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Old 15th Nov 2015, 3:53 pm   #1
Lucien Nunes
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Default 193 valves in 5 days - rescuing the Miller Classic IV organ

I hope this is in the right section - it's not technically household but it's vaguely connected with an earlier thread here that is. Last year I began work on a small home organ that I had hoped would be a quick project. Even so, work intervened and halted progress at the stage documented in this thread here: Burge organ restoration

In the meantime, thanks to AC/HL (Bill) I was put in touch with someone who knew of a very unusual all-valve instrument on a totally different scale that was still in a church, defunct but now in the way of building works and at risk of being scrapped as no-one seemed to want to take it on. Suffice to say, thanks to a couple of committed and enthusiastic people at the church who thought it was worthy of a fate better than dismantling, and one of my friends who championed its cause and would not take no for an answer, we got the opportunity to remove it complete and intact for preservation. I'll tell more of the trials and tribulations of this tricky process later, but first I'll explain what makes it special.

I mentioned in the Burge thread that analogue organs employing electronic tone generation, rather than electromechanical, commonly used a set of 12 oscillators (one for each note of the top octave) followed by chains of frequency dividers producing all the lower notes. This was conventional from the beginnings of valve tone generators right the way through to the 1970s models using LSI MOS ICs, with the 12 oscillators ultimately being superseded by a 'top octave generator' IC. In the early days the use of dividers rather than one oscillator per pitch reduced the size and cost of an instrument and gave better tuning stability. Latterly, advantage was taken of the fixed relative phase of the divider outputs, when adding them to form 'staircase' waveforms from which more complex timbres could be filtered. But that fixed frequency and phase relationship was also a major shortcoming of the divider organ, because the ensemble tones produced when the divider outputs are combined have a rather smooth and dull quality compared to those made by independent sound sources such as multiple pipes in a pipe organ or instruments in an orchestra. No two real instruments or pipes are ever exactly in tune and the resulting beats are an important part of the character of the sound that we miss in the divider organ's exactly uniform output. Along with lack of starting transients, noise, non-harmonic partials and other lesser auditory clues, locked phase was one of the main obstacles to realistic pipe sound.

Makers of electronic organs, especially those selling their products as a direct alternative to a pipe organ, went to some efforts to disguise the simplified waveforms their generators produced. A very widely used method was the moving loudspeaker, which modulated phase and amplitude of different frequencies by different amounts in a way that was harmonically unrelated to any of them. Distinct from the deep tremulant effect of the Leslie speaker that imparted a character of its own, the subtle modulation was supposed to be unnoticed by the listener. Allen 'Gyrophonic' cabinets rotated part of the baffle, Compton 'Rotofon' cabinets contained a large cruciform paddle with the HF units mounted in the blades, Dereux used a rotating diffuser above an upward-firing HF unit, etc.

The alternative was to bite the bullet and provide a separate oscillator for each 'virtual pipe' with concomitant size and cost penalties. Manufacturers of top-end classical instruments such as Allen in the USA and Miller in the UK offered models using this principle, limiting them to a more modest stoplist than their divider-driven counterparts. Thus they were made in small numbers, employed in situations where budget was not the primary consideration, and rendered rapidly obsolete when expectations of a full stoplist prevailed with the coming of newer technologies.

This thread will tell the story of the surprising journey of one of those rare survivors, a Miller Classic IV - 2 manuals, 4 ranks, 8 tone families and 193 valves - from near extinction to providing the entertainment at an upmarket soirée, in just 5 days.
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Old 15th Nov 2015, 7:09 pm   #2
davegsm82
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Not my cup of tea, but I certainly look forward to hearing more.

Dave.
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Old 15th Nov 2015, 9:15 pm   #3
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

What a beautiful piece of kit! Back in the 80s I used to have custody of a two channel power amplifier from one of these beasts as part of my home hifi, it was built on a plywood base and used a pair of KT88s in each channel with Gardners transformers, fed from a NAD pre-amp and driving a pair of Tannoy speakers it sounded awesome!
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Old 15th Nov 2015, 9:22 pm   #4
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Bet that's fun to tune. Well worth saving, and if we ever have another cold winter...
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Old 15th Nov 2015, 10:00 pm   #5
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Gasp - that must have cost several arms and legs when new! Looking forward to hearing the rest of the saga Lucien
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Old 15th Nov 2015, 10:02 pm   #6
Neil Purling
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

I hope that it has military spec capacitors and inductors.
Are the top octave oscillators each tuned by a variable inductor. The Hammond Novachord was also tuned like that, but is a very different beast indeed under the woodwork.
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Old 15th Nov 2015, 10:56 pm   #7
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Quote:
built on a plywood base and used a pair of KT88s in each channel with Gardners transformers,
Miller seem to have used a bit of a mixture of amps. This one has a pair of 807s and an extremely efficient L/S that filled the church, of which more later. I have a Miller Norwich divider organ that makes do with a mere 80 valves or so, intended for use in a smaller space and hence lower audio output. Three channels of amplification are provided, one per division, eccentrically each using a single ELL80.

Quote:
Are the top octave oscillators each tuned by a variable inductor.
Yes, almost all organ oscillators use an iron or ferrite-cored tuning coil, however in this case the 'top octave' distinction is absent as it is oscillators all the way down.

Quote:
I hope that it has military spec capacitors
Ah, yes, the capacitors. They will make an abrupt entrance into our story on day 4...
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Old 16th Nov 2015, 12:58 am   #8
Peter.N.
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Terrific beast that. A friend of mine built a valve organ kit back in the '50/60s. They sent a bag of components every week but as he often worked on it all night he was everlastingly phoning them for the next batch, they said 'you can't possibly be building it that fast' - but he was. Sounded very good when he had finished.

The first one I had used an octave of oscillators and lots of neons as dividers.

Peter
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Old 16th Nov 2015, 9:37 am   #9
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

It looks lovely and well built.
A big venue is clearly needed for listeners to enjoy it.
Very nice indeed.
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Old 16th Nov 2015, 10:35 am   #10
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

I see the console has half a dozen thumb pistons. Does that mean that the tab stops are motorised?

The size of venue isn't really determined by the complexity of the console or the tone generators. It's the amplifier powers and the sizes of speakers which have to match the hall. Maybe only a larger venue could have afforded such an extensive beast. But if you compare it to a typical church's pipe organ this valved machine is tiny and cheap. Pipe organs take a lot of maintenance and periodic rebuilds. You rarely find one in good tune across all departments.

David
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Old 16th Nov 2015, 6:33 pm   #11
Lucien Nunes
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Yes it has ordinary stop mechs, by Stero IIRC, and the diminutive combination action has a simple screw-contact setterboard under the cover left of the bass keycheeks. The manual pistons are double-touch with independently settable pedal combinations on second touch.

The three pairs of pistons above the Swell have a special function relating to the individual generator configuration, which is to assign one of two alternative voices to each generator rank, indicated by backlit legends above the stopkeys. You may have Flutes (of all footages) or Clarinets, but not both at once as they rely on the same hardware. I'll expand on this later when dealing with stop switching and voicing.

We have the cost and complexity of the pipe organ to thank for the evolution of the electronic. Had they not been such expensive and demanding animals, there might have been little impetus to develop a wind-less alternative.
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Old 16th Nov 2015, 7:22 pm   #12
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Hats off to your efforts, you should be given the DSO (Distinguished Saver of Organs)

Lawrence.
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Old 16th Nov 2015, 8:18 pm   #13
Lucien Nunes
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Act 1, Scene 1. Lucien's workshop.

L: 'Let's talk about the organ for the gala dinner.'
E: 'We're definitely taking a Melotone. Or what was that organ you were talking about with the squillions of valves?'
'The Miller? That's a classical job though. How about this 352, or we could bring the Palladium back from the store?'
'How many valves has the Miller got?'
'Quite a lot, and probably as many faults.'
'You've heard it make sounds though?'
'Bits of it work.'
'How many valves exactly?
'Maybe 160, 180, I've only seen it briefly.'
'Would you say it was the best all-valve organ you could lay hands on?'
'Well, yes, although for practicality you can't beat a Hammond, valves aren't always...'
'For this show they are. We'll stand the cabinet on the stage too so people can see inside. Can't do that with a Hammond.'
'OK, what about one of the bigger Comptons if you don't like the Palladium, at least we know what we're up against with those.'
'You fix valve stuff - you can fix the Miller. You'll be at the dinner so you can babysit it.'
'Sure but we have to get it out first and it's going to be...'
'OK in a Luton with a tail lift? Dan will drive and help you move it.'
'We can't get it out till the 5th, and the show is on the 10th, there's a lot of unknowns to resolve in five days.'
'Great!'
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Old 16th Nov 2015, 8:47 pm   #14
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Word like 'dropped' and 'in' and 'it' are going to figure in the next episode... I can tell.

David
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Old 16th Nov 2015, 11:48 pm   #15
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

And probably "sticky" and "smelly" too.

Of course it's supposed to honk when it's working as well.
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Old 17th Nov 2015, 5:10 am   #16
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

As ANY good Australian will do !! I'm sitting here with a cold stubby watching this performance !!!!
I DIDNT even know such beasties existed!!! And I thought I had it sorted as I sort of claim I know a bit about Hammonds
WOWEEE Top Job.
Let me know if you need anything !!! Although it won't get to Britain in time !!:-(

Joe
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Old 19th Nov 2015, 7:53 pm   #17
Lucien Nunes
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

After working in the live production industry for a fair few years, one develops an instinctive viability threshold for 'It'll be alright on the night'. As a project or performance approaches the threshold, the financial and emotional cost of success tend to rise exponentially. This one was close enough to merit a quantitative risk assessment and formal decision tree. In a nutshell:

Known positives:
*Apparently complete and unmodified
*Partially operational, has been powered up recently
*Very acessible construction, easy to work on
*Simple circuitry makes for rapid fault-finding

Known negatives:
*Peppered with minor faults through age and disuse
*Any systematic faults in oscillators may be present in multiples of 348
*Hundreds of Hunts Moldseals and tubular paper caps
*No spares of anything model-specific (e.g. coils) available

Unknowns:
*Can generator rack be removed in one piece (estimated >750 lbs)?
*After 50 years in one place, will movement / climatic disturbance precipitate faults that continue to manifest once it arrives at the venue?
*Are the likely residual problems ones that an organist can work around?
*Is it even suitable for the job?

Of course, there was always the option to have a backup instrument and I insisted on this from the start. But that would be a poor second, for true emergency use only, and not an acceptable way to justify unquantifiable risks of the Miller failing to deliver. The answer, had it been given on an AVO VCM, would have been at the right-hand end of the white bit between the red and green. I would take the risk.
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Old 19th Nov 2015, 11:25 pm   #18
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Surely, the capacitors alone are enough to make the task impossible in the time given. Even if some of it sort of works at the moment, the chances are that all hell will break loose as they warm up with the 1KW of heat from 193 valves.
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Old 20th Nov 2015, 12:47 am   #19
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

It's not just repacing the capacitors, it's also getting the right values and fine-tuning every oscillator for every note.

Impressive work.

David
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Old 20th Nov 2015, 7:57 am   #20
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Default Re: 193 valves in 5 days - rescuing the Miller Classic IV organ

Miller didn't use Hunts Mouldseals or waxed paper capacitors in that thing, did they? That sounds really stupid. An instrument of such complexity surely demanded components of a much higher spec than the normal stuff available to the radio & TV makers, especially when the environment in the cabinet was going to get rather hot.
By your comments it sounds like whatever components Miller used its various faults could be down to the need of a lot of urgent component replacement. OK, so it needs a lot of out of tolerance capacitors and resistors replacing. Will any re-cap need custom made components in the way that someone restoring a Novachord has to?
Then somebody checks the valves on a tester and wishes they hadn't.............
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