Allen Trem 3

[John Vanderlee]

Working on an Allen MDC 35 organ. Not the greatest instrument, but it's for a 10 yr old who needs a (free)practice instrument at home. We found it had a "grumble" when both a flute and reed had multiple keys depressed - as in a chord. It was traced to the trem 3 unit on the reed/string channel. No amount of tweaking was able to eliminate that. Finally we replaced it with a spare unit we had - it fixed the "grumble"; but on that one the trem was way too fast even at the lowest "rate" setting. Another one was similar. The third we tried was fine.

Question:No amount of tweaking the other controls seemed to put the range of the rate control into a usable range. I searched the forums here to no avail. Are these units defective or am I missing something?

And what is the "gyro speed" adjustment?

Thanks in advance

[Admin]

There shouldn't be any interaction between the trem and gyro rates with the other adjustments. The trem and gyro rates are generated with the same circuitry that simply switches between the trem and gyro control pots depending on the mode of operation. If the gyro rate is also too fast, it would point to shift in component values, or a problem with IC that switches between them. If the adjusting the gyro rate affects the trem rate, there's a problem with that electronic switch.

The gyro speed is the rate of the chorus shift emulating the Allen gyrophonic speakers. It is not in effect when the trem is on.

[John Vanderlee]

The gyro rates had no effect on the "too fast" terms.

John

[jbird604]

I think if you open the unit up you might find some controls inside that are normally set at the factory and not intended to be adjusted, but perhaps something has gotten out of whack.

And of course you can completely bypass the Trem with a simple male-to-male coupler. A classical model like that doesn't really need it anyway.

The Trem 3 was a great addition to organs when theatrical trem was actually wanted, but I have had to bypass quite a few of them over the years as they became overly noisy or introduced distortion. Most players never miss them, as typically they were ordered by the dealer for inclusion in a floor model so he could demo the effect for anybody that wanted it, and when he sold the organ to a church he didn't remove it. Many never got used at all and never noticed until they developed problems.