Fondling an EMG 4-spring soundbox with GLASS
Posted: Fri Jul 21, 2017 7:04 pm
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.
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.
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.
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.