Ghost Echo / spirit box

C

comradehoser

Well-known member
I kind of get the fuzz dog mods, but don't really know much about the Belton brick and how it works

R4 from 10k>18k to increase volume (because I'm increasing resistance to ground?)
R8 from 22k>12k or 10k to move the range of the reverb into self oscillation (because I'm reducing the resistance the signal has to overcome to initiate a feedback loop?)

Why also change the dwell pot from b5k>b25k or b10k? Is it to adjust so the self oscillation hits further down the range of the potentiometer, or...?
 
I could be wrong. It's been a minute since I've done some circuit work. R4 affects the output gain of IC1.2. R8 in series with C4 creates a EQ filter and altering that would change the frequency. Increasing the DWELL pot would slow down the sweep of the 2399 control.
 
Hmmm.

Well, the R8 and pot mods were published by fuzz dog and folks in this forum with respect to modding ghost echo v.1 to be like ghost echo v.2, where the dwell pot permits oscillation and maybe has a more pronounced effect.

I did the R8 swap (10k, socketed), and have self -oscillation, so I am wondering what the pot swap accomplishes/ changes at all, before I go desoldering those legs.
 
[edit: this is a record for posterity's sake to help whoever else goes through the build and wants to modify it]

Tried 10k and 12k for the dwell resistor at R8. Definitely like 12k more. I like hearing reverbs on the cusp of feeding back, that's more doable with 12k and the dwell and depth pots near the end of their ranges. 10k puts you early q straight into Belton brick "heee-hoooo-heeee-hooooo" self oscillation, which I have more than enough of with moonn's "space is fun" reverb, and which actually gets on my nerves after about 2 seconds. It's not an interesting or variable texture.

Replaced the pot from b5k to b10k. Makes the range more useable, think. Think I will try the b25k for funsies even though I lifted a trace.
 
Last edited:
The fuzz dog mods, 12k at r8 and a b25k pot for dwell gives me all the best ambient reverb this circuit can give, as far as i care to have it. 10k and b10k was too much.
 
comradehoser said:
I kind of get the fuzz dog mods, but don't really know much about the Belton brick and how it works

R4 from 10k>18k to increase volume (because I'm increasing resistance to ground?)
R8 from 22k>12k or 10k to move the range of the reverb into self oscillation (because I'm reducing the resistance the signal has to overcome to initiate a feedback loop?)

Why also change the dwell pot from b5k>b25k or b10k? Is it to adjust so the self oscillation hits further down the range of the potentiometer, or...?
Click to expand...
The 18k is supposed to combat the volume loss but in my experience it is somewhat a taste thing. Like it isn’t the CE-2 or TR-2 level of volume drop. In mine I used 15k there.

The 22k one you either jumper and just use a 25k pot (the most wild way) or you do a 10k pot with a 12/10k there for earlier and more noticeable oscillating. Mine is a c10 pot with a 12k resistor.

Im
Looking for the schematic page as all I’ve found so far is my hand notes which are illegible lol. Did you already buy / mount the belton? If not there is a slightly more expensive variable delay option that you can get and I highly recommend. It’s pin compatible and Between the different brick and the changes you mentioned you’ll get a mix of the original and a lot of fun weird settings.

The only YMMV disclaimer is that when modding the circuit in such a way the controls become very sensitive. Less a downside so much as an observation to consider when choosing your knobs / layout
 
jcpst said:
What is the name of it?
Click to expand...
Yeah, i'd also like to know even though I have already installed the Belton brick.

For posterity, I did do the 18k volume mod. Settled on 15k and 25k pot. Can self oscillate when dwell and depth are maxed and repeats are full CCW. I feel like the 18k volume made it a funner overall pedal. For some reason it changed the quality of the self oscillation so that it was less grating.

I usually run it just backed off of self oscillation as I really don't like the qualities of Belton brick oscillation

It's a cool pedal, but for this type of verb, you can definitely get there in more plush, dynamic, and interesting ways with the afterneath/deflector.

Actually, I wouldn't be surprised if this was the precursor idea/circuit to the afterneath.
 
comradehoser said:
Yeah, i'd also like to know even though I have already installed the Belton brick.

For posterity, I did do the 18k volume mod. Settled on 15k and 25k pot. Can self oscillate when dwell and depth are maxed and repeats are full CCW. I feel like the 18k volume made it a funner overall pedal. For some reason it changed the quality of the self oscillation so that it was less grating.

I usually run it just backed off of self oscillation as I really don't like the qualities of Belton brick oscillation

It's a cool pedal, but for this type of verb, you can definitely get there in more plush, dynamic, and interesting ways with the afterneath/deflector.

Actually, I wouldn't be surprised if this was the precursor idea/circuit to the afterneath.
Click to expand...
I was misremembering how I did it, but I used this one, if you look at the respective datasheets you can see how to make the 3 adjustable vs the 2. I used a trimmer, you can always add a pot.

I will crack open my spirit box which I used as the prototype for my own board and make a diagram / post pics for how I handled it. But more or less I remember just bending the extra pins and wiring off them. There’s also or was a 6 pin variant of the variable one but it was the wide body and I can’t find it for sale anymore, I believe that one had a wheel pot on it and was made more for karaoke / vocal circuits. Which explains why it doesn’t seem to be made anymore and also how / why they left off the extra control pins

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Belton BTDR-3H - Reverb IC

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