ENGL E320 clean vol mod

[blindboybenton]

Hello

I've been asked by a old friend if i can mod this Engl E320
engl-320-ii-schematics.pdf

My friend says that the amp has Clean and Lead Volumes and a master volume. But the problem is that the clean volume doubles up as the gain vol for the lead channel
when switched over to lead. So makes for a hard time getting the sound right if switching between channels on the same song.

Ideally when modded the amp will have clean vol pot that works just for the clean and does not double up as the gain pot for lead channel
He says he really likes the sound from the amp and dont want to get rid of.

anybody have idea's on what i can do.

bassman 1965

[Jazz P Bass]

The schematic link is dead.
If you have the file, zip it & reload it.

[blindboybenton]

Ok jazz bass it should be working now

[pdf64]

There's no obvious way around that.

[blindboybenton]

ive just clicked the link its working for me. The page has 2 links click the first one under the first line

bassman1965

[Enzo]

The 320 link works for me, the 330 link does not.

Add a new gain pot (or clean pot, your pick) then wire in a relay to select which one is in the circuit. Wire that relay coil in parallel with the channel switching relay REL1 that is already there.

[blindboybenton]

Many thanks enzo. i will look into it.

Bassman 1965

[Enzo]

Long time ago I helped a guy with his PV 5150 head. SImilar to you, he wanted separate post controls for all three "channels" - clean, crunch, and ultra. Stock there are pre and post controls only for clean and ultra, crunch is just a gain boost button. Separate pre controls as well, thank you. SO we added a relay or two working off the same control as the existing channel relays, and of course the added controls. Worked.

Then he decided he wanted separate presence and resonance controls for each channel. OK, some more controls and relays to add those. Worked.

That wasn't enough, he then decided on separate tone controls for each channel. SO we went with two more tone stacks made up complete, with in and out and ground wires, and of course some more relays to select which set of controls was in use. That worked too. At first we though we could use the ixisting tone stack and switch three sets of pots in and out, but considering the whole tone stack is the controls and a few little caps and resistors, it was easier to just wire up complete tone stacks. ALso saved a few relays that way.

Where did he put all those controls? On the 5150, the control panel is along the bottom, and a metal grille covers the front above that. He turned that metal grille into more control panel.

A lot more than I might have liked, but it was not my amp. But no matter how inconvenient it was, it was just a matter of straightforward circuitry.

[J M Fahey]

Enzo, please be careful.

Mesa Boogie started the same as you and now they use 47 relays per amp head

[Enzo]

It isn't ME doing it. When the customer says CAN it be done, I say of course it can. The guy with all the knobs was happy with it, so...

I never laid a hand on it, this was all done by internet advising.

[petard]

Hi friend, I have a head e320 without reverb, I would like to put a volume control on the clean channel, how could I do this mod? My amp leads gain, volume crunch and lead volume, thank you

[blindboybenton]

Hi Petard
This was a long time ago and i can't remember what i did, But i think i followed that enzo said
So you are wanting the same as what i was asking . The answer is already on this thread

BBB

[petard]

Hello friend I read Enzo's comment but I do not understand much what I should do, is there any scheme about this? Which pot should I use? How do I connect to the relay? If you are so kind to help me I would appreciate it, I searched the internet and the only thing I find is here thanks sorry my english i'm spanish

[blindboybenton]

The schematic is a link at the top of the page. If you don't understand what too do. I would suggest that you take it to a local repairer
There are a lot of high voltages in the amp.

I don't think this type of mod is something you should try if you have no electronics background

[petard]

Hi friend,sorry I think you have not understood my question ... I saw the link of the original amplifier scheme and I asked if there is a schematic with the mod, you can draw it? Is possible this?I do not understand the enzo instructions very much, it does not give values of the components Or anything, thank you again