Blues Deluxe to ODS build

[martin manning]

I suspect the problem is in the center of this picture.

[Amwatts]

I suspect the problem is in the center of this picture.

Did some major lead dressing yesterday .
Very happy with the results . Oscillation is gone, amps sounds fantastic . All I would ask for is a little bit more bottom end on the OD Channel , Bass trim pot is maxed and treble trimpot is minimal ...

Thanks for the advice folks, I didn't realise lead dress was so critical in the ODS .
I actually moved the tube sockets of V1 and V2 to line up with the board. And moved around the grid and cathode wires to the board until I was happy . The plate wires are the brown ones against the chassis .

Thanks again

tempImage6cvfYX.gif

[Amwatts]

After doing more research here. I'm thinking the V30 needs to go, I went with it as that's all I had laying around
Looks like the G12-65 is a popular choice in an open back 1 x 12 combo configuration , I'm not interested in the EV , too heavy.
Any other suggestions ?

Cheers
Watto

[pompeiisneaks]

I've used a celestion creamback, celestion alnico gold and an EVM 12L for different Dumbles. Love them all pretty much.

~Phil

[alkuz1961]

I've heard good reviews about Eminence Texas Heart with D-style Amplifiers. It is this speaker that can be heard in this famous video https://youtu.be/ap6odoC4itw
I used Eminence GB128 and it also sounded good.

[bepone]

Very happy with the results . Oscillation is gone, amps sounds fantastic . All I would ask for is a little bit more bottom end on the OD Channel , Bass trim pot is maxed and treble trimpot is minimal ...

Thanks for the advice folks, I didn't realise lead dress was so critical in the ODS .
I actually moved the tube sockets of V1 and V2 to line up with the board. And moved around the grid and cathode wires to the board until I was happy . The plate wires are the brown ones against the chassis .

Thanks again tempImage6cvfYX.gif

So you have drilled new holes? Good move.
Lead dress in this amp is everything.. Strange that you have less bass then usual. Try to increase cathode caps to 10uF, or just only close normally the cab and put it against the wall

p.s. i see v30, you need to take that out, G12-65 (97 dB) is safest bet for all, but also i like Celestion Rockett (95dB - quiet speaker)

[Amwatts]

Very happy with the results . Oscillation is gone, amps sounds fantastic . All I would ask for is a little bit more bottom end on the OD Channel , Bass trim pot is maxed and treble trimpot is minimal ...

Thanks for the advice folks, I didn't realise lead dress was so critical in the ODS .
I actually moved the tube sockets of V1 and V2 to line up with the board. And moved around the grid and cathode wires to the board until I was happy . The plate wires are the brown ones against the chassis .

Thanks again tempImage6cvfYX.gif

So you have drilled new holes? Good move.
Lead dress in this amp is everything.. Strange that you have less bass then usual. Try to increase cathode caps to 10uF, or just only close normally the cab and put it against the wall

p.s. i see v30, you need to take that out, G12-65 (97 dB) is safest bet for all, but also i like Celestion Rockett (95dB - quiet speaker)

V30 will be gone tomorrow, I rang a friend who is selling a WGS ET-65 ... That'll go in tomorrow .
Looking at the notes on the build from Retro Custom, I'm going to play with the values in the OD tone channel and delete C43, see what that does ...

[Amwatts]

Going through the build notes from Retro Custom , I found this
I'd built the amp as per the values on the BOM , These notes should IMO standard on the build
These tone mods are a game changer ... Especially removing C43 - brittleness GONE
Changing the Cathode bias to 4.7uf is a must .

Screen Shot 2023-02-28 at 7.14.26 pm.png

[martin manning]

Good to hear it's sounding more like it should. Oscillations are very likely if grid leads are running close to in-phase leads from following stages, and they are often triggered when signal levels increase while playing. That applies to all amps.

The notes are a little cryptic:
I see plate-cathode snubber caps are added to the OD tube socket (best practice, as in the original D layout). Did you also remove the ones on the board, C59 and C60?
Where is C37 circuit-wise?
Where is C38 circuit wise?
What is the significance of the text color? Is some of it original (from Lou) and some if it your editing?

[Amwatts]

Good to hear it's sounding more like it should. Oscillations are very likely if grid leads are running close to in-phase leads from following stages, and they are often triggered when signal levels increase while playing. That applies to all amps.

The notes are a little cryptic:
I see plate-cathode snubber caps are added to the OD tube socket (best practice, as in the original D layout). Did you also remove the ones on the board, C59 and C60?
Where is C37 circuit-wise?
Where is C38 circuit wise?
What is the significance of the text color? Is some of it original (from Lou) and some if it your editing?

The snubber caps are still on the board , I may pull them off the board and wire them directly
C38 is the cathode cap on V2 pin 8 from 1uf to 4.7uf
C37 is from V2 pin 6 to the next stage 0.001 is on the BOM , 0.005 is on most schematic variations
the different colours are revisions to the document , red 1st ,green latest

this PCB is based on the Blues Master (not sure which version) . I've just gone off Lou's layout, Now it's time to fine tune it .. I've been looking at the variations and will play with values , tune it to my liking as HAD did I'm pretty happy with the clean channel, Just want to fine tune the OD Channel now the oscillation is gone ...

[martin manning]

The snubber caps are still on the board , I may pull them off the board and wire them directly

Great, thanks. I would just leave the snubbers where they are. Just wanted to be sure you hadn't added more capacitance at the socket without removing the ones on the board.

[Amwatts]

I needed up putting the 1uf back onto V2's cathode , the 4.7 wasn't to my liking .

I've played this circuit (OD Channel) for a while today , and I don't think it's for me , It's too JCM 800 raspy to my ears . Clean is beautiful , But OD just doesn't grab me .... Maybe the Robben Ford OD channel is for me .... more research. That "Talk to Your Daughter" tone is more what I'm leaning towards .

Any suggestions ?

[martin manning]

Use part values from the #102 layout.

[Amwatts]

Today I went through the files here .
I used mdroberts1243's schematic for the blues master , as it's the same as Lou's Retro Custom PCB schematic on his website without the terminal blocks (easier to read) .
I used Tony Albany's #102 layout , And Ceriatones Ford Mustang layout (to cross reference and compare the two) .

Then I put the component value changes onto the schematic and removed the FET and Marshall Footswitch as Lou's PCB doesn't have that
The #102 changes are in Orange , The HRM removal is in Purple , And there's 2 thing I need to confirm

I can't find C35 and R13 on #102 , so I'm think I remove them and jumper the holes, Any Thoughts ????

and C47 - 47p cap between the plates of the PI (V3) isn't on #102 , I think I'll build it first and leave that optional.
NB I haven't drawn everything on the schematic yet , eg the components wired directly to the pots , and the 10M cluster of resistors etc wired directly to V1B ... I've only concentrated on the actual PCB components ...

I'll adjust as much as I can with the parts I have here, but I'll need to order a few components , that'll take a few days ... I'm enjoying this

I think I've got it right , if the experts here could run their learned eye over it for me and find any possible mistakes , that would be fantastic. Once it's all done , I feel it will be a good mod option for Lou's boards ...

regards
Watto

BluesMaster DClone 100W w#102 mods.pdf

[rootz]

I don't think the tone stack will work as expected. You are essentially lifting the bass pot with a huge 250k mid pot, thus providing something like a mega boost and rendering the stack useless. I only know this arrangement for the Bluesmaster preamp, where the mid pot is 25k. #102 front end looks a bit different. There the mid pot gets its own ground and the bass pot is grounded through either a 1k8 or 10k resistor (the latter in case of a Skyline stack).

C35/R13 are not present in 'normal' 4th gen ODS amps. They are in a HRM or Bluesmaster.

Your master and volume pots are arranged differently too. You now have a separate clean and OD master, instead of a ratio control feeding your master in OD. That is again typical for HRM, but not other Dumbles. The only exception I can think of is ODRS #60, but that is a different kind of beast because of the mixing stages of the reverb anyways.

Luckily, the conversion from HRM to #102 is rather straight forward. Just stick to the exact #102 values/schematic like Martin said.

On a sine note: you could make the HRM circuit/stack (foot)switchable. I think Two Rock did so in the Opal. I experimented with this and this way you can get a nice compromise between regular ODS and HRM. But never perfectly both! You'd need some more switching to achieve that as there are actually quite a lot of differences between regular and HRM.