Time is on my side...TITLE CHANGE - Time-staggered drive

[Mark Hammer]

I've long been intrigued with the recording engineering approach some players take, by mic-ing one amp close up, and another from across the room.  I thought  "Well, how big could such a room be, and how far away could the 2nd mic be?".

Forum member Thomeque generously designed and laid out an adapter board for generating thru-zero flanging in 2010 (available in MN3007 or MN3207 format) with a wide variety of simple flangers lacking that capability.  Run the "dry" signal through the adapter board, set for a very short delay time (e.g., 2msec), and now the modulated wet signal will be able to move "ahead" in time of the fixed-delay signal.

The stock adapter board can generate up to 9msec fixed delay, with no other parameters adjustable (i.e., no repeats or mix level, just a straight delay to whatever you feed into it.)  I thought I would incorporate this into my big modular system, and finally took some time to experiment this evening. 

My modular system consists of 8 different cabinets that can each hold up to twelve 4"x 2.5" modules, fed off a common power supply.  Pretty much every cab will have drive modules of some sort in them.  In a few cabinets there is an active splitter/mixer module, that sends the input to two send/return loops, that are mixed down to a mono out.  The idea is that I send the two splitter outs to different drive circuits, and "stagger" one of them to mimic mic-ing two amps from different distances.  Thomeque's module will produce roughly the equivalent of being 10ft away, for the drive circuit passed through the fixed delay.

So, I patched it up, and learned a few useful lessons.

1) Mic-ing at a distance also yields ambience, and not JUST delay time.  After all, unless one is mic-ing in an anechoic chamber, any room that lets you stick a mic 10ft away WILL have some space and reverberation.

2) Adjusting the delay between two harmonically different copies of the same signal has a filtering effect, due to the cancellation produced.  I did NOT get the close-up/far-away sound I was seeking, but adjusting the delay of one of the signals made for interesting comb-filtering of the A+B result.  The old EHX Electric mistress had what they called the "filter matrix" that simply applied a fixed delay, such that adjusting the delay of the (normally) swept signal would yield adjustable comb-filtering.  Of course, that does not allow for time-staggered comb filtering of two different signals.

Since the adapter board was optimized for TZF the delay times attainable may well be too short for what I wanted.  I actually built three of the the MN3207-based units, so perhaps I'll nudge the delay time a teensy bit longer in one of them (e.g., up to 15msec) and see if that makes a useful difference.

So, long story short, I got something interesting and useful, but not exactly what I was hoping for.  But a worthwhile exploration that I wholeheartedly endorse playing around with.

[StephenGiles]

Didn't Eric Clapton insist that the mic recording his amp (turned up to 12) was placed 10 feet away when recording the Beano LP with John Mayall's Bluesbreakers?

[Mark Hammer]

That may be one of the instances I was thinking of.

[Matthew Sanford]

Interesting and convenient to handle it electronically but as you said, ambience, and not just the verb from the room size but also shape, but also characteristics of the mics in question in regards to distance from source; after all, many a singer exploits the proximity effect.

Just glad we don't have to find just the right sized cave for correct delay time anymore (if the drummer would stop rushing) 

[amptramp]

There is always the garden hose delay - you have a speaker driver on one end and a microphone on the other and for variable delay, you can shove the microphone further into the hose.  You could record your music in a closet and still have the effect of a wall 20 feet away.  Wind the hose into a spiral and have a spiral microphone mount that can be fed into the hose at your chosen distance.

[Mark Hammer]

I have an Equinox PT2399-based "reverb" in my module arsenal.  I'll see if I can get what I'm aiming for by patching it in on one side.  I also have a couple of cab-sim modules.  So, one drive, fed from the splitter, should go to a cab-sim, then to the mixer.  The other drive, fed from the splitter should go to the short delay, then to the Equinox - or maybe to the other cab sim, first, and then to the mixer.  Atsa-lotta patch cables!

[ElectricDruid]

I've also done some experiments with this sort of thing. Rather than "close up, far away", I was trying to get the sound of multiple guitarists playing together. My approach was to take the input signal to an FV-1 chip, and then use different algorithms for the left and right channels. Combined with the input itself, that gave me three separate copies of the input. These were then taken to three differently-voiced drive pedals, and then the resulting three signals get mixed back together.

At some point I realised that it might make more sense from a noise point of view to put the delays *after* the drives, but that's a practicality. Soundwise it doesn't make too much odds, at least for simple delays. Since the FV-1 can do other things too, I wondered whether delay+chorus or delay+pitchshift might be good to give more of a sense of separate players playing together. For those, I think the order does perhaps make more of a difference, and especially in the pitchshifted case I hoped to use the drive to hide some of the "effected" quality of the sound.

The experiments were reasonably successful and good enough that I thought the idea needed more development, so it's something I've got sitting around waiting for me to do more to it.

[Elektrojänis]

Something to remember: If there is two amps in the same room, you can get a good separation by close mic-ing them. However, if you are micing one of them from the other side of the room, you are practically far mic-ing them both at the same time. Most mics are not that directional and if you find one that is, it will likely have other (tonal) problems. Other thing is that the reflections/reverberation goes everywhere and even if you have a very directional mic it will also come from the direction where you are aiming it.

I'd quess (and this is just my quess, I'm no recording engineer) that the near/far micing is more about the balance between the dry (less reverberation) close miced sound (proximity effect, bass boost) and far miced more reverberant sound (with less proximity effect) than the actual delay itself. I think I've even seen some producer videos where they time align the two channels (either by using a delay on the recording or nowedays just moving the recorded track in a DAW.

Oh... I have to add... I'm not trying to say you shouldn't experiment with this. As I see it the experiment was already a success. You learned something and came to tell us what you learned. As always, even if you don't find the sound you are after you might find something else, and it may be even better.

[Mark Hammer]

Your comment and concern is legitimate, Petri.  Of course, as a recording trick, an engineer might place the close-mic'd amplifier in a separate small room and the distant-mic'd amp in a different and larger room, precisely to avoid the issue of bleed-through, and retain the ability to adjust their balance in the mix.  The player, meanwhile, is hearing it all through headphones when playing.  Alternatively, the "distant-mic'd" version might be a re-amped copy recorded later on, without the player even present.

[Elektrojänis]

Separate room or re-amping are very valid points. I was mainly thinking, that sometimes the result is not fully what was intended, but if it sounds good, it get's used.

I don't really have much to add to this, but it reminded me of the story of Dire Straits Money for Nothing guitar tone. In interviews Mark Knopfler and the recording engineer have said that it was discovered accidentally when combining signal from two mics. That was with only one amp, but it probably produces similar comb filtering efects.

[Mark Hammer]

Though I wasn't aware of it before starting this thread, I see that Old Blood Noise Endeavours released a pedal intended to do exactly what I described - https://oldbloodnoise.com/pedals/p/beam-splitter - although I gather it uses a much wider range of possible delays; likely PT2399chips, given the retail price of the pedal.