The Hedgehog- A/B in, 4 send&return true bypass, A/B out.... help please!

[ghostinthescott]

So I've done a quite extensive mod and a few repair jobs before but I'm looking to build my first pedal completely from scratch. I've a customized idea in mind, particular to what I need for gigging.

Practically I know I can do it but need help with a few things schematic-wise.

It's going to have an A/B switch for the inputs (so I can switch between my guitar and theremin) then next in the chain 4 true bypass send&returns for some pedals and then another A/B switch for the outputs (handy for switching between amps at home and essentially a spare 5th true bypass pedal section if used with a 5th pedal in the chain and a splitter with the two leads going into it and on into the one amp). So I'm taking a schematic for a true bypass strip with master on/off and muting tuner ("schematic 1"= http://www.singlecoil.com/tb-strip/images/tuner_out.gif ) and attaching something like this ("schematic 2"= http://www.singlecoil.com/docs/ab.pdf ) on either side.

So,
Problem one:
On schematic one at the bottom left corner there seems to be additional information for one of the 3pdts... it seems like maybe you might link these extra bits up just like in a similar schematic on the same page ( Schematic 1b= http://www.singlecoil.com/tb-strip/dia12.html ). Can anyone confirm my suspicions?
I emailed the listed address hoping for help but they said they didn't have time to respond to individual queries like mine 

Problem two:
Can I essentially use that same schematic (but just change the inputs for the two A/B ends despite that the inputs end will be pretty much the reverse (ie 2 ins 1 out)? What would I change? I guess the jack connection types (mono/stereo) for a start....

Problem three:
Can I still use one single 9v power source to power my whole circuit? Will I need to change resistor values to compensate?

I may also need a little help with constructing the final schematic out of the 3 sections of it but cross that bridge when we come to it eh?   

When I'm done I'll be writing up about the creation and results of it and posting images etc for this site and singlecoil.com
Please give me a hand, all help will be very much appreciated and I'm a genetics student so can pay you in the form of four breasted women 

Cheers Scott.

[slacker]

Welcome to the forum

Your idea should work fine, and sounds pretty versatile, like you said it's pretty much just a case of cutting and pasting the different schematics together, anyway on to your problems.

The extra 3PDT in the first schematic is just a different way to do the tuner mute, it's the same as the one top left except that it includes a LED that lights up when the tuner is selected. It also grounds the signal to the true bypass loops to reduce noise when muted.

The AB circuits will work fine backwards, you can just use the 2 "output" jacks as you inputs and wire the lead that goes to the "input" straight to the input of the looper. Same on the output, you can just connect the blue and purple wires to the tip wire of the input on the second AB box.
If you are going to use a power supply to run it you can just use mono jacks, if you're using a battery you will need to make one of the inputs or outputs a stereo jack to disconnect the battery when not in use. You don't need to change any of the resistor values and you can power it with one power supply or battery.

Hope that helps

[ghostinthescott]

Wow, I'm amazed to see how quick and good a response I got there, I do indeed feel quite welcome to the forum now

Thanks very much for the reply good sir, I'll get to drawing up (ms paint style) a schematic based on those images I've got and post again with it just to check I've not made a hash of anything.

Cheers teh dee Slacker,

Scott.

PS after reading about the 'no foul language rule' maybe I should dish out some glow-in-the-dark turnips instead in case my women aren't so much appreciated...

[ghostinthescott]

Just before I draw this up and buy the parts I was wondering about maybe putting a buffer in the circuit somewhere...
I know the point of true bypass is to get around buffered systems but  I've heard downsides of all true bypass too (treble loss etc) as well. Was wondering if just one for the whole pedal might be a good idea?
Any suggestions anyone?

Cheers, Scott.

PS, probs gonna use this system if I do, http://johannburkard.de/blog/music/effects/Build-a-buffer.html

[asfastasdark]

Concerning the buffer: It's just a GGG buffer (Generalguitargadgets.com). GGG is a pretty respected site in the DIY stompbox world. Anyway if you plan on building this whole thing on perfboard (or anything else that is not PCB), you might as well just include the buffer circuit on the same piece of board instead of buying an entire PCB for it. If you want I can draw up a layout for this since it's so simple.

One idea though: I've never seen this done before, but it could seriously cut down on long cables and a messy pedalboard: Build in a regulated power supply as well with a knob that lets you reduce the volts as to simulate a dying battery, and add a master volume at the end of the whole chain. You could, if you wanted, make more s/r loops into the pedal to make it more efficient. Though that is up to you.

[ghostinthescott]

Hmmm, well since most of the components (leds switches jacks) are gonna be mounted I was thinking of just the buffer being on perfboard and nothing else (everyhitng else just connected by direct wiring), would this be a bad idea?

I had thought of maybe putting in pots at each in and out jack for volumes and maybe a master volume. What's a regulated power supply and how come the simulation of a dying battery?

Yeh, I might put in up to 5 or 6 S&Rs it partly depends how much I can comfortably fit in (hitting only one footswitch per 'stomp') to the 'project box' I bought a while ago off ebay.

Also does anyone have any good advice as to whether to add the buffer or not?

Cheers, Scott.

[asfastasdark]

http://www.beavisaudio.com/Projects/DBS/index.htm

[ghostinthescott]

oooooooo my sign-in timed out and I couldnt go back to the message I had wirtten 

The basic gist of what I said was- not gonna bother with integrated buffer cos I always just build it seperate and link it in to have it working as an optional extra or leave a pedal on at the S+R switch & 'off' at the pedal.

Also I'm gonna maybe use maybe 7-10 S+Rs to accomadate for future pedal additions and if the project box i have atm is too small then "we're gonna need a bigger boat".

The power source, batt sim and mast vol idea sounds good, cheers asfastasdark. I'm gonna go off and read http://www.geofex.com/Article_Folders/pedalbdpwr/pedalbd.htm to find out if I'm man enough to do it. If I went for it not sure whether I'd try one of the more complicated dying batt sim circuits or just go for pots for each one....

[The French connection]

Just before I draw this up and buy the parts I was wondering about maybe putting a buffer in the circuit somewhere...
I know the point of true bypass is to get around buffered systems but  I've heard downsides of all true bypass too (treble loss etc) as well. Was wondering if just one for the whole pedal might be a good idea?
Any suggestions anyone?

Cheers, Scott.

PS, probs gonna use this system if I do, http://johannburkard.de/blog/music/effects/Build-a-buffer.html

Hi! I'm not sure about the treble lost...and true bypass. But if you have long cable and patati and patata, a buffer should help...moreover if you put passive volume control...i think! Maybe a better brain should confirmed this.   
Anyway, i think this could help. It's just AB with 2 loops but easy to figure how to wire 2 other loops...
http://www.diystompboxes.com/smfforum/index.php?topic=66411.0

Bonne journée!
Dan

[ghostinthescott]

Cheers for the schematic Dan. That'll help when I come to try and finalize things. And I''ll look into the passive volume control thing- anyone know about it already?

The two things that have come to mind fom reading http://www.geofex.com/Article_Folders/Spyder/Spyder.htm and the previous one I posted about power supplies is that
1.) they stress safety in wiring, anyone know any good sites to learn about this? :S
2.) I'm in the UK so working with 230VAC (rather than 120VAC in the US?), problems? :S
      On the 'spyder' page it did however mention that the 50Hz/60Hz thing wasnt a problem.

[ghostinthescott]

I guess the only difference is I'll need a 240v to 12 v transformer instead....dumb question.