Tweed Bassman / Deluxe w/ reverb. any opinion?

[Tubenit]

Layout

Sorry, I don't have a layout for it. I use ExpressSCH for my drawings and tend to do all my layouts in a paralleled terminal type format like vox and hiwatt.

Best I can do is offer this for an idea. I did not include my tremolo on the layout board. I used terminal strips instead.

I could draw a paralleled layout for you but I know you can draw layouts also and perhaps prefer the Fenderish style.

Have fun with it, .... whatever you do. Again, this reverb has worked extremelly well for me on my builds.

With respect, Tubenit

[tubeswell]

Cheers

[txstrat]

TW
On your board you put the preamp filter caps in between the other components. I find this very interresting since it shortens the overall lenght of the needed power rails and that's what I like. You have any experience related to hum with this layout?

[tubeswell]

TW
On your board you put the preamp filter caps in between the other components. I find this very interresting since it shortens the overall lenght of the needed power rails and that's what I like. You have any experience related to hum with this layout?

Its more because I saw others doing this with their layouts (Hoffman etc). I just hope I'm right about my hunch that I'll only need 1 decoupling cap/supply resistor per 2 pre-amp tubes. (The 5F6A only has 1 x 10k & 1 x 10uF for the V1 and V2 tubes, so I'm kinda hoping it all balances out so to speak).

I don't think having the decoupling caps/supply resistors 'spread out' so to speak will induce hum, because its not the high DC potential lines that cause hum. It is unwanted AC getting into the signal path, or into the B+ (and so into the signal path). So hum might come from the fact that there is not enough filtering in the pre-amp (which can be remedied by upping the decoupling cap values - but I am cautious about over-filtering).

However I think I have got the stages arranged in the schematic so that they invert in such a way as to cancel out/minimise any opportunity for hum from AC getting into the B+ rail. (If I am wrong about this I trust somebody will let me know). Also doing stuff in the layout like keeping the tremolo oscillator circuit separated/screened from the tone stack driver by a decoupling cap and supply resistor should stop unwanted signal coupling back into more sensitive stages of the pre-amp. I also have tried to keep high voltage plate resistors and coupling caps etc in a logical layout that keeps sensitive circuits away from stronger ones etc. I would mind some comment on that if anyone can pick me up on anything.

[Tubenit]

Bassman R&T layout

Here is a possible layout for your idea (IF you wanted to try the D'Lite type reverb). The idea is to simply show the layout board not the layout of the entire chassis interior. I would ground the reverb dwell and RCA jacks to the reverb trannie bolt. All other grounds, I would attach to a buss wire running across the back of the pots.

Check for ERRORS and compare with the schematic I posted. I split the V1 cathode to get two additional tones. I eliminated the 220uf as the 25uf traditional Fender cathode cap should suffice for guitar. On the layout, terminal 16 should indicate being hooked up to node D on the B+ rail.

I haven't build this so keep in mind this is simply a concept. With respect, Tubenit

[tubeswell]

Thanks for going to the effort of drawing that tubenit. Its interesting to see how others interpret layouts.

Is there any particular reason why you have kept the NFB resistor on the left-hand side of the LTP plate resistors/6L6Grid bias resistors? (other than that is the way it is on the Fender 5F6A layout?). In my last layout drawing I moved this to be next to the LTP tail circuitry, more because it seemed to be directly next to where I had the presence pot, and that it joins the ground return side of the tail resistor anyway. Or is there some characteristic which would preclude this being in other than the traditional fender location do you think? (like not crossing the path(s) of the LTP plate wires maybe?)

[Tubenit]

NFB resistor

There is no particular reason. I have no idea if it makes any difference? This is how I tend to do my paralleled layouts and it has worked. I'm guessing the approach your suggesting would be fine also.

I agree there are lots of different ways of doing the layouts that can be successful. If it's a really high gain amp ...... I think it becomes more crucial to have a proven layout.

I used to own a Dano Centurian (great amp) that was PTP and violated all the grounding "rules" with grounding points all over the place. Very quiet and no hum at idle. Go figure?! Other amps I've done, small things seemed pretty critical to the success.

IF you build your amp, please let us know how you like it.
Have fun with the project.

With respect, Tubenit

[tubeswell]

V12 Schematic

Ok I had some more thoughts about this design and took out a whole pre-amp tube, and the dwell control. So now I'll save some more chassis space and it'll only draw 3.9A (including the lamp) on the (5A) heater winding I have, and I doubt that the verb will be seriously compromised in any way. Less work for the filter caps too. Layout coming up

[tubeswell]

V12 Layout

After much twiddling, here is the more spacious layout accompanying the earlier schematic. 1 notable change is the .1uF coupling cap from the 'verb recovery (instead of 250pF shown on the schematic)

I'm pretty sure this layout will work. The dark green wires are shielded cable - light green are the output grids and the red are the power rail.

Any suggestions/comments/snide remarks are most welcome.