Oahu output transformer

AndersN · Post by **AndersN** » Sat 04/17/04 3:46 am

I have just bought a Oahu JU28 (16watt) topp with a broken output transformer (maybe the american word for transformer is tranny?). I don't have any scematics on the amp, and the transformer is not marked, so i don't know which transformer to use, where I can get it, or if there, is a replacement I can use. Can anybody help me?

Post by **zaphod_phil** » Sat 04/17/04 9:39 am

What are the power output valves? Then we can work out what impedance is needed, and tell yo what options you have. The Hammond 125E is probbaly the most flexible general-purpose OT for push-pull amplifiers, as it can be set for all kinds of load impedances.

AndersN · Post by **AndersN** » Sat 04/17/04 10:26 am

Tank you very much zaphod_phil...
The amplifier is built in 1999 or 2000 and has productionnumber 0086. It is not built many I think. It is 16,5 watt and has two 12AX7 tubes in the preamp section and two EL-84 in the power amp section and one rectifier tube. This is all I know so far, I dont have the amp here (Hamar, Norway) until the start of March so at this point I don't have any more information. However, if this info is enough til decide on the transformer type, it would have been nice to have it ordered while I wait for the amp.

Post by **Plexi** » Sat 04/17/04 1:19 pm

All the links to Jester,are not working. But if you go with a different replacement,also look at it and make sure it will fit,how its mounted,so it doesn't hit the speaker. I don't know if Jester is still making amps,or they should have the replacement. The Heyboer Graydon sells might also be a good one to get,if it looks like it will fit ok.

Richie

Post by **Plexi** » Sat 04/17/04 1:21 pm

Oh i forgot,Jester Enterprises,Inc is who made it

Post by **zaphod_phil** » Sat 04/17/04 3:43 pm

AndersN wrote:... and two EL-84 in the power amp section a...

You would then need an OT set for around 8k load impedance. Like Richie says, you need to check the dimensions carefully to make sure any replacement transformer fits in without too much trouble. Good candidates are AC15 or Marshall 18W replacement transformers. As you're in Europe you can try Shinrock at www.shinrock.de and http://www.shinrock.de/shop/ for nice handmade ones. And like I said before the Hammond 125E is the more mass-produced alternative - http://hammondmfg.com/125a.htm

AndersN · Post by **AndersN** » Sun 04/18/04 4:28 am

Thank you for your kind help.
I will check the types and dimentions as soon as I get the amp.

Donations

Links

Welcome

Oahu output transformer

Oahu output transformer