New Fender "type" amp build suggestions

[foreverstrung]

Well, I ordered a Jupiter M12C from Tube Town. Couldn't find one anywhere in the US. Hopefully tariffs don't double the cost like the chassis did. I figured you recommended this speaker for a reason Biworm so I didn't want to settle for anything else even though I've got a couple good ones here to choose from.
I'm getting unwanted noise, harmonics and more from the MV past 5. Before 5 it's fine. I do get relatively clean tones with the volume at 2 and MV at 4-5. I'm liking it. The harmonics I'm getting after 5 I think might be grounds maybe. Cold solder. Appreciate any thoughts.
Also, reverb, I'm not getting anything. How I've got these RCA jacks mounted to the chassis, I have the sleeve direct against the chassis, so it is grounded. My wiring looks good. Mechanically anyways. It's not noisy when I engage the pot. I'll play with it some.
Any thoughts or suggestions about these issues are always welcome and much appreciated.
Dave

[JMPGuitars]

Always start with the basics in my signature for troubleshooting. It seems you have a voltage chart for Bieworm to review, and besides that, step 1 and 2.

[foreverstrung]

Always start with the basics in my signature for troubleshooting. It seems you have a voltage chart for Bieworm to review, and besides that, step 1 and 2.

Love it. #1, Lol. As a rule I almost always use old stock RCA, GE, etc. rare do I use new manufacturer tubes tho I have. JJ’s too in the past, but not as a rule. Almost always old stock. NOS, whenever possible. Right now I’ve got 2 old stock matching-ish RCA 6L6GC and then a GE 12AY7 in V1 and a RCA 12AT7 in V2 and then V3-5 I’ve got 12AX7’s, 2 RCA and a Mullard.
Dave

[foreverstrung]

Update.
Everything is working 100% getting to know my way around the settings. It is a beast. Or can be, but I can get it to chill out a bit.
Still have cabinet work to finish up. Speaker on order and I’m going to have a new faceplate made.
Very happy with this amp so far. After figuring it out.
Thx
Dave

[Bieworm]

For the excess gain you light want to play with cathode cap values on V1. Try to lift one leg and report back

About the noise in the MV.. mine are a tad noisy after 7-8. I mostly settle for 7, and in a situation where I need to get beyond that.. the noise doesn’t matter anyway. You don’t hear it while playing. And the premature saturation of the amp is why I like it. It’s on the verge of loosing control, and compresses in a very amicable way to me.

[foreverstrung]

For the excess gain you light want to play with cathode cap values on V1. Try to lift one leg and report back

About the noise in the MV.. mine are a tad noisy after 7-8. I mostly settle for 7, and in a situation where I need to get beyond that.. the noise doesn’t matter anyway. You don’t hear it while playing. And the premature saturation of the amp is why I like it. It’s on the verge of loosing control, and compresses in a very amicable way to me.

Actually gain is very controllable. I just really needed to get use to the amp and it’s settings.
However I am getting (more then I’d like) unwanted background noise, but I’ve also got extremely poor grounding in this home I live in. So there’s that. Battling grounding hum is always a challenge here, though I do have a couple of well grounded outlets so I use these most of course, but this is noise over and above the normal
I was thinking that none of these pots “bodies” are grounded to the chassis. This might have something to do with unwanted noise, right? If so, what pots, if not all, should I focus on grounding to the chassis?
I should have thought of this immediately. Certainly the bodies need to be grounded.
Thx
Dave

[Bieworm]

Maybe it’s best to solder a solid tinned wire to the back of the pots and make a ground connection on one end of that wire?
Watch out with soldering to pot bodies.
1. Turn every pot to 10 to avoid burning in of the wiper somewhere on the carbon track.
2. Sand the back of the pots to remove any residues and make better solder connection.
3. Solder a little blob of solder on the same spot on every pot to make a nice alignment of the solid wire
4. Solder the wire to the 1st pot and move on to the next until all pots are connected
5. Heat shortly, no more than necessary
6. Use a wire with alligator clips on both ends and look for the best grounding point
6. Solder a shunt wire from the solid wire to that point

[JMPGuitars]

How is it that the pot bodies are not connected to the chassis? If they are connected to the chassis (which is normal without adding isolation to the pots, which makes no sense), and you add a ground bus across them, you'll be creating a ground loop and additional noise.

[Bieworm]

How is it that the pot bodies are not connected to the chassis? If they are connected to the chassis (which is normal without adding isolation to the pots, which makes no sense), and you add a ground bus across them, you'll be creating a ground loop and additional noise.

If you look closer at his pics you can see he routed/grinded out the front and back of the chassis. The faceplates he had made were too thick and the threaded end of the pots are too short to put the nut on them. That way the pots only touch the plastic panels which they are bolted on directly. A buss wouldn’t make a ground loop then..

[JMPGuitars]

If you look closer at his pics you can see he routed/grinded out the front and back of the chassis. The faceplates he had made were too thick and the threaded end of the pots are too short to put the nut on them. That way the pots only touch the plastic panels which they are bolted on directly. A buss wouldn’t make a ground loop then..

Oh! That's not great- that whole section lacks shielding now. Rather than wiring a bus, I would remove the pots, and apply copper shielding tape to the back of the plastic and connect it to the chassis. Then test continuity and resistance.

Thanks,
Josh

[foreverstrung]

Oh! That's not great- that whole section lacks shielding now. Rather than wiring a bus, I would remove the pots, and apply copper shielding tape to the back of the plastic and connect it to the chassis. Then test continuity and resistance

That's a great suggestion. I've ordered another plate, 1/16" thick but it'll still be acrylic or some composite. Adding that shielding tape is a most excellent suggestion. When the new plate shows up, I'll apply the copper shielding tape before applying the plate.
Thx
Dave

[JMPGuitars]

That's a great suggestion. I've ordered another plate, 1/16" thick but it'll still be acrylic or some composite. Adding that shielding tape is a most excellent suggestion. When the new plate shows up, I'll apply the copper shielding tape before applying the plate.
Thx
Dave

Assuming you'll also be using some double-sided tape, make sure the tape has good contact with the chassis also.

[Bieworm]

That's a great suggestion. I've ordered another plate, 1/16" thick but it'll still be acrylic or some composite. Adding that shielding tape is a most excellent suggestion. When the new plate shows up, I'll apply the copper shielding tape before applying the plate.
Thx
Dave

Assuming you'll also be using some double-sided tape, make sure the tape has good contact with the chassis also.

Do you happen to have an example of double sided copper tape with conductive glue?

[JMPGuitars]

Do you happen to have an example of double sided copper tape with conductive glue?

This is one I use: https://www.amazon.com/dp/B07QQHQMYD

[Bieworm]

Do you happen to have an example of double sided copper tape with conductive glue?

This is one I use: https://www.amazon.com/dp/B07QQHQMYD

Isn’t that 1 sided?

[foreverstrung]

This is one I use: https://www.amazon.com/dp/B07QQHQMYD

This is the shielding tape I purchased yesterday. Even though it's one sided, could'nt I use the adhesive side to the chassis and then just a few drops of superglue to secure the plate in place, temporarily, until I lock in all the pots that'll hold it securely in place?
As well, I have the original rectangle pieces (3) that I cut out of the chassis. I was thinking I'd set the new faceplate in place and then with the chassis on edge, set these pieces, pre drilled, into place and secure the butt joints/seems with JD Weld epoxy. Then the face of the chassis would nearly be intact and the shielding tape as extra insurance.
Dave

[Bieworm]

Maybe put double sided tape to the back of the faceplate and stick the slick side of the copper tape to that? Then you still have the conductive glue side of the copper tape to make continuous contact with the chassis?

[JMPGuitars]

The tape works, and you can confirm with resistance/continuity testing after using it. Copper tape is generally made to be overlapped and maintain continuity/shielding etc. If it doesn't, it's junk.

I don't like that the chassis was cutout. There's no protection for the amp physically. What happens if the amp falls and the knobs hit something? Repairing the chassis is a good idea, but you need to mask the rest of the circuit and keep everything clean. Even better if you know somebody that can weld it...or replace the chassis. ...or build a cage on the front like window bars.

[foreverstrung]

I don't like that the chassis was cutout. There's no protection for the amp physically. What happens if the amp falls and the knobs hit something? Repairing the chassis is a good idea, but you need to mask the rest of the circuit and keep everything clean. Even better if you know somebody that can weld it...or replace the chassis. ...or build a cage on the front like window bars.

My thoughts exactly. All of it. I’ve got a good plan on putting it back together properly after ordering a new faceplate with the correct thickness. Something I should have just done from the beginning.
I’ll send pictures of what I do. I’m pretty handy with this kind of stuff. Protecting my electronics is a major priority.
I’ve learned a lot so far on this project. Laying out the chassis. Cutting/drilling. Custom faceplate options. Turret boards and soldering techniques.
Let’s see if I can get this one across the goal line.
Dave

[foreverstrung]

So here’s some pics of what I’ve done.
Cut out rectangle pieces of aluminum “nearly” the same thickness as the chassis. Drilled them out. Trussed up the pots out of the way and covered them for safety and then applied JB Weld hi heat epoxy, ever so gently.
Face does not look pretty, but it’s solid, flat and smooth. I had to let it overlap the face of the pieces some as the butt joints alone would not sufficiently secure the new pieces in permanently. The stuff was extremely hard to tool and it does not sand back easily, but I'm confident that it's secure and that the new faceplate will lay flat.
I’m not sure that I trust the continuity of the butt joints with the epoxy, so I’m going to cover the face with my 2” copper shielding tape.
Unfortunately my new faceplate won’t be here till early next week. I might need to ream the holes a pinch. I already have had to lower 3 slightly to meet the existing plate. ( New plate is being made from the template of the existing thick one, so layout should be identical)