ok so ideally I want an amp switch to toggle between the 4 guitar heads i have into 1 cabinet. I already have my abcd box, I'm not exactly sure whats involved once you start dealing with loads coming out of the head. I have tons of switches, wires, resistors capacitors and 1/4 TRS to build this with, I just dont know where to begin exactly.
Do i set it up as 4 Or gates, Nand gates or Xor gates.. Im a little jostled right now.
does anyone have any insight on this? I would greatly appreciate it.
Do i set it up as 4 Or gates, Nand gates or Xor gates.. Im a little jostled right now.
does anyone have any insight on this? I would greatly appreciate it.
Hi, In response to your second post, you are under moderation for the first few so be patient and when a moderator has time to clear the queue, we will.
Thanks and welcome,
Cal
Thanks and welcome,
Cal
what kind of rotary selector? I was hoping to put it in footswitch form... like how would i design the logic behind it ? and also would i need to have resistors on each output to compensate for load?
You could attach something like a 50 ohm resistor across the outputs. That should provide enough load to keep the transformers under control when not otherwise loaded. The effective output impedance (assuming a 8 ohm speaker) will drop to 7 ohms, close enough, and you might lose a dB or so of output, but that's trivial.
A circuit like what you're looking for is here:
Electronic Circuits Diagrams: Push-Button Relay Selector
couple things confuse me in this... first is there a way to do it without the 16 pin? i feel like that will degrade the sound enough to make me not want to use it... is there a way to use double or triple pole double throws to just kinda logic through all the functions?
also the relays in the diagram confuse me,... how many poles are those? is that just 6 pin dpdt ? or is it something else, cus to me it looks like a double pin triple throw...
also the relays in the diagram confuse me,... how many poles are those? is that just 6 pin dpdt ? or is it something else, cus to me it looks like a double pin triple throw...
Degrade the sound? How? No signal passes through it, just through the relays. Those are DPDT relays, the other two contacts are for the electromagnet that actually moves the relay switches. The output goes through the relays - the way it's done, only one relay comes on at a time. The ICs are just logic to switch the relays on and off. You could use a SPST relay if you want (as long as all the amp outputs already share a commonly connected ground), or a DPST to switch both poles.
The number 1 question is: is this for home use or pro use? If it was for home, I would just wire it it up a 4 SPST switches in parallel; i.e. full manual operation with nothing automated. You can put a resistor across the amp inputs to protect the heads. Disagree with 50 ohms as the resistor would need to be pretty big to dissipate all that heat, and it needs to be on the input not the output. I have seen 10K or so used in commercial tube amps.
It's for stage use or other pro use you really do need to build it with some logic as has been suggested to make sure nothing bad happens.
It's for stage use or other pro use you really do need to build it with some logic as has been suggested to make sure nothing bad happens.
well logic it is then lol... im gonna start procuring parts, once I get all the parts I'll jam it together n see what happens... I still am a bit lost on the relay portion of the schem... if its 6 pin, i am unclear as how to wire it up, especially since there are 8 things passing through it...
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Are any of the amps tube amps? Are you planning on driving all the amps all the time, or just drive the amp with the speaker connected?
yea 2 or marshall 78 and 79' JMP's which have been modded to the moon and back... the other is a soldano SLO, and last is a fender supersonic which has been modded for cleans. all are tube amps
I want to be able to switch between the 4 amps via footswitch, but only use 1 cabinet on stage. so all would be connected at one time, but only one will be playing at a time. I already have an ABCD box to toggle the guitar input from amp to amp, but they are set to 4 different cabinets with 4 different sets of speakers... so its kind of impossible to do that stage setup...
How many watts are these amps? What is the impedance of your speaker cabinet?
What kind of ABCD box? Does it connect to only one amp at a time? Or, can you play through more than one amp at once.
The problem I see is that tube amps want a resistive load near their nominal load impedance when they are not connected to a speaker. If you play into an amp without some kind of load, it could fail suddenly.
You really should have a box that not only connects one amp to the speaker while connecting the others to load resistors, but also switches the guitar to the amp that has the speaker connected. A significant problem is that it's a bad idea to have guitar switching and speaker switching in the same box. You would have to run all the speaker cables up to your pedal board and back again. Bad idea. Better to have a box on your pedal board that connects the guitar signal to the correct amp and also controls another box behind the speaker that selects which amp is connected to the speaker. Logic inside the pedal board box controls the speaker switching box via a cable.
the abcd box is 1 guitar input, 4 output, and only 1 output at a time... I built it, so its just a couple 3pdt's, a few 1/4 inch, a 2.1mm dc jack and 4 led's... its basic as hell, but its true bypass so it sounds great.
the cabinet is 16 ohms, however each amp can be switched to have 4 ohm, 8 ohm or 16 ohm output. I tend to stay at 16. I would like the pedal to output 16 ohms as well.
as for all in one box I figured it would be bad to have it in the same box but it was merely something to try and attempt... the only thing absolutely necessary is the 4 way toggle between the 4 amps... at this point hoping it would be simply a pedal that I could have 4 switches to 4 LED's, so that each one cancels out the previous one when stomped.
Connecting 4 amps to one box is an invitation to ground hum. And that's just on the input side. All kinds of strange things can happen when you try to connect the speaker grounds together. How many watts are these amps?
So in your ABCD box you can just push one switch and it automatically cancels the one already selected? I'd like to see that schematic.
To make this work well you will need four DPDT relays that can handle the current of the speakers (that's why I need to know how many watts). The grounds of the amps' speaker outputs will be isolated. On the input side the outputs to the amps need to be transformer isolated so there won't be any hum problems. There is a project like this a Geofex.
So in your ABCD box you can just push one switch and it automatically cancels the one already selected? I'd like to see that schematic.
To make this work well you will need four DPDT relays that can handle the current of the speakers (that's why I need to know how many watts). The grounds of the amps' speaker outputs will be isolated. On the input side the outputs to the amps need to be transformer isolated so there won't be any hum problems. There is a project like this a Geofex.
hey I searched all over geofex... where is this thing... I cant find it anywhere...
I found this. this is pretty much what I want to build except I need it to be able to switch between 4 heads and at will instead of in series.
http://www.ebay.com/itm/Radial-Tone...003?pt=Guitar_Accessories&hash=item2572c0dcc3
http://www.ebay.com/itm/Radial-Tone...003?pt=Guitar_Accessories&hash=item2572c0dcc3
Go to GeoFex, select FX Projects on the left menu, then Hum Free Splitter/A/B/Y Box. There are a couple of other similar projects. The idea would have to be expanded for 4 amps.
The thing on Ebay is the right idea for two amps. Not sure if the grounds are isolated between the two amps. Did you notice they suggest you locate the unit close to the amps to minimize the length of speaker cords and use a remote footswitch. But then the guitar signal has to run back and forth to the pedal board.
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