Busy Circuits ALM 010 O/A/x2 Review: Attenuverter Mixer - User Case Examples

ALM010: Do you need one of these?

It is easy to focus our attention on the latest Eurorack Modular VCO, Sequencer or Filter but a well-balanced Eurorack Modular System will always benefit from a complement of utility modules like the Busy Circuits ALM 010. Utillity modules like mults, attenuators, inverters, mixers (let’s not even mentions LFOs, VCAs…) are important in allowing us to make the most of those VCOs and LFOs for example.

The ALM 010 O/A/x2 is a 4HP-wide multi-utility eurorack module which, if delivers what it promises, could be just what your small skiff is missing or it could be a great way to fill that 4HP empty gap in your bigger eurorack case.


But… what can it do? And does it do it well? Let’s find out!

ALM 010 Features Overview

Busy Circuits ALM010 O/A/x2  is a dual channel Attenuverter with a few extra features including the option to function as a two-channel mixer. 

Two identical signal-controlling channels. For each channel we have:

  • An input for your signal
  • DC Offset to add/subtract +/ – 0 to 8 volts at the output
  • The Attenuverter to attenuate and control polarity of the incoming signal
  • The Output which combines both the Offset  and the Attenuverterd  Input Signal
  • Two LEDs  indicating polarity and level of the signal present at the output

If you want to use this as a two-channel mixer there is a jumper at the back of the unit. With the jumper plugged in, you will have the output of the first channel normalised into the second channel. In this case, the bottom-channel’s Output will present you both signals giving you a 2 channel mixer

The Attenuverter only proceses the Input Signal, therefore, with nothing present at the input, the Attenuverter does nothing.

The DC offset instead, doesn’t care about the input, it generates for us +/- 10 Volts at the Output. 

CLICK HERE to watch the DC Offset video section from the full video review

The Attenuverter attenuates whatever signal we plug into the input. In the case of a DC Voltage Signal, turning the knob CCW allows us to attenuate the signal to zero-volts, keep turning CCW and you will start inverting the input signal’s polarity. Fully CCW you will achieve almost a full negative value of the input signal (full inversion and beyond is achiavable when dealing with AC Signals). E.g. DC +1V at the input gave us DC -0.96V at the output with the Attenuator knob fully CCW.

Note that on AC Signals, not only you can achieve full inversion but you also have some ‘boost’ available, which means you can boost the input signal for both, positive and negative values, past the original signal voltage amplitude.

CLICK HERE to see ALM-010 attenuation/boost of a Batumi LFO AC Sinewave Signal. 

The video shows how you can send a boosted signal into a quantizer/vco to achieve higher or lower pitch 1v/oct notes-values, therefore using the boost to extend the overall range of your musical signal.

The maximum voltage values you can achieve at the output is just over +/- 10V. As expected, the maximum voltage output is slighlty below the power supply voltage. (Demonstrated here: CLICK to see video)


Time to test how the Busy Circuits ALM 010 can be used to have some live-perfomance control over voltage intended to generate 1v/oct values for your VCO.

We built a quick patch based on (Video below shows building and testing the patches. Easier to watch we think):

  • Xaoc Devices Batumi: LFO (to represent a voltage source for your melodies)
  • Ladik Q-010 Easy Quantizer: to quantize voltage to a selected scale
  • Erica Synths Pico Voice: VCO so we can hear the pitched results

The above patch is limited offering no control over the melodic AC range or overall transposition. All you can do is vary the LFO frequency which, in most cases is not what you want.

Then we built an improved patch to resolve the ‘lack of control’ issue. This time based on:

  • Xaoc Devices Batumi: LFO (to represent a voltage source for your melodies)
  • Intellijel Buffered Mult (mult-1):
    • to send one copy of the LFO signal to the Mordax Data (so we can ‘see’ the original LFO signal)
    • to send one copy of the LFO signal to the ALM-010
    • …(continues to the right…)
  • Busy Circuits ALM 010: this gives us real-time control (Offset, Attenuation and Inversion of the voltage-source) – The output of the ALM 010 goes into mult-2
  • From mult-2
    • we send a copy of the ALM 010 output to the Mordax Data so we can ‘see’ the processed voltage signal and compare it against the original LFO signal
    • we send a copy of the ALM 010 output to the Ladik Q-010 quantizer
  • Ladik Q-010 Easy Quantizer: to quantize voltage to a selected scale – Quantizer output goes into the PIco Voice VCO’s 1v/Oct Input
  • Erica Synths Pico Voice: VCO so we can hear the pitched results

By inserting the Busy Circuits ALM010 after the LFO voltage source we have introduced an element of real-time control over the signal, in this case we can transpose and limit the amplitude/range of the overall melody.

NOTE: videos below explain the patches and shows you the whole thing working. You can see and hear the before/after effect. Please watch the video for a clearer explanation and demo.

VIDEO: PATCH BUILDING - simple and improved patch

Simple Patch without using the ALM 010. Shows the issue of not having enough control over 1V/Oct pitch voltage-source. We then proceed to improve this patch by adding the Busy Circuits ALM 010. We re-build the patch for more real-time control over our voltage-source and melodic content.

(The video below will start at 10:35 minutes into the video-review, right at the beginning of the test-patch in question)

VIDEO: Demonstrating the improved patch (with ALM 010)

Now we have control of the overall amplitude/range of the source votlage. We can exapnd or limit the overall melodic range.

We can now also transpose the overall range

(The video below will start at 13:57 minutes into the video-review, demonstrating the revised test-patch)

Building a new 2-channel test patch: transpose/Attenuate + Additional Parameter control

This time we build another patch from scratch. In addition to the same set of Eurorack Modules used in the previous patch above, this time we also use a Doepfer A-118-1 to generate some random voltage. The Batumi LFO provides a signal controlling one of the voice-parameters of the Pico Voice.

We use the top channel of the Busy Circuits ALM 010 to attenuate the melodic range (more or fewever notes) and to transpose the pitch.

We use the bottom channel of the ALM 010 to control/attenuate the varialbe effect of the LFO over a voice parameter

The two videos below will show how we build the patch and the patch in use.

Building the patch

Building a patch making use of both the channels on the ALM-010 for more realtime control over the performance

Demonstrating the patch

Using the ALM-010 Offset and Attenuverter knobs to modify patch’s melodic range, pitch and voice parameter.

Busy Circuits ALM 010: Front panel

The front panel layout is very functional, I like that they went for a 4HP. A smaller 3HP panel may have required use of smaller, more fiddly knobs. These 4HPs have been put to good use offsetting the knobs to the left or to the right making space for fingers to get in there and grab the side of the knobs. No fingernails-grip required.

Then you have two LEDs instead only one single bi-color LED. These two LEDs give you direct explicit information about the ouput signal polarity. The brightness of the LEDs gives you indication of the voltage values.

The interface works, it is easy to use, the knobs are not bad at all, they are not wobbly. Decent amount of friction helps with small adjustments, of course mV adjustments requires some care. 

This section of the video shows the two LEDs in action giving you feedback on signal Polarity and Intensity. (Video below starts at 24:13 minutes into the full review, takes you straight to the LEDs demonstration).

ALM 010: Two Channel Mixer

Time to test the Busy Circuits ALM-010 as a 2-channel mixer for our lovely Eurorack Modules.

Note: having the jumper plugged into the rear of the unit does not negate any of the other functions we have discussed so far. The jumper simply adds the two-channel mixer functionaliy on top of the other single-channel functions (attenuation, inversion, DC Offset).

For a quick and easy to follow run down of this mixer (or not mixer) functionality I suggest to WATCH THIS SECTION OF THE VIDEO (CLICK HERE), much better than reading about it.

Or… keep reading :).

In other words, it is down to how you use the module. You can leave the jumper in place and with the jumper plugged in:

  • (attenuverter) If you plug an LFO at the input of a channel you will be atenuverting that AC signal and adding/subtracting DC Offset if you so desire.
    • use the ALM output/s to send the processed signal anywhere you need, as we did in the previous patches above.
  • (independent audio channels) If you plug the Output of a VCO into one of ALM 010 inputs, that ALM channel will be attenuating that audio signal. You can use that same ALM channel’s Output to send the attenuated audio signal to your sound card or another mixer.
    • Note, if you have an audio signal into the Top-Channel ‘Input’, unless you have a patch cable plugged into that Top-Channel ‘Output’, the Top-Channel signal is normalised ‘into’ the bottom channel.
      • to use the ALM-010 as two separate voice-channels you need to have a cable plugged into the Output of the Top-Channel (to break the ‘normalled’ path to the bottom channel)
  • If you have two VCOs outputs, each one plugged into one of the ALM 010 Inputs, you can use the attenuators, one of each channel, as if they were volume faders. The bottom channel output is the sum of both VCOs voices (As long as nothing is plugged into the Output of the Top Channel

I prefer to leave the jumper in place and patch things up based on what I need. If you understand how the ALM 010 works, you can simply leave the jumper plugged into the back of the module and get on with things. Basically it all comes down to remembering that: if nothing is plugged into the output of the top channel, any signal present in the top channel will get down into the bottom channel (normalled connection). As soon as you plug something into the output of the top-channel, the normalled connection is interrupted and the two channels are independent.


This video: ALM 010 as a 2 channel mixer - Demonstrated

ALM 010: A Look at the physical module

Busy Circuits ALM-010 feels well built. It uses four Alpha-branded knobs which offer good feel in use. As mentioned earlier, it also makes use of two separate LEDs (per channel) to clearly indicate polarity of the output signal (and voltage-intensity-based brightness). A couple of T074s in there.

At the rear you can find the yellow jumper (image to the right).

The ribbon power cable is about 25 cm long

The module is 4HP wide and although the manual mentions 32mm in depth, I only measured about 27mm from front panel to end of rear power-connector. Anyway, at under 30mm in depth, the ALM 010 is Skiff Friendly.

If you want to see the module out of the case, I show it in its physical glory here in the video, CLICK HERE to get to the ‘hardware look’ section of the ALM 010 Video Review. 


So, what do I think about it, well, Mr Blue likes it, that’s a good start. They have become good friends and, as you may have seen at the beginning of the video, they spend weekends riding around the desk 

Anyway, beyond that, yes I do like it. It has been in my case for some time.

It makes it into my small 84HP case, the one you have seen used in the video review. It makes it in there most times because in 4HPs it gives me options: a 2-channel mixer if I need a couple of extra channels of mixing, otherwise it provides dual channel attenuation, inversion, boost and offset.

One reason why I particularly like the Busy Circuits ALM 010 is that you get separate control/knobs for DC Offset and for Attenuverting/Boost, on both channels. 

‘Other’ multi-functional multi-channel modules, most times, they only give you one knob per channel and you cannot operate DC Offset plus Attenuation at the same time. Usually, with these other modules, if a signal is present at the Input they only offer Attenuation/Inversion . You only get DC Offset if nothing is plugged into the input of that channel. With the ALM 010 instead, the DC Offset/Knob always works, with or without a signal present at the input, both Attenuverter and Offset are available at the same time. Other modules may offer more channels, it depends on your specific needs. 

Also, having the ‘dual’ LEDs polarity indicator is much easier to use than when you only have a single LED. I simply remember that:

  •  Top LED lit = Positive
  • Bottom LED lit = Negative

I do not need to remember which colour means positive or negative or things like LED-Off is postive and LED-On is negative… Top-Positive and Bottom-Negative is easier to remeber, but yes, these two LEDs are of different colour, Red = Positive and Green = Negative (as used by other devices where color indicates polarity, in most cases)

I can see this Busy Circuits ALM 010 module being a valid option for people with big Eurorack Cases that have a small gap to fill. Who can say ‘no’ to a couple of extra channels of mixing or a couple of extra attenuators, a couple of Offset controls, some Inversion, a little bit of Boost. So yes, it is useful in that situation.

And in a smaller Eurorack Case, in a small Eurorack Skiff, where maybe you don’t need a lot of channels of mixing or you don’t need a lot of attenuation-channels, then this is definitely a very valid option considering each channel has separate functions. It is very hand to have around. 

So, Thumps Up for the Busy Circuits ALM 010 O/A/x2. Hopefully I have given you enough information about this module for you to form your own opinion.

If you find this blog-review useful please share it (Facebook, Twitter, Instagram, etc…). I will appreciate it if you can SHARE it. It would help me a lot. And sharing will also tell me these reviews are being of some use to the readers which in turn pushes me to produce more reviews. Feel free to comment, ask questions below or leave comments under the video review on the SonicVoltage YouTube Channel, I’ll do my best to reply. 

For a more practical look a the ALM-010 please watch the Video Review. Remember to SUBSCRIBE to the YouTube Channel, there are more videos coming. 

Ok guys! Thank you for stopping by and/or watching the video review.

Until next time… Happy Euroracking, Have Fun!