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[Big_Al]

Hi everyone,  just wondering if there are any electronics wizards out there that could tell me how to & what type of switch I would need to attemp the following;

This is a guitar/ effects/ amplifier problem.  I have two types of tape echo simulator pedals that both have really good individual programmes in them. By just "chaining" them up with patch leads & using bypass works but it seems to change the sound of each pedal from when it is used seperatley.

What I would like to do is have a single input lead from the guitar going to a " passive Switch/patch box" where one pedal is in operation and the other is totally cut out from the circuit. And then just one lead coming out to go to the amplifier.

I would prefer a foot switch operation but a manual switch would be OK. Also if two small lamps or "LED's" (I think they are known as) could be wired to allow me see which effect is on at a particular time that would be great.

So, the overview is that I am looking to build a pedal sized box or case with, a switch , in & out jack sockets for guitar & amp, in & out jack sockets for both effects units ( 6 mono jacks in all) and two idicator lamps. a 9v battery would be no problem to power these.As is building and wiring the thing. It's just the type of switch, the circuit & where the wires need to go that I am stuck with.

Bit of a tall order this I know but would be really grateful if someone could advise me.  Thanks ,   Big Al

[Chris_H]

Difficult to comment without knowing the input/output impedances etc.

If the "bypass" switches really are a bypass (i.e. passive switched dc connection in to out) there should not be a perceivable sonic difference.

My approach would be to buffer the guitar signal and feed it to both pedals then just route the guitar/pedal 1/2 to the amp with a switch.  I would want to ensure that there was no dc imbalance between the three output feeds so that you get a quiet changeover.  You could do that by using capacitors or buffering with offset-corrected op-amps.

[I_want_an_Omega]

Assuming that its a mono 1/4 jack plug config then this could be done quite easily.

By joining the earth (outer) connections together, then the change over could be done by a single changeover switch. This would be a "single pole double throw" switch - SPDT.

By getting a "double pole double throw" switch - DPDT then the "other" half of the switch could be used to select which of 2 LED's come on.

That way the actual switching is totally passive and as long as its in a metal box would be shielded and the impedances wouldn't matter. You might need another switch for the "on/off" of the light. However, RS used to do a switch with a centre off position which would give you A OFF B positions rather then A B.

Hope this makes sense.

Rob

[Big_Al]

Thanks for the replies so far . Thinking on what Rob has said if i used a on/off/ on switch operated by hand I would not need the LED's as I could just label the case showing which one was which.

The other point is that although in bypass mode when the 2 pedals are linked with patch leads there is a very noticeable difference in sound as to when the pedals are used separatley.

Rob would it be OK to PM you on this topic?  Thanks Al

[I_want_an_Omega]

Please do Al - more than happy to help out ....

[Kevin Wood]

Can you describe the difference in sound you are hearing? Distortion, noise, hum, frequency response different? Does it matter which way round the pedals are in the signal path? Just wondering what's at play here? Maybe there's gain the in pedal(s) even when bypassed and the second one in the chain is being overdriven?

Switching would be straightforward, as said, but it would be good to get to the bottom of what's going on.

Kevin

[Marks DTM Calib]

Guitar pickups are very prone to change thier response dependent on the laod they see....and ehcne the inout impedance is a bit weird.....so feeding a high output impedance of an effects pedal into a second pedal can give some odd response.

[Big_Al]

REPLY to KEVIN WOOD:   Kevin,   Talking with guitarists it seems to be a common problem when chaining up effects boxes for guitar. In this case  making the sound sort of "Glassy" is how I would describe it. I had a similar thing occur a few years ago when I got my first wireless guitar transmitter system - a very "glassy" sound when put through that. Upgraded to a better one and no probs since.

Thanks for the replies everyone . I am going to be in discussion with Rob on this one . I think it is probably quite a simple problem for someone who understands electronics. Another guitarist I knew had made himself the exact same thing as I am looking for - but he moved away and I have no contact details for him.

hopefully I can get this sorted.  Thanks again, I will let you know the outcome with Rob.

[Big_Al]

Guitar pickups are very prone to change thier response dependent on the laod they see....and ehcne the inout impedance is a bit weird.....so feeding a high output impedance of an effects pedal into a second pedal can give some odd response.

This does seem to be a real problem with all linked effects of different makes. In this case it is giving a "glassy" sort of sound when both units are linked. The units concerned are a Yamaha Magicstomp and a Zoom 508 Delay. Ihave tried them both ways   - zoom first then yamaha and vice versa- still the same glassy sound. just using one the sound is perfect!

Thanks,   Al

[Chris_H]

Guitar pickups are very prone to change thier response dependent on the laod they see....and ehcne the inout impedance is a bit weird.....so feeding a high output impedance of an effects pedal into a second pedal can give some odd response.

This does seem to be a real problem with all linked effects of different makes. In this case it is giving a "glassy" sort of sound when both units are linked. The units concerned are a Yamaha Magicstomp and a Zoom 508 Delay. Ihave tried them both ways   - zoom first then yamaha and vice versa- still the same glassy sound. just using one the sound is perfect!

Thanks,   Al

I suggest you open the boxes and put proper bypass switches in then.

[Big_Al]

Guitar pickups are very prone to change thier response dependent on the laod they see....and ehcne the inout impedance is a bit weird.....so feeding a high output impedance of an effects pedal into a second pedal can give some odd response.

This does seem to be a real problem with all linked effects of different makes. In this case it is giving a "glassy" sort of sound when both units are linked. The units concerned are a Yamaha Magicstomp and a Zoom 508 Delay. Ihave tried them both ways   - zoom first then yamaha and vice versa- still the same glassy sound. just using one the sound is perfect!

Thanks,   Al

I suggest you open the boxes and put proper bypass switches in then.

 

Chris, I don't really want to start taking the units apart, although I take note of your comment that the bypass switches in the units are probably inferior or of the wrong type. I have no real knowledge of electronics which does not help at all. I know that this idea I am looking at does work as I have seen it in operation for the same problem.  Thanks for your interest and replies,   Al

[Chris_H]

Guitar pickups are very prone to change thier response dependent on the laod they see....and ehcne the inout impedance is a bit weird.....so feeding a high output impedance of an effects pedal into a second pedal can give some odd response.

This does seem to be a real problem with all linked effects of different makes. In this case it is giving a "glassy" sort of sound when both units are linked. The units concerned are a Yamaha Magicstomp and a Zoom 508 Delay. Ihave tried them both ways   - zoom first then yamaha and vice versa- still the same glassy sound. just using one the sound is perfect!

Thanks,   Al

I suggest you open the boxes and put proper bypass switches in then.

 

Chris, I don't really want to start taking the units apart, although I take note of your comment that the bypass switches in the units are probably inferior or of the wrong type. I have no real knowledge of electronics which does not help at all. I know that this idea I am looking at does work as I have seen it in operation for the same problem.  Thanks for your interest and replies,   Al

My observation is that there appear to be no bypass switches in the units that you have.

You are proposing to build external bypass switches.

[Radiomarko]

A simpler solution :question may be to use a low gain or unity gain low noise amp immediately after the guitar, this would buffer the guitar pickups from seeing fluctuating loads.

[Big_Al]

Just an update - I am in consultation with Rob Lincs on this problem. I think with his wiring help I can get the thing made . Thanks for everyones interest.  will keep you posted    Al

[Marks DTM Calib]

To be honest Al, there is bugger all to it....just some pedal switchs and some 1/4 inch jacks

Do be VERY careful of ground loops and employ start earthing techniques to avoid hum and echo.