Aquaboy delay level too loud??

[gitaar0]

Hi,

I have build the aquaboy based on Madbeans PCB.
I have used the double delay time board with two V3205's, MN3102 and NE570.

It is working, but I have a delayed signal that is louder then I think it should be.
Mix at noon puts the delay signal already way above the dry signal. Also I have some distortion on the delays.
Also the feedback starts oscillating at 1 o'clock. Way too early.
I checked all components and readings. R31 is 22k in my build.

I accidently turned Q4 around and although that should not work it brought the signal to the right level and also the feedback was reacting better.
That made me think  that the delay signal is too loud because either the signal from the NE570 to the V3205 is too loud (which would explain the distortion) or the signal coming from the V3205 to the NE570 back is too loud (which would not explain the distortion). I do know that the delay should not be completely clean but this distortion is too much.  Could it be that we are driving the V3205 (in my case even two) too loud in this build??

All voltages read as posted elswhere. There is only one deviation in reading: NE570 pin 10+ 11 read 3,5 volts where it should be 4,1 volts.

Thanks for the help.

Best, Marc

[gitaar0]

In the mean time I have been working on this build again. Checked everyting three times.
Then adjusted all the trimpost using the method that is explained on BYOC video's.

The delay works well and I can adjust all trimpost so that I have the least noise and the best signal and delay time.

But the delay signal is still too loud. I think I will have to tame the signal from Q2 going into the V3205.

Any suggestions or other remarks?

Thanks, Marc

[madbean]

Marc: to reduce the overall delay level try this: socket R33 and try increasing values there, say 68k, 100k, etc. Or, while it's socketed, use a 250k pot set up as a variable resistor (lug1 on one end, lug 2 on the other) and fiddle with it until you get the right mix of delay and clean signal. Then measure the resistance across those two lugs and use the closest value fixed resistor you have.

[gitaar0]

Hi Brian,

I will try your suggestion but if I am correct then if I follow your suiggestion I am changing only the balans dry/delay.


I was wondering if I could change the delay level in another stage.
I would prefer to change the level going into the V3205's. Somewhere around Q2.
In that case I can reduce the distortion in the delay and at the same time reduce the feedback that starts ocillating before "noon".


Thanks for helping.

Marc

[madbean]

Gotcha. From the top of the circuit, you have a gain of 2 @ IC1A going into the compander, then some filtering and another buffer at Q2 to bring it back to unity. To reduce the signal at his point, you could leave Q2 out, and jumper the base to emitter. Leave the collector unconnected. You might jumper out C15, too, but I'm not sure.

This should knock the signal down so it's not so hot going into your v3205. Mind you, I have never tried this, so I cannot guarantee it is the best solution...but it might be worth your time.

[madbean]

Alternatively, you could try either a variable resistor or voltage divider right after C15 to control the level into the BBD.

[gitaar0]

Hi Brian,

That was an easy one to try as I have socketed my transitors. I jumpered Base to emitter.

It does bring the signal down but it is too low. I also tried jumpering C15 which had no effect.

I experimented by doing the same on one of the other transitor stages after the v3205 but without the right effect. Funny thing is that if i turn either Q2,3 or 4 around then the signal is of better quality, the level is right and the feedback is the right amount???

Any other suggestions?  Can I change the amount of gain in the Q2 buffer??

Thanks, Marc

[gitaar0]

Hi,

I missed your post suggesting the variable resistor or voltage divider. I still have to try that.


In the meantime I worked with an audio probe.

If I compare the dry and the delay level at R36 and R33 then it is very clear that the whole delay line is way louder then the dry line. (but we knew that already;))

Could it be that the NE570 is amplifying the signal too much? I have swapped the NE570 with a NE 571 I have and they give the same result so I guess the NE570 itself is ok. As I wrote in my previous post: NE570 pin 10+ 11 read 3,5 volts where it should be 4,1 volts. Is that indicating something??

Marc

[gitaar0]

Hi Brian,

I followed up on your siggestion ib ptting a variable resistor after C15. I used a 100k pot and found that with 56K I had an effect level that was cleaner and better in balans. Now the effect is at unity when the mix knob is at noon with a beautifull effect sound with no distortion.
The feedback however is still too sensitive. It starts feeding back at 2 -3 o'clock. I did not want to bring down the level at C15 more to tame the feedback as it would make the delay level too low.
The only thing I have to do now is to bring the feedback down a little so it will start feeding back at around 3-4 o'clock. I remember somebody writting about that so I will dive into that.

Thanks, Marc

[madbean]

Great! This is a good tip, then for balancing the delays.

For feedback control, socket that 22k off the feedback pot. Try increasing the values incrementally. That should do the trick.

[gitaar0]

Hi Brian,

I already figured that one out and used a pot to see what value to use and ended with a value of 30k.

So, to conclude I now have a working Aquaboy with double delay time and modulation board.
For future reference:
I have used  V3205's, NE570 and MN3012. I added a resistor of 56k  from C15 to the junction of R15 and the BBD to bring down the level going into the delay (and to control the distortion). I used a 30k for R31.

The delay is quiet and and clock noise is not audible.

Thanks for putting me in the right direction and for the pcb.

Best, Marc

[madbean]

That's great Marc.

Next week I'm going to create a 'mods' section on the forum to collect stuff like this into one area. This is very helpful info for future builders of this project.

[gitaar0]

I boxed the delay up today. I have build a few before like the PT 80, the Femtoverb and the Echobase. This could very well be the best of the them now although I have a long very good relationship with the PT80 that I use a lot on stage.

Highly recommended.

Thanks for helping.

Best, Marc

[gitaar0]

I do have some trouble getting the mod board to work right.
The modulation board works. I can get deep modulation and a high speed if I want but at certain settings (towards the extreme) the delay suddenly cuts out. Then I have to move either the delay time knob or the modulation board to get it working again. Even if I bring the clock time down (which was suggested before to be able to use the extremes of the modulation) I have this same thing happening. I already added extra resistance (a 50k trimpot) after the modulation depth pot to control the modulation depth but that does not solve this cutting out.

It does only happen in the combination with the mod board. Without, the delay works fine.

Also the speed extreme is to high to be usable. Where should I start to solve this? As I see I have three problems: the Mod depth is maybe too much, the mod speed is too high and the delay cuts out on certain modulation depth settings.

Thanks for helping.

Marc

[hoyager]

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