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Yeah, you're right, in the DMM schem there is a regulator. No point going above 15V then. But does it make a difference if you are below 15V? My Road Rage is supplying 14.8V at the moment.

On another note, does anyone know if you can bias the BBDs with a multimeter (no scope here) i.e measure the voltage on input and output pins and bias both BBDs so these voltages are equal? Or am I talking rubbish here?

Brian, are you able to make any comment on the changes to the future DLX3 layout vs the older Dirtbag design? I have built the Dirtbag on your pcb with 4x MN3008s @ 15V but when A/Bing it to my big box DMM have never really got it as close as i would like. This could be to do with biasing or any number of other issues, but I'm wondering if you have any suggested mods that I could try now, before the DLX3 project release? Mostly, I'm concerned with the repeats distorting (almost pitch shifting) quite badly after about the third repeat.

Should I just bypass the Road Rage and run this thing @ 18V to achieve more headroom?

Thanks

Did you play with the bias trimmers? It is quite easy to bias this up so badly that you receive no delay signal at all. I assume you are still getting clean signal when the pedal is engaged and the blend pot is set to minimum?

After some more research I realised my DMM does display the same phenomenon when adjusting the modulation control. It just isn't as pronounced. I guess this is to do with the pot taper or something? Anyway - can someone suggest the components to tweak in the Dirtbag circuit to reduce the modulation depth? I really only have a use the first 1/4 of the pot's rotation, the rest is far too 'seasick' for my needs. Should I be simply looking at subbing the chorus/vib caps (C36 and C37) for lower values? Or should I swap out the mod pot for one with a different taper?

Thanks

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Hi guys,

I'm busy tweaking my Dirtbag to my liking (and to closely match my big box DMM). It does have some component mods and is running MN3008s on double delay boards. It is running on 14.8V, powered by the Road Rage. One strange thing I have noticed is that increasing the modulation (turning the knob clockwise) has the effect of decreasing the delay time. This is especially noticeable at the max (500ms) delay setting. Removing the modulation chip (TL062) makes no difference (apart from removing modulation).

If anyone else, who has built the Dirtbag, is experiencing the same phenomena - is there a solution? 
I'm already considering reducing R55 to 1k, but realise this won't solve the issue.

Answering my own question - I soldered up these two double delay boards using the values aballen had conveniently noted on the pcbs themselves. The only modification was that I used 20k trimmers instead of the 22k trimmer specified. I ended up using header pins and mounting these directly to sockets on the main board (saved offboard wiring, but obscures the bias trimmers). If anyone else is considering doing this - be aware that some of the electrolytic caps on the main board will need to be folded flat and check the overall height of your enclosure is enough - mine just fit with 1-2mm to spare.

Aaaannnd Bingo! The Dirtbag works with double delay time. So I guess that means these boards are VERIFIED.

Caveats - I don't know if I'm truly getting double delay time - but it is certainly longer than it was without these boards. I do have the an old big box DMM to compare with, so I'll be sure to do an A/B shortly.

Build report will follow when I get the enclosure tidied up.

Hey guys,

So a grabbed a couple of these double delay boards from aballen (thanks again!) with the intention of completing the Dirtbag using 4x MN3008 (MN3005 fakes). For reference, the final layout and schematic is on page 2 of this thread. It looks to me as though the component values on the double delay boards have been designed/optimised for the Aquaboy and my question is - are these values suitable to use for the Dirtbag circuit? Looking at the Dirtbag schematic, it looks as though the more appropriate values to use would be those in the smallbear schematic:https://www.smallbearelec.com/HowTos/MN3005/3005_to_2x3008_SCH.pdf e.g 2k4 resistors and a 100k trimmer etc. Anyone got any hints for me? I've already had some fun desoldering parts of the Dirtbag board and don't plan on having to redo these double delay boards too. 

Cheers!

Hi Aballen,

Registering my interest: if you have any of these boards left, or you are still planning to get some more done, but I'd love to buy a pair from you at some stage if possible?

Thanks

Alan - I haven't got a quote from MacPherson - not a bad idea, though I reckon if I looked into it hard enough, I could fix it myself.

Scruffie - not even a Daphon?    But seriously, is it best to buy the MN3008s or the fake MN3005s from smallbear? I see they do both for about the same price ~$15ea.

Thanks guys,

Yes - the big box DMM works. The enclosure is very rusty (maybe the previous owner played gigs in the rain?!) and sometimes when switching from delay to bypass, it loses all signal. Then the signal slowly increases in volume over a few seconds kind of like a capacitor charging/discharging?? I thought it may be a problem with the switching relay but never investigated further. Its also quite noisy/hissy when turned on, though I guess this could be a power supply issue. Sorry LS, its not really for sale.

When starting the Dirtbag project I was aiming to get the DMM sound, but in a smaller (non-rusty) enclosure, able to run off my PedalPower ISO5 and with reliable switching. I was/am also keen for a challenging DIY - that being the inspiration behind this forum afterall!

nzCdog - Hey man, I recognise your handle from NZGuitars.   Have you built the Dirtbag?

Hi guys,

I have the Dirtbag board plus V3205 and MN3005 chips on hand. Which version should I build?
Sounds simple - "build the MN3005 version!", right?

Maybe, but its a little more complicated than that, here's the dilemma:

1. The MN3005 chips I have are in an original big box DMM - so using those chips will render that pedal a rusty paperweight. (This pedal is working, but pretty hammered and has some other switching issues, so is not in mint condition).

2. I have already started populating the Dirtbag board with the jumpers and all the resistors (incl Bean's latest revisions) up to R34, as I was planning to use the V3205 chips.

The only reason I'm having cold feet on the V3205 version is that I have just spent an hour reading threads on this forum where people appear disappointed with their V3205 builds and given that I already have I working DMM, there seems to be no real point in building a sub-par copy of the real thing.

So, while I realise this is solely my decision to make, does anyone have an opinion which might guide me?