Allen 225 RTC Organ

[Electrolux-dude]

Ok, so I've hooked up a pair of 8 ohm speakers to this organ. There are 2 brown cables in the back of the organ that have black and white wires. I've wired in the speakers with black being neutral and white positive. Is this correct? I haven't plugged in the organ to try it and see if it will play or not, unsure as to whether something might short out? All the other wiring and the amps look to be intact. The organ has apparently had a newer main amp installed, the amp says 2004 on it. Just need a little advice before trying this. I'm pretty sure those 2 brown cables in the back of the organ are speaker wires as they are hanging down in the rear of the organ, looks like when the organ was removed the cables were cut. Anyway, should I proceed to try the organ or not, or does it require further service?

[rjsilva]

White should be positive. Also, reversing the polarity shouldn't cause any problems beyond potential phase issues. I'd say it's safe to turn it on, just verify those cables really are speaker cables first :)

[indianajo]

Ordinarily in an unknown situation, I check things with a meter. With power on, no signal, and no load on them, do those two wires have AC or DC voltage on them?
120 VAC would be very bad for speakers. >.25 V DC could indicate a blown amplifier. Right about 24 volts would mean you've found the control relay feed to power up the remotely powered speakers which use remote 120 vac power. <.25 VDC probably those are the speaker outputs of internal amplifiers.
One then checks the speakers to see if each is about 6.5 ohms for 8 ohm speakers or 3.5 ohm for 4 ohm speakers sold after perhaps 1985.
If the voltage is correct and speaker read the correct resistance, turn off the power and hook them up. Which color is the hot is up to you, but use the same color code on all speakers hooked to an organ to avoid mixed phase effects on bass.
Note old allen speakers often have missing foam surrounds. If they rattle at louder volumes, see the threads about repairing the cones.

[Electrolux-dude]

I had the organ checked. It's going to need a main board, that controls the tone generator as it makes sound without depressing the keys, just a continuous sound. It's a 225 RTC organ, anyone have a good tone generator board?

[myorgan]

White should be positive. Also, reversing the polarity shouldn't cause any problems beyond potential phase issues. I'd say it's safe to turn it on, just verify those cables really are speaker cables first :)

RJSilva is right on. polarity doesn't really matter with Allen MOS organs, as long as they're wired the same on every channel.

The organ has apparently had a newer main amp installed, the amp says 2004 on it. Just need a little advice before trying this. I'm pretty sure those 2 brown cables in the back of the organ are speaker wires as they are hanging down in the rear of the organ, looks like when the organ was removed the cables were cut. Anyway, should I proceed to try the organ or not, or does it require further service?

Is there any way to provide photos first before we advise you? It sounds like the organ should have come with S-100 amplifiers, but were replaced with another amplifier. If the amplifier you have is an AM-100, you should be good. If it's anything other than an AM-100 or S-100, photos will help greatly. Then, there were at least 3 different types of S-100 amplifier, so that may cause an issue as well (if someone replaced an amplifier with an incorrect amplifier).

Michael

[jbird604]

By main board, do you mean the MOS board? That is the very large flat computer board that is the heart of the tone generation system. These boards can be factory exchanged by an authorized Allen dealer or tech, at a cost of several hundred dollars. Sometimes you'll see one offered on ebay for not much money, but they are a little bit rare, as your 225 requires the "MOS-2" type, not the original or "MOS-1" type that are so common.

If the person who checked out the organ was not a well-trained Allen tech, it's possible that he/she missed something, as failures of the MOS board are actually rare. There are some power supply voltages that must be properly adjusted, and there are connections that can get flaky and cause erratic operation. The organ is a nice one, and worth fixing up. Hope it works out for you.

[rjsilva]

... as your 225 requires the "MOS-2" type, not the original or "MOS-1" type that are so common.
...
The organ is a nice one, and worth fixing up. Hope it works out for you.

Is it a nice one? My church had a 225C (well, still has, in storage) before getting a Walker. It sounded poor and I would never play it because of that but it was the primary musical accompaniment since it was bought new. The acoustics in the church were poor at the time and I'm sure that made it worse, but I never liked the sound of it. Recently I've been wondering if the speakers weren't appropriate (non-Allen) and perhaps whatever limited voicing is available wasn't performed or wasn't performed properly. It was shrill at times and cheap sounding. I'm trying to convince the organist to take it as a practise instrument and I thought I'd help him getting it to sound a little better.

[jbird604]

"Nice" is of course a relative term ;-)

We just serviced a 225 the other day, and I do enjoy it whenever we see it. It's in a medium-size church with decent acoustics and with a double set of speakers (total of four HC-12 cabinets). In previous years we've spent time voicing it as best we can, as there are both bass and treble controls on each of the two output channels of the DAC board. Not as much voicing flexibility as many modern organs, but you can do a good job matching it to a given room if you take the time.

I generally like Allen sounds, so perhaps I'm biased. But I find the 225 and other MOS-2 models quite pleasing and fun to play. The bigger ones are of course much more fun, especially when you get up to the 1105 with all the possibilities in that system. But the 225 isn't bad at all for a small organ.

In a home, it takes some creativity to place the speakers in such a way that the sound doesn't blast you right in the ears. My own Allen at home has the speakers on top of a shelf about 5 feet off the floor with the drivers pointing straight up at the ceiling. So the sound has to bounce around quite a bit before it reaches my ears. I also have added a digital reverb, which is easy to do with ADC models but a bit more problematic on MOS organs due to the level and impedance matching issues. But digital reverb, when tastefully added, gives you at least the illusion of playing the organ in a larger space, which is more favorable to organ sound anyway.

No doubt the Walker organ that replaced your Allen 225 is a fabulous instrument and seems far more pipe-like. Walker has always done a great job. I imagine it has a large number of audio channels as well, instead of just two like the little Allen. But for what it is, the 225 can be quite nice.

[rjsilva]

With what you're saying I'm hoping even more the organist will take the 225. I thought I'd give him two of my full-range Walker speakers.

The Walker does indeed sound really nice. I think we have somewhere around 15-20 full range speakers and two subwoofers. I seem to have a preference for their sound over other builders. Among the many positive aspects, my favourite is certain flutes—they are so open and breathy, really pretty. A month or so ago I played the organ at Tenth Presbyterian in Philadelphia (Colby console and Walker sound) and it was a further step or two up in sound quality from my church's organ. Also two or three times the cost! Same character though. It does have a 64' Bombarde which I was fairly amused by :)

[jbird604]

It does have a 64' Bombarde which I was fairly amused by :)

No doubt that stop would be quite amusing to most people!

[Roger Memphis]

It does have a 64' Bombarde which I was fairly amused by :)

Would that sound be somewhat similar to a herd of elephants simultaneously passing gas?
:)
Roger Memphis

[Menschenstimme]

Would that sound be somewhat similar to a herd of elephants simultaneously passing gas?
:)
Roger Memphis

Remember that crazy bit on "South Park" about the "brown note" which was some kind of bizarre infrasonic(?) loud tone that would cause instant spontaneous diarrhea? LOL!

[Electrolux-dude]

A loud continuous tone that sounds like a bunch of stuck keys, especially when the crescendo pedal is opened. As for the amplifier it looks to have been replaced with a 2 way amplifier in 2004.

[jbird604]

A "beehive cipher" on an Allen is often caused by misalignment of the pedalboard. Try pulling the pedals completely away from the console and see if the problem clears. If so, then you have to carefully re-install the pedals, making sure to get them located correctly.