1987 clone mods.

[GtrScott]

Hi,
I've got a 50 watt 4 hole clone that I'd like to mod in stages. First, I'd like to combine the normal and bright channel and control with a single vol instead of two.

I'm probably searching wrong but I can't find any info on combining the channels.

Later I'll be using the remaining volume for a second, foot switchable volume for leads.

Thanks!

[pdf64]

A simple option is to link the plates of the input tube.
The two channels will then achieve an evenly balanced mix via their tube's internal plate impedances.
Then feed that mixed signal into the shared volume control, via coupling cap.
Need to decide whta to do about a bright cap, mixing resistors, treble peaking cap.

[Reeltarded]

Or move the volume after the mixer with a coupler. Weird!

You may as well go ahead and cascade it. You'll end up there anyhow. Everyone else did.

[GtrScott]

Thanks for the input. Both options sound a little confusing without something to look at.

Truthfully, I really like the bright channel and could probably do without the normal channel all together. Does that make it any easier/common? Or is this something that isn't done much?

[GtrScott]

Or move the volume after the mixer with a coupler. Weird!

You may as well go ahead and cascade it. You'll end up there anyhow. Everyone else did.

As I understand it, cascading introduces a lot more gain and I really don't want to change the character of the amp that way. Just looking for a single vol and then a second vol so I can set up a louder volume for solos or bring up the volume when I roll way off the guitar volume.

[RockinRocket]

I wouldn't internally jump the channels. If your not using a Y cable now to use both channels then you may not like the tone. I certainly didn't.

[GtrScott]

That is sound logic. So what might be the best way to disconnect the normal channel and leave the treble channel as is so I can free up the other volume pot to use as a switchable volume for the treble channel?

[Reeltarded]

Umm... it's complicated and what is there won't do what you are asking for, it will drive the amp harder.. it will be.. a cascade..

You can convert the normal to a brite channel and switch between them with a single input. You need to add a relay of some sort.

Anything you do is going to change the response of the amp some. If you peak over the normal channels mixer (doubling up on brite channels) it affects the brite sound on the stock brite, and vise versa. Requires some tweaking to get back to where you were..

Before you get started.. forget about switching inputs. You want this switch at the mixers and it will ground the channel you aren't playing at any given time. The pair of 470k resistors before stage 2.

It needs to be a couple relay channels, one to deal with the paralleled inputs one to deal with the mixers.

[Smokebreak]

That is sound logic. So what might be the best way to disconnect the normal channel and leave the treble channel as is so I can free up the other volume pot to use as a switchable volume for the treble channel?

This is how I'd do it, attchd.

Regarding removing the vol pot of the unused channel, most folks just get rid of the unused pot, and tie the 470K mixer to ground, and call it a day. Looking at the schematic, you'l see that depending on where the unused pot is in it's rotation, you can get anywhere from 470K to 1470K to ground. Honestly it's not a huge difference, but enough to fiddle with, and see where you like it, if you'r doing a single channel. There is also the coupler for the unused channel that goes to B+, which is kinda like ground for AC signal, but that's getting picky

Personally I like to jumper mine internally and put 2 pots on the front. High pot on 7 and low pot on 3 is sweet. Can't live without a little of that lo channel now

[Tone Lover]

That is sound logic. So what might be the best way to disconnect the normal channel and leave the treble channel as is so I can free up the other volume pot to use as a switchable volume for the treble channel?

.

Your opening up a can of worms you might not be ready for. Leave them stock and boost the front end with a clean boost for your solo. I know its not the answer you want. But if your asking this question you might not understand how hard it is to get the relay in and working and changing your wiring around.
Just my two cents .
Bill
PS. it might save you from this horrible addiction called amp building once you smell the smoke your lost.<G>

[JoeCon]

Guys

Sounds like he wants to control both channels with one pot, so wouldn't a dual pot work here? Come off the bright and normal coulpling caps to a dual pot...

How to use the second volume for a "foot switchable volume" I don't get...

[roberto]

This is what I usually do when someone wants to hide the mods, giving at the same time a complete new sound and versatility to the amp.

EDIT: is there any problem with the upload of the files? I've tried four times with no luck...

[Smokebreak]

I think so Roberto. Took me an hour to upload but it finally went.

Joe check my green schematic for footswitchable volumes. Each switch is one side of a dpdt relay. Alternatively you can also put in switchable master volumes before the PI, implemented in the same way.

[JoeCon]

Smoke

OK I get it now, still a lot of work for that option.
On the Plexi 6V6 I just built I use both volumes to dial in the tone I want with guitar about 6-7 and then roll up to 10 for full volume. It's nice to be able to add a liitle more bright or a little less normal channel and if I want just bright I turn normal down.

Thanks...

[roberto]

Done. Finally I succeed in uploading the file.
That one is another option you may like.

What about moving this thread in the Marshall sub-forum?