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Dear RobThanks for the link.This is a digital organ of the early 1990s based on the M114 sound cards. These are 8 bit and by today's standards primitive _but_ the sounds can be remarkably good if processed in the right way. This means adjusting amplifiers well,using specifically designed loudspeakers (not generic nor PA speakers) - which can make the most remarkable difference to realism achievable - and an octave coupler can be derived which can totally transform the effectiveness of the instrument, in particular regenerating the lost upper frequency harmonics that cause a chord in the right hand in the top two octaves to be lost, overpowered by a chord in the left hand. These can be applied selectively to certain groups of stops.I don't know the sound samples of this instrument but from the stop list on page 6 of the service manual, and being aware of two instruments of this character belonging to players on YouTube, one in Italy and one in South America, well voiced, the instrument should be capable of sounding superb.With regard to tuning of the Mixture, this is odd in that it cannot be out of tune with other stops on the Great, all of which are given pitch common to all stops by the generator board page 11, in particular chip U8, the LM567 main oscillator. This goes through the 4059 frequency dividers and then 4046 Phased Locked Loop chips which generate three seperate frequencies governed by the tremulants and in particular settings for pitch and chorus intensity given by the DIPswitches 1-3 and 5-8 on S1.I'd imagine that these might do something to your Mixture, possibly affected by how many stops are drawn, although I don't see a feedback mechanism for this, and it might simply be for the Celeste 8ft. Page 16 identifies switches 1-3 as Tuning Swell and 4-8 as Chorus Swell - this may be the Celeste. However, the block diagram Page 1 shows a SELCO . . . 73 bus which may relate to increasing "chorus" as numbers of stops are drawn.How therefore the Great Mixture can be out of tune is a mystery. This should be a question both for Roy Orme and for David Fetterman at Makins: you need someone who was dealing with these circuits 20 years ago. Which stops will be adjustable in volume will depend on groupings fed to the amplifiers but these are potentially choosable and alterable with links indicated on the voice cards, P12 to PA1-6 on the main bus. The potentiometers on these cards adjust a voltage bias, nothing to do with voicing, and can be responsible not only for distortion but also a thump, a bit like tracker noise, on each note.Page 16 indicates the general volume controls for each of the amplifiers on the amplifier cards, and the associated treble and bass controls for each channel. The extent to which these are useful controls depends on stop groupings.On this vintage instrument, there should be a connector or two for an "INDINOTE" voicing box. With the box one can adjust the volume both of individual notes, as well as individual ranks as well as the extent of chiff or otherwise.The amplifier boards use a TDA 7250 amplifier circuit controlling TIP142 and TIP147 complementary transistor pairs arranged in the spec sheet guideline: http://home.mira.net/~gnb/audio/pdf/TDA7250.pdfThis circuit should be a foolproof short circuit protected circuit, but even despite the fuses, F4 and F3, the short circuit protection fails and it is essential to take care not to short speaker wires by accident at any time that the organ is turned on.Certainly the Pedal department will be coming through its own amplifier and this should therefore be adjustable directly on the amplifier volume control - an easy adjustment. From Page 2 this looks as though it's the upper amplifier of Amp card A, the left hand of the pair. However, this will also adjust the 16fts on the manuals too . . . and if these are fine at the moment, one will need to use the Indinote voicing box.Best wishesDavid P
What sort of speakers would suit this organ do you think? With reference to the Mixture stop its not out of tune, its' basically a case that it's under volume compared to it on the swell I can easily tell when I listen carefully.As far as I can see there is no room for a voice box it simply doesn't have the connector for it, I did look underneath the manuals and rear but nothing was there.
Quote from: RobCharles1981 on January 20, 2011, 10:09:27 PMWhat sort of speakers would suit this organ do you think? With reference to the Mixture stop its not out of tune, its' basically a case that it's under volume compared to it on the swell I can easily tell when I listen carefully.As far as I can see there is no room for a voice box it simply doesn't have the connector for it, I did look underneath the manuals and rear but nothing was there.Dear RobSpeakers - well I see the stops and I see the amps but unless I'm blind don't see which stops are allocated to each channel. If you can possibly write out the stop list and then play each stop and determine which groups of stops are coming out of each of the existing speakers, I'll be able to give you some useful ideas.Mixture stop not out of tune - that's a relief! This might be adjustable via the treble control on the relevant amp but that will affect all other stops through that channel too so this might need the indinote box. The connectors for the voicing box may well be tucked away on a circuit board inside that might not be found easily. Roy Orme may know but David Fetterman definitely will. Both Jonathan Lane and "Hector17" (Paul) both on this forum and who are now both pipe organ men but know also about Makins of this vintage too and might have direct knowledge. You might usefully PM them. (It would be great actually if they might be persuaded to be more noisy in posting stimulating pipe posts!)Best wishesDavid P
Don't worry folks I've not letting this thread go to the ghosts - our Church are having a new Incumbnet in a couple of weeks, and I will tell him all that's gone on, and I will be getting rid of Makin Organs for good as far as I'm concerned.
I am new to this forum, and so hope I am not sticking my nose where it don't belong.
A toaster shouldn't be affected by the cold weather unless, perhaps, the building is damp and this is causing problems with contacts. If this is the case, then a simple low wattage tubular heater (dampchaser) might help. I've heard good reports about Ormatronix and they might be able to help. It's certainly worth asking the PCC to agree to you contacting them for advice. Otherwise, you might want to try what my first organ teacher did: He was Organist of a local RAF camp where the organ (this was in the early 1970's) was an awful Livingston Burge. Reg told me he used to pray for the Lord to send a thunderbolt from Heaven to strike the toaster so that the Air Ministry would provide a better one (It never worked for Reg, but a lightning strike on another local church did destroy the Makin one-manual and the insurance payout bought a far better 2-manual & pedal Good luck!N