Unrealistic Reverb

Bending Guide

Using This Guide
Bending Guides show specific bends that we have identified as interesting. Color-coded circles indicate separate bending points that all connect to a common point. We call this the Point of Origin (or POO) and indicate the POO with a circle marked with an “X”.

Occasionally a circle will be marked with a zigzag line . This means that we found it useful to add a potentiometer between this point and the POO. These are optional additions–the bend will function just fine with a normal switch.

Suggested Pot Values

• Red 1 – 10k
• Red 4 – 1k
• Yellow 1 – 10k
• Blue 1 – 2k
• Green 2 – 10k
• Green 3 – 20k

We appreciate that this is an obnoxious variety of potentiometer values, but these are the values we found gave us the best performance for each bend. If you don’t want to buy a bunch of new pots, just use what you have.

Additional Modifications

We also performed a few mods that we felt were outside our definition of circuitbending, but wanted to share as part of our build.

LED Indicator

In the original design, the LED indicator turns on only when you slide the power switch to the “Battery Check” position. We found this relatively pointless and wanted the LED to indicate when the unit was powered on.

The white boxes in the guide above mark the underside of the switch. The box on the left connects to the LED. The box on the right is the On position. Connect a jumper wire between these points. (Each box contains two solder points. Both points connect to the same position of the switch, so solder the jumper to either point in both boxes.)

Delay Rate CV

The pink points indicate terminals on the Delay slider. We thought it would be neat to control the delay rate with an external CV source, so we wired these points to a vactrol.

Mic Out Level

Since it’s no longer the 80s, we don’t have a pile of RCA cables laying around. So, we wanted to use the 1/4″ Mic Out instead. However, the Mic Out level was considerably lower in volume than the Line Out level.

There’s a factory-installed white jumper wire in the guide above that connects the Line Out to the Mic Out, through a voltage divider. We moved one end of the jumper wire from the black circle it’s in to the other black circle. This bypasses the voltage divider and results in full volume at the Mic Out jack.

Out goal was only to avoid having to buy RCA-to-1/4″ adapters, but the bonus outcome is that the Microphone slider now becomes a beautiful distortion level control.

Mix Options

There’s no true wet/dry mix on this device. The Depth slider controls the wet signal level, but no true mix option. The light blue boxes indicate the ends of a factory-installed blue jumper wire. This wire connects the dry signal to output op amp.

We tried replacing this with a pot for true wet/dry mixing, but found the results underwhelming. Due to the design of the op amp stage, the dry signal wasn’t audible for most of the range of the pot, making it impossible to achieve any meaningful mixing.

Instead, we opted for an On-Off-On (aka Center off) SPDT toggle, which gives us the option of: Standard mix, Wet only and Reduced dry mix.

Tinker with the value of resistor to get the reduced dry mix of your liking. We found that values greater than 120k attenuated the signal too much. When the wet signal was more prominent, it started to sound like two signals playing out of sync, rather than the mixed signal we were looking for.

(Feel free to use this as an example of when mixed signals are desirable.)

MN3207 Replacement

This device uses an older MN3207 BBD (“bucket brigade delay”) chip to create the delayed sound. The MN3207 has a maximum delay time of 51.2 milliseconds. We swapped this out with a CoolAudio V3208, which has delay times up to 102.4 milliseconds.

With longer delay times, you will start to hear a noticeable clock noise whine. We might revisit this in the future and add a passive lowpass filter to the output to tame some of the noise.

Built from: Radio Shack Realistic Reverb

Number of bends: 10 15

Description: Outfitted with 10 bends that create crushing walls of feedback and tone generation, the Unrealistic Reverb can be used as a noise generator in its own right.

**New!**

This was not part of our original plan for revisiting old bends in 2025, but we received a few questions about the old bending guide and thought it was worth re-exploring.

As the result of a dodgy eBay transaction, we ended up with a nonfunctioning unit. After some patient probing and parts-replacing, we were able to get it up-and-running again, but we’re not entirely sure it’s 100% right.

Because we’re not confident the unit was at 100% when we started, we offer this guide with the caveat that your results might be different from ours.

(Which should be a standard caveat for all bending projects.)

All of that said, we’ve really found some charming bends here. Many of our original bending points were still useful and valid, but we’ve found a few more to pad the total out to 15. Various walls of delay feedback. A few subtle timing bends. Top it all off with some sublime distortion and the result is a really fun slapback delay unit.

We’ve also documented some more traditional modifications that we felt added more value to the project. Specifically the Mic Out Level mod, which opens up a whole world of beautifully warm and creamy overdrive.

Demos

The following demos all feature a drum machine running through the Unrealistic Reverb. Each demo starts with a clean signal, then the delay Depth is turned all the way up, then the bend is connected. There is slight compression and limiting on the signal, but no additional effects.

Red 1

Red 2

Red 3

Red 4

Blue 1

Blue 2

Blue 3

Green 1

Green 2

Green 3

Yellow 1

Yellow 2

Yellow 3

Orange 1

Orange 2

Delay Rate CV