I had to work long hours today, and my back hurts bad, but I still wanted to put something together to keep Jamuary plugging along. Normally on days like this I would have done a quick patch on the iPad, but today I decided on a reasonably simple Make Noise feedback patch, using a very similar patch to my first feedback exploration. I need work on my feedback patching, but there are definitely many nice parts.
The quick and dirty notes:
QPAS L LP output > Mimeophon L Input Mimeophon L Output > Output mixer AND QPAS L Input Mimeophon R Output > Output mixer
With this configuration you’re monitoring from the Left and Right Mimeophon outputs. I also added a dark and dirty reverb, the Maneco Labs Otterley, before going to the output for a little extra murkiness.
Modules Used: Make Noise QPAS Make Noise Mimeophon Make Noise Maths Make Noise Function Make Noise Wogglebug Maneco Labs Otterley
I’m definitely a novice when it comes to feedback patches. I have only done a small handful, and recorded even fewer. After happing upon a very nice sounding feedback patch by Pete on the Make Noise YouTube channel and staring at my newly set up Make Noise synth, I decided to see what I might be able to accomplish. I didn’t set out with any goal in mind other than to explore feedback without blowing my headphones or ears in the process. I didn’t really set out to record this patch, even if I did. That’s one major advantage of routing everything through AUM; recording any patch is only ever one press in AUM away.
Although I was inspired by Pete’s patch, there is a small difference. Rather than monitoring from Mimeophon’s stereo outputs, I’ve reversed the I/O between modules, monitoring from QPAS’ Left and Right LP outputs. The core of the patch is very simple. The Left LP output from QPAS to a mult. One copy to Mimeophon’s Left input; the other copy to the output mixer. Mimeophon’s L output to QPAS’ Left input.
A few sources for modulation were used throughout, most notably Maths and Wogglebug, with an assist from some QPAS-ian self-pleasure via patching the Left HP output to a highly attenuated Frequency CV input.
Although I sometimes re-work a patch after recording it, I generally make a couple of obvious (to me) changes, re-record it, and move on to something new. But something about my Study of Addac’s new Swell Physics captivated me, and compelled me to go through several revisions and re-records to flesh out something interesting.
The base of the patch is the same: Swell Physics sends out modulation, which controls the level of the four voices of the RYK Modular Algo, and drives most of the modulation in the patch. The RYK Modular Algo output runs through a filter, and into Beads. All of these are mixed and sent to a reverb. But just about every aspect between those modules has changed. Modulation has been added, subtracted, and tweaked. I went through 4 filters before finally finding one with the right sound. I’ve experimented with different settings on all of the modules to find just the right sound. I added in delay to give some subtle length and a nice tail to the swells as well as the spray (which was also added). With dramatic results, I also changed reverb to the beautifully haunting Walrus Audio Slöer. All in all I spent upwards of 12 hours building and tweaking this patch, making no fewer than 13 different recordings, constantly evaluating the results and searching for way to improve it.
It’s hard to document all of the changes. There were so many. But suffice to say that nothing within the patch went without heavy scrutiny and experimentation. It’s the first thing that I’ve made which resembles something like a finished piece of music.
Ping Pong delay is easy, right? Just tick a box in a plugin, or flick a switch on your handy stereo delay unit and you’re done, right? Well, sure, but that’s all digital. What I’m talking about is ping pong delay, old school. Patching 2 mono, analog delay units in order to create ping pong delay in the stereo field.
When I first started thinking about how to do this, very few ideas came to mind. Of course there is the pseudo ping pong trick of setting one delay time at X with the other delay at 2X, which would give you a repeat on one side then the other. But that only works for exactly 1 repeat per channel. If there is any feedback, the first delay will sound again each time the second plays, which means it’s not really ping pong at all. It’s only kinda sorta ping pong. I wanted something better. The real McCoy.
As I started to research analog ping pong patching via Google, I was quickly dismayed. There aren’t really any good sources I could find to explain the method for patching ping pong delay. Nothing. Nada. After I couldn’t find the info I was after via research, I decided to ask. I asked on an audio engineer forum. Crickets. I asked a home studio group on Facebook and was met with “Just use a plugin. It sounds the same”, as if that’s a good answer to the question of how to patch analog hardware. I looked in my own studio recording books, which were all silent on the matter. It’s as if this information just doesn’t exist, or, more accurately, was outdated by the time the internet arrived, and the knowledge on how to perform this studio trick was simply never recorded digitally. It’s a lost art from the days of yore when everything had to be patched manually, and no one outside of studios used it. A voodoo spell that not even those inside of professional working studios seem to use any longer. Analog ping pong delay is dead.
After searching for what seemed like forever, I finally happed upon a video which explains using 2 analog delays in ping pong fashion, with the aid of a desktop mixer. The patch is fairly simple, even if it’s not intuitive.
Sound Source > Ch 1 input (panned center) Ch 1 Aux Send > Delay 1 input Delay 1 > split directly to Ch 2 input (panned hard left) and Delay 2 Input Delay 2 > Ch 3 input (panned hard right) Ch 3 Aux Send > Delay 1 input Mixer Stereo Output
Be sure that both delays are set to the same time. Be extra sure that the feedback (repeats) for both delays are set to the minimum (1 repeat). The Aux Send of input 3 (Delay 2) controls the number of repeats. BEWARE: This is a feedback patch. It can get out of control very quickly.Use the Aux Send wisely.
But I don’t have a desktop mixer, and although they can be had inexpensively, I didn’t really have much use for one outside of wanting to do tape echo ping pong delay. I used to have a Xaoc Devices Praga in my eurorack synth, which would have been ideal, but I sold it in favor of decentralized mixing alongside using a matrix mixer. Hmmmm….
A matrix mixer is nothing if not a set of inputs, sends and returns. “I think I can make this work, even in the context of my matrix mixer being full stereo”, I thought. And sure enough, after several drafts in my Notability folder for synth patching, and experimenting with dummy cable theory, I had a solid plan. I just didn’t know if it would work.
The theory with a matrix mixer is the same, but because mine is stereo, I had to use make clever use of some dummy cables in order to defeat L> R normalization at the inputs to ensure everything was in the correct channel at the outputs, while still having access to the dry and wet signals independently to mix their respective levels later in an output mixer. To mix the dry and wet in the matrix as it’s patched would leave the dry signal in the left channel only. No good.
Sound source > Input 1L, with dummy cable in 1R Output AL/R > mono mixer > Delay 1 Delay 1 > Input 2L, with dummy cable in 2R Output BL > Delay 2 Delay 2 > Input 3R, with a dummy cable in 3L (it is not necessary to use a dummy cable here, but I’m using one for consistency) Output CL > Output Mixer (Pan Center) Output DL/R > Output Mixer (Pan L/R respective, or use a stereo input)
Knobs with an X are fully CCW (off). Knobs with a green check are mixed to taste. Knob with the red check is controlling feedback for the repeats. BEWARE: Ch 3A is feedback from Delay 2 to Delay 1. It can easily run away out of control and blow your speakers, headphones, and/or ear drums. Use it sparingly.
This method also makes use of a separate mono mixer to act as a send for both the source and Delay 2 to Delay 1. It what helps make the magic happen. Without the mixer, I couldn’t get the source and Delay 2 to Delay 1 without getting channels mixed up. Everything must remain on discrete channels in the matrix. As a result of the several dummy cables, Ch A’s outputs are discrete channels being used in a dual mono setup rather than in stereo, with those signals being mixed separately before going to delay 1. It was the only way to accomplish the task of sending both the source and Delay 2 inputs to Delay 1 while keeping those signals unmixed and discrete inside of the matrix mixer for final output.
Heed the inputs and outputs used very closely. It seems a bit odd, but it ensures that the stereo field is intact and signals remain properly separated until the final output mix. Deviate at your own peril.
The dry output is from Ch C, with the wet stereo output from Ch D. Pan the Ch C output to the center, with Ch D being panned L/R respectively.
This patch can likely be simplified (and perhaps sound better as a result) by splitting the audio at the Delay 1 output rather than relying on the matrix mixer to send the output of Delay 1 to Delay 2. This experiment, however, is for another day.
Although I haven’t pondered the nitty gritty of this patch in a mono matrix mixer, I think it would likely be a better tool for the job, but my first inclination is that you would need 5 outputs, and not the standard 4.
One thing I’m not afraid to admit is that I’m a delay junkie. I love delays. Analog delays, digital delays, reverse delays, pitched delays, but most especially tape delays. I love tape delays so much I have a real one. Uh, make that 2 of them. But I’ll also admit, a bit more tentatively in a misguided effort at fooling myself, that I haven’t really gotten much use from a stereo pair. I’ve gotten decent use from one, but not very much at all from the other.
One thing that I’d always wanted to do was to do old school ping pong delay with my 2 tape echoes. In a world of simple-to-use plugins, ping pong delay is normally just a check box or button click away, but in the analog hardware world, it takes careful and deliberate patching, along with lots of level adjustments along the way. In fact, it seems that ping pong delay with analog gear is a lost art. A dark magic lost in the olden times when you had to patch everything manually. The patch itself is not terribly hard, but it’s also not necessarily intuitive, which makes figuring it out a challenge. It also takes a piece of gear that I don’t have: a standard desktop mixer. And not even a super fancy one. As long as it has 3 inputs and an AUX send, we’re good. I don’t have a performance mixer in Eurorack either. At least not after I sold the Xaoc Devices Praga (which would have been perfect for this).
But I do have a stereo matrix mixer, and the will to use it.
I’ll breakdown the patch in a post later this week, but suffice to say that it worked a treat. I got my ping pong delay. It took a fair amount of finagling, particularly with feedback, but I got what I wanted. As soon as I introduced any feedback into the system, it would tend toward self-oscillation, as one might expect. But one fancy trick about tape delays is that they do The Thing. You know, when feedback starts to build, and you can hear it, but it’s just on the edge, not blowing your speakers, riding a wave of sonic beauty, underneath your melody. It really is voodoo. Of course you can go overboard, but tape delays make it a bit easier to ride the wave rather than have it blow up on you. I’m sure the matrix mixer design helps too.
One thing I discovered about the AI Synthesis 018 Stereo Matrix Mixer is that, probably because it does not introduce any gain, is that it can control feedback fairly easily. Despite feedback running rampantly toward the end of the patch, it never once got out of control, and allowed me to play the tape delay via the echo levels, as well as the EQ knobs of each echo, creating some nice stereo swirl and howling tone changes, without being overly worried about a runaway train of feedback blowing my cans and my ears to smitherines.
My apologies for the repetitive sequence. This really was an experimental session for me, from figuring out the minutiae of ping pong delay, to playing with feedback through my tape echoes. I’ve never done either, and it was surely a treat.
