Master volume question...

[tubedogsmith]

What is the advantage of having a "master volume" control instead of using that control as the clean master and the level or overdrive volume as the master for the OD channel? It seems easier to balance the volumes with a dedicated clean master and dedicated OD master.

[Pete]

What is the advantage of having a "master volume" control instead of using that control as the clean master and the level or overdrive volume as the master for the OD channel?

After living with these amps for a long while I have personally come to the conclusion that it is just the older style, before the latest upgrades.

It seems easier to balance the volumes with a dedicated clean master and dedicated OD master.

That is my preference.

[Bob-I]

What is the advantage of having a "master volume" control instead of using that control as the clean master and the level or overdrive volume as the master for the OD channel? It seems easier to balance the volumes with a dedicated clean master and dedicated OD master.

The issue with the Dumble is the loading of the stages. In the 70's version without the post OD tone stack (HMR), the output of V2b is looking to 100k where the PI input is looking for 1M. Dumble solved this by putting the 100K as an OD ratio control and the 1M as a master volume.

The HRM changes this by creating the load for V2b. Then you can feed the HRM into a 1M pot and feed directly into the PI.

[tubedogsmith]

[quote="Bob-I
The issue with the Dumble is the loading of the stages. In the 70's version without the post OD tone stack (HMR), the output of V2b is looking to 100k where the PI input is looking for 1M. Dumble solved this by putting the 100K as an OD ratio control and the 1M as a master volume.

The HRM changes this by creating the load for V2b. Then you can feed the HRM into a 1M pot and feed directly into the PI.[/quote]


How would that manifest itself aurally?

[ryanf]

Don't alot of people like a master volume so that they can drive the preamp real hard but keep the volume down?

[Pete]

Don't alot of people like a master volume so that they can drive the preamp real hard but keep the volume down?

Yes, but I think the point here is Dumble specific. Somewhere in the Dumble Overdrive Special evolution there is a design (often refered to as Non HRM or 80s) which essentially has sort of two "master vol" when in overdrive mode. This changed to the HRM design which (among other things) has 1 MV for clean and 1 MV for OD. The control panel on these two designs look basically the same, just the function of some of the controls are different.