Premier 90

[Andy Le Blanc]

I inherited a multivox- premier 90 reverb unit last night.
It looks functional, after removing a mouse nest.
It has the original foot switch yeah.....

Does anybody have a scheme?

[Sonny ReVerb]

Try this one...

[Andy Le Blanc]

That's the one. The fellow scored it a yard sale for $4, then it ended up in a
stuff pile for a while, then I got it when the back porch was cleared off, funny.
It has original tubes Multivox/Mullards, EL90 and a 6EU7, nice to see.
The cabinet is covered in contact paper which is, of course, peeling.
I like the signal thru or "normal" level across the 6eu7 cathodes, looks like
a reverb-o-rocket. I'll try to post pics, 6 gigs one week, jeeez.........

Thank you, its nice to have a scheme.....

[Andy Le Blanc]

pictures..... it came with a mouse.

looks real easy to re manufacture.

[Andy Le Blanc]

Here's a few more, I forgot the limit of 5 attachments.

[Structo]

Let us know how it sounds.

That looks like a simple projet to build.

You know other than the heater voltage the 6EU7 is close to a 12ax7 in specs.

Is this thing made to plug into the front end of an amp?

[Andy Le Blanc]

I haven't tried the thing yet, I wanted to make sure it was safe.

Ya..... it looks like it goes on the front end of things, looks like it might work
through a loop too. A mouse nest, and a tube was floating around inside.
Looks good, but the PS filter cap still might pop when I power it up

jeez...... it really is plywood, contact paper, 2 little trannies, verb tank, etc...

You'd want a break for the one piece of mild steel, drill pess.....

[AJD]

That looks way cool; and for free to boot! I hope that it sounds great. When you are able to run a signal through it please post your impressions. I've been thinking about making an outboard reverb unit for a while now and I would like to know what you think of this unit/circuit.

[pula58]

I've been working on resurrecting one of these. The point to point wiring is like a rats nest! Lots of hum. I am adding a three-prong cord, grounding the chassis, and trying to get rid of the hum!

[Structo]

check out the heater circuit on that as a source of hum other than the filter caps that should be replaced anyway.

[pula58]

check out the heater circuit on that as a source of hum other than the filter caps that should be replaced anyway.

Yes, I replaced the filter caps, t'was the first thing I did.

The heater wires are twisted as they leave the power supply transformer, but as they get closer to the tubes they are not twisted. Hmmmmm

The 1st power supply cap is grounded near the power supply transformer (one wire of the B+ secondary is also connected to this same ground point). All other grounding is at a star ground near the two tubes.

The center tap of the heater output is grounded to the star ground near the tubes (hmmmmmm?).

[Structo]

Something you can try is to use two 100 ohm resistors and make a artificial center tap for the heater winding.

Disconnect the center tap and tape it off, then run a 100R resistor from each side of the heater to ground.

You can also elevate that artificial center tap by attaching it to a higher potential such as the cathode of the output tube.

[M Fowler]

Nice old reverb to work on, I wish I could find something like that.

I do have one customer that brings me cool old amps to work on, I do love that. This week an old Sears Silvertone 1481 and a Fender PA100 (mod ideas request for PA100) I said Andy Fuchs can do that.

[pula58]

I am slowly hacking -away at noise sources. Heater wiring was a mess!
Also, the output of the reverb circuit was highpass filtered into the grid of the reverb return triode. The corner frequency was 33Hz. I upped it to at least twice that....I may increase the corner frequency even more, possibly.


One weird thing is this: When I turn the vol. knob on my guitar (setup: Guitar -> premier 90 -> my guitar amplifier) I am hearing some scratchy noises. Yet, if I plug my guitar directly into my amplifier (instead of having the premier 90 in-between) I have no noise at all when I turn the guitars vol. knob..

I did install an output jack on the back of the Premier 90 (because the output cable was hard-wired as I received the unit). The cable to the output jack is shielded, and so, the metal plate the output jack is mounted on is connected to ground through the shield.

Do you think there are some bad grounds at the input of the premier 90 that could cause this?

[pula58]

son of a gun..there's 150mV on the hot connection of the input jack!