Dirtbag Deluxe

[Bret608]

Does the internal regulator kick it up to 15v even if you're plugged into a 9v power supply? If so that is one sweet touch!

[JakeFuzz]

Does the internal regulator kick it up to 15v even if you're plugged into a 9v power supply? If so that is one sweet touch!

No, I wish. That would be awesome. The regulator just takes it from 18-24 volts DC and pushes it down to 15 volts. To go up you would need a charge pump and a regulator. 

[Bret608]

Ah! That is still really cool though...I don't know of too many power supplies that will get you into that 15v sweet spot for high-headroom BBDs!

[JakeFuzz]

Ah! That is still really cool though...I don't know of too many power supplies that will get you into that 15v sweet spot for high-headroom BBDs!

Haha I know what you mean. I spliced up an old 24V Epson printer power supply to power both my Dirtbag and Warhead. Got it at a swap meet for 2 bucks.

[JakeFuzz]

So here is an interesting question. No matter what I do I cant get more than about 480ms out of this. Is it possible that I have one real MN3005 and one fake relabeled MN3008? Would this work out to about 450ms of delay time and would it even operate at all with different chips? I am guessing the audio probe could probably help me get down to it since we are checking each chip output individually. Very strange. One chip does have the smooth top border and other doesn't, but I have seen both styles on real MN3005's.   

[madbean]

It could be. It could also be your 240pF is not actually 240pF or your 100k delay pot is less than 100k. You can measure the pot easy enough. If you have the cap socketed you can switch them out.

One super easy way to test is to simply remove the second BBD. Audio probe pins 3 and 4 on BBD1 and note the delay time. Now switch the BBDs out and compare. You may need to adjust the bias slightly, but I bet not.

I did not measure my delay times precisely, but I'm pretty sure I got over the 500ms mark. That's what it "felt" like.

[JakeFuzz]

I used a 1% silver mica for the 240pf. The delay pot was around 97k but it don't think it should change it that much right?. Hmm ill do the individual tests tonight.

[Loztboy]

Nice build.
How do you guys meashure the delay time?

[mysticwhiskey]

I use a stopwatch - set the delay time knob to max, add in some repeats so the delays hang around for a couple of seconds.  Hit a staccato note on the guitar and the 'Start' button on the stopwatch simultaneously, and press the 'Lap' button on the stopwatch for very echo.  I just take the average of a few readings.

If you don't have a stopwatch there's plenty of free stopwatch-type apps or online tools out there for your phone or computer.

[JakeFuzz]

I record a set of staccato type notes into my computer using audacity. Then I take the selection tool and measure the time between the beginning of the first note to the same spot on the repeat. I usually have to change the time scale to milliseconds but it gives a pretty accurate time. I'd say with the right note types you could get within 10ms of the actuality time.

[jimmybjj]

Paul, did you reach a conclusion on your chips? I am very curious as we got our chips from the same source.

[JakeFuzz]

I haven't been able to get these checked out yet. Been crazy over the holidays with family. I will try and do it tomorrow or Friday. I tried to order two more from the same place but they canceled my order saying they were out of stock. I hope I just biased them wrong it looks like getting a hold of one more is going to be a pita.

[jimmybjj]

Hey Paul as near as i can tell i'm getting about 500ms out these chips. I'm not sure if i measured right, any critiques? I play a chord with the feedback all the way up. What is the average time in a factory dmm?

[JakeFuzz]

Yeah I think if I tune mine a little better I could probably get there. I still haven't been able to get my probe out and check them. I did record a demo. Waiting for it to upload right now. These high def files are huge! I think that is a good range for the dmm some people report delay times of 600+ ms. I don't think I can get there. I really don't care that much it still sounds ridiculously awesome.

[guycapuano]

Beautiful inside and out!