Messages

Yeah, report back and I'll offer any thoughts if I have them.

Wait, my bad. I forgot the component naming is different. D4/D5 are clipping diodes on the ETCHED Sunking layout. D1 and D2 are for the charge pump. IIRC, they are different because I redrew the schematic for the FABBED v3 Sunking.

Sorry for the confusion.

What kind of charge pump have you used?

Couple things that could cause what I'm seeing: D5 is backwards or dead, C19 is backwards or dead.

Maybe a pic of the top/bottom?

The problem seems to center around R8/R41/R22/R9/R10.

Try this: remove both PT2399s again. Now audio probe pin 16 only of IC2. Do you get a strong clean signal there?

If so, can we see a pic of the bottom of the PCB on the area directly beneath IC2?

Actually, looking at that schem again on SB- it shows +15v (I did not notice that before). This is confusing to me. His schematic appears to be wrong for +15v operation.

I'm totally confused here, when I look at the schematic up on small bear, pin1 is clearly GND.. how am I misinterpreting this?

Because he's showing you how it is set up for a -15v supply, not a negative ground supply. MN3008/3005 were designed to run at -15v (check any Deluxe Memory Man schematic and you will see what I am talking about). This is pretty inconvenient by modern pedal standards so when we use our regular neg. ground supplies, the ground and power pins are flipped so the chips can run off a positive voltage.

http://www.alldatasheet.com/datasheet-pdf/pdf/87983/PANASONIC/MN3005.html

You've got some mistakes in there. For an MN3005, negative ground supply, pin1 goes to 15v and pin 5 (or 8 in your schematic) goes to ground. The 100k resistor should be a pull-up (connect to 15v) not connected to ground. Pin8 on both BBDs (or pin14 in your case) should both be connected to Vgg.

Use this schematic as a reference. It's from the Aquaboy 2012 documentation. It's slightly different than the DMM way which your is based on but both varieties work.

Here A and C would be connected to 15v, and B and D connect to ground for MN3005/MN3008.

Resistor values around the PT2399s look good from what I can see. I'll second Jon on the audio probe. It's going to be necessary in this case. Your voltages seem okay and your components appear alright (not that I've looked at every resistor value in your build).

You need to audio probe: R8, R9/R10 junction, R11/R12 junction and R21. Do this with the Ghost switch off and using the Feedback knob all the down and then a little bit up.

Jacob hit most of the marks so I don't have much to add. Personally, I use Bill L's for my cables and I can tell you there is very little or no benefit to running a buffer with them. The loading just isn't there. How much of that is due to "low capacitance cable" versus simply not enough linear cable length across my pedalboard I don't know. It's not a solution looking for a problem in my case.

But, there can be arguments made for at least one good buffer in a looper and maybe in each loop for some people. Options are never a bad thing and a simple op-amp buffer is easy to build, cost-effective and very low part count. Nice thing about it is you can turn a buffer into an awesome (mild) clean boost with one added pot and a switch...that's all there is to it!

Not at all. I agree with you that the v3205 implementation just is not as good as other BBD types. But, I am also pretty confident it is not a deficiency in design as much as a problem with using that technology in this particular circuit. The DMM sounds best at 15v, and that limits our options if the project is going to be accessible enough to a wide variety of customers. And, frankly, that's why I have hesitant to re-release it. I think the changes I've made for 2013 have improved the project overall, but I haven't signed off on it completely yet.

Of course, I could change the approach and design it around 4 of the (8 pin) BL3208s to get the same delay time, and it would be an improvement. But, then we lose the option of MN3005 because I cannot fit that many 14 pin BBDs in a 1590BB enclosure without going SMD on some of it. And, in the end you will basically be building the EHX Memory Boy which you can already buy for $100 used (it uses 4x 3208).

Alternatively, I could make it into the vintage DMM, with positive ground, MN3005 only and require a 24v supply. But, that's going to make people unhappy for obvious reasons

Anyway, I'm not trying to "unload" here. Just explaining my thought process on this project and where it is going. Here's a snippet of the series resistor mods I've implemented for the 2013 version in case that is helpful.

I think you might have something going on then. You definitely should have some pulse to that LED. Hmm.

If you haven't, please double check your values for the resistors on the LFO (everything under the L1 lamp on the schem).

I'm not against the idea, I'll say that. Ideally, it would be nice to have such a thing be portable to single effects, too (relay based switching). I'm not terribly educated on the advantages of using a relay/trigger vs. some kind of PIC control, though. Obviously the former has the advantage of being a lot easier to implement as a project here.

One thing, you kind of lost me here:

When the boards are added to the enclosure/strip itd be nice if there was an ability to use the same sort of centre conductor found in good quality guitar cables to hook the boards together in the looper, i.e. a bigger hole in the board for better internal wiring.

Can you show an example of what you are talking about?

I'm going to guess you have an incorrect resistor value somewhere, but I'm not positive yet that is the issue. Can we have a clear pic to the top side of your build, please? I'd like to see two close up shots: left side and right side. Particularly, let's look at those resistor values around IC3.

Series resistance with the inputs of the two BBDs does seem to have a positive effect in reducing distortion on the v3205s, I've found. This is something I'm incorporating into the re-design. On the older Dirtbag, one more thing you can try is remove C15 and then put a 1uF and 100k or 220k in series in that spot. This will provide a bit of signal limiting on BBD1.

Lead dress could be the cause of hearing it in bypass. You might need to separate your wires more.