premier 88N

[Andy Le Blanc]

Last season I had a chance to reverse engineer a Premier 88N.
One of the ones you don't often see. Suit case, field coil speaker, red and cream bakelite knobs....
Pretty simple rig minus the vibrato circuit.
Its a split load inverter followed by a buffer stage, both 12au7, the first stage is a zero bias 12ax7.

Today I had a chance to noodle with it, scabbing it together in a test circuit.
Its a design that is ment for clean tone, and is wonderful.
The gain structure is mostly 12au7, and looks like it will be even better
with 6sn7.

Its similar to a gibson medalist, also some wards airline, danelectro models

Fat and clean, seems like a great tone for Les Paul, Chet Atkins.

A Standel is very similar in purpose but has a 12at7 stage before a 12au7 inverter.
The gain is used in a cathode coupled feedback/tone control.

The design is also very close to the 200w marshals aka "1966".

Any using an amp like this?

[Andy Le Blanc]

Here's a qwik scheme of what was used in the 88n, its a really simple thing.
It does that never really clean, clean tone, great rock a billy, and the break up
is gradual with a lot of harmonics, full on saturation sounds like it would be perfect for harp.

[Robster]

A friend brought this over the other day. Its an 88N in cosmetically rough shape but fixable. It does not have a field coil speaker. Big 12 inch Jensen.
I saw your other post about this before and it looked like it may have contained pictures that I could not see. I want to get this up and running and figured start with all the caps first as usual and test the tubes, clean pots and sockets, looked for burnt/brokens stuff. I have fixed lots of small amps in the past. This one does not look like fun to work on. I have it all apart now. I cant find a schematic. I also am confused as to the preamp tubes looks like a mixture of 12au7 and 12ax7.
Any help with this beast is appreciated!
Rob

[Robster]

I am new here and must be doing something wrong...

[ToneMerc]

Maybe this helps a bit, not the 88N though.

http://www.harpamps.com/premier/Premier ... rams_1.pdf

TM

[ToneMerc]

dup

[Phil_S]

I am new here and must be doing something wrong...

LOL! I think posting here was absolutely not wrong. Someone will be along.

[Robster]

I was not able to see the pictures in the old post about the 88N, now that I can login it lets me see them. I sent an email to Andy about the amp already. Not sure why I never found this amp forum before...
Have to check it out more.
Rob

[Ian444]

I like the sound of cathodynes, especially DC coupled ones. With the buffer/gain stages to protect the cathodyne from unbalance from output tube grid current, it looks real good to me. Must try it. Thanks for posting Andy. Never even heard of a Premier amp before.

Robster, welcome

[Ian444]

I built the Premier cct into a 10W PP test amp I have, preceded by a gain stage and tone stack/vol cct. When driving the output tubes hard into square wave clipping, the output signal remains very well balanced/symmetrical, unlike a standard LTP or cathodyne, which are capable of some weird waveforms as they really get pushed (as in uneven rise & fall slopes on the square wave, and varying duty cycle according to how much the output tubes get pushed). This Premier cct/Marshall major 200W cct is also very similar to the Williamson cct of hifi fame.

I'm wondering why this cct is not more common in guitar amps? Maybe symmetry in the output stage is not that desirable (less harmonics)? How hard can most guitar amps drive their output tubes, just to soft clipping or to extreme square wave conditions? Or do they generally have enough "spare gain" built in for low output pickups, and that extra gain may or may not sound good with high output humbuckers? If the output tubes don't have to be driven too hard, then the LTP or cathodyne seems to do the job fine. Sorry for newbie questions, I'm still in an early learning stage, and if there are references to this type of info on the net it would be nice if someone could post some links. Just wondering if I'm wandering down the wrong path, chasing something that doesn't need chasing.

[Andy Le Blanc]

Its not a bad circuit, nice and harmonic when its cranked.
The pre is really just simple zero bias stages, the trem is quirky.

The amp colors the tone, thats why rigs like this fell out of favor.
They have a clean tone thats never really clean, a "musical" tone.
These days where everything is a fender clone, its refreshing.

You have to remember that most old fashioned amps were never ment to be
used for their distortion.

The cover on these is contact paper, it has a field magnet speaker and
hopefully robsters is in good shape, nice to keep it as original as possible.
The wire dress in the thing will appear confusing when you take it apart.
Its dressed more like a radio than what you might expect in an amp.
be extra careful of the octal sockets, the metal contacts are flimsy and
might fall apart when you try to clean or retension them.
It will be full of old wax caps, hard to read, and old carbon comps with
fading paint bands, also hard to read.
The structure behind the switches is fun , the whole circuit is divided into levels.
Just take it apart slowly and carefully, this is one you will want to draw diagrams
photo, or what ever you have to do to put back together.

[Cliff Schecht]

Little amps like that love a good overdrive in front of them too. I agree that 6SN7s would sound awesome with that simple setup.

Andy, you should start putting values on your hand drawn schematics!

[Andy Le Blanc]

I dragged the original thread up.

Usually it's the form of the circuit thats more important.
The values on 10-20% carbon comps are all over the place.

If I remember, the power side was four 6v6, cathode biased with a 5.6k opt.

[Cliff Schecht]

I agree about topology but subtleties like grid leak values, coupling caps and plate/cathode resistor combos (and bypass cap size on cathode) also reveal a lot about an amp. Thanks for bumping the other thread.

[6l6y]

Hiya! Yes I know this thread is 10 years old, I am just wondering if anyone is holding an 88N schematic they'd be willing to share, even a rough one with clues would be useful. I have a highly modified one on the bench and I'd like to return it to original specs (plus, ya know, get it working). Fingers crossed.