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Ampeg B-15N tranformer question

nouroog

nouroog

Jan 14, 2010
603
317
France
#1
Hello everyone !
I'm quite new to this community, although I've already found a huge amount of information, insight, help, and in a way companionship by reading all your posts and discussions about everything I wanted to know about. :)
This being my first thread, I grab the opportunity to thank you all for that. :)
That said, I plan on buying an Ampeg B-15N. I found one that looks sweet, a 62, with the double baffle cabinet design.
It's not very expensive, probably because it has a changed transformer, quote :
" The transformer is changed. It is not an Ampeg transformer. It is a mystery, not sure who made it "
How can it affect the tone of the amp ? Is it a mod that should make me pass on this amp and look for another one, even if it increases my budget ?
(I live in France, so I have to count in my budget a good $600 to $800 for shipment only).
Thank you !
 

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#2
Yes it can really affect things, for better or worse. I'd say not knowing what transformer it is is a bigger deal. Whether it's the power or output also matters.

I'll let somebody with more tech knowledge take it from there. Fliptops.net is a good place to look and ask questions too. Lot's of B15 enthusiasts here with technical knowledge of them, you'll get some answers.

Mostly bumping this 'til one of them sees it.
 
#5
Ok, thank you guys, that's helping me already. I didn't know which one was the output / power transformer.
The problem if it's affecting the tone is that I won't be able to easily A/B it. Do you know how it might affect the tone ? If it is driving the speakers, maybe a cheap transformer might give a distorted signal and really ruin the sound ?
I will try to get some additionnal info from fliptop.net.
My feeling now is that I'd better pass on this amp, or count on the additonnal expanse of eventually changing this transformer back to an original one.
 
#6
You see B-15's with these types of transformers on a pretty regular basis. The reason is because those cans for the transformers weren't available or the repairman didn't know where to get them (or the client was too cheap to use them), so rather than throw out the amp, they just replaced it with a regular transformer that matches specs. It does bring down the value of the head, but chances are it sounds identical or close enough to where it's nothing to worry about. You can always replace it with a www.fliptops.net transformer with a proper can, though.
 
#13
I was lucky enough to find a B15 with a dodgy replacement PT - which made it much cheaper than one with an original Ampeg PT. I needed to replace it anyway - as we have 240V in Australia.

While you're at - it order a power capacitor replacement kit from Fliptops.net and get em shipped together. You will almost certainly want it.

I had my flip tops.net parts shipped to the Ampeg seller who was nice enough to box and pack the lot and send together. It worked out much cheaper.

One last thing: Make sure you check out Shipito.com. You may save yourself HUNDREDS of dollars in shipping. They are great - check out ozbassforum.com for reviews. A lot of happy customers there.
 
#18
I prefer that any old amp has at least the original output transformer to provide the perfect tone. I like the vintage iron but that is just my personal bias. After all, the new Heritage B15's also have modern replacement transformers and those amps sound pretty good. So you can go with a replacement transformer and the amp will sound fine.

The amp that you are looking at may sound great with the replacement transformer that is currently installed. You'll never know unless you try it. You can always upgrade later if cost is an issue.

When looking at a used B-15, it is important to consider how much rust is on the chassis. Everything else on these amps can be fixed. Ask if any modifications have been done to the amp. Maintenance is a good sign. Otherwise you will have to spend more to have the amp's power supply capacitors and power cord changed. Is the speaker original. Has it been re-coned. The original power transformer only supports 117 VAC which is used in North America, not the European line voltages. Fliptops sells a 115/230 volt power transformer if you want to change the original.

The cans on the original transformers were supposed to serve a purpose. They provide shielding from noise which makes the amp quieter. Transformers in cans were in vogue at the time that they adopted this for the amp design. They still are. The cans were potted with a waxy tar like substance. If you heat it in an oven, the potting compound liquifies. The purpose of the potting compound is to wick heat away from the transformer more efficiently than air. Both the cans and the potting are not really necessary in these amps but they look cool.

Floptops currently has a new old stock B15 output transformer available for $349. It is a model OT-214 which is what was used in the later 30W B15 amps. It is not the same as the OT-208 which is what the amp that you are looking at would have had. The good news is that the OT-214 would work fine in an early B-15 model and is actually a better transformer. Fliptops also has a modern OT-214 replacement for $219.
 
#19
Man, that's a full answer to my question ! Thanks a lot for taking the time to give it. That's why TB is so great.
I'm starting to feel I will be able to make an educated choice.
Thank you all. Please keep on posting on the subject.
 
#20
It's good that the originals are available. When the output transformer went on my '63, back in the '80s, there were ZERO replacements available, at any price. I had to go with a kludged replacement that sat in the bottom of the speaker cabinet.
 

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