Chassis layout questions

[Hardtailed]

Amp is based on a Marshall JCM800 2204 circuit, with some mods and tweaks.

I ordered an 8" deep chassis (16.5 wide, typical) which allows some leeway compared to the standard 6.5"

I've included two images of layouts I'm considering (yeah, it's the real parts on a piece of paper! I'm a hand-on kind of person I guess). One I've dubbed "classic layout" since old Plexis were done this way. Downside is having all the transformers weight on one side.
Second one is a "modern" layout, similar to Soldanos for example, with the preamp tubes at the front (board fits in the middle), and the transformers at each end... not sure where to put the choke though. Those amps seem to have it inside the chassis (it would actually fit under the power transformer).

Edit: Front of amp would be on the bottom from this point of view

Any suggestions?

Many thanks!

[octal]

I suggest the "classic" layout. It's best to keep both the OT and the PT well away from your input jacks. I built one moderate gain amp (An AC-15 with Top Boost) with my own layout (nothing like a factory AC-15) and had to do extensive shielding around the OT to prevent oscillation. Everything I've built with the other layout has been much more stable. YMMV.

If you wanted to get creative, you could offset your amp chassis in the head cabinet so that the transformers were more near the center.

[Hardtailed]

I suggest the "classic" layout. It's best to keep both the OT and the PT well away from your input jacks. I built one moderate gain amp (An AC-15 with Top Boost) with my own layout (nothing like a factory AC-15) and had to do extensive shielding around the OT to prevent oscillation. Everything I've built with the other layout has been much more stable. YMMV.

If you wanted to get creative, you could offset your amp chassis in the head cabinet so that the transformers were more near the center.

Thanks for the input

I'm just wondering... cause I see so many amps with the "one tranny on each side" approach. Hell, my DSL is that way.
Plus, with the preamp tubes on the front, the signal goes right to V1 without much cable run.
I could also run the OT wire above the chassis to prevent coupling with wires running inside it...

So many options

Of course... the classic layout is tried and time-proven!

[defaced]

I'm all for trying things, but if it ain't fixed don't break it. Wait a minute...

...but, if you really want to try the other layout, use a cake pan/turkey pan, mount all the tube sockets from the inside, and see what shakes out. The worst you'll have to do change is when you go to build it in the real chassis.

For what it's worth, I'm doing a high gain build this way (each tranny on each end) and at high volumes, I am having oscillation problems. Are they related? I don't know. People eat more ice cream in the summer, also more people drown in pools in the summer, but it doesn't mean the ice cream is making the people drown.

[daz]

The classic is close to what i used and my amp sounds fantastic and is higher gain than a JCM 800 yet extremely quiet. Tho my choke is in between the PT and OT.

[anson]

I'm a big fan of putting the handle off-center so that the amp can still be balanced when picked up despite having all its trannies on one end.

[Hardtailed]

The classic is close to what i used and my amp sounds fantastic and is higher gain than a JCM 800 yet extremely quiet. Tho my choke is in between the PT and OT.

That's one of the thing I was wondering: where to put the choke.
I've read on a thread here that it's actually better to have the OT very close to the PT but with the lams 90 degrees apart, which is what I did here. I'm also basing this on the pictures on the Ceriatone website.

[bnwitt]

Here is the classic layout and it works well. All trannies rotated 90 degrees from each other. Notice how the power tubes are right across from the OT to keep wires short. Notice how the first two filter cap cans are near the PT and the last Filter cap is near the preamp section. You should be designing your layout to keep wires as short as possible. This is why you don't want too deep of a chassis as that will make wires from the board longer.

[Hardtailed]

While we're at it, just for fun I did a layout with the classic "all trannies on one side" yet with the preamp tubes on the front (which does promote shorter cable runs, especially from the input to V1. See attachment.

From there, I coud probably move the 3rd cap can over the preamp section (board is basically between the two sets of tube sockets). Choke I'm not sure...

I probably will go ahead and do the classic thing. Maybe I should've gone with the 6.5" deep chassis, I just felt some extra room couldn't be a bad thing, and it was like 4$ extra.

[bnwitt]

Here's an inside layout from off the web which matches the standard layout:

http://homepage.mac.com/gaden/.Publi...V%20Layout.pdf

[daz]

That's one of the thing I was wondering: where to put the choke.
I've read on a thread here that it's actually better to have the OT very close to the PT but with the lams 90 degrees apart, which is what I did here. I'm also basing this on the pictures on the Ceriatone website.

Thats the thing. As long as they're at 90 degrees it's fine. In fact, i used that headphone trick before mounting them to determine whether there would be any noise and it was dead quite no matter how close, just as long as they were at 90 degrees.

[bnwitt]

Here's a layout for you size chassis

[Hardtailed]

Here's a layout for you size chassis

Oh, wow, nice! Thanks a lot!

I just received my chassis so I now have all my parts and can't wait to start.

Did you make this yourself or does it come from another website?

I'm just asking, maybe you also happen to have the board layout I'm looking for
I bought the 2204 board from Turretboard.com (also where I got the chassis... which I didn't realised wasn't welded in the corners... oh well) and I can't find a layout on the internet that fits it. I'll figure it out if necessary, but you know... could help

It's exactly like the picture on their website:


In any case, thanks for the layout!

[defaced]

Have you tried emailing turretboards for the layout of the board?

[Hardtailed]

Have you tried emailing turretboards for the layout of the board?

I did, all I got was "I believe this layout is pretty standard."