I just populated my Aquaboy last night. Fired up the first time no issues. But the repeats are absolutely filthy, and delay time / clock trimmer position has no effect on the dirtiness.
I've tried a couple different V3205s. I have found one that is slightly less sleazy than the others. But it's still really, really dirty. To be honest, I'm not a huge fan of analog delay in general, but I figured I'd try my hand at one anyway. I've played a few that were build around a single 3205, and none of them were nearly this dirty. I went with stock values on everything, except for the two 330p caps (I used 470p because that's the closes value I had).
I've read through some debugging threads, and it seems that R19 is a good starting point for adjustment. I believe that raising the value of R19 will pump the BBD with a higher voltage. Is this correct?
I'm not interested in adding on half a dozen daughter boards like GTR2 did. So if I can't get it reasonably clean with a few minor tweaks, I'll probably just sell it to someone who digs that kind of sound.
Here's a shot of the board:
(http://i257.photobucket.com/albums/hh218/reverse_engineer/b6d12838.jpg)
Umm...I didn't use any daughter boards to clean up my delay. Those boards are for the modulation and clickless true bypass.
To get cleaner repeats I did this, no supplemental board needed. I fooled around with a lot of different things and this sounded the best.
I added a 39k after in series right after c15 (I put the resistor down the leg of c15)
R15 - changed to 51k
R31 - With a 15k I can get it to oscillate right near the end of the repeats pots turn (this is based on changing the listed resistors due to the lower bbd input signal)
R19 - 9v regulator (This is a hair higher than what the data sheet recommends as the max )
The main power source is powering the pedal is 9.4v
Josh
Quote from: gtr2 on May 02, 2011, 01:08:46 PM
Umm...I didn't use any daughter boards to clean up my delay. Those boards are for the modulation and clickless true bypass.
I thought I read that you had a 4049 running to buffer the signal. Maybe I misread the thread.
Thanks for the tips. I'll try a few of these today and see if I can clean this puppy up a bit.
I do have a question about this:
Quote from: gtr2R19 - 9v regulator (This is a hair higher than what the data sheet recommends as the max )
The main power source is powering the pedal is 9v.
Usually a regulator needs a couple volts above it's rated voltage in order to supply constant, clean power. If you're powering the pedal with 9v, and using a 9v regulator in place of R19, wouldn't it just be easier to use a jumper? Or are you knocking down the extra 0.2 - 0.5v that many DC adapter put out? Also, are you filtering the regulated power with a cap?
Thanks man. :)
I did use a 4049 as a buffer for the clock at one point to compensate for two v3205's but it didn't help clean the repeats.
The reason I used a regulator was because I had toyed with powering at 12v and 18v in different "experiments" I was tired of changing resistors. I've got a good constant supply to the bbd's so I didn't mess with it. I did not use any additional filtering. I just stuck the regulator in at r19 and used the ground pad Brian provided. At the VDD pins the bbd's are running at about 8.8v I believe fwiw. I would run them between 8-9v at your own risk ;)
I don't know what compander you're using, but the cool audio version v571 gives cleaner repeats than the ne570. I compared both.
I did post my completed build here that has my final changes to the aquaboy board and modulation section.
http://www.madbeanpedals.com/forum/index.php?topic=1553.0
On my guitar with the hottest humbucker (non active) bridge pickup & no tone roll off, It will still distort some but it is greatly improved. I still have to do a demo, it really sounds glorious.
You do loose a little delay volume with the mods I listed. The first repeat is at unity with the initial signal with the mix in the max position.
Hope this helps. I wrestled this beast for a while...
Josh
Also, my Boss PSA power source puts out 9.6V. If you felt like that was pushing it and wanted that knocked down, use a 9V regulator I guess.
Jacob
Quote from: gtr2 on May 02, 2011, 01:39:21 PM
I don't know what compander you're using, but the cool audio version v571 gives cleaner repeats than the ne570. I compared both.
I'm using an NE571. Maybe I should order a CoolAudio version, though.
I've got a scope on its way to me, so maybe I'll hold on and see what it tells me about how things are working.
I used to have a Malekko Echo 300d, and it was so much cleaner than my Aquaboy. Same V3205 and V3102 chips. Maybe it's the compander? Or maybe just some careful tweaking post-build?
Raising R19 lowers the voltage into the BBD, which is what you want. You want to get somewhere around 7v or so. This seems to be about optimal for the v3205. Although the datasheet indicates an operation range of 5-8v, this doesn't jibe with my experience.
Quote from: madbean on May 02, 2011, 02:09:57 PM
Raising R19 lowers the voltage into the BBD, which is what you want. You want to get somewhere around 7v or so.
Ahh, got it. Thanks! I'll make some adjustments and report back.
Aight. I monkeyed around with various values for R19. The final is 2K2, which yields 6.99v on the BBD.
Incidentally, I ran the BBD at 9.2v, and nothing bad happened to it. Didn't sound great either, but at least I know it won't fry the chip.
I find that on this particular BBD, going below about 6.5v sounds bad, and going too much above 7v also sounds kinda bad in terms of distorted repeats.
As it is now, it's still dirty, but less dirty than before. Guess I'm just not an analog delay guy (a fact I keep trying to disprove, to no avail).
The only other thing I can think of is maybe lower the value of R7 a bit to reduce the gain of the first op amp. Not sure what that would accomplish, however, as there is a lot of circuit between there and the BBD.
Also, I used a NE5532 op amp, which is supposed to be quiet. Guess I'll try a few others to see if that helps any.
Quote from: culturejam on May 02, 2011, 01:59:27 PM
Quote from: gtr2 on May 02, 2011, 01:39:21 PM
I don't know what compander you're using, but the cool audio version v571 gives cleaner repeats than the ne570. I compared both.
I'm using an NE571. Maybe I should order a CoolAudio version, though.
I've got a scope on its way to me, so maybe I'll hold on and see what it tells me about how things are working.
I used to have a Malekko Echo 300d, and it was so much cleaner than my Aquaboy. Same V3205 and V3102 chips. Maybe it's the compander? Or maybe just some careful tweaking post-build?
Woops...I compared the ne571 and v571 my bad. But the results were the same, the v571 did a better job.
I bought a malekko 616 and I didn't care for the repeats it was either to dark(muddy) or too bright once the buffer was on. I was going to investigate the circuit but after comparing it to my completed aquaboy I sold it. Plus my modulation was much more tweakable. The malekko was either subtle or extreme with little in between.
I found it difficult to use a scope to calibrate. Id suggest Dirks BBD probe http://www.freestompboxes.org/viewtopic.php?t=1746 if you go that route. It is very hard to find the "right" signal when probing a bbd. I did it by ear in the end.
Quote from: gtr2 on May 02, 2011, 03:24:53 PM
Woops...I compared the ne571 and v571 my bad. But the results were the same, the v571 did a better job.
Sweet. I'll order one then.
Quote from: gtr2I bought a malekko 616 and I didn't care for the repeats it was either to dark(muddy) or too bright once the buffer was on.
I had one as well. Didn't like it either. It wasn't bad, but I couldn't deal with the "shhhhhhh" sound in the repeats. Also, I agree the modulation was hard to use.
I personally wouldn't mess with r7, the opamp is just a unity gain buffer and I think it would drop your dry signal. The best way to clean the repeats is to cut the signal right before the bbd with the changes I listed. (well in my opinion anyways ;) Maybe just try changing r15 to around 51k, that should help if you don't want to add a resistor behind c15. You pretty much have to cut the signal going in and boost it back up after the bbd for the v3201's to sound good. I'm pretty sure that's what dirk did with his memory man build, but I could be wrong. I didn't want to get in to boosting the wet signal so my repeats are a little quieter.
My repeats are clean unless I really hammer my guitar. They really sounded crappy like your describing before I made changes.
Quote from: gtr2 on May 02, 2011, 03:37:52 PM
I personally wouldn't mess with r7, the opamp is just a unity gain buffer and I think it would drop your dry signal.
It doesn't look like a buffer to me the way it is configured, but I think your other suggestions are a better way to deal with the distortion.
Thanks for the help.
I think I have a spare v571 I could send you. No charge for shipping. ;D
I didn't find the bbd operating voltage as much of a determining factor with the dirty repeats as long as I calibrated after each tweak so I just stuck with the 8.8 they were getting. Maybe there is a sweet spot, I just didn't find it.
I don't know enough about the opamp but It sounded like unity gain with my probe. You probably know better than I. I'm still a little green. :)
Josh
Quote from: gtr2 on May 02, 2011, 04:15:43 PM
I think I have a spare v571 I could send you. No charge for shipping. ;D
That's very generous, but you should hold on to it for a future project. I need to order some other stuff anyway, so I"ll just throw one in the cart. :)
Quote from: gtr2I don't know enough about the opamp but It sounded like unity gain with my probe. You probably know better than I. I'm still a little green.
It's got resistance in the feedback loop, which means it is outputting more than unity. But it's 4K7, so the gain is going to be not that far off from unity.
I changed R15 to 50K (didn't have 51K). I think that made the distortion worse. ??? :'(
Hmm...I know some have reported success with just changing r15 it was worth a try. I didn't, that's why I tied a resistor after c15 to form a voltage divider instead of just sending some of the signal to ground. I'm assuming that you recalibrated after the change.
I put in a 250K pot for R15. Doesn't seem to change the sound so long as resistance is > 0.
I tweaked the Bias all to hell and back. There is a tight sweet spot, but it's dirty all around.
I also tried a TSH221 dual op amp, but it made no difference.
That's why I added a resistor after c15, because I didn't have success like others did
I left a pot in for r15 and added a 33k down c15's leg into the pad. Then I adjusted the r15 pot till I was happy. I ended up around 51k for a compromise between delay level cut and dirt.
I put 100K back in, and I swear it sounds better. Can't figure this one out. Oh well.
Yeah, I know what you mean. My ears got tired with this one. I didn't like just lowering r15. It was either just really distorted delay or nothing.
I was looking at the schematic and thinking about what you said earlier about changing r7. Since it is a gain stage like you mentioned. I wonder if decreasing r7 and increasing r5 slightly would help with this issue. While mine is done and over with already, it would be interesting to see if this would work. I just wonder if something would need done at 1C1B as well to compensate?