delay for a mic & a di?

[Jeff Hague]

Hey all!
Does the search just suck now on the PSW forums or is it just me? I tried searching there and got about a million hits that had nothing to do with this...
Anyway, havent thought about this in a long while but "back in the day" I knew guys who liked putting a mic and a di on bass guitar. What I was told though was that you needed to add a very slight delay to the di because its signal would reach the board before the mic's signal. I never really gave it much thought because Ive always been pretty happy using 1 or the other but not both.
Now Im working with a band whos guitar players both use digital modelers and active wedges on stage instead of traditional amps. I have been using dis that they have built in to their pedal boards to feed the pa but the sound has been somewhat weak. I just read an article from a recent LSI about guitar micing techniques and they mention running both a di and a mic in a sort of stereo arrangement. They go on to say that some folks will add 1 or 2 ms of delay on one of the feeds to create a slight comb filtering effect on purpose.
So, do you need to delay the di signal relative to the mic signal in order for the 2 to sum coherently or not?
Last gig with that band I put mics on the wedges and ran the dis but not both at the same time - the mics do sound better but now Im thinking of using both.
Thanks!

Jeff

 

[Chris Gruber]

Re: delay for a mic & a di?

Boom Baby! http://www.radialeng.com/re-phazer.htm I love this little box and it does work as advertised.

 

[Kip Conner]

Re: delay for a mic & a di?

Not sure why you would want to create a combing effect unless you were just looking to kill the top end of the summed signal. Besides there should be enough of a difference in the sound of the pick-up versus the sound of the speaker rig to not allow that effect. I am like you and that I don't use both very often unless the bass player is creating something that only the speakers can re-produce. For instance you can get more grow out of bass by mic'ing the cabinet unless you are running through the lunch box version of a Purple Mic Pre.

As for which one you need to delay, it's going to depend on who is winning the race to the finish. The direct source should get to the console faster due to the inherit nature of low frequency propagation from the cabinet drivers. As for the amount- there's no magic number. It's going to completely depend on the phase response of the independent signals. The quickest way to do it would be to use the impulse measurement in Smaart (or the FFT of your choice) using the direct signal as the reference trace and the mic as the live trace. Not sure that I would use the delay locater for something like this, although I suppose you could.

That radial device looks like a cool insert in the analog signal chain, but you would still need something like Smaart to help determine where to place the dial. Otherwise you would just be shooting in the dark by what sounds right. But hey, at the end of the day we have to trust what we hear anyways, right?

 

[kristianjohnsen]

Re: delay for a mic & a di?

Hey all!
Does the search just suck now on the PSW forums or is it just me? I tried searching there and got about a million hits that had nothing to do with this...
Anyway, havent thought about this in a long while but "back in the day" I knew guys who liked putting a mic and a di on bass guitar. What I was told though was that you needed to add a very slight delay to the di because its signal would reach the board before the mic's signal. I never really gave it much thought because Ive always been pretty happy using 1 or the other but not both.
Now Im working with a band whos guitar players both use digital modelers and active wedges on stage instead of traditional amps. I have been using dis that they have built in to their pedal boards to feed the pa but the sound has been somewhat weak. I just read an article from a recent LSI about guitar micing techniques and they mention running both a di and a mic in a sort of stereo arrangement. They go on to say that some folks will add 1 or 2 ms of delay on one of the feeds to create a slight comb filtering effect on purpose.
So, do you need to delay the di signal relative to the mic signal in order for the 2 to sum coherently or not?
Last gig with that band I put mics on the wedges and ran the dis but not both at the same time - the mics do sound better but now Im thinking of using both.
Thanks!

Jeff

Hello Jeff.

If you are tapping a direct DI signal right off the bass and combining it later with a mic signal that has been through some digital modeling, delaying the DI signal to make up for the latency in the digital modeleing circuitry may have benefits for sure. Also, try polarity flip at there migh be an extra polarity reversal somewhere in either signal chain.

 

[Art Welter]

Re: delay for a mic & a di?

Hey all!
Does the search just suck now on the PSW forums or is it just me? I tried searching there and got about a million hits that had nothing to do with this...
Anyway, havent thought about this in a long while but "back in the day" I knew guys who liked putting a mic and a di on bass guitar. What I was told though was that you needed to add a very slight delay to the di because its signal would reach the board before the mic's signal. I never really gave it much thought because Ive always been pretty happy using 1 or the other but not both.
Now Im working with a band whos guitar players both use digital modelers and active wedges on stage instead of traditional amps. I have been using dis that they have built in to their pedal boards to feed the pa but the sound has been somewhat weak. I just read an article from a recent LSI about guitar micing techniques and they mention running both a di and a mic in a sort of stereo arrangement. They go on to say that some folks will add 1 or 2 ms of delay on one of the feeds to create a slight comb filtering effect on purpose.
So, do you need to delay the di signal relative to the mic signal in order for the 2 to sum coherently or not?
Last gig with that band I put mics on the wedges and ran the dis but not both at the same time - the mics do sound better but now Im thinking of using both.
Thanks!

Jeff

Since 1979, I almost have always used both a DI and a microphone on bass guitars.
I always ask the bass player to play a sustained low "B" or "E" and check for cancellation when combined, reversing polarity on one channel if required.

As it turns out, the phase response of a speaker cabinet/microphone output is so different from the DI phase response, reversing polarity seldom results in a dramatic level change, it is usually results more a change in "color", or tone.
In fact, I found the DI box I usually use for bass is pin 3 +, so most of the time the two signals were technically reversed polarity, while in actuality there is probably only one frequency that a 180 degree reversal takes place at.

Inserting a short delay would only correct phase at that one frequency.
That might be useful for "Johnny one note", but would not help most players sound.

Latency in digital modeling circuitry, as Kristian mentions, could be enough that a delay on the microphone might benefit, but it would still be a subjective assessment as far as the delay time decision.
Considering digital latency of a digital modeling circuitry is usually under 2 ms, I won't be worrying about them.

If it looks louder on the meter, sounds louder/better in the headphones and the mains, go for it. If it doesn't, play around with EQ, phase reverse, and also delay if you care to add even one more level of complexity to a subjective tonal decision.

Art

 

[Jeff Hague]

Re: delay for a mic & a di?

Very cool - thanks all!
I played with it last night and am starting to really like the results. I have to agree that both signals are sufficiently different that no noticable comb filtering takes place. With very little channel strip eq, the mic signal is warmer and fatter and the di signal cuts through the mix better. So for the SR guitar I panned the mic signal almost hard right and the di signal center and I mirrored that for the SL guitar. In the mix I favor the mic signals keeping the guitars seperated nicely in the stereo field. For leads I bring up the di channel which brings it out nicely and pulls it to the center. Im not sure that it would be any different though if I simply double bussed a single guitar feed, might try that sometime too.