Output Transformer for 7591 pushpull amp?

[retrorod]

Got an old Premier B160 Club Bass amp with a bad OT. Any suggestions on a new replacement for it? Uses 5Y3rect.,pair 7591A,12AX7,EF86 into 8ohm 15" speaker. Thanks for any recommendations...

[jrfrond]

A run-of-the-mill OT made for a 50W amp using 2- 6L6GC (e.g. Fender Bassman) will serve your purpose.

[imaradiostar]

I have triode electronics deluxe reverb TF in my 7591 based amp and I think it's fabulous and it was less than 30 bucks. made in the USA too!

jamie

[Chuck H]

A run-of-the-mill OT made for a 50W amp using 2- 6L6GC (e.g. Fender Bassman) will serve your purpose.

It's worth mentioning that I've never seen a PP 7591 amp using anything but the typical 6.6k primary. Many 6L6 OT's made for guitar amps are much lower. But many do use that primary Z and those would be fine.

I have triode electronics deluxe reverb TF in my 7591 based amp and I think it's fabulous and it was less than 30 bucks. made in the USA too!

It's also worth mentioning that a 7591A is good for over 20 watts. A pair at 450Vp can deliver 45 watts. I would want to know more about the circuit before I would use a Deluxe OT. If it's a low power amp it would probably be fine. If you do intend to use it for bass and not guitar I would probably want more iron than a Deluxe OT has for better fidelity.

Something like a Hammond 1620 is a little beefier. It is rated at 20 watts but believe me, it'll do 40 watts in a bass/guitar amp with no problems. Hammonds are VERY conservatively rated. A tech at Hammond told me that the standard practice with thier 1600 OT's is to go 1/2 the amps watt rating for use is guitar amps. I use a 1608 (rated at 10 watts but bigger than any 20 watt guitar amp OT) in a 20 watt amp that I run cranked all the time. It doesn't even get warm.

Chuck

[imaradiostar]

It's also worth mentioning that a 7591A is good for over 20 watts. A pair at 450Vp can deliver 45 watts. I would want to know more about the circuit before I would use a Deluxe OT. If it's a low power amp it would probably be fine. If you do intend to use it for bass and not guitar I would probably want more iron than a Deluxe OT has for better fidelity.
Chuck

Good of you to point this out. I figured with a 5y3 rect it was probably well under 30 watts output. It also has 4 and 8 ohm taps in case you need them.

Here is a link to the OT I spoke of:

Deluxe Output Transformer TF110-48/UL 6600CT 4/8 ohm

They also make one that mounts in the same holes but uses a size or two larger EI lams, paper bobbin and an additional 16 ohm tap. I have the lesser OT and it's surprisingly level down to 30Hz at 22 watts output in my amp. The waveform doesn't start to look mediocre till 20Hz at that power level. That tells me it should do 40Hz at 40 watts without too much complaint which is in line with what they say about it being good for 50 watts at 80 hz.

I only suggest it because it's cheap and honestly it's my favorite transformer for 7591's. At 29 bucks it's cheap enough that if you don't like it you can keep it on the shelf as a spare.

jamie

[Chuck H]

I have one of those OT's in a project right now. Killer price. No complaints. And it IS rated conservatively too as you pointed out. I only brought it up because I'm not familiar with the amp in question. Since it IS a bass amp it may be higher powered than a similar guitar amp (though probably not since it uses a 5Y3).

Chuck

[retrorod]

Thanks for the quick responses. This is called a bass amp but will be used by a harmonica player who appears to like to get loud and cut through the mix. I have read that the harp/mic signal can get pretty hot and spiky through the inputs.
I pulled the old OT and it weighs 3 lbs. about 2-1/2 X 2-1/2 X 3''.
Seems like I read also about the 6.6 CT for 7591's
I think the Hammond 1620 may be the best candidate for this amp, judging by the specs...?

[retrorod]

update

I got the Hammond 1620 mounted and wired and everything sounds nice with this Premier. I realized, after removing the bad OT, that it was not original to the amp. Maybe it was not correct for the amp, and thats why it crapped out?. I feel that the 1620 is MUCH beefier than what came in the amp originally..just a guess by the base holes...
Anyway thanks for steering me right...Rod

[MikeT]

An OT with a lower primary impedence of 3000 or 4000 ohms like for 6L6s would probably work...