PT for USA?

brett336

Greetings!

I just ordered the A15Mk1 today and then I realized that these kits are designed around 220V supply power.

What should I do to modify the kit for 110V?

Or will "Musikding" realize that I am in the USA and substitute a different PT?

Thanx for the help!

brett336

rincewind

Re: PT for USA?

You can either substitute the power transformer that gives you similar output voltages. Just like you mentioned.
Or you put a second transformer in front of it that transforms your 110 Volts to 220.

Otherwise you only get half the voltages into the amp and it will not work (or at least not with the desired results).

Jan

MAD

Re: PT for USA?

You can order the kit with PT and have to use a stepup PT or you can order the kit without PT and can use a 110/115V type from Hammond.
Regards, Martin

brett336

Re: PT for USA?

I was looking at the Hammond website and I connot seem to find the correct 115V PT to use.

What are the correct specs for the secondary side of the PT for the A15?

I have read that the secondary specs for the PT are:

265V @ 120mA
24V @ 100mA
6.3V @ 6A

Are there correct?

I cannot seem to find a 115V Hammond PT with a tap for the 24V.

The Hammond 270HX has a seconary spec of:
275V @ 200mA
6.3V @ 2.0A (heaters)
But only a 5.0V @ 2A (rec)

Can anyone provide a part number for a 115V Hammond PT?

Thanx!

brett336

MAD

Re: PT for USA?

Hi,

for the A15 you'll need a PT with secondaries like this:
230V / >100mA
20V / about 100mA (if you want to use it for the footswitch circuit too, the BIAS circuit only needs about 10mA)
6,3V / >2,5A

Regards,
Martin

brett336

Re: PT for USA?

Thank you for the information!

It is not likely that I will be able to find one "Off-the-Shelf" PT with these specs.

Can I use one PT for the power tubes and tube heaters (230V & 6.3V)? And then use a separate low voltage PT to get the 20V for the bias?

Is there anything special that I should do to accomodate the use of two PT for the 117V primary application?

Thanx for the quick replies!

Brett

brett336

Re: PT for USA?

But then again,

If I am going to add another transformer, I might as well just add a step-up transformer to take the 110V to 220V... Just like your original suggestion.

Is there anything special that I would need to do to add the step-up transformer? Would there be any additional noise as a result of adding the additional transformer?

Thanx!

Brett

MAD

Re: PT for USA?

A stepup transformer is the easiest way, you just build the kit as described in the documentation and then plug the amp in the stepup transformer. There is no technical disadvantage from this solution, the stepup transformer should be specified for >50W. For your convenience make sure, that the stepup transformer has a plug socket for german "Schutzkontaktstecker", then it's real plug and play
Regards, Martin

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