some point anyway )
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Old 2nd April 2004, 10:45 AM   #4
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Quote:
Originally posted by Nuuk
Selamat Pagi David,

If you spent the rest of your life reading through this part of the forum, you would still not have a definitive answer

Some like separate PSU's for each channel, some a single one.

I have tried both and can't honestly decide which I like best.

If you use transformers of at least 160VA rating, you could build two PSU's either of which would be capable of powering a Gainclone. You would then have the choice of trying one or two.

As regards the speaker impedance, if you use transformers with 18 volt secondaries they will do for both 8 and 4 ohm speakers.

Are you saying that it should be exactly 18 volts or at least 18 volts? I read this same place else but can't remember.
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Old 2nd April 2004, 11:58 AM   #5
Nuuk is offline Nuuk  United Kingdom
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Quote:
Are you saying that it should be exactly 18 volts or at least 18 volts? I read this same place else but can't remember.
Not exactly 18 volts but the general rule is lower voltage/higher current for speakers with lower (4 ohm) impedance and visa versa.

As a guide, the cut off point if you want to use 4 ohm speakers, should be somewhere around 20-22 volts (before rectification). 18 volts is quite a common voltage for transformer secondaries and that's why I quoted that figure.
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Old 3rd April 2004, 12:13 PM   #6
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Well also depends on the price of the transformers you acquire. If you can get a 18V 3A transfomer for $3 and a 18V 6A transformer for $25, then sure I would be much more willing to get the two seperate ones. My logic being your spreading the load....like doubling the surface area
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Old 3rd April 2004, 02:35 PM   #7
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Here's what's written on 47Labs site regarding second PS:
Quote:
Q. What kind of improvement do we get by adding an extra power supply?
A. By adding another power supply, you make it into a complete mono structure. It also adds more power (does not double though) and current capacity. The result is an airier, deeper soundstage and more authotity through the entire frequency range.
I kinda agree with that.
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Old 3rd April 2004, 03:02 PM   #8
BrianGT is offline BrianGT  United States
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Quote:
Originally posted by Peter Daniel
Here's what's written on 47Labs site regarding second PS:

I kinda agree with that.
I don't see how it would add more power, unless the initial transformer was underpowered for 2 channels. Would using seperate secondaries (4 windings) on a larger transformer have the same effect as dual mono?

I have a 1kVA 4x25vac transformer that I was going to use for my bridgeclone.

--
Brian
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Old 3rd April 2004, 03:16 PM   #9
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I guess 47Labs transformers were underpowered

But I think that overall impression of more dynamics applies here as well as improved soundstage.
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Old 3rd April 2004, 03:26 PM   #10
grataku is offline grataku  United States
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In general, when in doubt about Peter's statements please refer yourself to:
On snake oil and personal experience..

I happen to think that dual mono with separate GNDs and balanced operation is the only way to go but don't have Peter's stature in the forum to say it out loud, or to make a big deal about it.
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