B-15 Replacement Transformers are way too expensive!

[Matt Bowen]

Hey so I'm planning on building my own Ampeg B-15 shameless copy. I compiled my parts list and tracked down everything I needed but when I went to find my transformers all I could find were really expensive replacements potted in the original-style monolithic black doom boxes. I was wondering if anyone could please tell me the technical specs (voltage/max current per winding etc...)? Links would be appreciated if you happen to know of a relatively cheap transformer (output or power) that works (preferably under $100. Definitely under $200)

 

[beans-on-toast]

Start with the portaflex wiki, there is a lot of information available. Follow the links at the top of the page.

There are transformer specs here: Technical - Amplifier | TalkBass.com.

If you can swing it, Fliptops does sell the transformer sets unpotted at a lower cost. These are made by Heyboer in the US and are very good quality and the correct specs, not close.

Some people use Hammond transformers. Shop around and you can find some good prices on their products.

 

[rocksmoot]

I'm interested in this too.

 

[beans-on-toast]

There is a nice B-15 kit available: Trinity Amps - Vacuum Tube Amp Kits.

Having a nice chassis is half the battle.

The best cabinet on the market is available from Vintage Blue

 

[pasmithy]

Thanks a lot beans-on-toast!!! The thought of building my own B-15 would have never crossed my mind, until you put up those links...

 

[Rickenbackerman]

There is a nice B-15 kit available: Trinity Amps - Vacuum Tube Amp Kits.

^That's a nice looking kit, and I think the price is actually very reasonable!

 

[Matt Bowen]

Yeah I'm looking for more of a "standard" style transformer. One of the ones you could bolt straight to the chassis.

 

[Matt Bowen]

Thanks for all the input btw

 

[JimmyM]

You can always wind your own, too

 

[beans-on-toast]

Yeah I'm looking for more of a "standard" style transformer. One of the ones you could bolt straight to the chassis.

This is the unpotted B-15 power transformer. Power Transformer PT108 Unpotted - Product Details

 

[Martin Beer]

The specs of the power and output transformers are listed in the wiki on here, if you wanted to look for alternative transformers with similar specs. I've seen DIY builds using Hammond transformers or various guitar amp transformers - I think one suggested using a Fender Super Reverb replacement PT and a 6.6K Marshall JTM45 replacement OT, just as an example.

 

[Matt Bowen]

You can always wind your own, too

As a 17 year old high school student with a minuscule income I would much prefer to buy a transformer rather than buy the equipment needed as well as all the parts only to use it once

 

[Matt Bowen]

This is the unpotted B-15 power transformer. Power Transformer PT108 Unpotted - Product Details

Yeah I saw that one in my searches but the coil is still exposed. I'm looking for one similar on the exterior to say an SVT transformer (obviously smaller)

 

[Rickenbackerman]

The only visual difference between something that PT108 and an SVT transfomer (other than size) is that SVT PT's have endbells. You could email Heyboer and ask if they could sell you a couple of endbells for the PT108.

 

[BassmanPaul]

From experience Matt I can tell you that building a tube amp from scratch is a daunting process. There are so many “rules” that must be followed to arrive at a functional and stable conclusion. I am deeply concerned with your age. There are lethal voltages present in these amplifiers. Basically one wrong move could be your last. I am not trying to dissuade you per se but warning you building an amp is much more than soldering parts together.

That kit from Trinity looks great. If their instructions are as good it would be a better route to follow. Having a “road map” makes getting somewhere much, much easier and possibly safer.

 

[SirMjac28]

Thanks a lot beans-on-toast!!! The thought of building my own B-15 would have never crossed my mind, until you put up those links...

Beans is the man always willing to share his knowledge.

 

[beans-on-toast]

Yeah I'm looking for more of a "standard" style transformer. One of the ones you could bolt straight to the chassis.

Hammond 374BX.

 

[B-string]

The potting of the transformers has many advantages by the way, it is not just to "look" pretty.

 

[Coolhandjjl]

So you are looking for a transformer where you see the laminations of iron and nice bell housings on each side? The Hammond may be like that.

How about a just a transformer cover for the unpotted one? There are plenty out there complete with black crinkle paint finish just like the potted ones. But you will need to make a mounting frame for the transformer itself.

But if you are going to get the bare unpotted transformer, the reason many are potted is so they don't buzz. At least with the Hammond, it won't buzz, the coil may be be already potted in the bell housings. You could always plop one of the crinkle paint transformer covers over the Hammond one if you want the authentic look.

 

[DRafalske]

There is a nice B-15 kit available: Trinity Amps - Vacuum Tube Amp Kits.

Having a nice chassis is half the battle.

I own one of the Trinity's. Can't say enough good things about it or the company.
I was in a position similar to OP's; of wanting a B15 and possibly maybe building my own copy when I stumbled on to Trinity's website. This was a helluva lot simpler solution than trying to source parts from all over the place and hoping they all work well together in the end. It's a fantastic sounding amp and was a pleasure to assemble.