Distortion on Allen MOS Digital

[Vercus]

Hello,</p>

I'm going to be playing at a new church this Sunday, and they have a low end Allen MOS organ. It's got a lot of distortion on the principals and strings. Enough that it's quite obvious, and unpleasant to play and hear. Especially on the principals/diapasons. This occurs at all octaves/stops within that family. The flutes sound just fine, in all situations. Reeds are okay, but that may be just because MOS reeds aren't that good anyway. I should add that this distortion occurs evenly and without regard to volume level.
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I am a little confused as to what would cause this, and wondering if I want to take this position and have to play this wreck on a weekly basis. Does anyone have any ideas as to what could cause this?</p>

I don't know the model, but I'll tell you what I can:</p>

2 Manual, no capture action. Only 5 blind presets which don't appear settable unless it was from within the console. On the right was an single digit LED indicating which preset was active. </p>

No roll top, instead it has that flip top like they used in the 50s. No celeste of any type. On the left side, it has some rocker buttons: Sharp Attack Great, Sharp Attack Swell, Random Motion Off, and another which I forget. Had one expression pedal. No crescendo. Has 4 speakers. As far as my ears can tell, I haven't heard any separation from division to division. I have no idea how it's split up, if it is. It could all be mono for all I know.
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Has a fair amount of stops really, pretty complete for a 2m organ, minus the celeste. Has mixtures in each division, including pedal. Reminds me of a smaller version of my church's 632-D minus the choir manual, capture action, and card reader.
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It has transpose and brightness knobs.
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I thought that perhaps there was a slight upside- it has 22 full size chimes! Until I went to play them and half of them are either cracked or don't play right. Great.</p>

Playing this one just reaffirms my belief that the analog organs really were more enjoyable to play than their early digital counterparts. </p>

-Jon
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[arie v]

Re: Distortion on Allen MOS Digital



Jon,</p>

There are probably those on this list more conversant with Allen MOS 1 organs, but here is my try.</p>

If this organ is a 2 manual &amp; pedal, single computer, 2 channel instrument, I believe they audio channels were labeled MAIN and FLUTE. Sounds like the MAIN channel has distortion, either at speaker or amplifier. If you want to try something, try swapping the inputs to the amplifiers, and see if the problem switches between the stops. </p>

You could also try pulling the audio connections and reseating them. Sometimes over time, connectors end up with bad connections.</p>

Failing that, there may be a failure somewhere on the computer board.</p>

AV
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[MarkS]

Re: Distortion on Allen MOS Digital



The analog organs from thatera are no great shakes, either. Every small 1970's Rodgers I've played in the last decade has had terminal hum. Don't even think of a 35 year old Conn or dare I say it, Baldwin, unless it has been serviced regularly, even frequently. These are all old organs. Keep in mind that some pipe organs need major re-leathering/overhaul at that age. It is easy to forget that the earliest digitals are now approaching 37 years!!</P>


Typically, the flute channel included all flutes, plus the pedal stops and the 16' Fagotto on the Swell. Everything else was on the main channel. With a little luck it may be the audio connectors, as Arie mentioned. You might look at the speaker cones on the main speaker for any obvious problems. If it is in the amplifier or speaker you might be lucky and find two inputs on the flute amp so the main channel can temporarily feed through the flute.</P>


Good luck!</P>

[Guest]

Re: Distortion on Allen MOS Digital



It can only be a faulty DAC Board or MOS Board. If it's the DAC, it's not expensive to get fixed.</P>


Call Allen Organ Company in Macungie Pennsylvania and they'll put you in touch with the nearest Factory approved technician.</P>


Most likely they'll do an exchange board and have it fixed in under 30 minutes. There's plenty ofspare parts for this model</P>


peter@abinger</P>