Transformer Sources

[HBamps]

I have been building amps for a while now and have about 25 or so under my belt. I have pretty much been using blackface style Heybour trannys exclusively for all sorts of builds. They sound good but I am wondering what else is out there.

For example, I have been using Allen amps TO22 Allen Amplification - Parts Order Page for both 6v6 and el84 output stages (cathode biased). Other than the different impedance, would a marshall style OT sound much different?

I stumbled in the Vintage Sound web site Marshall Style : The Vintage Sound, Your source for vintage tube amplifier and guitar parts!. Seems they have alot of stuff. Anyone use their transformers?

And lastly, I have stayed away from Mercury Mag because I feel their prices are outrageous. Does their stuff live up to the hype? even close?

Thanks for looking

[Bruce / Mission Amps]

Mercury Magnetic transformers are very very good... but yes, they are over priced and some builders are hooked on the name regardless if it carries any real audio significance.
Heyboer, Lenco, Mag Com, TMI and a host of others are excellent too and do not carry a falsely inflated price tag.

[Chuck H]

+1 on Heyboer. Service is excellent and they even made some custom design protos for me at a very reasonable price.

I can also get behind the Hammond "off the shelf" models. I haven't used any of their guitar amp replacement models yet but I hear the Marshall OT they sell is great. I like the 1608 for a pair of EL84's.

I haven't used MM (because of price) but their stuff looks real pretty and reads really nice. They seem to have all the right ideas focused on guitar amp OT's, so they're probably really good. Twice as good? (as the price suggests) Probably not. But it's just about a given that using a MM OT is an upgrade.

Chuck

[Diablo]

I'll throw a few more names out there. Edcor, Pacific and Weber.

[jmaf]

Here's throwing my 2 cents behind Hammonds, they're often 50% cheaper than Mercury Magnetics and I can't say they're *any* worse. Other than that, my former shop partner here used to wind his own and I still use them, but he's often out of time to make them for me and it takes weeks.... I can't say they were any worse than MM's, so it *really* is hard to understand why those are so overpriced.

[Loogie]

There's something I've always wondered about, especially where MM's are concerned. It would seem to me that output transformers could be all over the board and there might be manufacturer that makes them the way you like them. But power transformers, if they supply the desired voltage and current, should just be power transformers, right? What impact would they have on the sound performance of the amp if they have the specs you're after and if they're fitted properly? In other words if I took an Edcor, a Hammond and an MM all with the same specs (assuming they exist) what possible difference could I hear? Assuming of course they all demonstrate the same reliability.

[EFK]

That seems to be a point of debate, apparently. I've always been under the assumption if the PT supplies the proper voltage, proper current and works, then there really shouldn't be a difference. Maybe some sag under load more than others? Any money I've put towards transformers, I've put towards the OT.

[jmaf]

I guess magnetic noise might be part of your design choice for power transformers as well. Toroids offer little or no noise.... Other than that, all I can say about PT's is that they must be reliable, work cold to warm at most so they're properly sized, etc, overall it's a quality and reliability issue, it's simpler and not all the voodoo we know about OT's. Just my 2 cents, hopefully other members will know more about power trannies.

[wizard333]

THe MM stuff really does sound good, but yes it is horribly over priced. I'm a MM dealer and I rarely order them due to that because most customers simply wont pony up for those kinds of $.

Anyone have a good source for Toroidals that have the right taps/voltages to be useful in guitar amps? I've always wanted to try them but never could find any that were useful for that purpose.

[Wilder Amplification]

Torroidal power trannys would be great, but from my understanding torroidal output trannys don't work very well with DC magnetization (high DC offset on a push pull output or the idle DC on a SE amp). Someone correct me if I'm wrong here?

[wizard333]

PT is what I was talking about, not OT.

[defaced]

Antek makes very reasonably priced toroid PTs. Antek - Transformers - Grid View

I don't think you can beat 50 bucks for a 100w PT. I am using these in my high gain build, and aside from the lack of a bias tap, which you can get around, they're really good and usually way over rated for what we're trying to do. 400VA is a hell of alot for a 100w amp.

[wizard333]

Are you using a separate bias supply transformer?

[Wilder Amplification]

He's probably either doing that or a capacitive divider bias supply.

If you decide to go with a separate bias tranny I recommend something like a 6.3VAC @ 2A power transformer hooked backwards off of the heater winding (i.e. feed 6.3VAC into the secondary and use the 120V primary as your "bias secondary").

[defaced]

If you decide to go with a separate bias tranny I recommend something like a 6.3VAC @ 2A power transformer hooked backwards off of the heater winding (i.e. feed 6.3VAC into the secondary and use the 120V primary as your "bias secondary").

Yep, and that was actually something I suggested to you in your capacitive bias supply thread, http://music-electronics-forum.com/t19248/. But yea, I've done it and it works great. Currently I am using a separate transformer which is part of the bipolar supply that is used for my MOSFET power tube drivers. Now that I know more, I would be willing to try a direct coupled bias supply from the HT. It would be interesting to see if the 5ma or so amps that the bias supply requires actually causes the PT to saturate and hum.

There is at least one PT that has bias taps: http://www.antekinc.com/pdf/AN-4TK400.pdf I wonder if it would be worth asking if you can get one with taps or not.