Preamp Recommendations??

[EETStudent]

Ive been messing with a jcm800 preamp for a while, and though its yielded nice results Im kindve tired of it. I want a new project to work on. I want something warm with a unique sounding distortion. Something bitey. Ive got 4 stages to work with. And I want something that I can also dial in some shimmery cleans with. Outside of Marshall and Fender Im not terribly familiar with much else. Suggestions?

[6267]

There are some interesting magnatone amps, but the varistors they used for the true vibrato are hard to find. I've heard they sound very good and have a full sound.

[tubeswell]

Soldano SLO100 has nice sounding OD channel (if a little bit thin on the Clean Channel for my 'single coil' ears).

It uses four pre-amp tubes (plus PI)

However the OD/clean could be done with two tubes probably for the basic effect. I did this to my Peavey C30 at one stage, gave it a much better OD, but didn't like the loss of the 1k5 25uF cathode combination on V1A, so I undid it. Possibly when I get around to it again I might reinvent something similar but a bit different.

[daz]

Hmmm.i don't understand that R/C coming off the first plate. It's totally bypassed and therefore does nothing. If there were a switch there i could understand, but theres not. What am i missing here?

[Paul P]

And what are those opto isolators for ? There's four of them on the heater
circuit, plus a footswitch ? And a couple tied to preamp tube grids.

Paul P

[Tubis]

The optos are for channel switching. The circuit is driven by a seperate 6.3 winding on the PT. It´s not the heater winding.
The shunted filter in the beginning is wrong.
The channelswitching on this is bad as the clean channel plays always.
The loop send level is to high and the eq is after the loop(i dont like that).

[tubeswell]

The RC coming off the first plate is the voicing for the OD channel. The channel switching isn't 'bad', because when the OD is engaged you can't hear anything clean anyway. So it doesn't matter that it is 'bypassed' either

Don't judge something by its schematic. Its the sound that counts. I quite like it as a OD sound.

[Tubis]

I do think you hear the other channel, but offcourse it blends into the other to create a mass. But to modify you always have to think about how the other channel is set, like clean/crunch and volume level.
One more opto that blocks that channel and make each channel sound good instead would be the way I would go.

[tubeswell]

Yes the SLO100 is designed so you can blend the signals in both channels, or just have the clean channel. (The isolators take out the OD channel). If you want just the OD channel you can dial out the normal channel vol.

I modded my PV Classic 30 using the SLO100 values from V1b, V2a, V2b and V3a in place of V1a, V2a, V2b and V1b in my C30 respectively. The relays in the C30 do the same job as the opto isolators. It didn't have the versatility of the SLO100, but I had the OD channel voicing, which sounded pretty good in the PV that way. (Better than the stock PV OD Channel, but not as good Steve Ahola's Blue Guitar C30 mods as far as the clean channel was concerned). However from scratch with a new preamp, the world's your proverbial oyster

[MattT]

I have an amp that is similar to a SLO and originally I had the clean channel still playing when the OD was engaged (like a SLO)...I tried adding another opto to shunt the clean channel and it did make a difference...I thought it sounded better with the extra opto but this preamp circuit was slightly different than a SLO (but the 'architecture' was the same).

The Dumble ODS uses two stages for the clean (very 'BF Fender' inspired) and then adds two more stages after those for the OD. So if you have 4 stages you might consider that...not sure if it's the sound you're after though. It's certainly not a 'JCM800' type of tone.

[EETStudent]

i dont really want a jcm type tone. Do you have a schematic for the circuit youre speaking of?

[EETStudent]

Oh the Dumble ODS. Is that the amp?

[MattT]

Schematic heaven is your friend.

[tubeswell]

SLO100 soundbytes

FWIW - don't know who the eff Paula is who's playing this (and I really don't care), but it gives you an idea what it sounds like anyhow. (BTW I'm sure these are two different clips - Edit - Dang! one of them didn't load up - never mind )