Reverberaton for Allen ADC-8000

[clhammonds]

I have just moved my ADC-8000 from a great location with perfect acoustics to a much smaller room with none at all. I have previously used Alesis NanoVerb units on each channel of a 11 computer MOS-1 Allen with fairly good results, but have not been able to make them work on the ADC. The ADC has 13 channels from two cages. I am in a room now that is only 13' x 30' and it is very dead. Sixteen HC-12 and 14 speakers at one end, and the console at the other. Any suggestions?
Carl

[davidecasteel]

Put some speakers in the bathroom. B-)

David

[clhammonds]

Reverberation for Allen ADC-8000

I have just moved my ADC-8000 from a great location with perfect acoustics to a much smaller room with none at all. I have previously used Alesis NanoVerb units on each channel of a 11 computer MOS-1 Allen with fairly good results, but have not been able to make them work on the ADC. The ADC has 13 channels from two cages. I am in a room now that is only 13' x 30' and it is very dead. Sixteen HC-12 and 14 speakers at one end, and the console at the other. Any suggestions?
Carl

What a great suggestion David! Thanks for starting my day off with a chuckle. As a matter of fact, my wife would tell you that's about the only place where there isn't any speakers. Unfortunately the bathroom is too far away.

[Leisesturm]

I tried using Alesis Nanoverbs on the preamp outputs of a 1960's analog Allen way back in the day. It sounded GREAT, but all expression went away if the pre-amp outputs could not be plugged directly into the final amplifier inputs. As I understand it, this is because Allen superimposes an expression signal in the form of a voltage circuit that gets broken by the Alesis unit. I never did satisfactorily solve the problem. I am surprised you were able to use 3rd party reverberation units on any Allen model given this design characteristic. Let's brainstorm a bit, shall we?

The room. Why is it dead? Carpet? 13x30 isn't really all that small. Your bathroom is smaller, just saying. The carpet could go away if you time it right and do it while the wife is away at the spa weekend that you lovingly arranged for her birthday surprise. I don't know what kind of standing wave pattern might be set up in a room so rectangular but... how bad could it be? This is dependent on the 8000 having at least rudimentary reverb capabilities built in. I would think it must... right?

If you have kept up with recent posts you may know I am not one who thinks more channels than two (or one!) per division means much. Its what goes INTO the amplifier that is important. Garbage in, garbage out. Amazing, realistic, awesome, sampled sounds in... ... Your main problem is that you won't have amazing, realistic, awesome, sampled sounds going into the final amplification. You 'need' the reverberation to save the day. FWIW, I have a Behringer cousin to the Alesis Nanoverb. It has a four channel mixer and all four channels have access to a small suite of reverberation and delay/chorus parameters. There are devices that can take speaker level inputs and then output microphone level or line level signals to subwoofers and other devices. I personally think you could do way worse that mix down that 13 channel rig into a 5.1 or even, (gasp) a 2.1 final amplification. You would be able to get rid of a lot of speakers, which is a good thing because you were already on a slippery slope when the wife got back from the spa.

The last ditch project I would try is to mike the speaker arrays with "choir microphones" and feed the output into a reasonable quality reverb unit. A Nanoverb might be in over its head. I might even feed the audio into a computer running reverberation software. That would be ideal since you could get the output in the form of a soundcard which could run any number of 3.1 speaker systems dedicated to making computers sound awesome to gamers. FWIW.

H

[clhammonds]

The first Allen I used the Nanoverbs on was a custom built, 11 computer, 26 channel organ. On that instrument, I intercepted the signal as it came out of the DAC circuit board just before the pre-amp box. From there it went to the expression control circuits and then on to the power amps. Two channels on each of the computers with a Nanoverb assigned to each computer. I was able to adjust each one individually, and it really was pretty nice. Of course, the ADC technology is completely different. I am assuming that I am between the pre-amps and the power amps as it comes out of the two cages. With the Nanoverbs connected between the cages and the power amps, ome of the channels work fairly well, but others distort or, are very weak. Not sure why. I think I am not taking the signal from the right place for the Nanoverbs to work. My electronics knowledge is sorta like my organ playing, weak and limited in scope.
As for the room, it is strictly set up for the organ with wood cathedral ceiling, all ceramic tile floor, nothing soft or sound absorbing but a little office furniture. I realize I could mix the 13 channels down, but that seems a shame. I have already given away all the antiphonal (13) speakers. The 16 I have left fit perfectly in one end of the room, so they are already there. The choir microphone might be a solution. I have seen that done with pipe organs in dead rooms. As for the quality of the ADC sound, it is old technology, but in the right space, it makes nice liturgical music which is my interest. In any case, it is more than enough to satisfy me if I can fix the acoustics issue. I am going to contact Allen but I know their solution is going to be very expensive. Before I moved, I gave up that original 3 manual Allen with all new console controls, 3 MIDI computers and 26 ranks of pipes. I feel I have to make this work. Many thanks for your suggestions.
C

[tucsondave]

Put some speakers in the bathroom. B-)

David

Antflushanal speakers?

[Admin]

I have just moved my ADC-8000 from a great location with perfect acoustics to a much smaller room with none at all. I have previously used Alesis NanoVerb units on each channel of a 11 computer MOS-1 Allen with fairly good results, but have not been able to make them work on the ADC.

Describe how you are connecting the Alesis units to your ADC 8000.

[Leisesturm]

It sounds like the channel that is not distorting is the one that is carrying the unexpressed divisions (Great, Pedal) and the one(s) that distort carry signals from expressive divisions. I don't know that you can get signal from anywhere else in the signal chain. I kind of mis-spoke earlier. It is probably not necessary to mix down the unprocessed audio, as any device that takes speaker level input will have some kind of pass through, so you can run your unprocessed audio through the same speakers as before, but hopefully you will now also have line level signals that you can feed to one or more Nanoverbs or sound processor equipped PC. A "typical" installation would have the console at the same end of the room as the main speaker battery and your antiphonal and/or reverberation speakers would go at the far end. You 'can' have both direct and processed sound coming from the same side of the room. This may be problematic with a choir mic type of situation because a feedback loop will occur at high levels of reverb, which you will want. Well I would want. If you are clever you can make your existing power amps do double duty and also amplify the processed audio from the reverberation units.

H

[clhammonds]

I am connecting the Alesis units in between the main console output cables that previously are connected directly into the 13 different power amps. Now, they go to the input of the Alesis, and the output from the Alesis goes to the input of the power amps.

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I can change the arrangement. Originally, I was going to put the console in the center, with the Great/pedal speakers in one end, and the Swell/choir in the other. I can change it around , but thought that putting the speakers all around the console would be like sitting in a pipe chamber. My experience has been the further away from the source, the better. In my previous installation, I had about 10 feet vertically, and then 20 feet horizontally for the sound to travel. The upper sound chamber was 20 x 30 on the second level. The console was on the floor of a 16 x 32 foot two story room. The acoustics were perfect. All hard surfaces, and lots of walls to reverberate. I do have multiple inputs on these Allen 100 watt amps.

[Leisesturm]

I am connecting the Alesis units in between the main console output cables that previously are connected directly into the 13 different power amps. Now, they go to the input of the Alesis, and the output from the Alesis goes to the input of the power amps.

And as you have discovered, just as I did 14 years ago, this does not work. But you would need to be an Allen technician to locate a place where you could get the proper line level signals to drive your Nanoverbs. Myself I don't think you can. Your only hope is to work with speaker level signals. If you Google: speaker level to line level adaptor, you will find lots of units at lots of price points to consider. The one concern is that none of the units I have seen so far have a pass thru function, they all seem to assume that you will not need the speaker level signal anymore once it has been knocked down to line level. They also seem to top out at 80W for low priced units and 400W for higher priced units. I haven't seen anything inbetween. Of course, subwoofers designed to work off of speaker level inputs are designed to pass thru the speaker level audio that is above the frequency range of the very low bass that is handled by the subwoofer. I wouldn't give up. Something is out there.

Failing that (so much for not giving up), Allen will not, I don't think, but an independent technician might tell you how to put your Nanoverbs into the signal chain without breaking the expression signal circuit. Perhaps with diodes and resistors, a bridge across the broken circuit can be created. It needs to be easy to solder together and also cheap, because you need to make 13 of them.

I can change the arrangement. Originally, I was going to put the console in the center, with the Great/pedal speakers in one end, and the Swell/choir in the other. I can change it around , but thought that putting the speakers all around the console would be like sitting in a pipe chamber. My experience has been the further away from the source, the better.

Oh I don't know, recording engineers all use near field monitors and do their critical listening up close and personal to the source. It's kinda the same thing I think. If you are playing a Flentrop tracker and other intruments like it you are very up close and personal to the amazing, realistic, awesome, definitely not sampled sounds coming from the pipes within. I have a friend in Arizona with a large Allen theatre organ married to a Hauptwerk classical organ. He has a large speaker battery like you do but it is less than 10 feet in back of the console. In other words, seated at the console, the organist is looking right into the speaker cabinets. All his reverberation comes from the same speakers that supply the direct sound. In my experience with my own instrument which has internal speakers from which both the direct and reverberated sounds emanate, it is not objectionable to be very close to the source if that source is reverbed. If not, then you would want to be away from them so the room has a chance to modify the sound. But your room is dry so no real benefit to backing away. I would also keep the entire organ together and not split Gt/P and Sw/Ch across large distances.

[Admin]

I am connecting the Alesis units in between the main console output cables that previously are connected directly into the 13 different power amps. Now, they go to the input of the Alesis, and the output from the Alesis goes to the input of the power amps.

You don't say what the problem is with this setup.

If the issue is lack of expression as described by Liesesturm, that is very easily remedied by adding a single resistor per channel to the chain.

[tucsondave]

What amplifiers do you have? D-40, S-100, a combination of both? What are the part numbers on them?
Is there a mixer in the console or do the cage signals go directly to the amp rack?

td

[clhammonds]

Thanks for your thoughts. I agree, Allen will never tell me how to use another manufacturer's equipment. I am sure they will be perfectly willing to offer a factory mod, but I know it will be lots of bucks. At this point, my best non-invasive option might be some arrangement of an external mike and reverb unit over the existing setup. For sure, that is not an ideal option, but outside of finding a interface between the console and amps, it might be all I can do other than Allen. In any case, I appreciate hearing your thoughts. This organ is like one of my kids (almost) in that I love tinkering with it, and I am so spoiled by the quality I enjoyed in my other home, this cracker box I have it in now is really hard to take. Thanks again!

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No, strangely enough, some of the channels are acceptable, but others are very weak and/or distorted. Actually, it seems so close to being an option, but I find it difficult to get the input vs output/pass through signal adjusted on the different channels. I thought it would make sense to just adjust them all the same and rely on the setting in the organ to make it consistent, but that is not the case.

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These are all S-100. Assembly # 905-1042, Schematic 081-541. It has been a while since I have been in the console, but to the best of my memory, they go straight to the Amps. I will check that though to be sure. Thanks td.

[Admin]

Rather than passing the signal through, have you tried to Y the signal so that you still have the signal passing direct to the S100's and the branch off each Y going to a mixer whose output feeds a Nanoverb? The outputs of the Nanoverb would then be fed to dedicated reverb channels and speakers. Mixing the dry signals, and keeping the reverb on separate channels is the way Allen does it and will give you better results than sending the mixed wet/dry signal to a separate channel. You're not creating a reverberant sound field if each channel has it's own reverb.

[don60]

The cage outputs on ADC organs are at line level and are compatible with all third-part audio equipment. Expression is applied within the cage and is followed by line amplifiers that eliminate the MOS-era concern of matching impedances to retain the expression action.

If some channels work satisfactorily with the external reverb while others do not, the obvious first step is to determine whether the faulty channels have something wrong externally such as defective cables, loose/dirty connectors, and so on. Swap the inputs to the reverbs and see whether the problem follows the cage outputs or the reverbs, amps, and speakers. The cage outputs are rather cheap tin-plated RCA connectors that are very prone to corrosion--maybe the problem is nothing more than a loose connection there. Inside the cages, socketed IC and card-edge connectors become dirty and need to be reseated; voicing pots develop dirt spots and need to be exercised. Do not discount the possibility that the low outputs showed up coincidentally as a result of all the rewiring and physical movement and that they have nothing to do with the external gear that you connected.

There is nothing deep or mysterious about the ADC audio--outside the cages it is strictly conventional. There is no Allen add-on solution to resolve issues with proprietary signal levels and such because none is needed!

Expression in the MOS 1 instruments with console-mounted amps has been well documented elsewhere on the Forum and in the Allen literature. Expression is applied by shunting signal current to ground through a light-dependent resistor actuated by the expression pedal. A high output impedance is needed to drive this expression network to ensure proper voltage-divider action. Inserting a device (such as a reverb) having low output impedance at this point in the circuit will cause the expression to remain at full. Again, this circuit was superceded by a more sophisticated arrangement in the ADC organs, and impedances are all standard at the cage outputs.