Fender 6G6 Build w GZ34 - Transformer Suggestions?

[Jecarroll7]

I've just been asked to finish a bassman 6G6 (tube rectified) project that's been sitting on a guys shelf for some time.

He hasn't purchased the transformers yet.

I was thinking MM or Heyboer. Heyboer has the Iso trans and choke, but the OT they are suggesting is a one off build and say its a bit pricy due to the way its wound.

I thought I would ask for suggestions from the group?

[Chuck H]

If price isn't an issue just use the MM and be done. Otherwise you could use a Hammond product. The 1650F is an off the shelf model and could be used at 3800 primary into a 4R or 8R load. The 1760K and 1760L are made specifically for Bassmans (of different years) with a 4200 primary and have a tapped secondary to allow them to be used into a 4R or 8R load. I've had very positive experiences with Heyboer also. But I don't see the need for custom iron here when many Bassman type OT's are available. In a side by side comparison I actually liked the Hammond off the shelf unit better than a custom Heyboer in my 20 watter. I'd go with the 1650F if this were my project. It's going to sound good, cost less and hang tough. I think the Hammond off the shelf models use seven interleaves. Original 5F6A OT's used eleven interleaves IIRC!!! I can't say about the 6G6 OT. But I've always been happy with the standard hammond models. I haven't used their guitar amp line for anything yet. The 1650F is actually made for a 7600 primary into 4, 8 or 16 ohms. So you run the 16R tap into and 8R load or the 8R tap into a 4R load to get the 3800 primary on the tube plates.

[Jecarroll7]

Thanks Chuck, I'll check out the 1650F.

Here is an interesting link that sorts Fender Transformers by Amp model

FENDER TRANSFORMERS, SORTED BY POWER TRANSFORMER

[Chuck H]

Nice link. I should caution that the Hammond standard models probably won't be direct mount replacements. So if this project is built on a proper 6G6 chassis you'll either need to retrofit or buy a transformer made just for that amp.

[Jecarroll7]

Any opinion on Classic Tone (Magnetic Components)?

[Chuck H]

I used one of theirs in a little PP el84 amp. No complaints. Sounded good. They have a good rep too. Never heard their 6G6 OT.

[Jecarroll7]

Chuck,

Unless I get overruled, I'm taking your first suggestion and going with MM. Form factor was an issue on the 1650F, although an interesting recommendation and one I'll keep it in mind for a future build. I certainly liked the price points on Classic Tone, but this project isn't the one to try them out.

The original 6G6 was 8ohm so I'm waiting on that decision, but for the record these are the units I'm going with;

Mercury Magnetics Tone Clone
PT FBBP Blonde - #125P5A
CH FC-BASS Blonde, Blackface, Silverface
OT FO50BM-1 Blonde - Single 4ohm Tap
OT FBLBASS-O Blonde - Single 8ohm Tap

Thanks again for your help.

[JoeM]

You're going to pay a lot more for the MM hype. Mag Components makes real good iron. I wont pay the extra $$$ for MM.

[deci belle]

You're going to pay a lot more for the MM hype. Mag Components makes real good iron. I wont pay the extra $$$ for MM.

Big deal. It's just money. The hype about the hype is just as lame— especially if you are just building one amp for yourself. If someone else is paying for the iron, well who cares?

The real issue is that PT is cranking out 380vac. Solid state rectification will see your plates getting 500vdc; Asian GZ34= 390v. Dual NOS 5U4GBs will net you 470volts. MM's 6G6a PT is rated even higher (385vac). Why are the Fender specs that much lower?

That does not explain why the SS rectified 6G6a schematic indicates 470vdc at the plates and the 6G6b schematic says 430vdc. All the voltages specified for the 6G6b are 40v less across the board than the 6G6a. The Fender specs are not jiving with MM's product, which is not manufactured to be an approximation, but a clone.

That's just screwy. I'm a little frustrated about it, but I tend to believe MM's take more than the Fender specs …they're just numbers on a piece of paper at this point (to me).

I'm running a 6G6b channel in my old Showman powered by a MM 5E8a PT (380vac), dual tube rectification that gives around 470v at the plates …sounds pretty awesome (usually). But I don't run it at 500v, which is what the SS rectifier is putting out.

I wish people with OEM 6G6a and b amps would measure their PT's ac output. That would help out a lot of people and me too!

[JoeM]

Big deal. It's just money. The hype about the hype is just as lame— especially if you are just building one amp for yourself. If someone else is paying for the iron, well who cares?

Fine. Just trying to help. Nothing personal.

[deci belle]

That's cool, man …soo am I. I'd just like to hear about the transformers themselves. We've all heard the popular shoptalk opinion about MM long enough, ya know? That Joe won't buy from them is simply awesomness!

Real help would be someone with actual knowledge about the subject of this thread contributing because I've been searching for months and haven't found any hard data from an original 6G6a OR b PT loaded or unloaded. I kinda matters I guess, in a way. But it also doesn't matter in a way as well, really.

I didn't decide to build the circuit because I knew anything— I was just looking for a 6L6-pair brownface circuit that had 470v at the plates cuz that's what I have to play with is all~ so just exploring I inadvertently stumbled on the (a) variant.

At first, just studying the schematics, the (b) circuit seemed like a subsequent and cheaper rendition due to the lack of coupling caps exiting the preamp, with just a .005 cap for the PI input. But after a/b-ing the slight difference, I found preferred the tone of the B circuit, so now there's no coupling cap on my second triode. I only implemented the 6G6b normal channel in my Showman, not the bass channel.

Other than the weird treble pot and the coupling cap removal, the only change other than a 220k plate load R for the second triode from the AB763 is a 10v drop to that channel's power node. It's a very easy mod for a very cool voicing; and not all that different from a lower-volume setting on a 5f6 to my ear.

I can appreciate now why it is so popular for some styles of music!

[big_teee]

"Big deal. It's just money. The hype about the hype is just as lame— especially if you are just building one amp for yourself. If someone else is paying for the iron, well who cares?"
I figure the guy paying may care a Lot.
I know I would.
BTW I did the Classic Tones on my JCM800 build 2 years ago, and they have held up great.
I've forgotten to plug in the Speaker Cab in a few times!
T

[JoeM]

That's cool, man …soo am I. I'd just like to hear about the transformers themselves. We've all heard the popular shoptalk opinion about MM long enough, ya know? That Joe won't buy from them is simply awesomness!!

Yep!! I can see you finally got it! LOL

In any event, my comment was for the OP. You seemed to have hijacked the thread.