Passive blender?

[jkokura]

I've looked at the mini blender circuit, but I'm wondering if there's a blender circuit out there that I could do without using any power?

Jacob

[John Lyons]

Most basically you can use a pot with the wiper as the output
and each signal connected to the outer lugs.
The actual blend mid point and ratio of blended signals
depends on the level of each signal which you can alter
with resistance added at either end.

[jkokura]

I think I'm understanding what you've described John. I have a volume pedal (Bespeco) I want to do this in, and to drill the power jack becomes awkward (nowhere to put it) which is the reason I'm looking at making this passive. So basically, I'd have to connect the input to the 'right' lug of the pot and to the send jack, then connect the return jack to the 'left' lug of the pot and the 'centre' lug to the output?

Just for curiosity though, what would be the benefits of going active to do this? I mean, if it's this simple, why is there circuitry that does this? What will happen to my signal if I just go through the pot and no active circuit? Does it change what my amp 'sees' from my pedal board?

Jacob

[John Lyons]

What are you blending here?
Guitar and pedal(s) as in a clean blend?

Any active circuitry is mainly for buffering the guitar or effects
so that they do not load each other down which mostly
changes frequency response (for the worse) via impedance etc.

Give us a little back ground on what you want to do more
specifically.

[jkokura]

Specifically, I would like to blend my signal from after my dirt pedals and before my amp. I'd like to take a reverb, a pog2, and a delay creating ambient synth type sounds and run it in the loop That way I can blend the dry normal guitar signal that goes through typical od, modulation and delay type pedals, and blend in this crazy neat ambient synth sound I can create. I don't have a POG2 currently, but this is the plan.

I've seen other guys do this with a mini blender in a 1590B style enclosure that has a super big knob to turn with their foot. I know it can work, and that it sounds awesome, I just don't know if I can make it happen passively - as I said earlier, the volume pedal enclosure I want to use for this works better if I don't have to drill a hole for a power jack. I will if I have to, and find a way to make it happen, but I hope passive will be fine. If the active circuitry is essentially a buffer (which it looks like to me) and I have a buffer earlier in the circuit I should be fine, right?

Jacob

[jkokura]

K, I tried this, and it didn't work. I put this together, passive - just the volume pot - with a Tubescreamer in the loop I got this CRAZY feedback thing. It didn't matter where the pedal was, as soon as my volume was up and the pedal was engaged it just went insane. When the tubescreamer was off (True Bypass) The guitar signal went back to normal, and the volume pedal didn't seem to do anything anymore.

John? Anyone else? Any ideas? Do I need to go with the active Mini-blender circuit?

Jacob

[Taylor]

In general you'll wind up with feedback, signal loss, noise, etc. when going passive, as you're seeing. Is there a reason you don't want to use power here?

[jkokura]

Providing power is kinda awkward in the enclosure I'm using. It's a volume pedal from Bespeco - think of the Line 6 Expression pedals.

I'm pretty sure I'll have to build the circuit, I was hoping someone could give me a passive idea to work with. Ah well.

Jacob

[Taylor]

This may not be any less awkward, but another way to go would be to build the circuit in a regular die cast box and run power and signals there, and then just wire the mix knob as a stereo jack and run a cable to the volume pedal. You'll need to rewire the volume pedal still, but this way you don't have to run power or all the send/receive and in/out jacks to the volume pedal - in this case it's just acting as an expression pedal to control the blender in the metal box. That also has the advantage that you can place the mixer box where it logically fits in your signal path on your board, but you can place the volume pedal where it's convenient to operate, and just run a single cord to it.

[jkokura]

I'll have to think about that...

I'm not sure how to wire an expression pedal though. Also, I've drilled this thing for four jacks now. I wonder how I could leave it as a stereo volume pedal/expression pedal... Any hints or directions Taylor?

Jacob

[Taylor]

Originally I meant to just treat the pot in the volume pedal as the mix pot in the B Blender. Run the out of the effect buffer and the out of the clean buffer to opposite outer lugs of the volume pedal's pot, then run the wiper back to the mixer box with the 2 signals mixed together. However, in that case you'd be running your audio through an unshielded cable. So, possibly not a great idea.

Of course, you can get more complex by using the volume pedal to control optocouplers to attenuate the 2 signals in contrary motion - this way you wouldn't be sending audio through the expression pedal cable. But it sounds like you're looking for a simpler solution. Can't think of a simpler way at the moment, though.

[jkokura]

Simple is better, and this is getting to be a crazy cool idea, but not easy applicable for me.

It would be much easier to just run the small mini blender circuit and find a way to run power into the unit. I'll have to just buckle down and get that 9V jack on there somehow...

Jacob