Hartke VX3500 mute switch?

[Mateybass]

It really annoys me that there is no mute switch on this amp. It's the only thing that spoils a great amp. So is there anyone here that can help me with modifying my amp?

What I want is the mute to kill the signal to the speakers AND the DI output, but leaving the signal to the effects send intact so I can tune silently and without sending the signal to front of house. If it helps, I always use the DI output in post-EQ mode. Looking at the circuit diagram, it seems the pre-EQ mode takes the signal before the effects send. I'd go as far as to say that the pre-EQ switch is pointless since I can do the same thing by linking to the amp input from my bass plugged directly into a DI box so I might even hardwire the DI to post-EQ and perhaps use the switch for a mute.

I am competent with a soldering iron and fitting switches to the front panel, I just need to know where to break into the circuit and what sort of switch I'm likely to need.

I'm using this diagram

Thanks in advance

[Enzo]

FX send to your tuner. DI to post. That much you know.

All you need do is kill the FX return signal.

You could switch the RE terminal of CN401 to ground or find R201 and do it there - electrically the same.

You could short across R204.

You could short across R237, just left of the graphic EQ chip. Since R237 is wired directly to a pin on the EQ I/O switch, that might be a convenient spot to pick it up.

In fact, I would try each of those with a clip wire to see which pops the least.

You could also open the signal path somewhere in that area, rather than grounding the signal off. But that would be more likely to pop, and we'd have to add a resistor or two.

[Steve Conner]

Why not just use a tuner pedal with a mute function in your FX loop?

I have a Boss TU-2, and its default behaviour is to mute the signal when it's in tune mode.

[MarkusBass]

I suggest that you look for Hartke 4000 schematic (which has such a switch). The schematic of the preamp is not the same but it should be quite easy to use the same idea in HA3500.

Mark

[Mateybass]

Why not just use a tuner pedal with a mute function in your FX loop?

I have a Boss TU-2, and its default behaviour is to mute the signal when it's in tune mode.

It's a good idea which I had thought of except for two reasons why I'd rather have a mute switch:

A: I like to be able to monitor tuning whilst I'm playing i.e. unmuted.
B: I would have to buy one of those types of tuner.

I suggest that you look for Hartke 4000 schematic (which has such a switch). The schematic of the preamp is not the same but it should be quite easy to use the same idea in HA3500.

Mark

I had a look at that schematic but it mutes well before the FX send, which is where my tuner is plugged in. It has given me an idea though so thanks for the pointer.