Aquaboy delay level too loud??

[gitaar0]

Hi there, could I use a larger value resistor in place of R15 instead of adding another to limit the volume to the chip? The last one I had built was distorting too much, no matter how I calibrated it (double delay mod).]

Cheers
Andy

Hi Andy,

My experience was that the BBD was getting too much signal and that was causing the BBD to distort.
I replaced R15 with a trimpot to find out at what value the signal was loud enough and clean enough. Then I removed the trimpot and measured the value at wich the trimpot was set and used that value for the reistor at R15. So yes you can substitute R15 with a different value, but you have to find out what works for you or follow my suggestion in a few posts back.

Success,

Marc

[hoyager]

Cool, thanks. So you effectively have a 156k resistor for R15?

The last one I built with mod and double delay had a similar probllem where the delay seemed to cut out at the fastest setting but it ended up being a kindof distortion which was quite cool. So you're not alone there!

The higher settings were kind of bunched toward that end of the pot, was that the case with yours too?

Andy

[gitaar0]

Cool, thanks. So you effectively have a 156k resistor for R15?

No, I think I ended up with 56k (I used a 100k trimpot to find the value and measured 56k when I removed it and so I used that value (56K) for R15) But it might be different for you.

The last one I built with mod and double delay had a similar probllem where the delay seemed to cut out at the fastest setting but it ended up being a kindof distortion which was quite cool. So you're not alone there!

The higher settings were kind of bunched toward that end of the pot, was that the case with yours too?

Andy

No I noticed no distortion at the cut out point of the mod depth. I have not found the best solution yet. I now have a trimpot connected to the Mod depth pot to limit the range up to the point that it does not cut out. I still have to find a better solution. Untill now no one responded to that question regarding this problem yet.

Yes the higher settings were bunched towards the end of the pot with me too. I guess replacing it with a log pot would help....

Marc

[hoyager]

Awesome thanks, I think i'm gonna roll with a 68k, seeing as I have those, and with the stock 100k it wasn't unusable.

So, B is Linear, and A Log? I've read there's been some swapping of codes... The build pdf sepcifies 1MB, that should be log?

[madbean]

1MB is linear. "A" is audio (log).

[hoyager]

Cheers, so is it supposed to be like that with the short times bunched up? I mean is that a design feature?

Out of interest, I've built a second pedal complete with dd and mod boards, but used all green / brown mylar caps, and the blue HV ceramic caps and it has come out much darker than the one before with Wima film caps and regualr ceramics. The feedback tick when the knob is full from nothing is much much deeper as well. I quite like it... although I used the multi layer cermic caps at the 330p values and I think they are causing a bit too much overdrive / distortion, its either them or the blue HV ones, I'm going to swap them back gradually, to see thats the case

Is it possible to have a switch cut the dry signal out, or the mix knob cut it out, so the pedal can be used as a send effect for dubs?

Andy

[madbean]

If you use a switch in place of R36 you can kill the dry signal. You just need to lift out the signal coming from IC1A.

Not sure what you mean about the shorter delay times bunching up. With a 1MB the time transitions are pretty smooth in mine.

[gitaar0]

If I read the last few posts I think we are mixing two things up:

I my post I said that the higher settings were bunceh up towards the end of the pot meaning the higher modulation rate settings being bunched up on the speed pot. I was not talking about the delay. I already tried a log pot wired in reverse and that spreads the speed evenly. My recommendation would be to use a reverse log pot. I am still fiddeling with the mod board so maybe this decission will change later.....

In my experience the delaytime pot on the aquaboy is quit evenly spread over the range of the pot.
(I have also a double delaytime board and V3205's)

Marc

[madbean]

Oh! My bad. I have two each of the mod and double delay time boards form Marcus. I really need to get those built and added to my existing Aquaboys so I can speak intelligently about this 

[hoyager]

Hi, I've just built another version and am having what sounds like the same problem with the signal going to the chips too hot.

I've tried replacing R15 with a smaller and larger value which has no effect for me. Swapped out all transistors and all chips, checked all resistor values and caps. Have adjusted all the trimpots for optimimum too. I've got 1.5k at R19 and I'm using green caps for all the large values 47n up and a mix of box caps and mylar for the smaller, tone shaping values

The only thing I haven't tried is jumpering out C15 and am wondering if its possible do that leaving it in the circuit and bridgeing the connections?

I feel like a cap is faulty or one of the diodes, somehow, and there is too much current flowing and/or the chips are being overdriven. I think it would sound ok if played aggresively, on a guitar, but its not as nice or subtle as the other versions I've made and as soon you play chords into it it becomes quite obviously overdriven.

Are there any other components before the delay chips I can check?

Andy

[hoyager]

Here are some voltages, maybe be a better picture

v3205 x 2 DDT mod board (pretty much the same for both)

1. 0 (2nd chip)
2. 3.35
3. 3.95 (4.24)
4. 4     (4.25)
5. 7.4
6. 3.38
7. 3.7
8. 6.35

This from a previous version I've built which is cleaner (very similar in cap choice (green mylar for large values and an assortment for smaller values)

1. 0   (2nd chip)
2. 3.38
3. 4.08  (4.54)
4. 4.11  (4.52)
5. 7.35
6. 3.36
7. 3.65 (4)
8. 6.3

The only thing funky on both of them is a 120pf instead of 100pf at C21 after the clock. The cleaner version also has a 47k at R3 instead of 475k, doesn't seem to make any difference somehow... Also on this version I had the diodes swapped, one for the other, and it worked and sounded pretty good (they are switch to spec now though)

Here are some audio comparisons, cleaner older version then newer darker version

http://littlemp3.com/daf48c7

http://littlemp3.com/b09750c

http://littlemp3.com/e8b8f72

http://littlemp3.com/d2e661e

http://littlemp3.com/76d4eb8

So obviously the new one is voiced darker, but I was trying to disguise the overdriven sound. The darker one has alot more bottom end content even when playing higher notes

Am I just imagining that is sounds bad?

Andy

[gitaar0]

Hi Andy,

The clips sound like they should mostly.

I was thinking of a few things to check maybe, if you have not done that yet.

- the signal going in your delay could be too loud, using that piano.
- I read that you adjusted the trimpots as they should be, but how did you do that? Did you use a scope or did you do it by ear. I could imagine that doing it by ear with, for example a rhodes sound, is not going to give the right comparison. Adjusting the trimpots is a pretty precise job. That is why some use multi-turn trimpots in this build.
- if replacing R15 with either a lower or a higher value is not changing anything then that makes me think that your signal driving the delay is too maybe way too loud, as it should really chance with a different value. (Or you are chosing values that are too close to one another of course).

I hope this helps.

Marc

[hoyager]

Hey thanks for your suggestions. The rhodes is perfect for revealing any distortion because the signal is almost a sine wav and its def not going into the delay too hot. As far as trimpots go, I'm absolutely sure they're dialed in, I mean my ear is a lot more sensitive than my hand holding a screw driver.

I think I was after a technical solution. I've tried replacing 2 of the 220n green mylar caps with wima box and no difference there. I've added a 2.2k resistor to the 1.5k at R19 to giving about 900ohms which *seemed* to clear it up, but only slightly

I've tried a 10k at R15, should be 100k, but it didn't affect the distortion, just the amount of feedback. It seems slightly quieter (just listening to the wet signal with feedback dialed down) but the distortion is still at the same level.

I'm also thinking maybe I should put in 4 new mpsa18 incase any of them were damaged during my previous swapping, or they are faulty? I think someone else experienced this too?

here's another example with the same sample at the same level going through the *questionable* delay, then the one that works well, all with the same settings; wet only signal, level on full, modulation off,

http://littlemp3.com/c632a29

Andy