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 Post subject: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Fri Jul 21, 2017 7:04 pm 
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Victor III
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I'm Getting Ready for my Mother In Law
Joined: Sat Feb 28, 2009 1:52 pm
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I do try my best to make the introductory Subject lines interesting to hook you and reel you in slowly! I have gotten to work on the EMG 4-springer that came with the Xb. I have thus far replaced the leather washers with mid-hardness silicone ones. I have a weird lust for silicone....seems to be my mystery material of choice. The three back plate screws also received a silicone washer each, plus a small ⅛" long piece of clear silicone medical tubing slipped over the threads to isolate the screw body from making contact with the back plate. The mounting insulator.....I am waiting for Chunny's replacement part to arrive, but in the meantime I have been using the original (while hardened, still works...kind of).

I retained the original aluminium diaphragm and installed it with new soft butyl rubber tubular gaskets. After a bit of tuning and tinkering with the new set of adjustables, I was able to obtain a good balance between bass, treble, and midrange. No doubt this will be much better when the new mounting sleeve arrives from Chunny!

The sound is good....very good. But, it lacked clarity and definition. For those Yankees that know me, I am a "bit" of an obsessive.

:lol:

Ok, I am VERY obsessive.

I removed (carefully) the original alum diaphragm and replaced it with a piece of German glass I received from Norman Bruderhofer. He has been producing these for the superlative Victor Exhibition, and just as luck has it, it is of identical diameter to the EMG. After replacing the diaphragm with glass, there were additional adjustments I made to make sure the diaphragm would sit NEUTRALLY, and allow itself to work its wonders with little to no resistance.

Firstly, when attaching the back plate to the soundbox body, I held the unit horizontally (face bezel down) and inserted the 3 insulated screws which hold the back plate to the face bezel. I turned them clockwise until their washers TOUCHED the back plate squarely, then each screw received ONE complete revolution. This assures (assures ME, anyway) that the diaphragm is being held LIGHTLY in place, and thus is allowed to vibrate and reproduce low notes sympathetically with the needle bar. When this was in place, I nextly adjusted the needlebar with slight outward bias, so that when the soundbox sits on a record with a needle, the foot of the needlebar just barely touches the glass diaphragm. When this adjustment was completed, I used ONE TINY DROP of 3-second cyanoacrylate glue on the needle bar foot to secure it to the glass diaphragm.

And this is my empirical system.

Acoustic records reproduce with a crisp and mirror-like clarity. Instruments that would otherwise be muted by aluminium or mica diaphragms are now CLEARLY audible. You can hear the tuba player puffing away in the back row of Sousa's Band, now! Acoustics are best played with a SOFT or MEDIUM tone needle. LOUD tone needles offer no advantage.

Electrically recorded discs....same rule applies. SOFT or MEDIUM tone needles. The clarity and "river of sound" coming out of the massive 29.5" horn is downright amazing. Ambience and Presence, more than any loudspeaker could achieve without all that electronic mumbo jumbo tied in with a jumble of wires and equalization settings.

Is it Loud? It isn't so much Loud as it is clear and distinct. Loud enough but not overpowering. I feel it is a refinement ABOVE the aluminium diaphragm (which now lives in a small box inside the Xb's elephantine cabinet structure.).

My current distinction: Before with the alum diaphragm I was ENJOYING. But with the glass diaphragm, I find myself LISTENING.


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Fri Jul 21, 2017 7:18 pm 
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Victor IV
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"Did you ever stop to think that pleasure is a duty?" (Victor sales pamphlet)
Joined: Thu Jan 08, 2009 5:19 pm
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Wonderful post!
I hope to hear an EMG Xb or equivalent someday in person. YouTube postings don't do any of them justice!
If I owned one I'd certainly have you service the soundbox.
Thanks for the great photos and text.
Bob
"Comparison is the thief of joy" Theodore Roosevelt


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sat Jul 22, 2017 3:58 am 
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Victor III
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Location: near Utopia, UK
Thanks so much for posting, MM! Wonderful to read about your experiences and a really fascinating experiment - evidently highly successful!

MicaMonster wrote:
You can hear the tuba player puffing away in the back row of Sousa's Band ... ... The clarity and "river of sound" coming out of the massive 29.5" horn is downright amazing. Ambience and Presence, more than any loudspeaker could achieve without all that electronic mumbo jumbo tied in with a jumble of wires and equalization settings.

I'm very fortunate to know exactly what you mean, and I love the way EMGs give rise to amazed observations and lyrical superlatives like this! Yes indeed, the visceral immediacy of the sound without filtering through all that electronic soup (except the recording apparatus in the case of electricals)...

May I ask - do you have rubber washers BETWEEN the front and back plates? One of the major adjustments is the 'holdoff' between the faces. So long as the diaphragm gaskets are still achieving a seal, the gap can be quite large - one of mine is optimum at nearly a millimetre. I wonder whether this was why the aluminium diaphragm was less than satisfying - and you may have an even greater revelation in store!

Also the springs - I imagine you must have them adjusted optimally given the results, but just in case, they only need to be touching quite gently to achieve the diaphragm's null point. As with the body screws, adjustments of as little as ⅙ of a turn can have significant results.

I know everyone has their preferences, but over here we all use natural rubber for the gaskets - but I'm sure there's a lot to be said for butyl: low resilience (i.e. rebound/bounce) and low transmission (i.e. high isolation) and I'll look forward to experimenting one day.

I'm sure other EMG fanatics will chime in as I'm far from highly experienced or authoritative - just giving my simple thoughts!


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sat Jul 22, 2017 4:00 am 
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Victor III
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Location: near Utopia, UK
P.S. Do please post photos of the rest of the instrument!


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sun Jul 23, 2017 9:02 pm 
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Victor III
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I'm Getting Ready for my Mother In Law
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Orchorsol wrote:
P.S. Do please post photos of the rest of the instrument!


Thus far, I don't have space to set up this beastie


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-Antique Phonograph Reproducer Restorer-
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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sun Jul 23, 2017 10:42 pm 
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Victor IV
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A new blank with authentic formula and spiral core!
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Location: 615 1/2 South Main Street Princeton IL 61356.
That looks like a wonderful rebuild of this reproducer. I have a Victor No. 2 reproducer that has a glass diaphragm, and they sound much better than mica. I also like glass in model C reproducers, The right diaphragm offers a nice clear sound plenty of bass and less distortion.


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Tue Jul 25, 2017 4:37 pm 
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Victor III
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I'm Getting Ready for my Mother In Law
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Posts: 665
Location: the Adirondacks
here is the completed sound on YouTube. turn up your speakers!!!

http://youtu.be/LJJ-xtstUDo
-Antique Phonograph Reproducer Restorer-
http://www.EdisonDiamondDisc.com
Taming Orthophonics Daily!


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Tue Jul 25, 2017 5:18 pm 
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Victor III
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Location: near Utopia, UK
Sounding great (as far as one can tell over Youtube, of course!) and looks a really beautiful example!


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sat Jul 29, 2017 5:31 pm 
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Victor IV
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A new blank with authentic formula and spiral core!
Joined: Wed Oct 21, 2009 10:50 am
Posts: 1324
Location: 615 1/2 South Main Street Princeton IL 61356.
very natural sound, good bass, mids and highs.


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 Post subject: Re: Fondling an EMG 4-spring soundbox with GLASS
PostPosted: Sun Jul 30, 2017 3:36 am 
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Victor V
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Location: Where there's "hamburger ALL OVER the highway"...
Great sound!

As for the "weird lust for silicone", I am sure you will find a board somewhere online that caters to that.... 8-)

Bill


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