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hmmm/ quite the conundrum since the pots is a resistive divider... hmmm\\\\
I had figured a simple circuit like the four-way MULTIPLE moog CP-251 would send the CV to multiple places at once...

using the pot in the expression pedal as a resistive divider isn't so hot since you've got to run your signal through the extra cable length... (would that be right?)

the solution does lie in using a better OTA, or something in that nature.
maybe you could a four way multipled CV and use two for tapering the clean, and two for tapering the effect, and then just put an active mixer?


I wonder how the TheGigRig_WetBox does it with it's expression pedal?....

till then i can just use one of these that i have

That's a good point for sure, Kev, but I didn't notice any loss of tone through a 10 foot expression cable. Luckily the signals being mixed are direct from op-amp outputs so driving a short run of cable is no biggie. If they weren't basically buffered signals I probably wouldn't try to get away with it.

The control voltage setup worked pretty darn well and I do wish that's the route I could use. I used a dual opamp to buffer and invert the control voltages and it provided 4 outputs to control the OTAs as current controlled amplifiers.

My problems with that circuit are a couple of biggies.. one, it added about 30 components including two dual OTAs and one dual opamp.. a huge addition to an already complicated circuit. But worse, LM13700s don't sound great... I'm planning on having another go at them just for my own experimenting curiosity, but I found them to be noise and hissy with a tonal quality of their own. The problem is there's basically only two OTA choices readily available/still in production... I think OTAs are much better suited to being control elements and not processing audio but to replace the mix pot for the RRR the signal has to go through one, twice.

I can't use a control voltage to control mix unless the circuit is setup completely different. Basically to use a CV input means running through OTAs, I don't think there's a way to do it without using them, and I can't compromise the sound of the pedal just for simpler expression control. Using 2 expression inputs is no big deal anyway as long as there's a suitable stereo expression pedal or a mod that I can do to one, and there will be. I'd probably make mods for all the stereo expression pedals available since as long as they have a dual ganged pot with a relatively low resistance (less than 25ish k) they can be made to work with a snip here and a solder there.

The thing I was most excited about with the CV setup is that anything with a CV output could control the RRR.. like say you had a Goatkeeper trem, it could output a CV voltage that would affect the mix according to the setting of each stage... I could see that sounding pretty cool.

Frustrating situation but I'm going to keep experimenting! Love chatting about it too, so thank you for the chat, sir!

Badass pic there, too, I see Avalon gear! Are those preamps or compressors or what?

Kev, I got a solution possibly sorted out tonight... it's working pretty well although still needs further tweaking. I replaced the B10k resistive divider for the mix control with LEDs and LDRs. This allows both stereo channels to be controlled by one regular pot, not dual ganged, and will let any 10kish TRS expression pedal work. For both channels at once. No stereo/dual expression pedal required and only one expression jack required on the pedal. Unless I add a second jack for decay but that's a whole other experiment....

This LDR system has the added benefit of not requiring the op amp stages to drive the expression cable run. The mix control is still a B10k pot but now it's dividing the voltage between two LDRs so the audio signal doesn't have to come out of the box and travel down a cable to the expression pedal and back. The downside is it uses 4 Vactec Vactrols which are about $3.50 each at Small Bear.

I just had to let you know that development since we've been discussing it lately!

after trying to find a solution i read some guy on the internet was gonna try this:

replaced the B10k resistive divider for the mix control with LEDs and LDRs. This allows both stereo channels to be controlled by one regular pot, not dual ganged, and will let any 10kish TRS expression pedal work. For both channels at once. No stereo/dual expression pedal required and only one expression jack required on the pedal. Unless I add a second jack for decay but that's a whole other experiment....

This LDR system has the added benefit of not requiring the op amp stages to drive the expression cable run. The mix control is still a B10k pot but now it's dividing the voltage between two LDRs so the audio signal doesn't have to come out of the box and travel down a cable to the expression pedal and back. The downside is it uses 4 Vactec Vactrols which are about $3.50 each at Small Bear.

do i get a bigRRR?




i'm pretty excited that you found a work-around!

those are two avalon U5 DI boxes.

I definitely owe you for the dialogue we've had about the bigberator! It's made me realize I need to go back to a design with top mounted jacks too, even if it means using the 1790.. top mounted everything! So I'm on track with top mounted everything, on track with a better mix control, on track with executive soft touch stereo switching, and my first prototype is going to have an expression input for the decay control too.. that's an experiment that's just got to be done.

You must have some pretty nice recording gear if even your DI boxes are Avalon!

Hope you had a quieter night last night too, really sorry to hear about your recent drama.. sounded really scary.

any progress in this last week?

how impossible would a predelay knob be to implement?

Hey Kevin!

There's not really any way to add a predelay knob.. the thing is, I have no control over the patches or the digital aspects of the circuit. Even my decay control is totally an analog hack that wasn't meant to be used with the chips but I'm making it work. I can only add analog hacks to the circuit, nothing that affects the character or nature of the reverb patches. Adding in a circuit for predelay would just add too much complexity to a circuit that already has over 150 components plus more than likely it would have a negative impact on the sound quality of the wet signal. (That's an assumption based off the fact that I don't have a really clean and transparent delay circuit readily available to slow down the signal going to the reverb engine.)

I've basically got 2 pcb layouts ready now, rounded up all the parts I need to experiment with, and am now just focusing on getting the pcb prototypes ready so I can build a couple protos and really make sure some of these features will work in the box. I'm still debating the box size too, I'm still on the fence a bit about what size to use. I've got a layout ready for the 1590BB, horizontally positioned with side mounted jacks. I've got a layout ready also for the 1790NS, horizontally positioned with top mounted jacks. I'm also doing a layout for the 1590DD, horizontally positioned with top mounted jacks, as I don't have a good source for the 1790s but I can get the 1590DD through 4Site and I could use the extra space too that the DD provides anyway.

The features that all of the prototypes will have are:

-true stereo in and out, 2 fully separate audio paths
-decay control
-global modulation with rate and depth controls
-stereo expression control for mix (controls both channels with one exp pedal)
-expression control for decay
-soft touch relay switching
-beefy power supply protection that can't be hurt by reverse polarity adapters
-*maybe* - internal choice of buffered bypass or true bypass

WOW!

-decay control
-global modulation with rate and depth controls

we're spoiled.

with all that going on, there's really no need for pre-delay.

Dude, the prototype is going to sound AMAZING! Modulated reverb? Yes, please.

OH WOW this thread just got super duper awesome.... like electronics porn....

Dr. Scientist FOR-EVA!!!!!

Aren't top mounted jacks a problem if someone spills beer on a pedal with an open jack?

top panel mounted jacks.



small bear has some 1790NS
http://www.smallbearelec.com/Detail.bok?no=567
not sure if it comes with that battery door though?

&
http://www.effectsconnection.com/oscomm ... d8699610e9


but how reliable these places are...

4site electronics sells joysticks....

this is gonna be good!

This is sounding fantastic...

Whew, glad you guys like the sound of those upgrades!

Thanks for the links to those guys, Kevin, I've been using Small Bear to get my 1790s for prototyping. For the record, I've done lots of business with both of those stores and they're both awesome.

I've spent the last few days totally focused on another box layout that I think is my new favourite, although it's by far the toughest for the pcb layout. I'm down to two favourite box layouts now, one in the 1590BB and the other in the 1790NS.

My plan now is to make pcb layouts for each of these boxes and build them both and then see which one sounds better (lower noise) and builds better. I really like using the smallest size box possible but the circuit is so jam packed into the 1590BB that I don't know if it's a great idea... mixed analog and digital layouts usually like some space between everything. The expression jacks are on the side of the box as that makes most sense for building as I can use pcb mounted jacks in that position and save the chore of wiring 12 connections just for those 2 jacks. Otherwise I'll be using my standard Switchcraft jacks in my standard top mounted position and I'll standardly hand wire them as usual.

I'm hoping to have these pcb layouts ordered within the next couple weeks and then we'll really get to know about some of these features, like the decay control I worry so much about.