clean voice foot switch

[jasonh333666]

Has anyone done a mod to the ht stage 60 that would give foot switch control to clean voice control.

[ht40guy]

Hi, seems this has come up a few times before and no-one has suggested anything mainly because
1. It would void the warranty
2. BS keep the schematics hidden in a deep dark cave, guarded by a fire breathing dragon that even hobbits couldnt get to.
3. With the PCB having SMD components it doesnt lend itself to modding as much as say, an old Fender will..

But, it would be a great feature, maybe someone will think of something sometime.

Cheers.
Glenn

[jasonh333666]

Yes I am aware about the warranty issue,I still think this would be a great addition. the way i look at it if it's done for OD 2 should be possible for the clean.I'm going to look inside myself ,I was just hoping someone else could give me pointers.I thought the member trininty had done this but couldn't find any info.

[thephantum]

It could be done, but would require some surgery to the amp (thus voiding the warranty) . Specifically, some rewiring to tap into the existing switch and the addition of a jack on the back panel to go to a foot switch.

[darthchadius]

I have just modified my HT Club 40 to control the clean voice switch with a foot switch. I waited until my warranty was up before doing the mods.

It turns out the voice switch is pulling to common when pushed in. To operate with a foot switch the voice switch needs to be in the out position. I made my mods without removing the board from the chassis, which was convenient as taking all the nobs and switches off the front panel was not something I wanted to do.

Note: This mod will void the warranty and could leave your amp susceptible to ESD damage later on. The amp would most likely not pass CE EMC testing either. The stage 60 OD voice switch and the other foot switches have ESD protection nicely designed in by Blackstar. I am only posting this as I am sure others that love the clean and the crunch sound you can get from the club 40 clean channel and that they want to have easy access to both remotely as I do. These are great amps don't reck yours. Know what you are doing before making any mods.

I was able to follow a trace back to a resistor by the PIC mcu. Between R335 and R33(4? I think, my mod covered the silk screen on this resistor) connects to the clean channels voice switch. Shorting this point does the same as pushing the voice switch in on my club 40. Yours may be different. Becareful, the other side of R33 (4?) connects to VCC (3.3V). I have a pic to post to show the location of my mod. Sorry but I did not check the pcb revision before closing the amp back up.

The easiest way to verify the correct resistor is to do a continuity test from common to the resistors whilst pushing the voice switch in then out. It will read 0 Ohms and out will be open.

My club 40 had a DB9 cut out in the back panel that only had the back label covering it. So, I only needed to cut the panel label to install the foot switch jack (no drilling required).

The Mod:
Connect a jumper wire from the common/sleeve pin on the channel select foot switch jack pin to the sleeve contact of your new voice foot switch 1/4" jack. Connect a jumper wire from the tip contact pin of you new jack to the identified resistor point. Mount the jack on the back panel.

In the pic I will post you will see I made my connection through a 4148 diode. This is only because I am using an active switch and do not want to feed voltage back into the amp.

[darthchadius]

Here is the pic of the clean voice switch mod.

[darthchadius]

I should have also mentioned to use an isolated 1/4" jack. Meaning that the sleeve is not connected to chassis ground. There is about 100 Ohms between common and chassis ground.

[ht40guy]

Hi, just thinking about doing this (my HT40 is a 2010 model so warranty is not an issue)...and I was wondering about some details about the footswitch and socket.
Would this be a stereo (TRS) or mono (TS) socket?
Would the footswitch be Latching or Unlatching?
Would you need just one switch - On for Modern and Off for Boutique sort of thing?
and finally, could you wire up some sort of LED indicator?

Thanks for any help....

Cheers
Glenn

[thephantum]

• Would this be a stereo (TRS) or mono (TS) socket?
  • Definatley a TS...if you look at the picture of jack (the last one), there's only 2 wires coming off.
  Would the footswitch be Latching or Unlatching?
  
  • 99.9% sure it's lataching based on these two statements:

  It turns out the voice switch is pulling to common when pushed in.

  The easiest way to verify the correct resistor is to do a continuity test from common to the resistors whilst pushing the voice switch in then out. It will read 0 Ohms and out will be open.

  Would you need just one switch - On for Modern and Off for Boutique sort of thing?
  
  • Yes. Unless you want to also switch the OD voice. Then you would need a dual swtich, and a TRS jack (plus you'd need to find the point on the PCB to connect to).
  
  and finally, could you wire up some sort of LED indicator?
  
  • Yes. The switch pulls to ground when pushed in. So you'd just need to wire it up so that it engages an LED as well. I would do it with a relay, but you could isolate it with another diode as well.

[darthchadius]

Yes, use a latching switch.
I used a TRS jack as 1) I plan to connect the OD voice switch a footswitch as well and 2) I have a few of them.

I used a Marshall TSL 5 button footswitch for my mod. I needed to modify the switch as well, but that is how I got my LED. You should be able to use the same Blackstar footswitch that comes with the Club 40. Since there is 3.3V on the trace you are connecting to, the LED will light when the switch is open. I will give it a try and let you know.

One of the main reasons I went with the TSL footswitch was so I could go from OD to clean with one switch. I modified the footswitch to turn the OD off at the same time as switching the voice switch. The TSL switch also controls the reverb and I am using the FX switch to contol the effects loop.

I run my clean channel volume quite high, around 3 o'clock to get really good crunch tones. So when switching to the clean position I usually need to back the guitar volume off to prevent breakup.

Let me know if you would like any more info.