Rock/Jazz switch

[sgp]

Is the Rock/Jazz switch shown in the Rock position on the schematic?
Do most of you agree that the jazz position is not very useful?

Also, If I use the switch to change from HRM/non-HRM, I'll need to switch out the HRM, the pre-OD network and other components throughout the circuit? seems like this can become rather messy real fast.
Thanks

[glasman]

Every schematic I have seen it is shown in the Rock position.

Gary

[sgp]

Thanks Gary, that's what it looked like to me.

I know you have switched the HRM in and out, Do you have any tips/pointers as to what gets switched and what may not need to be. I don't want to compromise either circuit, but the idea of switching a daughter board in and out (like yours) sounds like what I want to do.

[sgp]

Just to clarify, I'm trying to switch between a hyb-a and the s3988009.2 circuits. and Now I see the 1997 specimen, which uses HRM, No pre-od network, but lacks the PAB. Isn't the PAB a good thing with the HRM?
Now I'm spinning.
I'm thinking that a good way might be the Hyb-A with a relay to switch the HRM, No pre-OD network, and a switch on the rear panel to disconnect the CL2 feedback when using the HRM.
Thanks for any comments you all might have.

[dogears]

My 2c is that if you do it, do it right...... I am not sure whether there are HRM amps that use the high gain traditional pre OD network. The schematic that shows no wierd network is not correct. I think Steve Ahola or someone else just made up there own diagram based on several sources of info. My sources tell me that the only confirmed HRM config HAD the low gain network. Any other schematic that doesn't have it is mere guessing and speculation. My ear tells me HRM is designed around the low gain network. HAD used a 1M bass control in the HRM. Without the low gain network in place and wothout PAB on, you need to set the bass at about 30k. THis is only 3% of the trimmer. In correct HRM config, the trimmer can be up 1/2 way or more!! So, the fung shai of it also says low gain network!!!

If you want to leave the hybrid's pre OD net in place, I would suggest using a 220k feeding a 25k trimmer with a 24k tail. Make the tail a 20k and 4.7k in series. Short out the 20k when in HRM mode. You will need to play with the tail values to get the right amount of gain in each mode. I can tell you with 100% certainty that the gain settings that sound nice in non HRM sound like CRAP in HRM. Especially with PAB on. You need to reduce the gain dramatically in HRM. In the end, the only thing that worked for me was to make the networks switchable with their own trimmers. This way I get exact gain levels in both modes.

No need to have your head spinning if you realize that those Blue Guitar schematics, although helpful, are chock full of guessing and inaccuracies.

[mlp-mx6]

Be sure to COMPLETELY remove the loading of the HRM stack for a true non-HRM mode. (Lift from ground is one way)

[skyboltone]

OK:
I want an acronym list for this bulletin board.

HRM?
PAB?
HAD?

That's probably only 1% of the group lingo on here. Make it sticky at the top of the list and HTMEGSIU. (Have the more exprienced guys set it up)

[mlp-mx6]

OK, I'll start with what you listed.

HRM = Hot Rubber Monkey, the *bizarre* name for the post-OD tone stack.
PAB = Pre Amp Boost - the boost switch that disconnects the clean tone stack from ground, so you basically run the entire signal through the treble cap. BIG jump in gain/volume. (S3 on the Hybrid A schematic)
HAD = Howard Alexander Dumble

[Normster]

I've also heard that "Hot Rubber Monkey" was code for "Hot Rod Marshall." (And that "Blues Master" was code for "Bassman.")