Make Bluesmaster OD Channel sound more like regular HRM

[martin manning]

10thTx, C-HRM schematic has an error- extra pot at OD entrance.

[10thTx]

10thTx, C-HRM schematic has an error- extra pot at OD entrance.

It sure looks to me like there is a 250k potentiometer on the layout board used as a variable resistor (?) going into the 250ka OD trim pot on the back panel.

Look at J1 on the OD trim pot connecting to what I think is J1 on another pot which is similar to the trim pots on the HRM tone stack board ?

http://www.ceriatone.com/images/layoutP ... RM-50W.jpg

With respect, 10thtx

[martin manning]

I believe the pot on the back panel is a C-tone addition, not seen on D HRM's.

[10thTx]

I believe the pot on the back panel is a C-tone addition, not seen on D HRM's

Yes, that is my understanding also.

The original poster asked:

Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM

I left it in there since the OP seemed to be wanting it to sound like a C-tone HRM. Remember I posted some SCH versions if anyone wants to edit and repost.


With respect, 10thtx

[The_Nuge]

Thanks for the prlies everyone!
And, just to be clear: we're talking about Ceriatones here! As I've never played a real Dumble, I have no idea how they compare...

I've tried comparing both the diagrams posted here and the ones on the Ceriatone website, but it's not as if the differences are small! Unfortunately, my knowledge of the working of amps is limited, and I have no idea of where to start...

Cheers

Es

[martin manning]

Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM? All while not changing the sound of the clean channel!

I'm going to say not likely. The signal flow in these amps has the clean preamp output feeding into the OD preamp (or not, if it's in "clean" mode), and the result (clean or clean + OD) is then fed into the phase inverter. The clean preamp stages affect the sound coming out of the OD preamp stages, and the PI affects the sound in both clean and OD modes. To produce the HRM OD you would have to convert the clean, OD, and PI stages to HRM spec, and then you will lose the BM clean sound (which really isn't totally clean). This doesn't mean that you couldn't reach some compromise, but others who have tried have not been successful.

[bluesfendermanblues]

Thanks for the prlies everyone!
And, just to be clear: we're talking about Ceriatones here! As I've never played a real Dumble, I have no idea how they compare...

I've tried comparing both the diagrams posted here and the ones on the Ceriatone website, but it's not as if the differences are small! Unfortunately, my knowledge of the working of amps is limited, and I have no idea of where to start...

Cheers

Es

Since you seem to be fund of the Bluesmaster clean as is, you should start by tweaking the OD to your liking. Obviously you should begin by adjusting the post OD HRM trimmers, before you start modifying the amp! (You will probably end up with settings quite similar to a fender twin - with treble around 2 o'clock, mid around 11 o'clock and bass around 9-10 o'clock.)

And the Bluesmaster will not produce a very good lead sound in OD mode alone - you need to use it in OD + PAB (tone stack lift) mode.

If you want to beef up the OD only mode, you might consider removing the HRM circuit OR simply clip the ground of the Mid trimmer. This is in effect a tone stack lift of the HRM and it will sound more like a regular (#102) OD. Its a simple mod and easy to revert back to spec. if you dont' like it.

However, as Martin Manning points out, it will not produce more distortion, due to the weaker output of the Bluesmaster tone stack, but it will produce more mids and OD volume.

Another idea is to use the vacant side of the PAB realy and have two stack lift resistors on the (V1) tone stack. One position could be Megaboost (22mohm) and the other could be a smaller lift (22k).

[The_Nuge]

Thanks guys!

We've fiddled with the HRM trimmers, which did help a lot, and also now use the OD in conjuction with the PAB (on both amps), which is also a good thing!
We'll try clipping the mid HRM and see wht that does, but my feeling is also that the two amp sounds can't be combined - maybe a new build is in order

Cheers

Es