Dual Toroid outputs...

Yoda · 26th September 2001, 09:40 PM

OK, my new 300VA toroidal transformer had dual outputs, i plan to use this for a stereo amp. I plan on using two seperate power supplies (rectifiers/capacitors and such), one per channel. Will i get better channel separation if i give each rectifier its own output lead, or should i wire the transformer's outputs in parallel and have each rectifier feed off of the one line? is this like haveing two transformers?

tsz · 26th September 2001, 09:58 PM

I think you should give each rectifier its own winding, It would give somewhat lower cross-talk but it's probably inaudible anyway.
No it's not quite like having 2 transformers, but again the somewhat lower cross-talk of 2 separate transformers is probably inaudible and probably not worth the money.

/Tobbe

GRollins · 26th September 2001, 10:35 PM

Yoda,
Some pieces of the puzzle are missing yet.
Is each secondary equipped with a center tap? You may need to use both windings together in order to achieve positive and negative rails.
Is each winding of sufficient voltage to run the circuit? They may need to be run in series in order to get enough voltage.

Grey

Yoda · 27th September 2001, 12:08 AM

upon furthur inspection of the scematics, it actually needs a railed 30-0-30 supply, thats why i need dual secondaries. thanks for pointing that one out ;-)

PassFan · 27th September 2001, 03:19 AM

You might check out the power supply for the A75 at passlabs.It uses a dual sec. but still maintains seperate bridges and caps for each channel plus a regulated front end. Might be what your looking for.

Alex M · 27th September 2001, 01:36 PM

The big advantage of using separate windings (or separate
transformers) for two channels of a stereo amplifier is that
it allows you to isolate the ground connections of the
channels.

A rational system has the chassis ground connected to signal
ground only at one point (preferably in the preamp) and the
signal grounds completely independent throughout the rest of
the signal path. This should really reduce the chances of
hum loops and noise pickup.

Of course most systems don't do this - CD players in
particular tend to common the grounds of the two channels -
which means that you really have to switch signal grounds as
well as the signal itself at the source selector in the
preamplifier. However, if you're building the system
yourself at least you have a chance to do the job properly!

Alex

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26th September 2001, 09:40 PM	#1
Yoda diyAudio Member Join Date: Jul 2001	OK, my new 300VA toroidal transformer had dual outputs, i plan to use this for a stereo amp. I plan on using two seperate power supplies (rectifiers/capacitors and such), one per channel. Will i get better channel separation if i give each rectifier its own output lead, or should i wire the transformer's outputs in parallel and have each rectifier feed off of the one line? is this like haveing two transformers?

26th September 2001, 09:58 PM	#2
tsz diyAudio Member Join Date: Aug 2001 Location: Göteborg, Sweden	I think you should give each rectifier its own winding, It would give somewhat lower cross-talk but it's probably inaudible anyway. No it's not quite like having 2 transformers, but again the somewhat lower cross-talk of 2 separate transformers is probably inaudible and probably not worth the money. /Tobbe

26th September 2001, 10:35 PM	#3
GRollins diyAudio Member Join Date: Feb 2001 Location: Columbia, SC	Yoda, Some pieces of the puzzle are missing yet. Is each secondary equipped with a center tap? You may need to use both windings together in order to achieve positive and negative rails. Is each winding of sufficient voltage to run the circuit? They may need to be run in series in order to get enough voltage. Grey

27th September 2001, 12:08 AM	#4
Yoda diyAudio Member Join Date: Jul 2001	upon furthur inspection of the scematics, it actually needs a railed 30-0-30 supply, thats why i need dual secondaries. thanks for pointing that one out ;-)

27th September 2001, 03:19 AM	#5
PassFan diyAudio Member Join Date: Aug 2001 Location: Central FL	You might check out the power supply for the A75 at passlabs.It uses a dual sec. but still maintains seperate bridges and caps for each channel plus a regulated front end. Might be what your looking for.

27th September 2001, 01:36 PM	#6
Alex M diyAudio Member Join Date: Apr 2001 Location: Hampshire, UK	The big advantage of using separate windings (or separate transformers) for two channels of a stereo amplifier is that it allows you to isolate the ground connections of the channels. A rational system has the chassis ground connected to signal ground only at one point (preferably in the preamp) and the signal grounds completely independent throughout the rest of the signal path. This should really reduce the chances of hum loops and noise pickup. Of course most systems don't do this - CD players in particular tend to common the grounds of the two channels - which means that you really have to switch signal grounds as well as the signal itself at the source selector in the preamplifier. However, if you're building the system yourself at least you have a chance to do the job properly! Alex