Bell Electrolabs - ADT Automatic Double Tracker [schematic]
I thought this might be of interest. It's a kind of modulated doubling delay.
This particular unit is quite distressed. I've traced it to help debug it.
Switching and power are not shown. It has it's own plug, and i couldn't be bothered to follow the wires around a transformer and bridge rectifier etc. There's a couple of regulators for +15V and -12V.
I'm not very experienced with this stuff, so please take it all with a grain of salt.
It seems like a previous owner tried some repairs/maintenance (like that Mod pot that's been replaced)
So far i've replaced a couple of electrolytics, a tropical fish and both cmos ICs that were damaged.
I've found some resistors to be way off spec and will be replacing those shortly.
Some of the tropical fish have some small cracks on their surface, should i be replacing those too?
I've got it running but not getting any modulation so far. The Delay and Dev(iation ?) seem to be working.
Probing indicates that U6 (on my schematic) is oscillating but i can't hear it at all when probing around the 4046.
R50 & R51 are two of the resistors that need replacing (R51 is that big resistor near the 4046 that seems to have been previously replaced)
I can upload/take more pictures if necessary.
This particular unit is quite distressed. I've traced it to help debug it.
Switching and power are not shown. It has it's own plug, and i couldn't be bothered to follow the wires around a transformer and bridge rectifier etc. There's a couple of regulators for +15V and -12V.
I'm not very experienced with this stuff, so please take it all with a grain of salt.
It seems like a previous owner tried some repairs/maintenance (like that Mod pot that's been replaced)
So far i've replaced a couple of electrolytics, a tropical fish and both cmos ICs that were damaged.
I've found some resistors to be way off spec and will be replacing those shortly.
Some of the tropical fish have some small cracks on their surface, should i be replacing those too?
I've got it running but not getting any modulation so far. The Delay and Dev(iation ?) seem to be working.
Probing indicates that U6 (on my schematic) is oscillating but i can't hear it at all when probing around the 4046.
R50 & R51 are two of the resistors that need replacing (R51 is that big resistor near the 4046 that seems to have been previously replaced)
I can upload/take more pictures if necessary.
- Dirk_Hendrik
- Old Solderhand
Information
Information
- Posts: 3
- Joined: 14 Nov 2023, 10:41
Hey Krystal
I have one of these myself, been trying to chase one down for over a decade and finally got one.
I'm very keen to get another however so if you wanted to sell this one as is, I'd be certainly interested!
So glad someone finally traced one of these! Thank you!
For years I thought these were the same as the pedal version, but when I got in contact with Tony Koorlander of Bell Electrolabs, he confirmed that PA:CE redesigned the circuit to a basic long delay time chorus and released this unit, which he often states is inferior to his design. I'm trying to get my hands on the pedal version too but this is much harder.
I also know the pedal version has been traced by someone I know but as they paid for someone to do it, they naturally don't want to release the schematic publicly. Needless to say Tony's original ADT design is very unique!
Cheers, if you are interested in selling this, I'm very keen!.
Alex
I have one of these myself, been trying to chase one down for over a decade and finally got one.
I'm very keen to get another however so if you wanted to sell this one as is, I'd be certainly interested!
So glad someone finally traced one of these! Thank you!
For years I thought these were the same as the pedal version, but when I got in contact with Tony Koorlander of Bell Electrolabs, he confirmed that PA:CE redesigned the circuit to a basic long delay time chorus and released this unit, which he often states is inferior to his design. I'm trying to get my hands on the pedal version too but this is much harder.
I also know the pedal version has been traced by someone I know but as they paid for someone to do it, they naturally don't want to release the schematic publicly. Needless to say Tony's original ADT design is very unique!
Cheers, if you are interested in selling this, I'm very keen!.
Alex
Hi there.
I'm afraid i finished fixing it and sold it already. It sounds pretty great, but it was just worth enough that i couldn't justify keeping it. I've been thinking of breadboarding it to try and see if i could get close with a charge pump and +9/-9v or something.
If you get your hands on a pedal version i'd be interested in seeing the differences in the circuit.
I'm afraid i finished fixing it and sold it already. It sounds pretty great, but it was just worth enough that i couldn't justify keeping it. I've been thinking of breadboarding it to try and see if i could get close with a charge pump and +9/-9v or something.
If you get your hands on a pedal version i'd be interested in seeing the differences in the circuit.
Information
- Posts: 3
- Joined: 14 Nov 2023, 10:41
Hey Krystal
No worries, I'll keep looking. There is one in Liverpool at the moment but I have no means of getting it unfortunately.
From what little I've seen of the schematic for the pedal version, it basically arranges the 4 delay chips into different configurations (series parallel etc) depending on which mode is selected, and the deviation control on the pedal version works much like the Intensity knob on the CE-1, where it just controls the speed of the LFO (but the depth is fixed).
Thanks!
No worries, I'll keep looking. There is one in Liverpool at the moment but I have no means of getting it unfortunately.
From what little I've seen of the schematic for the pedal version, it basically arranges the 4 delay chips into different configurations (series parallel etc) depending on which mode is selected, and the deviation control on the pedal version works much like the Intensity knob on the CE-1, where it just controls the speed of the LFO (but the depth is fixed).
Thanks!
- robinbowes
- Solder Soldier
I've just picked up one of these, in good condition but faulty. Sounds like a bad/failed op amp though as I can hear the delay and modulation through the buzzing, crackling, & distortion!
Should be relatively easy to trace/fix.
R.
Should be relatively easy to trace/fix.
R.
- robinbowes
- Solder Soldier
Well, it took me a while to around to doing this, but it was indeed bad op amps. I replaced U2 and U3 and this unit is working perfectly again.robinbowes wrote: ↑21 Aug 2024, 09:48 I've just picked up one of these, in good condition but faulty. Sounds like a bad/failed op amp though as I can hear the delay and modulation through the buzzing, crackling, & distortion!
Should be relatively easy to trace/fix.
@nihilandvoid66 Alex, are you still looking?
R.