I have 2 transformers which are identical i can get 35.5v out per transformer
which configuration would be best to use to power an amplifier and would stacking them be a problem ?
20210403_132724 by glenn jarrett, on Flickr
20210403_132736 by glenn jarrett, on Flickr
which configuration would be best to use to power an amplifier and would stacking them be a problem ?
20210403_132724 by glenn jarrett, on Flickr20210403_132736 by glenn jarrett, on FlickrEither one works. Configuration 2 is a bit more tolerant to mismatches between secondaries and you have the option of putting them outphased if it helps with induced hum elsewhere in the chassis. They are independent power supplies connected in series. If you do this, wire them that way. Then you can make two separate twisted pair from the rectifiers to the caps if you’re putting them out in the middle of the chassis to heat sink them. Twice the diode drops. Stacking toroids isn’t usually a problem electrically. A bit trickier mechanically. Padding between them is a necessity unless you want to see a bright flash one day when something wears thru.
If in series as you show, no big deal, both configurations will work fine.
The big problem comes when paralleling them, not your case.
In theory they can be stacked, BUT always a little flux leaks out, even if toroids, so I would separate them by a , say, 12/15mm disk made out of MDF or plywood.
The big problem comes when paralleling them, not your case.
In theory they can be stacked, BUT always a little flux leaks out, even if toroids, so I would separate them by a , say, 12/15mm disk made out of MDF or plywood.
Both options will work, but the first is preferable for a number of reasons: lower part count, lower diode losses, and more subtle, a better utilization of transformers: when the amplifiers work to amplify VLF (defined as lower than 2*Fmains, probably 100Hz in your case), each transformer of the second situation has to work alone to supply the corresponding output polarity.
This increases the rms load, because the individual peak currents are increased even though the total average remains the same, and because of the way the rms value is computed, it has an impact.
Most of the energy of an audio signal occurs at relatively low frequencies, thus not to be neglected.
It isn't paramount either: unless you use your amplifiers at max power in a disco, it will have little effect.
Transformer mismatch is a non-issue if you use industry-made, identical types: they are exact to the turn (unless a production incident has occured, which should have it discarded at the final test)
This increases the rms load, because the individual peak currents are increased even though the total average remains the same, and because of the way the rms value is computed, it has an impact.
Most of the energy of an audio signal occurs at relatively low frequencies, thus not to be neglected.
It isn't paramount either: unless you use your amplifiers at max power in a disco, it will have little effect.
Transformer mismatch is a non-issue if you use industry-made, identical types: they are exact to the turn (unless a production incident has occured, which should have it discarded at the final test)
So what's the BIG problem paralleling them? I'm about to parallel power supplies for a pair of mono amps. All amps and PSUs are in separate chassis with umbilicals. I'm planning to piggyback two identical PSUs per amp. I will attach power diodes in series on the psu outputs to keep them charging only themselves. Each psu currently has a pair of 6800uf caps which I will also upgrade to each a pair of 10,000uf. Their is currently no soft start. On/off is integral to the volume pot in the separate pre. There is a little pop on turn on which is part of the design so I suppose the overall increase will now require it. Is there something you guys think is wrong with this approach? I get that there is a compromise in doubling the transformers rather than using a bigger one but the PSUs are factory oem to the kit which I happen to have on hand and sitting one on top of the other looks killer. The amps are 100 watts each, the PSUs are 250va each. So I will end up with 500va per amp, less some waste plus the overall increase in C.
