Pre-Delay----discuss please?

Jon Light · From: Saugerties, NY

I've never gotten the hang of how to work with pre-delay settings when working with a unit that has this parameter. I currently encounter it on some of the models on my Pod xp. How is this typically used.

Marc Jenkins · From: Victoria, British Columbia, Canada

Jon, pre-delay, in real-world terms, is the time it takes for the source signal to reach the source of reverb, ie you strum a guitar, and .1 seconds later, it hits the nearest wall.

To make sense of while programming your Pod, imagine the size of a room. Note that if the pre-delay is too short, it can sound very synthetic, especially with a long reverb tail. If the pre-delay is set too long, it will sound removed from your source.

Hope that helps some!

Cliff Kane · From: the late great golden state

Hi Jon,
what we used to do in the studio was to run a signal through a digital delay or a tape delay and then send the output from the delay to a plate reverb. When mixing the dry signal with the wet reverb signal we could then use the delay as the reverb's pre-dealy to control the time between the dry signal and the start of the wet signal. So, in addition to controling the blend of dry and wet, and the legnth of the reverb's decay time, we also had control over when the reverb effect would begin in relation to the sound of the source/dry sound. You are not really hearing the sound of the delay as you are using the delay in series with a reverb to add another parameter of control; however, some delays will color the sound of the signal before it hits the reverb, so a reverb that is in series with a tape delay will sound different than a reverb that is in series with a digital delay. This technique would give us more sounds from our plate reverb, as we could now create more space in the sound. This effect works when you have a mixing board to blend wet and dry signals, but I think most digital and software reverbs have a pre-delay parameter to simulate the effect of mixing a dry sound with a delayed wet sound.

Cliff

Jon Light · From: Saugerties, NY

Thanks, guys. I think I get it. I guess it's actually pretty much what I had assumed it to be. I just didn't know how to use it. I would think that it would help to avoid muddiness when using reverb.
Let me go play with it. On Pod xt (not my Win xp).

Pete Burak · From: Portland, OR USA

I got hooked on pre-deley after getting a Lexicon LXP-1.
It makes the reverb into like a soft delay, and the orignal note doesn't lose any steam.

I tried to use a delay pedal in line with the reverb send/return lines on a Twin Reverb (using an RCA>1/4"-jack adapter), and it didn't work (must not be a deley-able signal???).

How do you rig pre-deley into a Twin Reverb amp?

Brad Sarno · From: St. Louis, MO USA

Pete, good luck getting some pre-delay on a Twin. You'd have to insert a delay somewhere before the reverb driver tube.

One perspective with reverb and pre-delay is that it controls the illusion of distance. If you hear a sound with zero or very short pre-delay, then you get the impression that the sound is coming from far away. If you begin to add pre-delay of time values over say 35ms on up to 120ms, you then bring the sound source nearer while still getting to have a good amount of reverb. To me pre-delay is a "distance" control. It detaches the initial sound from the reverb, which in a way is how we perceive distance in an acoustic space anyway. Imagine being in a large gym or cafeteria and a person yells. If that person is at the far end of the room from you, then you'll hear their voice and reverb at about the same time. The brain can tell it's distant. But if that person is only 10 feet away from you and yells, then the reverb will come later. That person is so close that their voice reaches you in 10ms or so, but the reverb won't reach you until their voice has time to travel to the walls of the space and bounce back, which can be 30, 50, 150ms later. There is a time lag between the initial sound and the reverb. For guitar or steel, I like pre-delays around 40 to 70ms. This seems to bring the guitar closer and not sound smeared by the reverb. This also lets you get away with a lot of reverb without it muddling things up too bad.

Pre-delay on snare drums is real cool too. You can time it to the rhythm of the song. Maybe an 1/8th or 1/4 note later, or maybe a triplet. It's a cool effect and if the timing is just right, you don't notice it, but you get the bigness of the effect.

Brad

Pete Burak · From: Portland, OR USA

Jon Light · From: Saugerties, NY

You've got a hammer and a saw, right? How hard can it be?

Is it a line/instrument level issue or an impedance thing or what?.....

I would think that it is do-able but I'm just saying that.

Cliff Kane · From: the late great golden state

"How do you rig pre-deley into a Twin Reverb amp?"

You can do this:
Plug your guitar into a Y connector/splitter.
Plug one Y output into the non-reverb channel on the Twin.
Plug the other Y output into a delay pedal; set the delay pedal's mix control to maximum wet so that the only thing coming out of the delay pedal is the delay.
Plug the delay pedal's output into the Twin's reverb channel.

Now you can use the Twin like a two channel mixer, the non-reverb channel controls the volume of a dry signal and the reverb channel controls the volume of a wet signal which is the reverb with delay pedal. This is similar to the way reverbs with pre-delay are used in a mixing studio.

This is one of the things that makes Fender amps very useful. Using one of the old tube Fender PA heads for this would be pretty cool. My Magnatone has three discrete channels, each with its own seperate reverb send and voicing! Why don't they make amps with cool features like this any more?

Cliff

Jon Light · From: Saugerties, NY

hmm...I was going to jump on that to comment on how the two channels are out of phase--the reason that you can't jumper between two channels in bf & sf Fenders (unless you have done the two channel reverb mod which puts the channels in phase with one another----but then this pre-delay scheme wouldn't work). But once you introduce delay into the equation, 100% wet, I guess that takes the phase cancellation issue out of play, eh?

Cliff Kane · From: the late great golden state

That is interesting, Jon. I didn't realize that the channels are out of phase with each other. Why would they do this? It seems like that would complicate the point of having two channels to play two sounds or instruments through at the same time. You could also do the jumper thing with a two channel amp, like guitars players somtimes do to get both channels going, where a channel's two jacks have a common circuit. I think this would work also by plugging into the non-reverb channel, annd jumpering the other input jack into a delay pedal and then into the reverb channel. Sometimes messing with the phase makes things mix better, anyway, so even if there is a phase thing going on it might sound cool.

Jon Light · From: Saugerties, NY

Yeah---there's an addition gain stage in the reverb channel. Each stage flips/flops the phase and they end up flipped instead of flopped. There is no law that you can't jumper them. But you will have to contend with some frequency filtering that could range from 'interesting' to just thin. But it seems to me that once you throw delay into the mix, you are eliminating the direct affect of phase cancellation.

All signals interact and create unique new sounds that are the result of some freqs cancelling, others reinforcing--whole new timbres being born. But one signal getting inverted and emitted from a single source (the speaker) in real time (totally in sync as opposed to time delayed with a delay effect) is most likely to get significantly degraded. Now--if you throw in a variable--say a sweeping function of some sort, you might have something like....a phaser!

John Groover McDuffie · From: LA California, USA

One thing to add about Cliff's cool idea above: I don't think you can get reverb without having the volume of the channel up.You can turn the reverb to 10 but you will always have some of the dry (although delayed) signal in the mix. So it won't be pre-delay strictly speaking. It will be a single delay with heavy reverb.

I'd still like to hear it, but I think all my Fender amps with reverb have the reverb-in-both-channels mod, so I'll have to borrow an amp to try it.

I guess having the reverb on 10 would be close to pure reverb return anyway in a typical Fender.

Cliff Kane · From: the late great golden state

Hmm, goes back to Brad's post about a patch point....something like a post preamp / pre reverb insert. Are there any amps that have an effects loop return patch point that would somehow go between the preamp and the reverb? You could probably just use a delay pedal, a reverb pedal, and one of those little micro mixers or one of those Boss pedals that lets you mix two loops, and do a dry/wet mix into one channel on an amp, or of course just use your Pod!----Naw! Too easy. Shocked

)

I am going to start using my three channel Maggie more to try mixing with the amp. It seems like one could do a lot with this approach.

Cliff Kane · From: the late great golden state

Hey John,
your right, there will always be the dry input to the reverb channel with the reverb added to it, but the pre-delayl would go before the input to the channel, so you would still be able to blend the time between the undelayed channel and the delayed channel, albeit the delayed channel will not be totally wet unto itself. Does this sound correct?

I'm going to try this when I'm at the rehersal space where I keep my Twin.

John Groover McDuffie · From: LA California, USA

Absolutely correct, Cliff. Exactly what I was trying to say.

Cliff Kane · From: the late great golden state

Yep, that's what you said, just wanted to make sure I got it. I bet it would sound cool, you can play with the tone controls, too. It seems like people neglet the additional channel on their amps, but why not use these amps as two channel amps, even if you're only putting one guitar through them.

Pete Burak · From: Portland, OR USA

Here is a pedal that does the phase inversion needed to use both sides of a stock Twin:
http://www.proguitarshop.com/product.php?ProductID=724&CategoryID=

I do think that the 100% wet/deleyed signal would eliminate the phase cancellation issue.

I know for a fact that if I plug a guitar into Ch.1, then jumper to Ch.2, if you put the volume of Ch.1 on 3, then slowly turn up the volume of Ch.2 from zero to ~3, you will hit the "Phase Cacellation" spot, and hear virtually all the bass frequencies dissapear.

I have been using this ART Tube Pac unit I bought way back when (for recording vocals), which has a phase inverter button on it, and also a bypass (allowing you to bypass the compressor/limiter effect) so it just flips the phase, eliminating the cancellation issue.

funn Stuff!
Pete B.

Brad Sarno · From: St. Louis, MO USA

Interesting ideas. Cliff, one problem is that it's true you'd have to turn up the dry signal to get some signal sent to the reverb. Even with the reverb on 10, there's still dry signal there, which would be bad. But you could get in there and snip, so that the only thing coming thru that channel is reverb with zero dry. Then phase is no issue, and your delay pedal would control the pre-delay. Sounds doable.

If you snip just before the 3.3Meg resistor/10pf cap pair, that would mute the dry signal while letting the reverb thru. EASY PROJECT!

Here's the image of the layout. This is pretty easy to find. Just lift the cap/resistor from that eyelet, and leave intact so you can replace it in the future.

So just plug the guitar into the normal channel jack 1. Then jumper jack 2 out to a delay pedal. Then from the delay pedal to the the reverb channel. Turn up normal channel for guitar volume, and turn up the reverb channel and reverb knob for verb. Set your delay for one repeat and 100% delay only, no dry signal. Actually it may be cool to have some repeats happen too, but keep the delay pedal effect only so you avoid any instant reverb, only pre-delayed reverb.

Let us know Pete.

Brad

Ivan Funk · From: Hamburg Pennsylvania, USA

This is interesting. I don't think that gadget is needed when a delay is being used for reverb channel.
Without a pre-delay the dry part of the signal coming out of channel 2 will have cancellation but the trailing spring reverb signal should sound fine.
Then when using a delay to channel 2, depending on the length (time) of the pre-delay, phasing shouldn't be an issue. Even with two amps that are in phase, with the original signal in one and a delayed signal in the other, the delayed signal would be out of phase to the original signal. I think that's a small part of what makes it sound cool.
Different timing of the pre-delay will give different phase positions (and cancellations) to different frequencies. I imagine watching the wake of two boats moving in the same direction, one being a bit behind behind the other.
Really though I just twist knobs around till it sounds good.

Brad Sarno · From: St. Louis, MO USA

Yeah, what Ivan said.

And really, if you are not actually gonna hear the delay, but instead only hear the reverb that follows the delay, phase problems are no longer an issue at all since you aren't really blending in a true delay signal with the original. Just the reverb smear is what winds up coming out of the 'verb channel.

Pete, how's it coming?

Brad

David Mason · From: Cambridge, MD, USA

I always just used the pre-delay to keep the pick attack from going boink-boink-boink-boink-boink and to keep really fast sections sounding clear, but now that I know you have to be an electrical engineer to use it, it probably won't work anymore, huh. Sad

(There's a "pre" in some big-box choruses & flangers that's really cool, you can set it to NOT whoosh except till the very end of long, sustaining chords, which are starting to get kinda dull by then usually anyway.)

Cliff Kane · From: the late great golden state

The priciple of using a pre-delay can be applied in other ways to other effects. For example, how about a pre-fuzz flanger, or a pre-delay pre-fuzz flanger? I think it's just imaging in and outs as inserts and loop points. For example, the Electro-Harmonix Q-Tron Plus has an insert patch point between the input and the effect circuit. This gives the filter more flexability in that you can add a fuzz after the input, or trigger the filter's envelope with another source. I guess using both channels on a Twin is related to adding a loop, in that eveything gets summed at the ears of the listener?

Last night I fired up my '64 Magnatone Imperial: I jumpered the three channels together, using one for vibrato, a couple of different tones going to the reverb. It was pretty cool, it added to the sound of the amp.

Pete Burak · From: Portland, OR USA

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