cool reverb apart from switch spdt 'pop' issue

[chromesphere]

The title of this thread needs to be changed to 'best god dam DIY reverb ever '

Well...it SOUNDS like there is a volume increase...If your using it live I think a volume pot would be useful.  Two reasons I went for a volume pot 1) didn't have a trimpot on hand 2) The loudness of the effect varies.  Some settings are louder then others.  That's just my opinion.  What do you guys think?

Also Mike, its probably nit picking, I thought I would just mention it incase you were editing the layout.  Pretty sure it was c5.  It was a tight squeeze, I had to force it in a bit.  And I didn't use a socket for u2 either!  Yeah just though I would mention it.  If there's space maybe knock it southward a few mm.

Apart from that incredibly small detail the PCB was great Mike!  I've just finished recording the build report and I've mentioned it in that video as well.  Thanks again!

Ill add the videos to this thread when they are all done and uploaded.

Paul

Edit: Also, does anyone care to explain what sw1 does? Mine might have a solder bridge or something, but its not doing anything interesting at all

[R O Tiree]

Ahh - I used the template for little 0.3" x 0.1" box caps. I take it you used a "greenie" or something? I'll make that template larger for v1.4

As to the switch not doing anything... not entirely sure what's going on there. I checked continuity and also no continuity before solder masking. At least, I though I had done it exhaustively? The switch should connect to either +9V or 0V to move the Gate of the J201 up and down so it switches in that little filter circuit below it. Could you check that the switch is serviceable, please? OK, I've just re-checked the pinout on the J201 and it's correct. If there was a solder bridge then the switch would end up connecting +9V direct to GND, with obvious results for your battery/PSU. Next, check the voltage at the junction of R16 and the reverse-biased diode as you switch. Again, that should switch from 0V to about +9V. Next check the voltage at the Gate as you switch. Double check orientation of both the J201 and the diode - the line on the diode case should be pointing at R16, not the JFET Gate.

If all those checks are OK, then check the filter circuitry, R15, C10 and C11 for continuity. If that's OK, move onto check that the Drain and Source voltages are both at Vref (although, even with the FET switching system, it would pop like a bastid if those voltages were way off).

What it's supposed to do is switch from Bright to Warm. Rob (deadastronaut) found a mod to do this and ended up wanting to be able to switch it in and out... Hence why he started this thread and I came up with the idea (having exhausted simple resistor fixes) of using a "slow" FET switch, as often seen in Ibanez and Boss switching systems.

[micromegas]

[/quote]

Why doesn't that Belton brick look like the ones I'm used to see?

It looks exactly like the BTDR-3 that Cusack announces in his new reverb...

[chromesphere]

Mike, the cap was a box type as well.  I don't know why, but for me it was a really tight squeeze!  I was just thinking if someone built it with a socket they would have no chance of fitting it in.  Maybe it was just how I installed the opamp...anyway, probably doesn't matter.

Now I remember.  Its a bright switch, yeah it was working at some stage.  Looks like I stuffed something up, ill check it over tonight.  Thanks for the detailed directions.  I start with following those.

Cheers,
Paul

[selfdestroyer]

I must have missed the discussion about the volume boost. Paul, Rob, selfdestroyer, quad, what would you like to see on the board to cater for this? Space for a trimmer, hard-wired voltage divider or pot? Thinking about it, I could provide pads that could be used for any of those methods.

So, which would be best? Make R8 or R9 adjustable? Vol pot? Your judgements, please?

I finally got mine done with a volume knob and its just perfect. I am looking of making one with a short brick also and the oscillation can go from subtle to insane with a slip of a switch which is exactly what I wanted. The one think I can suggest is maybe make your ground mask not so tight to traces. I actually took your layout into Photoshop and trimmed the ground mask down a bit to help with my toner transfer.. not your problem.. more of my problem. You feel comfortable sharing the Eagle files so we can add some mods and what not? If not I understand. I am working on a small boost/fuzz to add to this to get it closer to the new Death By Audio Sunshine reverb. This is the closes I have found to the sound. Thanks again.

[chromesphere]

You nailed it in the first line Mike   The pad that the +9v goes to the gate of the j201 was actually cracked and disconnected.  Not your fault, I think I was a bit rough with the soldering on that one....anyway, easy fix.  All good now thanks for the help!
Paul

[deadastronaut]

@micromegas:  i cut the pins shorter.  ( its a btdr-2h.)

@paul:  glad you got it going,...the tone switch i wanted that for my electro-acoustic, and just to add a little brightness for recording etc..
thanks to mike and his silent switching solution.

volume:  i just plugged mine in to test, yep, there is a volume increase, i just put a trim on the output of mine, set n forget...just for one less pot..  

but for neatness , and full control on another build of this , i'd use another pot for overall volume.....

[R O Tiree]

My bad, Paul - I just realised that the template for a TL074 is wrong... 14-pin DIL packages should, logically, be 0.7" long. The TL074 (according the the TI datasheet) has a max length of 0.775" for the PDIP format, the same length as for their 16-pin packages. Weird. I can see why they kept the 14-pin the same size body as the 16-pin version (reduced number of dies in their machines) but it's still weird that they decided to do that. I'll change the template and re-work the PCB. Thanks for the heads-up and it's no wonder it was a squeeze. Glad you found the snag on the switching system.

@ selfdestroyer - I use ExpressPCB, not Eagle. This defaults to 12mil clearance from the GND plane. That seems to be the happy medium between pad sizes you can work with and allowing the GND plane to actually make contact and get between pads spaced at 0.1" into the next area.  I know that Eagle uses oval pads for some components which would alleviate that problem to some extent (not an option with ExpressPCB). Bottom line is that I just don't like Eagle - it's counter-intuitive, inflexible and definitely too expensive for the full version (which some of my bigger projects would need). I suppose that, fundamentally, it's using toner transfer instead of UV photo-resist - it's very difficult to do isolation routing using toner transfer. If you like I could make up a board for you with the mods you want, complete with solder mask? GBP4.00 (via PayPal) including postage world-wide.

@Rob - Noted the Vol pot vote. Is there any reason why the original circuit went for a 1M output resistor? I can't see any reason that it has to be that big, given the relatively large 1µF output cap... I think a 100k pot should be more than enough? Even 47k would be ample?

[chromesphere]

That would explain it Mike!  Good to hear you worked it out!

I used a 100ka in mine and it still goes above unity on max, so yeah, im not sure why it would need 1M either?

Paul

[deadastronaut]

morning,    the 1M pulldown resistor?...

i put that there to stop 3pdt pop..without it, it popped...dead silent now.

[chromesphere]

Im confused are we talking about the output volume pot value or the PDR on the output? 

[deadastronaut]

me too?...heres the final schemo as i recall

[selfdestroyer]

@ selfdestroyer - I use ExpressPCB, not Eagle. This defaults to 12mil clearance from the GND plane. That seems to be the happy medium between pad sizes you can work with and allowing the GND plane to actually make contact and get between pads spaced at 0.1" into the next area.  I know that Eagle uses oval pads for some components which would alleviate that problem to some extent (not an option with ExpressPCB). Bottom line is that I just don't like Eagle - it's counter-intuitive, inflexible and definitely too expensive for the full version (which some of my bigger projects would need). I suppose that, fundamentally, it's using toner transfer instead of UV photo-resist - it's very difficult to do isolation routing using toner transfer. If you like I could make up a board for you with the mods you want, complete with solder mask? GBP4.00 (via PayPal) including postage world-wide.

Thanks for the reply but as of right now I think I will stick with the one I etched last week. I really like the sound of this pedal and I just need to box it up. The volume boost is not a buzz kill for me since I usually leave it on most of the time and if needed I can control the overall volume with my VP Jr but the volume trim would be a nice idea.

[R O Tiree]

OK, I've slightly re-jigged the layout to cater for Texas Instruments' decision to put 14-pin devices in 16-pin package sizes...

Here are the new files:

Schematic (same as v1.3)
Layout
PCB artwork

I've "un-shared" the v1.3 files. If anyone wants them, I can email them.

[R O Tiree]

I thinking about the output resistor - R10 - I don't think it needs to be so big as 1M. If people are going to replace it with a pot, I'd think that 47k would be big enuff, given the large output cap - C9 at 1 µF.

[chromesphere]

Oh, i learnt something today!  of course we are replacing the output PDR with the vol pot   ha.  I just tacted it on the end.  Still sounds the same, that 1m res additional to the 100ka pot mustn't matter too much, but yeah i'll remember that next time. Actually I might clip it off.  There would be a small amount of signal leaving the output to ground via that 1m res if i had to guess...

I swear this thing can do faux-shimmer.   It's surpassed all of my (high) expectations!  Thanks Rob / Mike for putting it together.  This thread deserves more attention imo.

I recorded the sound demo last night.  I upload 2 videos a week, so theres a bit of a backlog, (15 videos in the queue!) but im going to push these ones froward, otherwise it will take 2 months to upload them Will leave links to the demo's in this thread when they are up.

Paul

[R O Tiree]

Well, the 1M resistor ends up in parallel with your 100k pot giving a total "PDR" of a shade under 91k. You could lose the 1M completely and just go with the pot, taking the wiper lead to the stomp switch.

Looking forward to the videos

[chromesphere]

Ahh Parrellel!  Not series...learnt something else today. Yep, might as well clip it off i think!  Thanks for the explanation Mike

Paul

[quad]

It's been a while... but finally I took the time to finish it. I'll get my mic out and record some sounds out of this thing. Oh, right, there's a slight increase in volume indeed. A trim pot on the output will take care of that.

[R O Tiree]

Very handsome pedal, there, quad. Beautifully done.