Replacement S-100 Amps

[dw154515]

What are the possibilities for replacing an S-100 amp on an Allen 632 MOS-I?

http://www.organforum.com/forums/sho...is-Allen-organ


I have an amp that is not working (Allen S-100 -- see picture -- top right corner of picture). The breaker reset button has previously been pushed through the amp. Not sure if that's the only problem or not. I see another S-100 on eBay right now, but it got me to thinking: what would a good, modern replacement be?

The speakers are Allen HC10's. (8 total) and an "En Chamade" speaker.

I am familiar with both the Pro Audio and HiFi worlds (Crowne, QSC, Peavey, Mackie, Beheringer etc. in the Pro Audio world) and Anthem, Integra, McIntosh, Yamaha, etc. in the HiFi world.)

Would something like the Integra DTA 70.1 (http://integrahometheater.com/model....m=DTA-70.1&p=i) be capable of replacing the entire amp rack? It has 9 channels. I cannot find the Ohms rating for those HC10's anywhere. I've read that the S-100 gives out 100W (the Integra DTA 70.1 is 150W/Ch. @ 8Ohm.) Looking strictly at numbers, it seems possible, but there's always more to this than meets the eye I'm afraid.

I am very familiar with Integra products - I sell them daily - it's the organ that I have the concern for.

What about the expression pedals? Do they interact with the amps in any way? I've read in a few places that make me wonder about it, as well as the low-level signal that comes out of the DACs of the organ.

Any input?

[michaelhoddy]

I would imagine your main issue would be the input- MOS1 organs did not use a conventional -10 dBv unbalanced line-level input, and this would cause difficulties with any non-Allen amplifier. Later organs are different.

Every Allen speaker I've run into is 8 ohms, and I would image the HC10 to be no exception. Your organ is probably set up as 2 HC10's per channel on a 4-channel organ, presenting a likely 4-ohm load to each amplifier.

Because of the above, and the relatively low cost of a replacement S-100 from the used market, or a repair (the S-100 is a very simple topology than any decent electronics tech could fix), I'd suggest just repairing or swapping the amp. It'll cost less, and there are many less variables involved.

[Momboc]

A simple way of doing this is to:

- disconnect the coaxial cables from the Organ
- set up some RCA cables with 'F series to RCA' adapters on one end and 'RCA to 6.5mm' adapters on the other end
- connect each Organ output respectivley to an input channel of a mixer
- use the Mixer's input gain controls to bring up the Allen signals levels
- use the Mixer's direct outputs to feed a multichannel amplifier
- connect your speakers up
- adjust your levels and away you go.

Cable adapters



8 Channel mixer (if you have fewer Organ channels then you can use a smaller mixer - just make sure it has direct outputs for each channel)



Multichannel amplifier



The advantages with this approach is:
- that you can use each mixer channel/strip to adjust the relative volume of each Organ channel
- you can also use the main output as a stereo mix down of all of the Organ's channels
- you can connect a headphone to the Mixer for private listening

[indianajo]

The above suggestion by Momboc would disable the expression pedal on a MOS1, as I remember. There was a workaround listed under organ building and repair, electronics, but I can't remember how to find it yet. Catawampus or somebody posted the schematics 2 years ago, trying to remember her handle.
update
Well, I think her handle was CPV real given name Cynthia, but the post that google finds is not the one with the MOS1 schematics on it. She was trying to mix down 6 channels to two into her stereo to avoid powering 6 allen amps to provide the mixer signal.

[dw154515]

Yes, this seems pretty obvious, honestly. My problem is, as indianajo said, the expression pedal issue. I am very familiar with mixing consoles et al but it was the expression issue on an MOS-1 that I was wondering about. Luckily, Indy has a great company called "Spectrum Sound" which, as long as I've known about them, have been able to fix just about everything I've ever referred to them - speakers, amps, receivers, turntables, microphones, synthesizers, etc. so I may just buy the S-100 currently on eBay, and send the non-functioning one to be fixed and have a spare. It really seems like the most logical way to go at this point. Thanks for the info, though! Much appreciated.

A simple way of doing this is to:

- disconnect the coaxial cables from the Organ
- set up some RCA cables with 'F series to RCA' adapters on one end and 'RCA to 6.5mm' adapters on the other end
- connect each Organ output respectivley to an input channel of a mixer
- use the Mixer's input gain controls to bring up the Allen signals levels
- use the Mixer's direct outputs to feed a multichannel amplifier
- connect your speakers up
- adjust your levels and away you go.

Cable adapters



8 Channel mixer (if you have fewer Organ channels then you can use a smaller mixer - just make sure it has direct outputs for each channel)



Multichannel amplifier



The advantages with this approach is:
- that you can use each mixer channel/strip to adjust the relative volume of each Organ channel
- you can also use the main output as a stereo mix down of all of the Organ's channels
- you can connect a headphone to the Mixer for private listening

[dw154515]

We got an S-100 on eBay. I'm taking the "dead" one to have it repaired soon. Thanks for the help!