Ultralinear fender?

[OrganicBud]

Howdy!

I'm replacing the output transformer on my 65 Fender Super Reverb. Ive settled on the Hammond 1650NA. Now, the curios thing is that Hammond mentions it having 40% screen-grid taps on the primary for Ultra-Linear operation. Now, I'm a beginner, but I know Fender=Awesome clean amp and Ultra-Linear=Hi-fi and Hi-fi=Super clean (duh), and I was wondering how I could incorporate this into my amp. I'm pretty handy at working on old fenders, so I can probably handle any wiring required.

I've poked around an old Mullard 5-20 schematic and I can see how these taps are incorporated, I'm really just wondering if these are feasible in a Fender.

[Wavebourn]

Why don't you try?
You may love the sound. I remember long time ago one ultra-linear class A guitar amp, it's sound was awesome.

[llwhtt]

In the early 70s Fender used the ultralinear output design, not the most desirable amps in the Fender lineup, I'm being polite.

Craig

[oldmanStrat]

yeah, but you guys aren't telling him how to do the UL...

[OrganicBud]

Well, I'm thoroughly afraid of blowing up a $122 xfrmr. But I guess I could try. The Mullard schem shows 1k resistors between the screens and the 40% taps. Would those be the same for a fender?

[OrganicBud]

Yes, I've seen the 135 watt Ultralinear Twin... but you have to take into account that it was CBS and they could ruin even the best (the silverface era... ughhhh) of ideas. I'll go ahead and make it switchable so I can see the results.

[jjman]

Guitarist who claim to have heard both are almost unanimous that the UL approach is less desirable when using the amp for guitar. Is the OP tranny intended to be used on either design?

The UL used SS rectification with no choke. The “normal” ones used tube rectification and a choke.

Schematic for the UL model shows 470ohmers on the screens. Same as with the non-ULs including the original 1965 and the reissue.

Reissue:

http://www.schematicheaven.com/fende...per_reverb.pdf


Original 1965

http://www.schematicheaven.com/fende...b763_schem.pdf


UL

http://www.schematicheaven.com/fende...-bmstr_rev.pdf

[Key]

Honestly I doubt you would like the sound. The Fender "clean" tone is really not all that clean. It has lots of harmonics and color. Try taking an electric guitar and recording it directly into a computer and you will see the direction that ultra linear will bring your tone. A truly clean tone - an electric guitar running direct into some hifi speakers - will sound very thin and bland.

[Merlinb]

Originally posted by oldmanStrat
yeah, but you guys aren't telling him how to do the UL...

Disconnect the pre-existing screen grid supply from the screen grids (pin 4 usually). (Easy enough to just remove the old 470R or 1k screen resistors that are often wired right on the socket)
Connect the transformer UL taps to the screen grids (In the same way that you would connect the anode connections to the anodes really... You sure you're pretty handy at this, you've asked a very simple question?)

[OrganicBud]

Originally posted by Merlinb



Disconnect the pre-existing screen grid supply from the screen grids (pin 4 usually). (Easy enough to just remove the old 470R or 1k screen resistors that are often wired right on the socket)
Connect the transformer UL taps to the screen grids (In the same way that you would connect the anode connections to the anodes really... You sure you're pretty handy at this, you've asked a very simple question?)

I will readily admit that my modding of Fenders is based entirely off of basic stuff. I generally work with the eq and preamp stages, and I occasionally convert the power stage to use 6CA7s. I've never dealt with a true tube Hi-fi circuit, so my understanding of the ultralinear designs in them is next to nil. I was really just worried if the values of the screen grid resistors would change, or something along those lines. I'll give this a try. Who knows, I could make it a dandy new monoblock...