Electronic organs - circuits, experiences and interests

[joebog1]

Its hardly the same instrument!!!. But I can see what you are saying. All you could hope for is that the origional modder kept decent notes , sketches and circuit diagrams.

Joe

[Lucien Nunes]

If he made any record of how it was before he started, that was over 50 years ago, and it is some years since he was alive. Much original information that was in the Compton offices was destroyed when the factory was bombed during WW2, so there probably isn't a single document in existence describing this organ's innards. However, a few similar ones survive, at least one of which is in fairly original condition. Many aspects will also follow Compton standard practice; although it was their very first electronic organ, the console is wired exactly like that of a cinema pipe organ, of which they had already made hundreds to very standardised layouts and specs.

Although I mentioned in a recent post that Compton typically used interchangeable fixed resistors for voicing instead of presets, unfortunately in these very early generators they did use presets, so even on the surviving original generators that we could copy, it is unclear how the voicing has been changed since manufacture. Not everyone agrees how an electronic imitation of an organ imitation of a trumpet should sound. It can't be copied exactly from later, unaltered instruments because the generators have a different complement of waveforms leading to a different method of building up the pipe tones.

I will post better pictures of  the generator rack at a later date. I tried to capture the views inside the generator shed, but even with a wide-angle lens it is hard to see what is going on. The equipment is laid out as three islands with narrow gangways for maintenance, but you can't readily stand and take a picture of the front of any of them. A few attempts below - this is one of the three islands containing most of the original material for this instrument, although with later generators and different amplifiers. The relays and voicing chassis are original. Picture 3 shows one of the maintenance gangways. In total, the generators for the two instruments occupy the whole of the wooden shed, which connects to the organ room on the right via two 4-inch plastic cable ducts visible over the door.

[joebog1]

WOW !!!, thats not dissimilar to a large transmitter shed. I could spend a month in there, just getting to identify the various bits and pieces.
This MUST come under the heading of REAL engineering. Its a truly beautiful thing that I didnt even know existed before I read Luciens posts here.
But then, I was amazed at a tour of the projection room of a 1930's odd cinema in Sydney. A full compliment of Westrex equipment,
complete with five channels of 300B's, so that Fantasia could be played " as it was intended ".
Shortly after my visit that theatre was torn down :-( , I wonder what happened to the amps?.
( which did hum pretty badly ).


Joe

[Lucien Nunes]

It's a shed full of stuff, with six whirring motors, 72 generators producing 1272 waveforms, 924 relays of between 10 and 21 poles each, 84 valves etc. But you could do it all much, much better with a PC and a decent multi-channel soundcard and amplifiers sat in the back of the console. That's one of the problems with collecting vintage analogue organs. Vintage HiFi is expensive but produces results reasonably comparable to modern. Vintage radios don't produce comparable performance but they are cheap and easy and fun to work on. Vintage organs are incredibly hard work and produce generally inferior results. The interest has to come very much from the historical angle. There's no difference to the user interface (console) whether what's in the shed is a PC or that behemoth of a generator setup, but from the resulting sound the PC is 5000% better. I get annoyed that historically important analogues are gutted and turned into digitals, because my interest is indeed from the history side. If you just want to play music, it's a no-brainer.

I mean, not only has the generator installation got rows of shelves for spares, hooks to hang popular tools and test leads, and patchable monitor speakers on the wall so you can hear what you are achieving as you work, there's a clock so that you can keep track of the hours of your life ticking away as you tweak the voicing, oil the generators, clean the relay contacts... What sensible human would do that?

[BusyBee]

Personally I prefer older things as they look and sound like older things. I like to immerse myself in the feel of things when possible. At least I can lie back and listen to my 78's with my eys closed and dream that I am there. I have no room for an organ and cannot play one anyway but I'm glad some people do. History cannot easily be re-lived, even realisticly with virtual reality, as yet.

'What sensible human would do that' makes me think how times may have changed as they would have done that when they were in service.

Tracy

[Lucien Nunes]

So do I, however the majority of owners of electronic organs just want to play music on the most effective and suitable instrument for their style. If one is going to invest effort in playing, does one want the results of that effort compromised by using an inferior method of tone formation? Hammonds are the odd one out here: They have a very distinctive character that is recognised as itself, not as an imitation of something else which was the original intention 88 years ago. Today, one owns a Hammond to play the Hammond, not to imitate a pipe organ.

But classical-style and theatre-style electronics are still mainly regarded as the imitations of pipe organs as they set out to be, for which purposes a better imitation is a better organ. The Electrone evokes the wrong kind of history; not the glorious rich sound of the cinema organ nor the majesty of the cathedral organ, but the early, crude, not entirely successful attempts to imitate them. Enthusiasts of that aspect of the history are few and far between. It's like watching snooker on a 14" monochrome TV - vintage TV fans would do that but snooker fans would not.

[joebog1]

I agree with you Tracy, BUT!! it would need be smellavision to get that nice ozone flavour.
Not to mention valves running quite hot and a neat covering of dust to add to the effect.

Joe

[joebog1]

So I just watched " Songs of Praise ".
A normal visit for me every sunday. Sometimes I watch it all, sometimes its right on the wrong side for me.
Today was from Halifax, West Yorkshire. A VERY nice pandemonium, ( which is what I call a large and well played pipe organ ).
I do have a subwoofer playing quietly, and the sound is one I have only heard with a true pipe organ.

Electronic organs can get the same frequency, but lack ( totally ) the harmonic content that comes from pipes.
This is a very good discussion and I thank Lucien for taking the time to educate me on what was/is available in GB.

Thanks Lucien.

Joe

[Lucien Nunes]

The difficulty of reproducing bass was one of the early obstacles to recreating the sound of a pipe organ. Granted, the pipe organ needs big pipes to do that but once you have bitten the bullet, you get powerful fundamentals down to 32Hz, or if you are ambitious and add a 32 ft. stop, to 16Hz. Such frequencies were almost impossible to replicate at realistic SPLs with available amplifier powers and speaker designs during the early attempts at electronic tone generation, so even if the waveform could be produced faithfully, the acoustic result was weak and unconvincing to the audience.

Pics below show the giant 27 cu.ft. bass cabinets used by Compton with 18" drivers. Note the steel cross-bracing rods. The treble units were in separate enclosures. The whole system was bi-amped all the way through i.e. the bass generators fed the bass amplifiers fed the bass speakers, to avoid intermodulation. The amplifier chassis each had a bass and a treble channel, and the OPTX in the bass channel was twice the size of that in the treble to enable it to deliver full power at the bottom end.

They did include a 32 ft. pedal stop in the specification of many of their better church models, including the 347 to which these cabinets belong. It just-about works but it wouldn't fool anyone that they were listening to a pipe organ. If space constraints dictated smaller cabinets, e.g. the freestanding types often located in the chancel, the 32 ft wasn't really usable. My hunch was that the stop was included primarily for specsmanship, not for musical performance.

[Radio Fixer]

Well its off topic as its a pipe organ but worth 8 minutes of your time to play. Off course the PC and no big speakers done do it justice. Beautiful building as well. He plays wonderfully.

https://www.youtube.com/watch?v=sOxIoqATFWE

Gary