2 toroids in monoblock?

[markre]

I opened my old Goldmund srm monoblocks and found 2 toroid (same size) transformers inside. Can anybody tell me what the idea behind this design is?

[barefootwhistler]

It most likely has two power rails: a power supply with a positive and negative half that are at the same voltage from ground (ig +30V and -30V). This is often done with two separate windings on the same transformer, but for availability or other reasons they went with two transformers. (perhaps two were cheaper than one special made one)

[tommy1000]

No, it has not two power rails. The srm monoblock has only one rectiflier.
The transformers are connected in parallel. If this really helps this amp is debatable.
From what I understand they only buy one size of toroidal transformers used in most of there amplifier products.

[oz7aff]

No, it has 4 rectifiers, so dual power rail is no problem

[tommy1000]

In these pictures of the srm monoblock here are only one rectiflier.

[oz7aff]

It is a bridge rectifier, and there is 4 rectifiers inside.

[Ian Finch]

Let's be clear, there are 4 diodes in a bridge rectifier. That doesn't mean it handles any more than one supply of balanced, +/- rails. If there are 2 rail voltages, there need to be 2 bridge rectifiers. That's a total of 8 diodes.

In the R/H pic, the windings from each transformer are paralleled at the PCB connection, so 1 trafo supplies one rail, the second supplies the other.

Anyone like to suggest how else it could be wired with effectively only one winding from each trafo?

[oz7aff]

You can wire a +/- supply with only 2 diodes with the disavantage that the ripple will be 50 Hz and there will be a demand for bigger filtercapacitors.

And making +/- supply with only one bridge rectifier is no problem, you can use 2 bridges, but that only ad noise and power loss to the system.

[Elias]

Originally Posted by markre

Can anybody tell me what the idea behind this design is?

To balance the weight evenly accross the enclosure, to make it feel more 'hifi' ?


But only 1000uF filter caps ??

[Ian Finch]

You can wire a +/- supply with only 2 diodes with the disavantage that the ripple will be 50 Hz and there will be a demand for bigger filtercapacitors......And making +/- supply with only one bridge rectifier is no problem, you can use 2 bridges, but that only ad noise and power

Quite so, those are possible rectifier arrangements for dual winding transformers.

However, neither follow the wiring of the posted image, where there is, effectively, only 1 secondary winding in each trafo, because each pair of leads from each trafo is simply paralleled before rectification.
ergo: It cannot be either A or B circuits.