Getting a head of myself - Marshall 2204 JCM800 inspired build

[kuDo]

Most of my parts are from Tube Town. They have been fast and reliable so far.
I really like their website.

The headshell is this one:
https://www.tube-town.net/ttstore/ttc-u ... g-054.html

Most of the electronic components are from Mouser.

I will put tolex on the headshell, but have yet to order it.

[kuDo]

Today marks the moment that about a year ago I started making plans for my DIY guitar amp project.
It has also been a year of being inside a lot because of obvious reasons. So if am being positive, than I would say that this year has learned me a lot. I took upon myself the challenge of building my first complete tube amplifier. The project contained a lot of aspects that I was not sure of if I could tackle them.

- Designing my own Turret board layout from a schematic of a 2204 JCM 800 like design.
- Adding an extra tube driven effectsloop stage.
- building a turret board
- applying a good grounding design.
- tollexing a headshell
- designing my parts layout in the chassis
- creating a clean chassis with hole punch an drills.
- designing my ow front and back faceplates

But today I finished my amp. The end result is really pleasing me. I am super happy with it.
Everytime I look at it fills me with joy. So much fun, that after enough perseverance the end is finally there. it is finished (almost )
Instead of sitting in front of the telly, I managed to start building something with a great result. So fulfilling.

I hope you like the pictures.

I do have to tweak the hiss that hides inside the first stage, but for that I ordered some new part which haven’t arrived just jet.
When it is dealth with I’ll post again.

[romberg]

But today I finished my amp. The end result is really pleasing me. I am super happy with it.

Congratulations! Doing all the steps you did will make this amp yours in a way that no other amp can really be.

Mike

P.S. The tolex looks really nice! I'd never guess that was your first go at it.

[kuDo]

P.S. The tolex looks really nice! I'd never guess that was your first go at it.

Thank you Mike.

A big bart in the succes is the glue I used. It seems that you simply can't go wrong with it.
Also I watched the "Uncle Doug" video which helped my greatly.

[erwin_ve]

Nice job! I like you faceplate design and posting the whole process is interesting.

En hoe klinkt het beest?

Erwin

[kuDo]

Nice job! I like you faceplate design and posting the whole process is interesting.

En hoe klinkt het beest?

Erwin

Thanks Erwin,

I get real inspired by posts of other people creating thinks they love, so that's why I shared by journey.

I also got real inspiration from the Dirty Harry build you did. It was that thread that got my into designing my own face plate!

The amp sounds good, but I have a problem with, in my opinion, excessive hiss.
I am waiting for some new part to try to sort it out.

I have a little clip on page 5 and also of the hiss
The sound clip is a little low on volume, but once you turn it up, you'll get a good impression.

Met een tube screamer er voor denk ik dat hij beestachtig gaat klinken

groet,
Douwe

[erwin_ve]

Nice job! I like you faceplate design and posting the whole process is interesting.

En hoe klinkt het beest?

Erwin

Thanks Erwin,

I get real inspired by posts of other people creating thinks they love, so that's why I shared by journey.

I also got real inspiration from the Dirty Harry build you did. It was that thread that got my into designing my own face plate!

The amp sounds good, but I have a problem with, in my opinion, excessive hiss.
I am waiting for some new part to try to sort it out.

I have a little clip on page 5 and also of the hiss
The sound clip is a little low on volume, but once you turn it up, you'll get a good impression.

Met een tube screamer er voor denk ik dat hij beestachtig gaat klinken

groet,
Douwe

Ah thats great, thanks!

[Reeltarded]

love the amp!

i hear radio static.. it happens when the master is UP and the pre is DOWN..

We need to look at the lead dress starting at the master and work back to the input. All the grids should be shielded on the drive stages.. that half of the static and more.

Hiss? SSSSSSSSSSS it should sound like a waterfall without the static popping..

[kuDo]

love the amp!

i hear radio static.. it happens when the master is UP and the pre is DOWN..

We need to look at the lead dress starting at the master and work back to the input. All the grids should be shielded on the drive stages.. that half of the static and more.

Hiss? SSSSSSSSSSS it should sound like a waterfall without the static popping..

Thank you!

Currently only the first two stages are wired with shielded cable to the grids.
Would you advise to wire all the stages that way?
I connected the shield wire that is surrounding the core wire to the ground. The same shield wire at the end of the grid is not connected.

Do I understand you correctly that there might be two problems?

So the buzz and the hiss are two different animals?

[Reeltarded]

It sounds like something is picking up noise when the preamp is zero and master is full up.. hmm

[kuDo]

It sounds like something is picking up noise when the preamp is zero and master is full up.. hmm

Probably true. The hiss however, when you have the master at 1/3 en the preamp at 10 is the biggest issue.

Such a bummer that this chassis is so cramped. It will be a real hassle to redo the input wiring.

[Reeltarded]

I am used to a wall of hiss!

It's the 'eeeeeEeeeeeeeEeeeeeeEeeeeeee' that drives me insane..

It may be nothing. I normally stay just under 5 with master volumes.

Here is good news if you decide you need to reroute grid wires: I fly all mine so they lay against the bottom of the head shell.

Don't do anything drastic, yet.

[romberg]

Do I understand you correctly that there might be two problems?

So the buzz and the hiss are two different animals?

Yes. In guitar amps there are a few words commonly used to describe various kinds of noise. They each have a different source:

• Hum - Sounds like Hummmmmmmmmm.... This is has a frequency of 60Hz (same as your wall supply) and comes from the line voltage or heater wiring.
• Buz - Sounds like Buzzzzzzzzzzzzzzzz... This is a higher frequency 120Hz (twice your line voltage) and comes from your rectifier in the amp.
• Hiss - Sounds like Hissssssssssssssss... This is from thermal noise. Atoms get hot and move around when this happens it can change the electrical properties (like resistance, etc enough that it creates it's own signal. When this thermal noise occurs in the early stages of an amp it gets amplified.

Hum and Buzz can be minimized by isolating the parts of the amp from the noisy bits (power supply). Hiss is more tricky and can not be 100% eliminated The best you can do is use metal film resistors (they have less thermal noise) on the first gain stage or two. The first grid stopper and plate resistor makes the biggest difference. The hum and buzz can be minimized via shielding and other techniques.

Merlin has a good chapter on noise in his book. I recommend it:

http://www.valvewizard.co.uk/

I'd start with the things that are simple and easy first. Don't dive in and do major changes before trying easy simple ones. Try a new higher wattage metal film first stage grid stopper and see if that alone makes any difference (assuming it is easy to replace). Then try another simple thing. Etc...

Mike

[kuDo]

Yes. In guitar amps there are a few words commonly used to describe various kinds of noise. They each have a different source:

• Hum - Sounds like Hummmmmmmmmm.... This is has a frequency of 60Hz (same as your wall supply) and comes from the line voltage or heater wiring.
• Buz - Sounds like Buzzzzzzzzzzzzzzzz... This is a higher frequency 120Hz (twice your line voltage) and comes from your rectifier in the amp.
• Hiss - Sounds like Hissssssssssssssss... This is from thermal noise. Atoms get hot and move around when this happens it can change the electrical properties (like resistance, etc enough that it creates it's own signal. When this thermal noise occurs in the early stages of an amp it gets amplified.

Hum and Buzz can be minimized by isolating the parts of the amp from the noisy bits (power supply). Hiss is more tricky and can not be 100% eliminated The best you can do is use metal film resistors (they have less thermal noise) on the first gain stage or two. The first grid stopper and plate resistor makes the biggest difference. The hum and buzz can be minimized via shielding and other techniques.

Merlin has a good chapter on noise in his book. I recommend it:

http://www.valvewizard.co.uk/

I'd start with the things that are simple and easy first. Don't dive in and do major changes before trying easy simple ones. Try a new higher wattage metal film first stage grid stopper and see if that alone makes any difference (assuming it is easy to replace). Then try another simple thing. Etc...

Mike

I have been reeding Merlin’s book. It is great. I used it the build my amp according to his philosophy (no pun intended).

- My interstage filtering caps are close to their stage.
- Grounding is done as he teaches. No loops and the most important en sensitive stage get the cleanest power. The ground trail runs from most sensitive to least sensitive item in the amp. There are no chassis connections to the circuit except for directly at the input socket. The only place where the connection to ground is made.
All in and output are isolated from the chassis.
- I used metal film resistors for all resistor where possible.
- I applied twisted heater wiring as tight as possible and along the side of the chassis. Also I use elevated heater supplies with a humdinger potentiometer to dial in the most quit result.
- I kept the transformers as far away from the first stages as possible and al of the transformers are rotated so they have the least chance of feeding into each other.

So far I have done a couple of things:
- I have replaced the first preamp tube with a low noise version.
- replaced the first stage grid stopper for:
https://www.tube-town.net/ttstore/metal ... 8-1-k.html
These two adjustments had now effect.

[kuDo]

Finished this amp almost a year ago. But it kept nagging me that it was incredibly hissy.
So I tried a lot of things to improve it. But nothing seemed to help.

Eventually I have started removing parts of the amp to see the effects.
And as I already concluded earlier, it had entirely nothing to do with the rest of the amp.

Removed the power amp.
Removed the tube effects loop stage.
Removed the phase inverter.
Changed the tubes.
Changed resistors.
Changed the lead dress.

And than I decided that I would start over…