CHASM REVERB

[abakuzam]

Hello again folks, i'm having some problems again My friend wanted chasm reverb to use it on a record, everything is good till this point. He send me a soundclip :  http://s000.tinyupload.com/index.php?file_id=07927315184193377675  and he told me when he open up the reverb knob that sound appears. Also he told me he watied fo 2 hours and plugged the pedal in , played a little then that sound again İm suspacting about regulator (78L05) , hope he didn't destroyed the brick. Any ideas? Btw, when i made the pedal i checked every value, every voltage, every polarity before running it for the first time, we can be sure there is no solder joints etc. pots wired correctly. Also there is no straching noise, like brick clipping. Maybe he used the pedal with ossilation swtich on all the time? Mayve pt2399's locked up? Thanks.

[DK1]

First post, novice here:

Before I start, thank you for the design! It's my 6th pedal so far, and my most ambitious to date.

I'm curious if anyone has used a btdr-3 with this circuit. I have, and I'm getting a lot of noise with the depth control. If I increase the depth (dual 10k pot), a white noise creeps in. If I crank the damp control, that reduces it, but my understanding is that it's just bleeding off some highs. Keeping the depth low gets rid of most of the noise. Has anyone encountered this? Further this noise comes through even if the circuit is being bypassed, and if I've got the depth set to max with the osc on, it will start to feedback even when if the circuit is disengaged. I've tried battery power to no avail (was hoping it was just a dirty power supply).

Otherwise, I think I have the full thing working. All knobs and switches function as advertised. It's a vero board build, so no gut shots because it's hideous in there.

Thank you,

DK1

[Mgt280y]

im about to start on this one, can somebody give me a size reference as im using a plotter to cut a vinyl mask for the pcb and want to check that i have scaled it right.

[DK1]

I'm curious if anyone has used a btdr-3 with this circuit. I have, and I'm getting a lot of noise with the depth control.

As a follow up, I checked in with Belton, and received this (edited) response.

"With the BTDR-3, it is normal for the noise level to increase with an increase in the depth control. If the noise is too high, the circuit may have too much gain in the recovery circuit for the reverb. /Hyun Park"

Helped me feel a little better about the issue, and perhaps helpful if anyone else tries the BTDR-3.

DK1

[samhay]

I have a reverb on the breadboard that uses a BTDR-3 and dual 100k pot driving the brick's depth control. I hear no significant white noise at any point on the depth setting.

The depth control of the BTDR-3 appears to set the amount of feedback around the brick - i.e. from somewhere near the outputs back to the input. There is no such feedback in the BTDR-2 brick, so this is part of the circuit in the CHASM and other BTDR-1/2 designs - via the feedback/decay control. If you turn this fully ccw, does that help with the noise as you turn the brick's depth control up?

[DK1]

If you turn this fully ccw, does that help with the noise as you turn the brick's depth control up?

No. It doesn't really interact with the decay control. The decay control seems to be very subtle. I really only notice it when I've got the osc on, where it really impacts the feedback.  I'll recheck that part of the circuit to make sure I have no errors.

Thank you,

DK1

[traktop]

I did notice like a white noise "blow" as well, but only with headphones; when playing straight to my amp I can´t hear that noise, so no complaint.
My problem with it happens when the chasm is off...
It works great: The reverb is lush and versatile, the buffer is completely transparent to my ears, and I´ve got trails. The strange thing happens when the chasm reverb is off and then I turn my naga viper booster on in front of it. The booster is set so there is a bump in volume, and when that happens, that increase in volume level seems to trigger the reverb for a while, (when the chasm is off as I said before...).
It didn´t happen all the time, only when I´ve got the boost on and I hit the guitar really hard...
Any idea?

[traktop]

Maybe I missed something on earlier posts, but what is that depht knob about? My chasm build only have 4 knobs, (level, mix decay, and damp), and the oscillation switch...

[DK1]

I did notice like a white noise "blow" as well, but only with headphones; when playing straight to my amp I can´t hear that noise, so no complaint.
My problem with it happens when the chasm is off...
It works great: The reverb is lush and versatile, the buffer is completely transparent to my ears, and I´ve got trails. The strange thing happens when the chasm reverb is off and then I turn my naga viper booster on in front of it. The booster is set so there is a bump in volume, and when that happens, that increase in volume level seems to trigger the reverb for a while, (when the chasm is off as I said before...).
It didn´t happen all the time, only when I´ve got the boost on and I hit the guitar really hard...
Any idea?

I've noticed something similar. I think that's just a side effect of having tails instead of hard bypass. With my white-noise issue, I can get feedback from the OSC loop even when the effect is "off". If I flip the OSC switch, it goes away... again, even with the effect off.

Maybe I missed something on earlier posts, but what is that depht knob about? My chasm build only have 4 knobs, (level, mix decay, and damp), and the oscillation switch...

Yup. I used a BTDR-3, which has 4 extra pins compared to the BTDR-2. Those are wired to a dual gang 10k pot to control depth within the brick itself, so it requires no modifications to the pedal circuit otherwise. After doing it, I think it's not worth the trouble, but I wanted to give it a shot for fun. Pure speculation: I think probably adjusting the value of the dual pot or the OSC resistors might be required to make it play well in the circuit. With both the Decay and Depth knobs as I have them, the Decay only varies the "echoes" slightly and the strength of the OSC feedback in my pedal. Most of the effect control comes via the Depth knob. YMMV, and I'm square out of my knowledge depth discussing such things. I just used the 10k dual gang suggested in the Belton datasheet.

Another follow-up from Belton, re the BTDR-3 here:

A feedback loop has been added around it to increase the depth, but it can also lead to instability and unpredictable behavior. This module was not designed for this application. The TL074 (DK1 note: I used a TL074 rather than two TL072s) is a bit noisy, and the resistor values chosen will increase the noise as well.

Having two TL074s in the feedback loop will increase the noise as the depth control is increased.

That said, the simplest suggestions I can offer are:

    -Try replacing (with a) the BTDR-2. Some are quieter than others.
    -Try replacing the TL074 with a TLC2274.

I hope it is helped for you.

Have a wonderful day.

Best regards/Hyun Park

So,yeah, the BTDR-3 is probably not worth it. I might eventually fiddle with it to see if tweaking the Depth pot value(s) helps, but mine works well enough for now and still sounds good.

Thanks,

DK1

[traktop]

I was wondering if there is a way of turning the pedal switching system to true bypass like the prismatic/allstar reverb, I mean, bypassing the buffer completely.

[Mgt280y]

Just finished and tested my first board worked first time  sounds great, built as per pdf build doc only change is a 25k pot replacing the 22k, just got to design box and fit up, great work deadastronaut  !!!!

[deadastronaut]

excellente'...

look forward to seeing your build...

uk is 22k / usa 25k... not a lot in it..

[Mgt280y]

Reverb is all boxed up working well,
Have found an a slight thing ... Get it all set and playing away through amp only in a clean channel, if you then switch to dirty with the amp over drive the reverb becomes too much and needs adjusting down but then go back to clean and the reverb is non existent can't seem to find a happy medium.

On a side note can some one confirm the Spdt toggle I'm supposed to be using  is it (on - on) or (on - off)
Thanks dan

[deadastronaut]

on off IIRC....

thats a weird issue.....

the output should be the same regardless....

have you tried it in your amp loop?

[Mgt280y]

Thought you were gonna say that  I'll change the toggle for the right on then.
I was running it guitar to pedal into amp combo as I say clean is perfect but switch to dirty on amp and it is too much I'll try and get a clip of the two if I can a post it

[deadastronaut]

your pushing reverb into a distorted channel...

thats like putting delay before distortion...it will be more boosted.

have you got an fx send return on your amp? try it through that.

before you swap the switch..

[Mgt280y]

I'll check tonight, just looked for the toggle can you link to the right one somewhere all on off ones only have 2 pins and there's 3 on the pcb sorry still learning

[deadastronaut]

my signal :  guitar-dist-reverb-delay....amp clean channel.

your signal: guitar reverb/delay ....dist on amp channel.

it will sound weird..

heres mr wampler demoing that very issue...around 4:50.

https://www.youtube.com/watch?v=dAWxd2bES_s



you want on/off SPDT.  (3 lugs) Double throw

not SPST.  (2 lugs) single throw.

[Mgt280y]

Ok just watched, makes sense now I'll re locate the pedal, one other check point the I have wired the foot switch as per your build doc, for wiring the led does it matter if I connect ground to lug on Dpdt  and live to the fs1 point on the pcb as I have more room to connect there

[deadastronaut]

yep should be ok...


another vid: using fx send/return..

https://www.youtube.com/watch?v=r9BrW9AGrJ4&t=0s