Digital Reverb (Accutronics BTDR-2H)

First of all, let me say this. I love my amp. It has great tone, and breaks up at a friendly volume level. But it lacks one thing that I rely on to cover up my (many) mistakes: Reverb. I didn’t want to just build another pedal. I wanted this project to be a special one. As I keep reverb turned on 85% of the time I thought instead of building a pedal (that would take up valuable board space) why not build a little unit to sit on top of my amp. Influenced by the lovely Fender tube-based spring units that sit on top of your amp I set out to create my own little op amp and digital circuit.

I purchased an Accutronics BTDR-2H digi-log reverb from a friend from over the pond and the rest of the parts from local suppliers. I based my design off a vero layout found at While his design was originally designed for the BTDR-1 Brick, I was able to modify it with help from the brick’s designer, Brian Neunaber. Brian was a fantastic help and answered my E-mail within one hour (very impressive to say the least).  As I was using a DPDT toggle for the switch I used a Millenium 2 bypass wiring to enable the use of an LED.

Accutronics BTDR-2H Vero

Red text shows the correct pinout for the BTDR-2H rever brick.

Since it was going to be sitting on my amp I wanted it to have more of a visual impact and instead of using a small enclosure I decided to go big with a Hammond 1590T die-cast box.  This left me with plenty of workspace and I had no problems fitting all the components nice and neat. Here’s what it looked like when I was just finishing up with the heatshrinking and cable management and such.

You’ll see I used sockets on the reverb module. These bricks come in Short, Medium, and Long decay models. I’m using a Long decay module, as, well, like I said, I like reverb.

Remember when I said I wanted this build to be epic? Well to really test my patience I decided to cover the enclosure with Tweed tolex, much like vintage fender amps. I purchased a small amount of the authentic material (I found out that many of the suppliers online sell a vinyl simulated tweed – Do not want) and began measuring and cutting. I won’t post a tutorial here, but one of the most difficult parts is making sure that thepattern in the corners line up just right. I somewhat suceeded in this, but hey, it was my first try.

After doing a bit of research I decided on coating the tweed with several thin coats of Minwax Polyshades Honey Pine. This is a stain/poly mix that will protect while it stains. I used 4 coats and wetsanded afterwards. I wasn’t too particular about getting exactly even coats as I wanted this reverb to look like it’s been through years of gigs and tours. Here’s the final result. I really should have taken more pictures of the process…

It fits nicely on top of my small 5F1 clone, and sounds beautiful, with no digital artifacts or loss of volume. I was surprised that this quality of sound was available from a small digital circuit with just a few ICs and parts. For anyone looking to build a reverb, those little bricks are highly reccomended.

    • ieatmumble
    • June 7th, 2012

    Hey! Any details on the changes provided by Brian Neunaber?

  1. When I asked Brian if the two units were interchangeable this was his response…
    “They are not quite interchangeable. If you want to use the BTDR-2 in mono, you need to sum the two outputs together. This is best accomplished with an active summer. You can use the passive summer that is shown in the datasheet, but the output level will be lower than that of the BTDR-1.

    So, there are two ways you could use one layout:

    Using the passive summer for the BTDR-2–but you would need to change the gain at the output of the reverb (by changing a couple resistors on the op-amp) when changing modules.
    Using an active summer for the BTDR-2 that is bypassed when using the BTDR-1. You would be wasting an op-amp when using the BTDR-1, but this may not be a big deal if you have one left over from dual or quad package”.

    I’d like to add that Brian responded to my E-mails within an hour of me e-mailing him, and his answer was both comprehensive and easy to understand. I definitely recommend his reverb products not only for their sound, but for the level of customer service Brian provides. Hope this helps you as much as it helped me!

    • Vincenzo
    • July 5th, 2012

    Great looking build! I suggest that you try an even bigger LED to achieve an even more retro look! And maybe put some big rubber feet underneath the bottom plate! 😉

    • Heyhey. Thanks for the compliment! My original plan was to cover the LED with a pilot light jewel from a Fender Amp. I still might do that, but I haven’t gotten around to it yet. And I don’t think it shows in the photos, but I do have some clear rubber bumpers on the bottom plate. Thanks for visiting!

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