Hammond 1650 impedance selector

[Maurizio]

Hi all,
I have tried to do a search on the old ampage forums but I seem to get only software errors at the moment, so here I am with a question that's probably already be answered a million times: is there a way I could hook up a Hammond 1650 OT so that I could use a selector to switch impedance? I know tubesandmore sells something like that but I live in Europe and don't feel like paying loads on shipping for something that maybe can be done with a 3 positions 3 poles rotary switch or something like that.
Has anyone done this before and cares to share some schems?
Thanks in advance
Maurizio

[Joachim]

Hi Maurizio,

Have a look at this:
http://dst-engineering.com/TN.php?n=OTWiring

All you need is a solid three position rotary switch with 3 levels. I'm sure you will get one also in our old Europe ;).

Ciao,
Joachim

[Maurizio]

Thanks Joachim, With a bit of patience I was coming up to pretty much the same solution. What I can't understand is why Hammond sticks with these odd output configuration but hey oh...as long as it works in the end.
Cheers

[Ray Ivers]

Maurizio,

My guess is that Hammond wants to use reasonably-sized secondary wire to keep transformer size and cost down, and yet maintain their full-power specifications into a 4-ohm load. According to Kevin O'Connor, Hammond had a line of output transformers with conventional 4-8-16 ohm secondaries, but I've spoken to three people at Hammond and none could confirm this, or find the part numbers in a computer search - maybe these are only available in Canada.

I agree - it can be a real PITA to replace a 4-8-16 OT with a Hammond.

Ray

[Jon Anderson]

Check out the AX84 October

http://users3.ev1.net/%7Ecliffchappell/amps/AX84/October/AX84%20October%2005.09.28.html

It uses a 1650F and a impedance switch, and the schematic has a wiring diagram.

Jon