MN3008 Dirtbag

[LaceSensor]

Hi gang

Jumping on the back of another build report this week, I have finished my THIRD dirtbag PCB.
I decided to buy some MN3005 fakes from Smallbear and try them. I typically use shorter delay times anyway. I guess in the future I might be able to add either real MN3005s if I find them, or do a double delay board setup in it. Might need a bigger box for all that though.

Anyway, I wanna jump in now and say a MASSIVE retrospective thanks to Madbean, Scruffie, Jkokura and all the other folks that provided me some advice/recommendationsd/help/therapy during my time trying to get the v3205 version to work. I also wanna say a sincere sorry if I ever came across as a douche and to Bean if my at times strong comments ever offended you. I still cant get my 2nd one work properly (v3205). The first one went to Scruffie and I dont think he ever got much joy out of it. I got a hunch its just shitty chips. Ive build 5 or 6 analog delays now. The ones with MN chips all work and sound awesome. Ones with v3205 just dont sound good, or dont function correctly (2 x Dirtbags, 1 x AquaBoy). 

Right now, unless people need the 500ms delay, Id recommend buying some MN3008 from Smallbear and having the real sound.

So onto the build.
Anyone that has done one of these knows populating the board is no joke. This one took me about 5 hours with a couple breaks for coffee. Think the first one I did was about 7 hours. I made up a road rage board with an LT1054 (Futurlec) and tested it, was getting a consistent 15.0x volts. As I was recycling the enclosure, once it was tested and working, boxing it up was easy.

One thing that almost proved a problem was where to put the roadrage. I used 35 / 50 volt caps just to be safe. They are quite big! Luckily I got clearance round the footswitch and output jack, as shown below.



The next shot is pretty much the same, but I wanted to include it. I date all my builds. Almost 6 months to the day since I made my first v3205 in that box and posted up here



One thing I encountered before wiring up, during the biasing, was that using a battery was a bad idea. Was getting very ropey sounds. This was late last night, so I figured, either something is wrong, or its the battery. This morning when I hooked up a 9v power supply, I was able to bias it clean very easily.

In testing, it was very easy to set the Gain Trimmers now to only provide the real runaway choas at max on the feedback know - awesome. Last, the only change I made from the BOM was to make the clock cap 330pf. I intend to mess with this. with 240pf, the delay time was about 250ms. Using 330pf pushes it to (by my ears) close to my Auqapuss builds (approx 300ms). There is some clock noise at the extreme on the delay time knob. I reckon 300pf here might be the sweet spot.

So here it is, something that I am very proud of and will have a spot on my pedal board.



Good luck to anyone on this endeavour.
I might even be tempted to make another sometime, if the PCBs get restocked.

[midwayfair]

Good to know one of your builds finally works properly and gives you the sound you want! It's a shame that the v chips give everyone such a hard time.

Building one of these is my goal for this year. I have to say ... watching all your frustrations work out in the end gives me some hope.

[marmaliser]

Glad it worked out for you.  AFAIK the only way to build these is with MN* running at 15v.
FWIW I don't think you were being a douche at all but were right to demand answers for the product you had bought that was not behaving as advertised.

[LaceSensor]

Glad it worked out for you.  AFAIK the only way to build these is with MN* running at 15v.

TO be clear when I say I was testing with a battery I mean battery > Road rage > Delay board
Likewise with the 9v power supply.

[RonaldB]

Good job Lacesensor,
My congratulations 

It's a beautifull delay once working properly

RonaldB

[marmaliser]

Glad it worked out for you.  AFAIK the only way to build these is with MN* running at 15v.

TO be clear when I say I was testing with a battery I mean battery > Road rage > Delay board
Likewise with the 9v power supply.

Yeah I got that, I meant as opposed to messing with the 9v v3205's
Btw it looks fantastic.

[Bret608]

I tend never to go over about 300ms for delay times anyhow, so I think I would follow your lead if I ended up building one of these. Based on the Dirt Bag build reports of the last few days, it seems a consensus is emerging that MN3008s or MN3205s are way preferable to the v3205.

[LaceSensor]

I tend never to go over about 300ms for delay times anyhow, so I think I would follow your lead if I ended up building one of these. Based on the Dirt Bag build reports of the last few days, it seems a consensus is emerging that MN3008s or MN3205s are way preferable to the v3205.

We need to remember that quite a few people have made perfectly acceptable v3205 builds, but if it was me, I wouldnt wanna risk it again. With a couple dual delay boards, and 4 x mn3008, it will be pretty much as good as it can get, without the mn3005 lottery (!)

[LaceSensor]

Glad it worked out for you.  AFAIK the only way to build these is with MN* running at 15v.

TO be clear when I say I was testing with a battery I mean battery > Road rage > Delay board
Likewise with the 9v power supply.

Yeah I got that, I meant as opposed to messing with the 9v v3205's
Btw it looks fantastic.

Cheers dude.