5E9 Tweed Tremolux phase inverter question

[Victor Denance]

Hi!

I'm looking at the 5E9-A schematic... and I must say the PI kinda confuses me somehow. I was expecting a 5E3 like cathodyne but I've never seen such a thing.

How would you call this design?
Was it used in some other amps? (when I think of it, the Marshall 18W may have something similar... not sure though...)
How does this PI work?
How does it compare to a 5E3 cathodyne PI?
and how about the SOUND of it???!!!

Thanks so much!

Victor

[MWJB]

It's a paraphase PI, very common in many, many cathode biased amps up to the mid '50's. Vox also used a variation in fixed bias amps (AC50/AC100). See also Fender 5C3/5, Mascos, early/mid '50's Gibsons/Maestros, variations in Ampeg Jets/Reverbrockets ...the list could go on & on...

A proportion of the signal from the first triode of the PI is tapped off and fed back to the grid of the second triode, to feed the 'out of phase' power tube.

This typically adds a degree of distortion/grind, less headroom than cathodyne or longtail PI...very much a contributor to an early 50's sound

Largely dropped out of fashion as fixed bias amps became prevalent/designers looked for more headroom.

[Moid]

As far as the sound goes. Its killer! Like a 5E3, but bigger and more lush. I built mine stock except added adjustable, fixed bias. Its got great clean tone that is very touch sensitive. With a strat at full volume you're still on the edge of clean. With humbuckers you'll get a nice grind and sustain going at about 1/2 volume on up. The amp loves pedals as well. Compared to a black face tremolo, I think this amp blows it away. I never used the tremolo on my Pro, but do all the time with the Tremolux. Somehow this amp never got the attention it deserves. You can't go wrong.

[Victor Denance]

Thanks for the great replies!

Now that I think of it, I built something like a 5C3 Deluxe w/ paraphase PI and noval preamp tubes years ago... Unfortunately I made it for harp and didn't bother to tune it for guitar so I've no idea how is the sound! It was super warm though...
I turned that amp a few days later into a 5E3 Deluxe and realised how great the cathodyne PI is.

Moid, how is the gain level of your 5E9? Does the crunch go as far as a 5E3?
I'm asking cause it has one less gain stage than the 5E3
(gain stage >>> vol / tone control >>> PI vs. gs >>> vol/tone >>> gs >>> PI for the 5E3).

Thanks!

[clayman]

I have a bogen chb100 modded to a plexi preamp,w/12ax7 longtail.It sounds pretty good.But I also have a 1941 bogen with a paraphrase that sounds killer.Now I am thinking of trying a paraphrase in the chb100.I have alot of head room,and am looking for more warmth in my distortion.I will let you know how it sounds. Clay

[Moid]

Sorry, but I didn't look at the title of your post closely enough. I built the 5G9 cirucuit which is a bit different. It has the long tailed PI. Sorry for the confusion. Anyway, I would say the amp is cleaner than a 5E3, with more headroom. At full volume though the gain is very rich and detailed, although not what I would call crunch.