new dumble build in bassman head chassis

[Structo]

Cap phasing-
It's just one of those things taken in combination with other component choice and lead dress that all add up to a Dumble.

Try to build it as close as possible.
You may have to make some tuning tweaks to your liking later, but start with the original circuit, no matter which model you decide to build.

[andresound]

Thanks Tom,
It is going to be a 2nd Gen build (#40), with the built in dumbelator in the extra hole and the addition of a PI trimpot. Will also use mini-toggle switches instead of slide switches. Other wise have sourced most NOS parts.
Cant seem to find Silver Mica locally, so placing and order with Mouser. Will have to wait.

[Structo]

For small pf caps buy several types and values.

Ceramic
Polystyrene
Mica
Film

[andresound]

Partly assembled main board
[IMG768]http://i48.photobucket.com/albums/f214/andresound/Mobile%20Uploads/4A3E5CB8-9E6D-4BCD-BECC-A34FE6E318F2_zpsca6taano.jpg[/img]

Got photo's to work again

[andresound]

anyone spot mistakes in this layout??
[IMG576]http://i48.photobucket.com/albums/f214/andresound/2015-09/27B7F1AF-DAA8-43B4-BFFD-97AF8CEFE5CF_zpsaeqwmpld.jpg[/img]

[andresound]

Managed to get a few hours with the build. Finshed the output section cabling and some perimeter wiring.
[IMG:768:1024]http://i48.photobucket.com/albums/f214/andresound/Mobile%20Uploads/3E1E7405-C692-40EF-A9E4-000A13A677A7_zps6jmbzktf.jpg[/img]
Fully populated board
[IMG1024]http://i48.photobucket.com/albums/f214/andresound/Mobile%20Uploads/2015-10/3F3D2CAE-77AD-482B-B017-1D4E3FB6911C_zpsfdc67to6.jpg[/img]

[Structo]

Lookin good.

Be sure the bias cap is oriented with the + to ground.

Hard to tell with that yellow cap because it appears to have plugs at both ends which can sometimes indicate smaller caps inside.

[andresound]

Thanks Tom. The yellow cap is non-polarized!! It was all they had in stock at the time (I'm in Africa), so battle with component supplies. Is a polarized cap really necesary considering there is a 14007 diode in circuit? Would this not "polarize" the cap, but allowing current to flow in only one direction?

Exuse the ignorance, I am a nube.

[Structo]

Well, I'm not sure about that either but since this is negative voltage, it may be important to use a polarized electrolytic.

Most Dumble amps use a 100uF 100v cap in the bias.

[andresound]

Trust your advice on this Tom. Will chase down the correct cap. The installed Cap is a 100v 100uf, just not polorized.

[Structo]

Maybe someone else can jump in and say whether or not your cap is safe to operate.

[JazzGuitarGimp]

As long as the applied voltage to the cap does not excede 100V, the non-pol cap is fine.

[andresound]

Anyone else have some input?? It is really not a major PIA to change

[didit]

Lou has already given fine advice. Unpolarized is fine.

Best .. Ian

[andresound]

Amp is now basically finished and sounding great. Many thanks to all who helped. Amp is surprisingly quiet (hum free and noise free).
Some pics prior to installing the FET board. Added an OD entrance trimpot and exit trim. Next is the cabinet which I stripped and used Danish oil finish. Awaiting powder coating of trim pieces etc. Face plate is proving to be a challenge. I will use with a temp one for a while.