DeltaLab Effectron, I, II, III ADM (Blue) Digital Delays From The 80’s (what I know so far)

First of all, I have an Effectron II ADM 1024 and it sounds Amazing, particularly the way it clips. I am on the hunt to figure out, if possible, how to retrofit these to slave to an external MIDI clock, or otherwise sync to a DAW.

I’m posting this because this has been quite a research project and if you’re trying to do the same thing, maybe you’ll have an easier time.

I got mine completely dead for ten bucks from a friend, popped the top off and got it to power up (I think it was a fuse… I’ll confirm that and update this)

Mine had dirty pots which I WD-40’ed and now sound pretty much perfect.  I think my input gain still crackles from time to time but I don’t ever need to adjust that after getting the primary level.  I also had to replace one Potentiometer since the knob shaft was broken off. I was able to do that easily.

Some stuff I learned:

  • The only place to get a schematic for the ADM 1024, unless DeltaLab writes me back with a copy, is HERE. For the sake of attribution, I’m going to leave this as an external link, but I have the files from that site saved and if that site ever goes down, I’ll upload them to my own site.  The schematics are pretty hard to read and I think there are some holes in the scans.  Better than nothing.
  • As far as I can tell, it’s totally possible and relatively easy to increase the maximum sample/delay length in these things just by adding a resistor or two and some inexpensive ram chips.  See HERE. On that page the author increases an ADM 1020’s max memory from around one second to around two seconds by adding three additional chips.  What I’m not sure of is if you can up it to four seconds by adding nine. The RAM, I’m pretty sure,  is MK4564-20.  There are some on eBay right now for about two dollars each. Found an Allegedly identical part for around eleven dollars each, so maybe they no longer get made.
  • [quote from same site:] DeltaLab used a special type of Adaptive Delta Modulation (ADM), which they continuously improoved over the years. You might take a look at US-Patents #31720, #4190801, 4254502, #4305050, #4313204 and #4462106. This is much more sophisticated than the cheap ADM projects that were published in various magazines as musical diy projects. (Elrad Delta-Delay, and others) The great thing is that the patent text even has component values shown !

  • I’m currently in discussion with someone over at Molten Voltage about whether or not one of their PedalSync products can be used to make my ADM 1024 slave to MIDI Clock from my computer.  Probably their MV-64. I will update this if I get anywhere.
  • I’m also currently talking to some nice stranger via the forums about the same thing.
  • [On that forum “q_u_e_s_t said:]…the clock comes out on pin6 of IC38 (4528B) [see above schematic link]. it is a 0 to 12v digital signal varying from 250kHz to 1MHz. it has a fixed pulse width of 0.5?s for the high period, and the low period varies in length to make up the remaining time… [and]…the way this delay pedal works is very similar to BBD. basically, BBD is a long line of buckets that hold an analog voltage level. but, in this device, its a long line of buckets that hold a digital voltage level. as a result, it needs to be clocked faster, as 1 bit of data (1 logic level) doesnt carry as much information as 1 analog bucket. so you need a bunch of digital buckets to get read in the same amount of time. so, what this means for their kit, is wether or not it can clock fast enough. ask them what the highest clock rate on the kit is. it needs to go to 1MHz…

10 Replies to “DeltaLab Effectron, I, II, III ADM (Blue) Digital Delays From The 80’s (what I know so far)”

  1. I am trying to find 8248 10k pot mine broke off.
    It is a 4pin mounts to PC board and controls the output.
    Not having any luck I hope you can help….

  2. chris,
    All I can say is most ICs and even more so, most old-school components like pots, resisters, capacitors Etc, are commodities in the sense that many manufacturers make the same part.

    There’s probably a part number on the potentiometer that you can google…

    If not, the main thing to know about pots is whether or not they’re “linear” or whatever… Beyond that, a pot’s a pot. In the case of 4 poles, I think that’s probably two pots in one. But with a cheap volt/ohm meter, you could easily verify whether or not a pot you buy has the same lead configuration as the one you’re removing.

    Anyway, try googling whatever cryptic numbers are on the pot.

    Let me know if you find it!

    good luck.


  3. Hi! I’m currently looking a photo or blueprint that shows how to reconstruct the dog bone assembly underneath the push button assembly. When I got mine all the buttons were locked up. Previous owner attempted to too free up the buttons that his kid had jammed in. all the parts are there but I have no idea how to lay these progressive linkage parts together to make the buttons work again. looking for suggestions on how repair this duct tape to hold in the button I want is my only fix at the moment LOL

  4. re the ALPs pots breaking off, I have the Effectron II missing shafts from R4 and R5. Just ordered some 10k pots w/6mm shafts which I hope I can cannibalize for the wiper/shaft assembly. Especially that one with the fourth terminal – there is a small board mounted to the back of the pot with a trace going over to that terminal. But it has the same numbers on it as the other. It occurs to me now that board could have been added on by Delta – but I’m not where I can look at it now. Will have to get back with results after the new parts come.

  5. Soo, cannibalizing did not work… the parts I had were not quite the same. Fortunately, the 10K linear pots are easy to find. The center tapped pot for the feedback control will be tougher. They were used in the 80’s for 20 dB pads on pre-remote stereo amps, like my NAD. But I found a 3pack on ebay from Thailand, only it’s stereo. And the center tap comes out the top. Good news is the three terminals at the bottom go in the correct places for the pot shaft to come out the control panel faceplate, there is room to attach a jumper from the top mount CT to solder pin 4 (on your right as you face the unit), and its easy to take off the back channel pot; it does not support the front mechanism. I retract my guess about DL adding the CT board, it’s just a part I had not seen before.
    Put the front on to hold the pot in place while you solder it (from the bottom). And be aware that the top and bottom machine screws are different sides. Also, be careful of the signal and overload LEDs seat back in their holes in the front plate.
    So, unit is up and running. Caution: switching delay settings (the lockout buttons which choose phase, echo, etc) will send out a pretty big pop. I had forgotten this. So turn down the volume as you make order of magnitude time changes. Company arrived before I could really explore this old box with new ears – but I did get some nice phaser effects on fretless bass, enough to confirm the repair.
    And I have an extra few dozen 10k pots in inventory now. Got two blue knobs with the lot, and they match well enough.

  6. re Rob

    I also am attempting to repair a DL Effectron with a broken four terminal potentiometer. I am curious how you solved the center tap issue when you replaced it. I haven’t been able to find a suitable replacement. Any help would be greatly appreciated.

  7. I have an effectron 1, 2 and 3 . Recently the III just puts out garbled noise and I have yet to find a solution . Great units that I’ve been using for years though .

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