Re: Isolation Transformer

On Sun, 27 Nov 2005 22:11:22 GMT, "west" <westley@xxxxxxxxxxxxxxx> wrote:

>What size (V-A) Isolation Xfr would you recommend for a bench?

I use a 2000 VA unit, because I can! (Got it free from an old signal
streetlight) I would say the bigger the better... you don't want to worry about
powering a 500 watt amp from a 500 VA transformer - it will screw everything
up...


>Also, if you
>wanted to permanently install an isolation Xfr in a tube amp, how would you
>calculate the size needed with a bit of marginal safety?

Well, I guess you need to know the rating of the amp!!

If there is no electrical plate on it, you'll have to guess... for a tube amp,
you can look up the power requirements for the tubes filaments, and then take
the audio power out of the amp and multiply by three, that will give you a good
idea of what the amp needs, and double that to find the size to use.

EG a 50 watt mono amp with two 6L6 outputs and three 12AX7A tubes would want
about 200VA or so... I'd double it at least for a safety margin and get a 400VA
unit... of course it depends on your budget as well!


> To sum it up, we
>are talking about 2 xfrs, one all-purpose for the bench and the other for a
>particular amp. Thanks so much in advance. All comments are most welcomed.
>
>Cordially,
>west
>

.

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