ODS Eyelet Boards

[martin manning]

SSS Bipolar supply board has been updated to include a current limiting resistor at the bias tap input, and a balance/bleeder resistor across the positive output.

The 33 ohm AC input resistor reduces the peak charging current pulses by about half, and reduces the RMS current drawn from the PT by about 30%. As far as I know, no one has lost a transformer using this driver supply circuit, but it seems worth the effort to add this feature, and it may help reduce noise. The output voltage drops a few volts on each side, but there is still more than enough for the circuit to operate. The complete adjustable bias supply network is also shown, with values adjusted to recover the original design bias voltage, and reduce the current draw slightly.

The 330k resistor across the positive side partially balances the current draw from the bias circuit, and also acts as a bleeder. It could be located anywhere, but it"s convenient to place it across the output eyelets on this board.

[martin manning]

The SSS bipolar driver supply board in the first post has been updated again with some fine tuning. The bleeder resistor mentioned above has been reduced to 150k to balance the current draw on the positive and negative sides, and to allow the voltages on both sides to drain in about a minute after shut-down. The AC input current limiting resistor has been increased to 47 ohms, with the result being the RMS current is still about 30 mA. The resulting loss of a couple of volts DC will not be noticed. The text in the first post and in the .pdf have also been edited for clarity.

[dorrisant]

Always one step ahead of the game... Love it, Martin.

[Matt J]

Quick question Martin on your relay power supply board designs for radial capacitors:
The lead coming off the 1k resistor for the panel LED, is that meant to power both LEDs for each PAB/OD/FET footswitch, or should a second 1K be split off from leg 3 of the voltage regulator to power each LED?
Thanks!
Matt J.

[martin manning]

The idea is the 1k on the power supply board is just for the panel LED. !2V from the regulator with no current limiting resistor goes to the foot switch jack, so the limiting resistors are intended to be installed in the foot switch enclosure on each switch.

[dorrisant]

Martin, do you have a schematic example for the Separate Masters, HRM, BluesMaster OD Relay? In particular, the NO2 and NC1 connections. It does not jive with the schematic I have. Could be my version of the schematic. In any case, could you also post the schematic you derived this from?

[martin manning]

Martin, do you have a schematic example for the Separate Masters, HRM, BluesMaster OD Relay? In particular, the NO2 and NC1 connections. It does not jive with the schematic I have. Could be my version of the schematic. In any case, could you also post the schematic you derived this from?

Could it be that the difference is that I show connections for OD "on" when the relay coil is energized? My thinking was to make them all the same. See the note on the relay connections page.

[dorrisant]

What I'm referring to is that the connections to the OD relay shouldn't be connected to the Clean Volume pot before the second triode. Rather, it should be connected after what is normally thought of as the Master Volume. At least it is labeled that way on my schematic. Does this make sense?

This is the schematic I am working with. Let me know if I should be looking at something else.

[martin manning]

Ok, I see. In this table, I left out the word Master. It should say Clean Master Vol Wiper and OD Master Vol Wiper. Then it's exactly like the schematic above.

[dorrisant]

Thank you for the clarification!

[Matt J]

Ok, I see. In this table, I left out the word Master. It should say Clean Master Vol Wiper and OD Master Vol Wiper. Then it's exactly like the schematic above.

What would be the best way to implement this kind of design with a 2nd/3rd circuit with only Overdrive and Level controls so that Level becomes the OD Master and an extra control can become the Clean Master? I have one of Erwin's 2nd/3rd gen chassis I'm planning for a build and have thought about drilling an extra hole for this but want to understand the switching better before I dig in any further.

Matt J.

[martin manning]

I think something like that was done here: https://ampgarage.com/forum/viewtopic.p ... 08#p466508

[dbharris]

I think something like that was done here: https://ampgarage.com/forum/viewtopic.p ... 08#p466508

Hi Martin, my build keeps the standard master volume (level) like a non-bluesmaster amp would have. I just added the OD level control on the back of the chassis for dirtier tones while being able to match volume between clean and overdrive channels. It sounds fantastic and thanks again for your help with that

I think Matt is looking for the 2nd Gen Hybrid like here with separate channel masters. Charlie's post #5 on the first page of this thread.

https://ampgarage.com/forum/viewtopic.p ... Hybrid#top

-Dan

[martin manning]

I think Matt is looking for the 2nd Gen Hybrid like here with separate channel masters. Charlie's post #5 on the first page of this thread.

Thanks for the pointer, Dan. That one is wired exactly like the table posted above.

[martin manning]

Made a small update to the ODS eyelet board .pdf, specifically to the relay supply with board-mounted regulator. Just tidying up a bit.