New 183 build

[ijedouglas]

I believe the red wire with blue stripe is the return from the standby switch. The black is from the OT and purple goes to the screens.

Hmm! I thought that too for a while... if the BLK is the CT (B+) for the OT though, it would sharing the node with VIO (or purple) with the screens (B+2); B+ and B+2 together? I can't quite get my head around that. There does indeed, seem to be another Red/blue stripe wire hanging around the back panel of the chassis near the switches, but that looks like it connects up with the ground switch.

Tony's layout WRT the power supply is correct (https://ampgarage.com/forum/download/fi ... &mode=view) I have verified this with the precision power supply in a real Dumble.

[bepone]

Agree! I think this is where Tony's layout is the more reliable as well. I see now it is possible with the 183 board as well:

183 PS topology(2).jpg

it is very simple GND-ing in 183.. only 2 gnd points to connect, one for high currents, one for low, cannot miss with this one.. although can be also little bit better with separate star on each stage, and connect dedicated electrolytic minus pole to each star

183.1_cr.png

[ijedouglas]

it is very simple GND-ing in 183.. only 2 gnd points to connect, one for high currents, one for low, cannot miss with this one.. although can be also little bit better with separate star on each stage, and connect dedicated electrolytic minus pole to each star

3 grounds... reservoir goes to ground 4

Maybe I'm missing something here. These layouts have been verified over the years and many builds have been completed using them. The ground scheme seems pretty simple. Not sure what the hangup is here?

[Stephen1966]

it is very simple GND-ing in 183.. only 2 gnd points to connect, one for high currents, one for low, cannot miss with this one.. although can be also little bit better with separate star on each stage, and connect dedicated electrolytic minus pole to each star

3 grounds... reservoir goes to ground 4

Maybe I'm missing something here. These layouts have been verified over the years and many builds have been completed using them. The ground scheme seems pretty simple. Not sure what the hangup is here?

I see three as well. Thanks for confirming.

[pompeiisneaks]

All Dumbleland/SSS/ODS/ODSR that I am aware of were built 100% from scratch.

I've now seen multiple ODS that were built in a fender chassis, not from scratch no? He gutted them, and rebuilt, or did he actually get fender identical chassis' sent to him empty?

Maybe I've been mistaken but they always looked to me like a gutted chassis with existing transformers and everything else rebuilt... thus my statement it was rebuilt. to me 100% from scratch is buying an empty chassis, even if pre drilled etc, and building/buying an empty cabinet and buying/installing a speaker etc 100% is 'from scratch'. Reusing nothing. Copying nothing.

but I might be wrong. Again I've only seen some of the builds here, not all, only in photos, and by far that's a very small percentage of his amps.

~Phil

Really, please direct me to just one. I know Dumble was rather insistent that he do everything. He screened and painted his chassis, built his own head shells and speaker cabinets and so on. The ultraphonix were the only amps I know of that he used the original Fender chassis.
chassis.
CW
Can you "Dumble-ize" a Fender amp to the point that it shares the Dumble philosophy and sound, or would it be a compromise?

It's a compromise. The actual physical construction of the Fender limits what can be done. In fact, after the last Steel-String Singer mod I did to David Lindley's amps, he no longer uses the Fender Bassman I Dumbleized for him. He wanted this luscious transparency and response--like floating in white clouds--and I came up with special circuitry. I can use a Fender chassis, but you have to rip everything off of it, fill in all the holes, and re-drill it. They're just a little bit too squashed. A distance of half a centimeter makes a big difference in the way something sounds. It's a science involved with what's called circuit constants.

Then I stand corrected, so he only reused transformers in those chassis and had his own made? Gotcha, I definitely misunderstood. I knew of the tweedle dee's and the ultraphonix and the stuff he did recently for clapton and thought that had always been the MO.

~Phil

[bepone]

3 grounds... reservoir goes to ground 4

correct 3 total, i was marking preamp and power cathodes for clarity

[Stephen1966]

Here is the layout for the PS board.

DELTA 183 - PS board.jpg

This has the standby switch after the reservoir caps and I've updated the schematic on the first page to reflect this. It also includes a couple of extra nodes for the onboard Dumbleator/FX loop. I'm going to be playing with the different kinds of dropping resistors so there are plenty of eyelets which will make swapping the resistors somewhat easier.

[Stephen1966]

Sometimes you have to step away...

I wasn't happy with the illogical order of the B+4 and B+5.

Here is the PS board now.

DELTA 183 - PS board.jpg

[bepone]

you are designing your own board?
if this will go to production, i need to say that is too low clearance between the Ub+ lines and GNDs.. in theory with varnish can pass but why not to be on the safe side..give at least 3-5mm between.. FR4 is porous material , and with time will soak humidity and between Ub+ and GND will be carbonised areas with higher conductivity/ lead to even higher carbonisation, and - smoke - one day

[Stephen1966]

you are designing your own board?
if this will go to production, i need to say that is too low clearance between the Ub+ lines and GNDs.. in theory with varnish can pass but why not to be on the safe side..give at least 3-5mm between.. FR4 is porous material , and with time will soak humidity and between Ub+ and GND will be carbonised areas with higher conductivity/ lead to even higher carbonisation, and - smoke - one day

I did wonder about that... I can't make the board any bigger (125mm x 110mm), I wouldn't be able to fit it along with the PT and preamp board. But I can reduce the width of the traces. These are 4mm wide at the moment and I could probably get away with 3mm - could it be even less with the GND traces?

[bepone]

you can reduce width , yours is for 3 Amperes, not needed.. it is good ofcourse to have thick traces, better than thin from all aspects.. here clearance is more important because you have high voltage 470V on pcb, so priority on safety..

after short looking,
red to be increased ,
orange optional, but will bee good too. it is possible to save space on bleeding resistors they have very low current and importance, and small pcb pad is ok for them

DELTA 183 - PS board corr.jpg

[Stephen1966]

you can reduce width , yours is for 3 Amperes, not needed.. it is good ofcourse to have thick traces, better than thin from all aspects.. here clearance is more important because you have high voltage 470V on pcb, so priority on safety..

after short looking,
red to be increased ,
orange optional, but will bee good too. it is possible to save space on bleeding resistors they have very low current and importance, and small pcb pad is ok for them

DELTA 183 - PS board corr.jpg

Yes, I see what you are saying... thank you.

[Stephen1966]

After going at this a bit intuitively I decided to redraw the traces on bepone's advice.

There's a handy little tool if you want to design your own boards: https://www.digikey.com/en/resources/co ... race-width

I've made the nets feeding the power tubes 4mm wide (this is all on 35um copper) and the traces downstream 3mm wide. As bepone suggested, I could have made the pads to the balance resistors smaller because they carry very little in the way of current but I've made these 3mm as well to help radiate off some of the heat that is going to be generated, a temperature rise of 10 degrees C is expected. Generally speaking now, there's a minimum of 3mm between the traces and I will be applying a layer of solder on the traces to improve the current handling, and then a layer of lacquer on both sides of the board to seal out any moisture that might penetrate. I don't actually know if the pcb board is FR4 but it doesn't hurt to assume it has a similar porosity to FR4.

Here's the new layout, and for anyone considering drawing these up in Illustrator - Don't do it: life is too short I draw my other boards in DipTrace and it is a lot faster. I like the precision I can get in Illustrator though...

DELTA 183 - PS board.jpg

[bepone]

nice,
now is better, also with the components where is heat expected .. you can make few holes 3mm on pcb below them .. R74, R77.. also other is ok too.. resistors you can mount on 10mm height from the board so they can radiate temp in the air..and not heat up the pcb.
increase copper to 70um , and then all together you have space shuttle pcb

[Stephen1966]

The preamp board layout

Prreamp board.jpg

This includes the follower side of the FX loop. A number of extra eyelets have been added to aid the tuning process. I always found the grounds of V1 and V2 cathodes to be problematic and similarly, the shielded cable is susceptible to overheating when swapping out components that share an eyelet so I've isolated these with extras. The components may change but the eyelet spacing shouldn't be a problem, I used the largest components where alternatives exist.

The board is 80mm x 215mm FR4 and I'll be lacquering it before I press the eyelets in.