new dumble build in bassman head chassis

[Gibsonman63]

If you really want to re-use the eyelette boards, you might try treating them (carefully) with a heat gun. I have done it one a vintage Fender that I rebuilt with good results.

[andresound]

Cleaned the boards with a solder sucker first, then a blade (scraping all the old flux away), then an abrasive pad. Lastly a wipe with a damp cloth and then 1hr in the convection oven.

Before cleaning , I measured 35 meg between closest eyelets!

I am being guided by David Root with regards the build (very generous with his time!). I think new boards is the right way to go.

after going through info on Dumble files sectiopn, I am also leaning towrads a #124 build. This is probably the most documented Dumble available.

Would love to include the active Fx loop in the chassis.

[andresound]

pots out!
4x 021 250k AUD 2-35 137. 6913
2X 02183 1MEG AUD 137. 6905
2X CARLING slide switch's 4A/125v

[IMG768]http://i48.photobucket.com/albums/f214/ ... kq2qsq.jpg[/img]

[Duble]

pots out!
4x 021 250k AUD 2-35 137. 6913
2X 02183 1MEG AUD 137. 6905
2X CARLING slide switch's 4A/125v

[IMG768]http://i48.photobucket.com/albums/f214/ ... kq2qsq.jpg[/img]

You might try cleaning/testing those pots, and using as many as you can if they're good.

[andresound]

Tested as follows;
214k
289k
249k
250k
1.01meg
1meg exactly!

[AtomCap]

Depending on how creative you can get with your build it might be a tad tight jamming a dumblator into that chassis! Might need to work up a custom board to condense and save space- bassman chassis aren't roomy

FWIW, you're absolutely wasting your time and effort salvaging the tattered old board- seriously. I mean no offense by that- if its shot, shorting,cracked, warped water damaged just scrap it and go for a perf board setup..
or one of those universal jobbies at some point it will just lead to issues..

[andresound]

No offence taken. New boards is the plan. No looks like I will be doing a #40 build.

[andresound]

parts for build should be with me in 6 weeks. Really looking forward to this build. In the meantime, my Epress is sounding better by the day!

[andresound]

I have been advised by the guru's here on the forum to iinvestigate a aluminium chassis.
Suggestions. If anyone has a CAD file I could take to a local laser cutting firm, I could have a chassis made up. The build is going to be a 2nd gen #40 with built in d-lator.

[Duble]

I have been advised by the guru's here on the forum to iinvestigate a aluminium chassis.
Suggestions. If anyone has a CAD file I could take to a local laser cutting firm, I could have a chassis made up. The build is going to be a 2nd gen #40 with built in d-lator.

Another thing highly suggested is to study photo's from that era of actual dumble amps, pay close attention to the lead dress, it has a huge impact on the way these amps sound in the end. As Alexander Dumble has said before, a difference of a centimeter with wires can make a profound difference. Putting plate wires next to cathodes on the V1 and V2 gain stages makes a huge difference, and pay very close attention to voltages of every stage. There are many things you can do in these types of circuits to end up with a great sounding amp, and all that information is here on the Amp Garage as long as you read.

Most of all, good luck, have fun, and stay safe.

[andresound]

Looks like I am going to stick with the challenge of doing this build in the donor chassis as the thread title states!!

I understand the importance of lead dress and will take pointers from anyone as I go. Also ideas on a building schedule or procedure, i.e. what goes in first (to avoid having to remove or undo things because of bad planning), etc.

I did manage to build my TW express by carefulling studying layouts etc, and that amp is quiet, stable (with everything dimed), and is sounding great.

I am told that the steel chassis might present earthing challenges. , and there is always the debate about the sound being affected by a steel chassis.

I DO HAVE THE FOLLOWING ADVANTAGE;

1. I have a great stock of NOS tubes to choose from.
2. The CORRECT vintage "seasoned iron.
3. A collection of authentic components (not all, but most)
4. And of course, you guys!!!

[andresound]

This is what I found
[IMG:640:480]http://i48.photobucket.com/albums/f214/andresound/82FB9C2A-AE09-4BAB-A85E-3B98B4C7E120_zpskx5bkxps.jpg[/img]

[andresound]

Ok, Parts have arrived and the main board and Power supply board are partly populated before soldering. Next will be, to see if everthing is going to fit. For example , the FET board needs to be close to the input, but I have to avoid the cabinet and chassis screws that go "though" the inside of a bassman chassis that hold the chassis firmly in the cabinet. There are 4 of them.

Interestingly, the outer foil markings on non polarised Caps (orange drops) are NOT always correct. Have been testing each one with a scope, and found a few to be incorrect! batteling with posting pics with my iPad, so will post from my phone tomorrow.

[martin manning]

Interestingly, the outer foil markings on non polarised Caps (orange drops) are NOT always correct.

In fact the orientation of the printing is completely random.

[andresound]

That is a real PITA. Since the scope is a new aquisition (im a newby), I have to revisit my TW Express build.
I would imagine that particular circuit would benefit from such minor adjustments. Also a bigger PITA because all components are painstakingly tightly bound around the turrets!!