Transformer for Gainclone

[syklab]

Hi Peter,
I am planing to start building the Gainclone purchased a while ago, I am think about ordering a transformer for a dual mono setup but with 1 transformer having 4 secondary windings. Is the following spec looks ok? Will there be any ground loop problem?

Thanks

TRANSFORMER, 400VA, 4 X 25V
Power Rating:400VA
Secondary Voltages:4 x 25V
Secondary Current Nom:4A
AC Power:400VA
Current Rating:4A
Output Voltage:25V
Regulation:5%
Secondary Power:112.5VA
Single Primary Voltage:230V
Single Secondary Voltage:25V
Transformer Type:Toroidal

Primary 1: 0-112.5
Primary 2: 0-112.5

Secondary 1: 0-25V
Secondary 2: 0-25V
Secondary 3: 0-25V
Secondary 4: 0-25V

[frank1]

Originally Posted by syklab

Hi Peter,
I am planing to start building the Gainclone purchased a while ago, I am think about ordering a transformer for a dual mono setup but with 1 transformer having 4 secondary windings. Is the following spec looks ok? Will there be any ground loop problem?

Thanks

Ground or earth loops are not dependant on the mains transformer but on the external interconnection between units.
I always incude earth loop isolators nowadays.
See Earthing (Grounding) Your Hi-Fi - Tricks and Techniques Figure 4 is what I use.

Personally, I think you would be better off (and cheaper) using one or two 0-25, 0-25 transformers.
400vA is massively over the top for the typical stereo "gain clone". I would be inclined to use a single 160vA or it you are a determined "dual mono" fan, 2x 100vA.
I guarantee, you won't hear the difference.
And please use an adequate amount of smoothing as the original "gain clone" smoothing is minimal in the extreme. (and Yes, I have proved this for myself by listening tests)

Frank

[syklab]

Hi Frank,
Thanks for the helpful information.

[Peter Daniel]

Originally Posted by syklab

Hi Peter,
I am planing to start building the Gainclone purchased a while ago, I am think about ordering a transformer for a dual mono setup but with 1 transformer having 4 secondary windings. Is the following spec looks ok? Will there be any ground loop problem?

If you keep everything separate (true dual mono) there shouldn't be any ground loop problems.

As to transformer specs, if there's no size restrictions and your budget allows it, I don't see a reason to go with anything smaller.

It also makes me curious, why the previous poster insists on larger caps but smaller transformer?

[nigelb001]

Originally Posted by Peter Daniel

It also makes me curious, why the previous poster insists on larger caps but smaller transformer?

Me too.

An individuals listening tests are so subjective and are sometimes contradicted by another individual. so here's my contradictory listening tests. I found that using a large transformer and smaller caps gave me a noticeable increase in dynamics and transient response. With a stereo supply rather than dual mono the orginal build used a 160VA that I had hanging around but upped later to 300VA, Caps finished up as 1500uf on amp boards and 470uf on PS board no snubbers etc. For me the other important thing was keeping the amp compact with really short lead lengths rather than large enclosure with spaghetti wiring that is often seen in forums.

Just my alternative view.