Subwoofer power

[John Vanderlee]

We hope to install an Allen ADC4500 in a venue until the pipe organ is repaired. Besides the 8 HC12 speakers we are putting in, we're adding a subwoofer as well. It means we have to add an amplifier to drive it. The sub I have is what came with a collection of speakers from a Phoenix organ. It uses a high end 15" speaker from Parts Express in an approximate 18cu. ft enclosure that has 2 tuned ports. We ran it off a 65 watt amp, and the 16' and 32' pitch was very clean but we feel there should be more output.

I'm thinking of using this:
https://www.parts-express.com/dayton...emote--300-785

Especially since it has a variable crossover built-in. The organ uses the 4 unit ADC amp now. Could we just "Y" from the input that carries the bass channel to this extra amp? Would it load down the input of the ADC channel?

Any thoughts on this appreciated!
John

[John Kinkennon]

My choice would be a Crown XLS 1002 which also has built in DSP capabilities including low pass filtering. In bridged mode it can drive an 8-ohm load at 700W. The extra power isn't needed so much as the assurance that the amp will not be over-driven which is perhaps the most common cause of speaker failure.

I can't speak to paralleling off the existing Allen amp without knowing the current load on the amp (one speaker?) and the impedance of the parts-express driver in the Phoenix sub.

[rjsilva]

John has a good point, in that it’s better to have more power than you need rather than push what you have too much. Not that 230W RMS (bridged at 4 ohms) is too little, but you need to weigh the situation—how close was the 65W amp to getting the volume you want, was it driven to max, is that 65W RMS or peak, etc.? 230W may be perfect, but it also may not be.

[toodles]

It makes NO sense to add a subwoofer to an ADC-4500. This is a theatre model, and the lowest pedal pitch is 16 ft. The HC-12's will handle this pitch with no problems whatsoever. If you need additional bass, adjust the voicing and level controls on the organ.

[John Vanderlee]

First:
This is the driver:https://www.parts-express.com/dayton...-coil--295-514
With its coils in series it's 4 ohms.

Second I meant "Y" off the ADC amp input, using the line level signal to drive an out board sub-amp.

That was 65 watts RMS

I could also consider a 500 watt rms plate amp like this:
https://www.parts-express.com/bash-5...w-rms--300-752

- - - Updated - - -

Hi Toodles, you may have a point there. I just wanted to explore the options if it proved insufficient. Thanks!

[toodles]

You certainly don't need that subwoofer for a 16 ft. stop. Save your money at least until you find out you have an issue. It is unlikely that there will be a problem, since the HC-12's provide service in many church installations with no problems.

[jbird604]

As to the "Y" cable question -- you can certainly do that. The output from the Allen ADC cage is very low impedance, possibly under 1K ohms. And the input to the ADC amplifier module is probably 100K or very close to that. Just about any modern line level amp will have a similarly high input impedance. Driving two or even several amps in parallel off a cage output should be no problem.

On the MDS45 at my church I added an additional amp channel to supplement the four that it came with. I use a "Y" cable to drive two amp modules with the channel 4 output of the cage (which carries the 32' pedal stop). The added amp drives a large Walker sub through a simple passive crossover and gives an incredible boost in power on the 32' stop.

I see in your first post above that you mentioned a 32' stop on this organ. Maybe it's not a 4500 but rather a 5400?

[John Vanderlee]

It is a 4500. We tested the sub on a Rodgers that had a 32ft stop.

[jbird604]

Well, it usually seems that the HC-12 is more than capable of handling 16' pedal stops. But if the organ is going into a large room you still may need a lot of bass to make the organ sound as full and powerful as you want. A sub might be helpful. Won't hurt to try one.

For a number of years I played an old Conn 720 in church, and if of course only has pedals down to 16'. But I ran it through some big amps and some hefty subs to make those 16' pitches in the bottom of the Bourdon really shake the building. Not the same sort of thing you get with a 32', but quite satisfying. You might enjoy getting that kind of bass boost with only the 16 footers on the 4500.