My question is about reverb, usually a pro item, even though the application is for a home system.
I would like a cheap delay system for speakers. I see plenty of used reverb units on the market.
Reverb is what happens when the original signal is delayed a certain amount, and the delayed signal then rejoins the original signal.
I see controls for ms of delay on the reverb, but my question is this: is it common for these reverb units to allow you to eliminate the original signal entirely, so that only the delayed signal comes through?
I would think that a control that varies the relative amount of original signal versus delayed signal might do this-if the original signal knob has a zero setting. Similar to a balance signal on an amp.
Is that pretty much a normal feature?
I would like a cheap delay system for speakers. I see plenty of used reverb units on the market.
Reverb is what happens when the original signal is delayed a certain amount, and the delayed signal then rejoins the original signal.
I see controls for ms of delay on the reverb, but my question is this: is it common for these reverb units to allow you to eliminate the original signal entirely, so that only the delayed signal comes through?
I would think that a control that varies the relative amount of original signal versus delayed signal might do this-if the original signal knob has a zero setting. Similar to a balance signal on an amp.
Is that pretty much a normal feature?
It's certainly quite easy to do that, and most decent delay units have the facility. It's commonly used for time domain compensation in big PA rigs, etc.
However, is it really what you really want? Reverb re-introduces a portion of the 'wet' signal into the delay line to give the familiar effect. If you filter the input signal from the output, you will just have a delayed signal, with no 'interesting' characteristics.
However, is it really what you really want? Reverb re-introduces a portion of the 'wet' signal into the delay line to give the familiar effect. If you filter the input signal from the output, you will just have a delayed signal, with no 'interesting' characteristics.
I think you want a delay unit rather than a reverb. reverb has many delay times which are mashed together. a delay only has 1 or a lownumber (and u can disable the other ones) most modern effects units can do both anyways. and they have a dry/wet control which mixes between the original and processed signal.
Sorry - just re-read your post, and I see that IS what you want!
The frequency response and signal to noise level of cheap units is pretty poor - not hi-fi by any means!
I suggest that you contact your local pro audio dealer and discuss second-hand delay units (rather than reverbs). As I mentioned, these are used for time compensation - very similar to your application - but it depends how much you want to spend, and whether you want to pay that much.
You could always DIY, of course - it's a relatively simple matter to make up a shift register based delay unit.
The frequency response and signal to noise level of cheap units is pretty poor - not hi-fi by any means!
I suggest that you contact your local pro audio dealer and discuss second-hand delay units (rather than reverbs). As I mentioned, these are used for time compensation - very similar to your application - but it depends how much you want to spend, and whether you want to pay that much.
You could always DIY, of course - it's a relatively simple matter to make up a shift register based delay unit.
Hi Pete
Ok, brief rundown of reverb. The process works by continually feeding back a decreasing amount of signal into the delay circuit, via various EQ and volume settings. The delay setting you see, is properly called predelay, and allows the reverb to be made more realistic by delaying the sound of the reverb effect an appropriate amount of time to suit the space being simulated, i.e. a big hall will have greater predelay than a small room, because it takes the sound a certain amount of time to reach the walls and be reflected.
Does that make sense?
Ok, brief rundown of reverb. The process works by continually feeding back a decreasing amount of signal into the delay circuit, via various EQ and volume settings. The delay setting you see, is properly called predelay, and allows the reverb to be made more realistic by delaying the sound of the reverb effect an appropriate amount of time to suit the space being simulated, i.e. a big hall will have greater predelay than a small room, because it takes the sound a certain amount of time to reach the walls and be reflected.
Does that make sense?
Al:
Yes. The reverbs are built to recreate the experience of hearing the sound first ounce off the floor, then off one wall, then off the other, then off the ceiling, then off the back wall, etc etc.
So reverbs are out for simple delay purposes.
dnsey wrote:
Al recommended these units as well. After a few day's checking on Ebay, however, I have yet to come across one-at least that I know.
Online stores which sell pro gear pretty much know what they have and charge accordingly. The prices are sharply reduced-but reduced from an original price of $1000 or more. Pro gear is expensive, partly because it has to be extremely durable and reliable, partly because when you're living relies on a piece of equipment, you don't quibble about price nearly as much as a consumer would.
I am seeing home delay units for quite reasonable on Ebay-people getting rid of their old stuff from the eighties and even earlier. That wouldn't bother me much, but the problems are:
A) They work only for two channels-the project requires four.
B) The delays don't seem to be separately adjustable for each channel. Left and right channel gets the same delay.
Problem A) can be resolved by buying two delay units.
Problem B) can possibly be due to the fact that, since delay mechanisms seem to be voltage controlled, the unit simply feeds the same voltage to each channel's delay mechanism. A few minutes disconnecting the stock voltage feed and installing two opamp circuits might be all that is required.
While I haven't built a full size amp or preamp, I have built signal generators, etc. I can set up and solder in a small opamp into a piece of existing equipment for a voltage feed-that much I can do.
Still, I would like to buy a ready-made unit before modifying anything. That's why I thought I would ask about the reverb units, which seem to be easy to come by. Apparently, however, not a good idea.
Yes. The reverbs are built to recreate the experience of hearing the sound first ounce off the floor, then off one wall, then off the other, then off the ceiling, then off the back wall, etc etc.
So reverbs are out for simple delay purposes.
dnsey wrote:
Al recommended these units as well. After a few day's checking on Ebay, however, I have yet to come across one-at least that I know.
Online stores which sell pro gear pretty much know what they have and charge accordingly. The prices are sharply reduced-but reduced from an original price of $1000 or more. Pro gear is expensive, partly because it has to be extremely durable and reliable, partly because when you're living relies on a piece of equipment, you don't quibble about price nearly as much as a consumer would.
I am seeing home delay units for quite reasonable on Ebay-people getting rid of their old stuff from the eighties and even earlier. That wouldn't bother me much, but the problems are:
A) They work only for two channels-the project requires four.
B) The delays don't seem to be separately adjustable for each channel. Left and right channel gets the same delay.
Problem A) can be resolved by buying two delay units.
Problem B) can possibly be due to the fact that, since delay mechanisms seem to be voltage controlled, the unit simply feeds the same voltage to each channel's delay mechanism. A few minutes disconnecting the stock voltage feed and installing two opamp circuits might be all that is required.
While I haven't built a full size amp or preamp, I have built signal generators, etc. I can set up and solder in a small opamp into a piece of existing equipment for a voltage feed-that much I can do.
Still, I would like to buy a ready-made unit before modifying anything. That's why I thought I would ask about the reverb units, which seem to be easy to come by. Apparently, however, not a good idea.
I am not sure exactly what you are trying to accomplish. We are throwing around the terms reverb and delay here with no regard to their meaning. In th pro audio world reverb and delay mean specific things.
Reverb is an emulation of the sound of a large room or a cave or a stairwell. Many echoes all blended together for an intersting effect.
Delay is just that, the original signal, but delayed some amount of time. This results in a clear echo effect. This can be used as a musical effect or as a speaker system tuning aid.
Within both these things, various parameters can be adjusted. But some of these adjustments sound similar. For example a delay unit might measure the amount of ddelay in milliseconds. A reverb unit might also measure its pre-delay time in milliseconds. Both units have a "millisecond" adjustment, but it means very different things.
A reverb unit will have a decay time, which means how long it takes for the reverberance to die down. A delay unit can be fed back into itself to get an ever repeating echo. We call that feedback, not to be confused with the squealing feedback when your microphone gets in front of the speaker.
Most any unit of any quality has either a mix control for blending the orignal signal with the effect signal, or simply wet and dry output jacks.
WHAT ARE YOU TRYING TO DO?
If you want the nice addition of the reverb effect to add some spaciousness to the sound, that is one thing. SOmething not often added to hifi, but quite common to guitar amps. On the other hand if you want to time align various speaker cabs, then the delay unit is more what you want.
Many professional effect units include BOTH effects. Reverb and delay. You can indeed spend a lot of money on pro effect units, but there are pleny inexpensive ones as well. Behringer does make a line of effects that are very inexpensive and still work pretty well. Old Yamaha SPX90 and similar units should be on ebay. Yamaha makes a million models of everything. SOme delay units and reverb units do only that. Some are multieffect units that do all kinds of things beyond just reverb. They will do pitch shifting, panning, etc.
A quick look through Musician Friends flyer finds A t.c.electronics M300 for $199. and a Nady SDP20 for $109. A Lexicon MX200 for $199. An Alesis Multiverb 4 for $199. And Behringer DSP2042P for $99, and their REV2496 for $179. All those products are aimed at the sound reinforcement (PA systems) or recording applications. There are fine guitar efect units that would also work. ANd many of these are stereo units.
If you are planning to add the reverb effect to dry signal for home stereo or home theater, how do you plan to mix the reverb signal back into the system? It would seem to me that the easiest thing to do would be let the effect unit blend them together. or are you thinking to have rear speakers deliver only reverberation? You might find it sounds better with a dry/effect mix back there.
Reverb is an emulation of the sound of a large room or a cave or a stairwell. Many echoes all blended together for an intersting effect.
Delay is just that, the original signal, but delayed some amount of time. This results in a clear echo effect. This can be used as a musical effect or as a speaker system tuning aid.
Within both these things, various parameters can be adjusted. But some of these adjustments sound similar. For example a delay unit might measure the amount of ddelay in milliseconds. A reverb unit might also measure its pre-delay time in milliseconds. Both units have a "millisecond" adjustment, but it means very different things.
A reverb unit will have a decay time, which means how long it takes for the reverberance to die down. A delay unit can be fed back into itself to get an ever repeating echo. We call that feedback, not to be confused with the squealing feedback when your microphone gets in front of the speaker.
Most any unit of any quality has either a mix control for blending the orignal signal with the effect signal, or simply wet and dry output jacks.
WHAT ARE YOU TRYING TO DO?
If you want the nice addition of the reverb effect to add some spaciousness to the sound, that is one thing. SOmething not often added to hifi, but quite common to guitar amps. On the other hand if you want to time align various speaker cabs, then the delay unit is more what you want.
Many professional effect units include BOTH effects. Reverb and delay. You can indeed spend a lot of money on pro effect units, but there are pleny inexpensive ones as well. Behringer does make a line of effects that are very inexpensive and still work pretty well. Old Yamaha SPX90 and similar units should be on ebay. Yamaha makes a million models of everything. SOme delay units and reverb units do only that. Some are multieffect units that do all kinds of things beyond just reverb. They will do pitch shifting, panning, etc.
A quick look through Musician Friends flyer finds A t.c.electronics M300 for $199. and a Nady SDP20 for $109. A Lexicon MX200 for $199. An Alesis Multiverb 4 for $199. And Behringer DSP2042P for $99, and their REV2496 for $179. All those products are aimed at the sound reinforcement (PA systems) or recording applications. There are fine guitar efect units that would also work. ANd many of these are stereo units.
If you are planning to add the reverb effect to dry signal for home stereo or home theater, how do you plan to mix the reverb signal back into the system? It would seem to me that the easiest thing to do would be let the effect unit blend them together. or are you thinking to have rear speakers deliver only reverberation? You might find it sounds better with a dry/effect mix back there.
The units mentioned, including the Behringer 2496 as well as the others, all seem to have promise.
Now, another wrinkle.
As we go through the project, we realize that the best thing is not to have the delay come in for the whole frequency spectrum. That is, we'll be needing a setup where there is no delay up to 200 Hz, 300 Hz, or possibly even 500 Hz, but to have delay above that frequency.
Are there any units capable of that? for instance, can you program the Behringer 2496 to feed a 10 msec delay to a speaker from 300 Hz on up, but no delay below that?
Now, another wrinkle.
As we go through the project, we realize that the best thing is not to have the delay come in for the whole frequency spectrum. That is, we'll be needing a setup where there is no delay up to 200 Hz, 300 Hz, or possibly even 500 Hz, but to have delay above that frequency.
Are there any units capable of that? for instance, can you program the Behringer 2496 to feed a 10 msec delay to a speaker from 300 Hz on up, but no delay below that?
COnsider biamping. In large halls such as churches, we sometimes mount "presence projectors" further back the hall from the main front of house speakers. Essentially these speakers are just the treble portion of the program, and they are delayed to match the wavefront from the front of house.
Are you aligning drivers within an enclosure? In that case mechanical means might be easier - set the HF drivers further back. Or are you aligning multiple enclosures spread about a room? In that case delay makes sense. But to control only within a limited freq band, you would also want an electronic crossover. Biamping assumes this already.
Are you aligning drivers within an enclosure? In that case mechanical means might be easier - set the HF drivers further back. Or are you aligning multiple enclosures spread about a room? In that case delay makes sense. But to control only within a limited freq band, you would also want an electronic crossover. Biamping assumes this already.
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