Allen 505 - 'Howling'

[Guest]

I have recently made my first acquaintance with an ancient Allen 505. It has been overhauled by the makers in the recent past but the Hohl Flute 8' howls or growls when two or more notes are played simultaneously in the Tenor register. A chord of D minor elicits a noise not unlike the old Compton Harmonics 32' Mixture stop and, puzzlingly, with an entirely different tone colour to the Hohl Flute - more akin to a Fagotto 16'. It happens only on this stop, though to a lesser extent on the 4' Flute.</P>


Is this a wiring fault, design fault, speaker problem or what? Michael (Maine) in an earlier text refers obliquely to this problem but suggests it is a consequence of harmonics in this range. If this be so why does it not affect other Gt 8' stops and why the totally different sound produced? Do others suffer from the same?</P>


This 'newby' would be most grateful for any advice or observations.</P>

[myorgan]

Re: Allen 505 - 'Howling'



[quote user="m-freke"]Is this a wiring fault, design fault, speaker problem or what?[/quote]</P>


The short answer to your question is, "Yes." However, it is odd you're just now noticing it after 25+ years. Has something on the organ changed in the recent past?</P>


Too bad you live on the other side of the pond! I just visited a 505 in New Jersey a month ago to help with a problem they were having. Someone had really messed up their organ!!!</P>


I learned after I posted the initial inquiry that this issue is a known issue (inherent)with the MOS-2 organs on particular stops. I found a couple of ways to correct it.</P>

1. <LI>I learned that if I tuned Computer B slightly sharp or flat of the current setting, I could practically eliminate the "wolf" in the tenor register. I noticed it more with the Dulciana stop, but it may have been the Hohlflöte as well. I can't remember. The drawback to this is that the Celestes will not be quite as warm, or pronounced (depending on which way you tune).</LI>
   <LI>Separating the speakers of certain channels also appears to help as well. I cannot remember which ones I separated, but it did work. It provided space between the two offending speakers for the "wolf" to disappear.</LI>

It is probably not a wiring fault, as it exists in all Allens of that vintage. I'm told it is in the programming of the organ and was corrected on later Allens (ADC).</P>


Meanwhile, I've found a positively charming "must have" tone card for that organ. I purchased the Flute Celeste card, and it yields the most WONDERFUL sound!!! I think the church might be getting tired of it now.</P>


Hope I've helped in some small way.</P>


Michael (from Maine)</P>

[Guest]

Re: Allen 505 - 'Howling'



Sincere thanks to Michael (of Maine). As my original post said, I have only just met this instrument; who knows, the problem may have been there from the start! I shall get to work on your suggestions.</P>


Martin</P>