the Dynacord VRS-23 analog delay

(click images to enlarge)

The VRS-23 was a quite successful BBD delay in the 80’s and some thousands of units were sold during that time. It’s a mono-in / stereo-out device and capable of delay times up to around 400ms. Providing also very short timings and a modulation option makes it capable of creating chorus and flanger type of effects as well. There were different revisions available and shown here is a later one with the white faceplate.

The BBD delays are great companions not only in the guitar rig but also for the classic analog mono synth (as well as their digital recreations). In the delay/echo mode of the VRS-23, the mono input signal splits up into two internal lanes to form a sort of ping-pong effect. Each lane contains 5 BBD chips in serial and the delay time switches on the front panel are allowing access to four different taps of the delay line. The separate delay knob then allows to fine tune the timing by simply changing the clock speed for the BBD’s. In its reverb mode, the clock is faster and the individual taps are getting mixed altogether.

Having a look into the interior and on the mainboard unveils two Phillips NE570 as the compander chips and this actual unit uses 10 Philips TDA1097 BBD chips, each of them featuring a 512 stage BBD line. The TDA1097 is basically an 8-pin version of the TDA1022 where data sheets can be found much easier as of today. The older VRS models were using different chipsets.




  1. Can’t be better than NastyDLA. :p

  2. I’m glad you understand that circuit board. I thought I was looking at Darth Vader’s chest plate.

  3. Cool thing in the 80´s. Nothing that we cannot do today with any delay that comes integrated on any host. Am i missing somehitng?

    • tajikawaoo says:

      yep. distortion characteristics and delay time-dependent filtering.. it’s not that common for a vst to emulate those interactions. (as well as more esoteric other things, it seems)
      but the more i investigate, the more i find that it’s easier to build one in hardware taking advantage of existing designs, than trying to understand every parameter to re-model. the only problem is the same old one : PSU and current filtering. besides that, 70-100 euros and you have made it.

    • There is a lot of mojo missing in a plain digital delay. If outboard is an option for you, buy a cheap used one as long as they are still working or grab a DIY kit …

      • I have not (yet) found a plugin that sounds like a bbd delay…
        I have the vrs23 delay in my rack and its simply amazing!

      • tajikawaoo says:

        the new korg monotron delay seems to be a little noisy, but with ms-10 filtering and bbd delay it’s a no-brainer, for 40€. on tap tempo effect pedals, I have recently implemented an old trick to inject the clock using pulse waveforms, so I can sync it with every sequencer through midi inst or audio tracks. it’s just two electric components, and it works like a charm. (it’s not even 100% precise, there are still some sweet fluctuations, and that’s a +1 for me)
        anyone interested?

        • sounddemo, pleeez 🙂

          • tajikawaoo says:

            a demo of the effect pedal syncronized or of the monotron? atm i only got a cheap digital pedal (a behringer, just to test the circuit without wasting $$), but the trick works with every device that supports pedal (button, or external switch) tapping tempo… i can post a video if you are patient. but if i could understand better the bbd circuits i’m sure i would find the right spot where to inject an external source…it just takes to understand which kind of signal is involved, and where.. if it is a dc at low voltage pulse, the game is easy to play 😉

  4. Oh, a good friend of mine has got one. Really a piece of gear to be jealous for! ❤

  5. Well i can’t say anything bad about it otherwise you will delete my comment again.. ?

  6. OK, I know this is an old entry so it is probably pointless that I still comment but it is for the sake of accuracy, so here goes.
    The TDA1097 is NOT a version of the TDA1022,
    It ofcourse is a BBD-chip but it has 1536 stages not 512 as mentioned in this article.
    The datasheet can be found in the 1985 RS data library wich can be found online.


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