Blue Warbler (Version 2) Envelope Vibe/Trem (Schematic, layouts, and demo vid)

[midwayfair]

After a long, long, long road, I have finally settled on version 2 of the Blue Warbler. Version 1 never got a full build thread on here, but it was hidden in the Turkey Day contest thread.

This has been a very frustrating process, but I'm really happy with the new circuit.

Schematic


What it sounds like ... Well, mostly.

I changed the depth control after shooting this video. It's almost identical, but I improved the depth further to have a better feel to dial in subtler settings.

How It Works/Build Document

I have written an EXTENSIVE "How It Works" in the build document, which also contains a perfboard layout.
https://docs.google.com/document/d/1aM2U7PL7NiMd_RaaV-7s5epvqRBPM0ZSbdbKHx96tRw/edit#

Here is a brief rundown:
The audio path is based on the Tim Escobedo Wobbletron and Bearfoot Magnavibe, with a couple changes to get what I felt was a better overall circuit. It's a simple two-stage phaser that mixes some of the output from the source with the oscillating output from the drain. The tremolo mode simply disconnects the steady source output.

The build doc contains a list of LDRs that work right in this circuit, with notes. My favorite was the Silonex 7530/7532 (they're the same thing), which Smallbear carries. To be thorough, I also tested a bunch of photocouplers, but they had worse performance (and they're more expensive).

The LFO is a variation of the basic phase shift oscillator in the EA Tremolo with some modifications. The depth control is the biggest reason this took so long, as I've been searching for over a year to find a phase shift oscillator implementation that can drive multiple LEDs and turn them on at minimum depth. In the build doc I detail some ways to adjust the speed range of the LFO.

The Envelope control is a simple one based on what I used for the Bearhug Compressor. The new Sense control  is pretty cool -- it controls the threshold, decay, and a low pass filter all at the same time, which helps dial in different pickups.

As far as what's different in the new version from Version 1:

• Even cheaper to build. The most expensive parts now are a $1 photocoupler and a 25c BS170, both of which have less expensive substitutes.
• Better depth control. The old one (and the one in the Magnavibe) loses bass as you turn down the depth, and was mostly useless for tremolo mode. The new one works just like you expect a normal depth control to work and does not change the tone. It also doesn't interact with the speed as much.
• Better tremolo mode with a simpler implementation -- and no more volume drop! The volume between the two modes is pretty much identical.
• Better input impedance.
• Smaller less complicated circuit overall. The perfboard layout even fits in a 1590A if you're careful.

Jacob's (JMK's) PCB project will be very close to this, but there may be one or two adjustments to his preference.

[Kipper4]

Excellent work Jon.
Thanks for sharing. My pad isn't showing the vid yet so I'll look as soon as I can.
I see you found a good use for the PSO.
Thanks again I'm thinking another for the list
Rich

[midwayfair]

Here's an etch mask. I just did it from the perfboard layout, since I wasn't really happy with anything I was doing in Eagle. Parts layout is the same.

https://dl.dropboxusercontent.com/u/9878279/Jon%20Patton%27s%20mini%20layouts/Blue%20Warbler/Blue%20Warbler%20etch%20mask.pdf

[Jdansti]

Sounds great, Jon. Thanks for all of the info on this.

BTW, I've noticed on your last few vids that you're not in the kitchen anymore. Did you get kicked out?

[midwayfair]

Sounds great, Jon. Thanks for all of the info on this.

BTW, I've noticed on your last few vids that you're not in the kitchen anymore. Did you get kicked out?

The neighbors complained ... I built a practice room in the basement about a year and half ago and moved all my stuff down there. I wish I could get it to sound as good as our dining/living room. Somehow being in a small enclosed space also makes things noisier.

[Jdansti]

Start saving those egg cartons for the walls. 

[duck_arse]

hey jon, I think your C8 in the osc is backwards.

I am currently working on some pso enveloping mayhem, involving an ldr, which I think can be grafted onto your warbler, or garbled onto your wobbler, not sure which. would you be interested enough for me to diagram-up my, well, we'll loosely call them ideas?

[midwayfair]

hey jon, I think your C8 in the osc is backwards.

I am currently working on some pso enveloping mayhem, involving an ldr, which I think can be grafted onto your warbler, or garbled onto your wobbler, not sure which. would you be interested enough for me to diagram-up my, well, we'll loosely call them ideas?

Always interested in seeing your ideas

The schematic link should be fixed so that it's visible now (but it's huge ... I'll have to generate a smaller image and replace).

I have all the + sides facing the collector in the PSO ring (C7-C9). Are you saying that's not correct? I actually had a hard time finding an example with polarized caps and maybe I should have gone with non-polar.

[duck_arse]

I have written an EXTENSIVE "How It Works" in the build document, which also contains a perfboard layout.
https://docs.google.com/document/d/1aM2U7PL7NiMd_RaaV-7s5epvqRBPM0ZSbdbKHx96tRw/edit#

in ^ that doc, C8 has the (+) pointing to the rate pot, which we'll call ground, and the (-) end to the Q3 emitter, which will be called V+ quite often. unfortunately, C9 is also drawn backwards whenever the Q3 is off, as the base of Q4 will be higher than the grounded R10.

as jimi would say, beyond my payscale. big boxcaps look v. attractive at times like this. (if it weren't for Q3, R10 could go to V+, taking those two cap (+)'s with it.)

I'll hack out some diagram tomorrow, I hafta go and watch the cycling now.

[midwayfair]

I have written an EXTENSIVE "How It Works" in the build document, which also contains a perfboard layout.
https://docs.google.com/document/d/1aM2U7PL7NiMd_RaaV-7s5epvqRBPM0ZSbdbKHx96tRw/edit#

in ^ that doc, C8 has the (+) pointing to the rate pot, which we'll call ground, and the (-) end to the Q3 emitter, which will be called V+ quite often. unfortunately, C9 is also drawn backwards whenever the Q3 is off, as the base of Q4 will be higher than the grounded R10.

as jimi would say, beyond my payscale. big boxcaps look v. attractive at times like this. (if it weren't for Q3, R10 could go to V+, taking those two cap (+)'s with it.)

I'll hack out some diagram tomorrow, I hafta go and watch the cycling now.

huh, interesting. This has me worried since I might be reverse biasing an awful lot of tantalum capacitors at the moment, even though I haven't had a problem yet.

[midwayfair]

Just giving everyone a heads up that JMK PCBs has released the PCB for their version of this:

jmkpcbs.com/product/blue-warbler-2/

Also, the build doc was updated a while ago to include a two-stage version for people who want something that sounds a bit more like a phaser.