EMG Flyers

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emgcr
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Re: EMG Flyers

Post by emgcr »

Thanks for your photos Iain and, although I have had this box for ten years, I have not rebuilt it and have used it only occasionally—it sounds reasonable but could well do with new gaskets. This is the first time I have considered it in great detail---thank you for bringing that about !

The hooped springs are indeed located and held between the main case extensions and the “lock nuts”---except, of course, that the nuts are not acting in a locking sense at all ! The slotted set screw heads and nuts are wound tight together thus it is not obvious why the nuts are there in the first place—they are merely acting as spacers. The natural curvature of the springs at that point is what is producing the tension to keep them in place, much as you describe in your example which, of course, is of a different design altogether. I am not sure if my set-up is what “came out of the factory” or if someone has modified it subsequently. It doesn’t really make sense does it but may have just been part of the development process ?

The pointed ends of the springs sit in an inscribed “track” or scored line which is interesting as this prohibits sideways movement—ie any lateral adjustment at all. Presumably the thinking was that it would be advantageous to maintain exactly the same lateral point-loading positions on either side of the knife edges. The springs themselves are of quite thick section, crudely made and therefore not too flexible---experimental perhaps ? I have also noticed that the platform has two redundant threaded holes (just seen in my final photo) which point to the fact that this may well originally have been an Exhibition type box with spring arrangement identical to your own ! That would explain the lock nuts which probably were used in the correct way in that iteration. This would certainly appear to be a very early experimental example incorporating hooped springs.

I am afraid I do not know of anyone currently making such springs but would think that your soundbox might well, in this comparison, give better results than mine ! Eternally fascinating and thank you again.

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Re: EMG Flyers

Post by IainW »

Graham, I guess that the EMG soundbox currently on offer on ebay is yet another iteration lying somewhere between the two you posted in this topic earlier, having the hooped springs and aluminium diaphragm, although that appears in a pretty parlous state looking to have corroded right through. Am in two minds about whether to put in a bid but no doubt it will end up selling for several hundreds of pounds. Is the engraved EMG on the outer face unusual? I cannot see anything similar on Chunnys website.

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Re: EMG Flyers

Post by emgcr »

Yes indeed, the one on eBay is of similar period and I have a couple of examples shown here. It is interesing to note that one has an aluminium needle holder and the other brass. Also, the back castings on both are nickel plated whereas the fronts are left in parent brass. The one on the left came with its original Grape Street box. They do not seem to be common with top inscriptions, these being the only two I have seen until the current item for sale. The one in the box came from the Roger Thorne auction in 2011 and the other (no box) came to me from Belgium in 2008 where it had apparently graced an Expert Junior.

The eBay example is likely to sell for a good price even though the diaphragm is in a parlous state. It is a moot point as to whether it is repairable given that there is likely to be much oxidation under the hardened rubber gaskets. Holes can sometimes be bridged with thin foil but such repairs are not always successful in the long term. Time will tell............
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emgcr
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Re: EMG Flyers

Post by emgcr »

For the sake of the future of this thread, here are photos of the item currently for sale on eBay so that they don't disappear when the sale is history.
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Inigo
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Re: EMG Flyers

Post by Inigo »

Curiously, emgcr, in your latest examples, the adjustments of the springs seem different. The one at the left has the points of springs roughly in the center line of the plate, as in line with the knife points underneath, so no lateral pressure is exerted on the plate, except when vibrating, and the hooks of the springs play their damping role. In the other (right side) the points seem to be set at both sides of the center line of the knives, exerting an initial lateral pressure, one against the other. This action is observed also on the exhibition soundbox, where the lateral springs have to be adjusted with a certain tension to avoid buzzing. In this, the two springs have to be balanced so no lateral bias tension is induced on the diaphragm. Things settled in this way on an exhibition, I always wonder about the asymmetric effect it will have if the two springs are not exactly equal in thickness and stiffness, as it might be in a factory mass produced soundbox. Surely EMG and Expert might have adjusted the springs to be equal... precisely handmade.
Or would a certain bias be tolerated, or even maybe needed for any reason?
Inigo

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emgcr
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Re: EMG Flyers

Post by emgcr »

Inigo, thank you for your well-observed comment but I posted the photo of the two soundboxes really just to show they exist and that there are different designs but perhaps I should have pointed out that the one on the right is not currently in use and has not been rebuilt for many years. You are quite right---it is not adjusted for optimal performance but will be when the time comes. I agree with you that equal pressures are usually desirable for maximum sensitivity and performance. I apologise if this was misleading.

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Re: EMG Flyers

Post by Inigo »

Don't apologize at all! You all know I'm curious, and I'm always working sidelines to the main aim of the thread :oops:
Anyway, in the standard (if there was any) of emg/expert soundboxes with two springs only, what was the intention? To place the points centered or to place them aside and balanced one against the other? If seems that the four spring soundboxes overcame this by separating the roles of both pairs of springs. One couple being aligned with the centerline of knife supports, just to provide the fixing of the plate and avoid buzzing, and the other couple dedicated only to provide the lateral balanced forces for damping. This design allows much more delicacy in providing these lateral balanced forces, being freed from the plate supporting mission.
One tends to think that on the two spring models, the springs had to do the double work, as in the exhibition.
Inigo

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Re: EMG Flyers

Post by IainW »

Thanks for the advice and pictures Graham and the points raised by Inigo are fascinating. Although I have had my EMG for more than 35 years, it is only since joining this wonderful forum that I have learned so much more about them.

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emgcr
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Re: EMG Flyers

Post by emgcr »

Inigo wrote: Wed Mar 10, 2021 5:23 am
Anyway, in the standard (if there was any) of emg/expert soundboxes with two springs only, what was the intention? To place the points centered or to place them aside and balanced one against the other?
The great thing about EMG/Expert/Astra boxes is that they have many ways to alter the performance---perhaps too many ! I find it is sensible to start with the spring points directly over the knife edges and then tune as required from there according to the sound you want---with reference to the needle type and record content. That might well include altering the points away from the centre line equally and in opposite directions. Position, pressure, washers, gasket material and wall thickness---all are important and play their part. In my experience, fine tuning a soundbox and getting that magical last one percent out of it can often take a long time and drive you completely mad in the process !

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Re: EMG Flyers

Post by CarlosV »

emgcr wrote: Wed Mar 10, 2021 6:13 pm
The great thing about EMG/Expert/Astra boxes is that they have many ways to alter the performance---perhaps too many ! I find it is sensible to start with the spring points directly over the knife edges and then tune as required from there according to the sound you want---with reference to the needle type and record content. That might well include altering the points away from the centre line equally and in opposite directions. Position, pressure, washers, gasket material and wall thickness---all are important and play their part. In my experience, fine tuning a soundbox and getting that magical last one percent out of it can often take a long time and drive you completely mad in the process !
I agree, and moreover the fix does not last long! as you play records and time goes by, the pieces slowly move, rubber tubes and leather washers stiffen, and there you go tweaking it again. A neverending job indeed.

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