Behringer RD8 MK2

Apologies for not providing any further updates/ or pending mod descriptions for this project any longer. I describe many mods here (more than the classic mods for the original), including mistakes and spelling glitches, and feel I rather want to spend time on other synth modding/development projects.


Originally, this MK2 move made me a bit concerned – synths as fast fashion or something… this didn’t come from some “vintage rules” or “replification istead of clonisization” angle, but simply made me feel that I had to balance my joy over the democratisation of music making against the affective and ecological dynamics of a business model of high sales with small margins. Treehugger much? Yep, baby, cats and cuddles instead of car and kids! As for other MK2s or Mk1s for that matter, I’ll go more with a “let’s wait and see first” attitude.

Anyhow… below you find some comparison between revisions, some thoughts on the clap circuit, and, of course, very soon, mods for the MK2 and some suggestions for tweaking the MK1 towards MK2 sounds. The differences are not huge, anyways.

Comparison MK1/MK2

Around a year ago I checked out the MK2 against the background of being familiar with the MK1 circuits: There weren’t many A/B clips in that report, so first of all, here is some more decided MK1/MK2 testing.

Both machines were recorded via a MOTU828ES into Logic with the same gain from the phones out (going for same signal polarity, which is inverted on the MK1’s main out). Sound settings on both machines were identical. When you hear slight differences of pitch, that’s on account of general (minor) tuning differences in both machines. For instance, the two snare oscillators on that MK2 I recorded were more detuned than those on the MK1.

The first hit in each recording is always the MK1, followed by MK2 (then alternating betwen 1 and 2). For the BD clip I used some panning (Mk1 left, MK2 right) to make the difference clearer as there are some staccato hits for the legendary “kick buildup” effect.

Bass Drum

Snare Drum



CL/RS (MNK1 is a “Rimzilla” version, see my RD8 page)





Demos with more/all instruments playing will come along soon!

Reports on my Clap have been exaggerated

The pitch differences in both claps are apparent but these are on account of a different resistor value that sets the cutoff of the noise body lower on the MK1. Deep88 got in touch with me immediately when A/B-ing his and I helped them modding their MK2 to go lower:

Here’s what the retromodded (lol) MK2 clap sounds like:

Now, let me be a bit obnoxious… As for the BA662 clone in the clap rattle circuit (Mk1 uses a 13700 OTA here, which counts as an acceptable substitute), spotting differences is less easy. Listen to this (bit of a longer file) and guess which is which:

Let’s take this to absurd lengths – here’s a setup that approximates an SH101 (As3340 VCO, As3109 filter, then As662D VCA vs /LM13700 VCA). Which is which?

Don’t get me wrong, I do love me a BA662, but a magic formula it ain’t/the surrounding circuits do have an effect here too! Which kinda brings me back to my Amazona review and the feeling of “less PR and more R&D and passion, please!” After all, the only (noise) trimmer in the MK2 is labelled “function”- wow…


ATM you will only find some mods here, so best also check my MK1 modding page. There I describe the basic circuits (which are the same here, except improved instrument summing) and link a range of sources with further 808-style mods.

Let’s kick off with some extreme FX tweaks…

Bass Drum

Extended Decay: This mod extends the longest possible decay of the bass drum and can/should be done as a fixed tweak as it basically just alters the long range of your BD decay knob. Simply wire a 1,5M-1M (more ohm = less maximum decay) across R435 (47k). This increases feedback of the T-bridge and makes your kick ring longer.

Example with 1.5M resistor across R435:

Note, how the lengthening also depends on the centre frequency of your kick – lower tuning = more decay in this case. Also note how buildup effect sets in quite drastically when you use long decay and fast notes.

Change pitch sweep amount: R312 (6.8K) sets how much the pitch envelope of the kick affects tuning. If you want to increase the effect, simply replace R312 with a 4.7k resistor alternatively, toy around with replacing R312 with a 5k potentiometer and a 3.3k resistor in series (pot set up as a variable resistor). Easiest solder points are collector T28 and top terminal C259.

Example with 10k across R312 (more extreme):

Example with 20K across R312 (less so)

Make click filter stronger/click duller: use this as a fixed tweak as this simply extends the maximum muffling when the tone knob is all the way down. Add a 100nf capacitor to C232.

Hammer”-blam trigger conditioner mod: increase the value of C263 to 100nf by wiring a switch and a 100nf cap across C263.

Snare Drum

T-Bridge Boost: I like this one as it gives more oomph to the snare. Snappy and snare body (the “plonk” bit) are passively summed and with this mod you simply increase “plonk” level. Either replace R330 (100k) with s 51k resistor or wire another 100k resistor across the existing one.

Snappy decay: C331 (0.47uf) sets the decay time of the snappy bit. You can increase this decay time with a fixed resistor (on the machine I just have here 100nf on top sound rad!).

100nf on top:

4.7uf on top (way too much):

Variable snappy decay: Alternatively, you make this time variable by adding a much larger capacitor (try a polarized electrolytic 2.2uf-4.7uf – cathode is the bottom terminal of C331) and then wiring a 1M pot between the cathode of your enlarged capacitor and ground. You may want to toy aroudn with different cap and pot values for finding your sweet spot!

More low freq on snappy: snappy is practically just filtered noise, and toying with this filter circuit can be fun. Test adding a 100nf capacitor on top of C337 – this opens the filter a little bit on the lower end. Go crazy and use larger cap values (or not…)!

Variable snappy cutoff: By replacing R590 (22k) with a 50 pot and a 2k resistor in series, you can have some fun! Here’s just a quick and dirty clip where R590 toggles between 22k and ca. 10k resistance..


I seem to find toms on classic XoX machines feckin boring, so hard pass this time… (check my Rd8, MK1 page and/or my Roland CR-800 pages though for ideas…)

Clave and Rimshot

quite a couple of things more are possible, yet I find RS tune and CL tune the most interesting modifications.

RS Tune: replace R173 (5.6K) with a 10k pot (set up as a variable resistor) and 1k resistor in series.

CL Tune: replace R533 (1k) with a 2k pot (set up as a variable resistor) and a 200ohm resistor in series. NB if you go too low (say, by using a 5K pot), the circuit starts beeping by itself. Coll for techno stuff maybe…


Here you hear offset, fuller body, frrp mod and “pitch “tune” mod in one file:

Fuller body: you *need* this, especially when doing the pitch/cutoff mod too. Wire a 220nf capacitor across C235 in order to unleash that clap body!

Frrrp: clap consists of two main components, some reverb body and some initial frrrp (a saw wave modulating a VCA). Now, you can easily tweak that initial frrrp by replacing R492 (on the original Tr808 this is R354 with 5.6K) with a 50k resistor (set up as a variable resistor). This interacts nicely with the offset mod Behringer already implemented.

Reverb on/off: simply wirer an on/off switch between ground and the cathode (lower terminal in the picture) of D47. Engaging the mod switches oof the “reverb” component and gives you a clap as dry as they come.

Tune/cutoff: the main “body” of the clap consists of filtered noise. By making the cutoff of this filter variable, you get something akin to tune (as that filter is resonating it emphasises the frequencies around the cutoff point very strongly). Do this mod by replacing R139 with a 25k pot (set up as a variable resistor) and a 1k resistor in series. If you want your clap to go even higher, reduce that resistor value – but mind your ears!


Sadly, the cool cowbell mod of the original 808 cannot be done as easily on the Rd8 as the hex-noise tuning in the latter is done per CPU… re wiring everything to 808 is doable but tedious… pester Behringer for tuning options in the firmware!! 😉

Decay: for longer cowbell decay, augment C269 (0.47uf) to anything you like 🙂

Filter tuning: the cowbell is two square oscillators sent through resonant filters. You can change the cutoff of these two filters and foreground different characteristics of “yoiiink,” if that’s your kink. Simply exchange R160 (2.2k) with a 5k or 10k pot and a 100ohm resistor in series.

Cv input: as easy as feeding cv into the cathode )lower terminal) of D52.

Hi Hats

Again, more is possible (see my Rd8 and my RD6 pages), but this is what I like best.

More body: the hats, as they are, sound okay, although I sometimes miss the force&shimmer I know from my CR-8000. Anyhow, you can extend the bottom end a bit by wiring a 1nf capacitor each across C233 and C231. Shoddy demo of various hat settings (occasional click when I put the cap in by hand):

NZ attenuation: the main component of hats and cymbal are six bandpass filtered square waves. The bandpass filter is fun (see cutoff mod below), but it also has a great part in whether the metal works in the TR/RD shine or screech. I find attenuating the input of the filters by wiring a 1k resistor between the top of R317 and ground makes for a generally smoother sound.

BP Cutoff: you can change the cutoff of both bandpass filters by replacing R238 and R283 (560ohms) each by a 200ohm resistor and a 2k pot in series. Toy around for some extreme sounds!

NZ IN: C267 and C295 are the audio inputs of OH and CH, as it were. Here, the bandpass filtered metal noise comes usually to play, but you can also lift these caps from the PCB and use the upper terminals for feeding in white noise (use a toggle switch to have metal/white as options). Note that lifting SMD caps can be a bit tedious — be patient!

Nerdy excursion – exchanging VCA transistors with high HFE types

Reading through Yocto and other fora about 808 circuits, you often read that the swing type VCA transistors in the hat circuits (and the snare snappy, for that matter) should use transistors with a HFE factor of over 300. Basically, better amplification & shinier hats…

Behringer uses stock transistors here, which are not too shabby in that area (if memory serves I measured HFE of around 240). Out of curiosity I exchanged them for BC547C with some higher HFE, and here’s an A/B recording….

First, let’s hear the stock version on the closed hat. I simply sweep the tone knob up:

Now the higher HFE types, same sound/pattern:

Worth it?

White dot markings by me…