matchless hotbox/vibrobox questions

[wsaraceni]

i recently posted about a set of transformers i had sitting around. i recently found a schematic on schematicheaven for a matchless hotbox/vibrobox that uses one of the transformers i have.

here is what i am thinking and i could use a little help on how to accomplish it. and by a little help, i mean a lot of help.


i want to make it a head. kinda like a fender reverb unit.

the front panel i want a power switch, all of the potentiometers, an on/off switch for both effects(possibly via a push/pull pot) and a pilot light,

the rear panel will have the power cord, a separate input and output for each (1 set for the hotbox and 1 set for the vibrobox) this will allow me to insert pedals in between the two as well as reconfigure the order of the effect (trem before distortion/ trem after distortion. etc)

so if nobody sees any huge issues above id like a little help with the following.

with it being a remote head, id like to have 2 1/4" jacks on the back to be used as a footswitch. id like to keep them 1/4" to have the option to use a midi switcher in the future. how do i go about doing this and still maintaining the use of the two switches on the front when the footswitch isnt hooked up.

2nd question. the schematic calls for 5 33uf/450v caps. if i use the cans that have 2x33uf each, can i use 3 of those (leaving one unused) what brands are the best ones to go with

im sure ill have more questions later but this is all i can think of now

[wsaraceni]

also, led's on the footswitch would be nice.

[ampdoc1]

Parallel the footswitch and front panel switch legs. That way either will turn the unit on/off. But you'll have to turn off either end you are not using: 1) Front panel switches off or 2) the relays unactivated or footswitch unplugged).

On the footswitch, run a cable with:
1) +VDC supply for the relays/LEDs
2) Ground wire
3) one control line for each of the switches

You ought to be able to use the power tranny heaters or 5VAC supply and rectify it for DC to the footswitch. Just insert an LED in series with each of the relay coils.

Attached is a wiring diagram of the relay boards I sell. It uses these basic concepts to enable front panel or footswitch control.

If you need any help, email me.

ampdoc1

[wsaraceni]

thanks for the info. how can i tell if the heater will have enough power to support the board and circuit?. i have to be honest. i get what you are saying about converting it to DC there as well as the switching setup, but that pic you of the board is very confusing to me.

can you tell me what that circuit is doing there to help me understand

how much for the board?

[ampdoc1]

Send me the schematic of the circuit you're planning to use, along with the specs of the power transformer, and I'll draw up a connection diagram for you. A couple of relays and LED would have a very low current pull.

Email direct: ampdoc@juno.com

My relay board sells for $50 including shipping in the US.

ampdoc1

[ampdoc1]

This should work OK. If you use sensitive relays (OmronG5V-2-H1) and standard LEDs, their total current draw will be ~1/4A. Should be negligible as compared to the current on the tubes.

This circuit allows true bypass by switching the ins and outs. I think this would be the best way on both units, rather than turning on/off the vibrato.
And, the same circuit can be used for both.

[wsaraceni]

that sounds like a good idea. how big is the board? got any pics of one installed in an amp.

[wsaraceni]

one more question. how would one go by changing this from a bass and treble knob to just a tone knob?

[Structo]

Having both the bass and treble would be advantagous with this circuit.
If you are trying to keep the real estate small you could use a concentric pot with dual knobs.

[wsaraceni]

ah


never thought of that. i didnt order any POTs. my other option would be to put the output volume on the back panel. which isnt the best of ideas although all the inputs and outputs will be back there.