Here is a look into mid-50's HiFi speakers. General Electric A1-400 coaxial speakers in GE A1-406 cabinets (c. 1954/1955):
corner speaker design:
eBay sourced images below. I have not opened mine up this far yet:
The cabinets originally had legs, but they were removed prior to my possession; two were wide in the font, and the other two were narrower in the rear. I intend to mount a new set of legs on them of likely 6" height. I might offset the front from the rear to kick the speakers into an upward tilt, maybe? Well see.
I'm thinking about 6" for the speakers and matching 4" legs on the mid-century console to even their height out to be level across the tops.
This is a discussion that I found archived at AudioAsylum regarding these speakers; interesting insights:
GE A1-400's
• Posted by Tubes n' Hornz (A) on August 9, 2003 at 09:59:47
I've got a pair of GE A1-400's in the original A1-406 cabinets from the early 1950's. Has anybody done anything with these speakers, as far as sound improvement, or should I leave well enough alone? Thanks - Steve
Re: GE A1-400's
• Posted by Bold Eagle (A) on August 9, 2003 at 20:31:12 In Reply to: GE A1-400's posted by Tubes n' Hornz on August 9, 2003 at 09:59:47:
I had one of these back in 1955. My first decent system using an Eico HF-20 with a Garrard RC-88 and a GE phono cart.
I'd leave them alone and enjoy them for a piece of history. When I had mine, I tried various "improvements" and all I did was degrade them. My opinion of them is that they were exceptionally well engineered. I just didn't realize it in time.
The closed back tweeter crossed over at 1500 Hz, and had a dispersion screen over the tweeter similar to the ones used by Kloss on the KLH 6 and later KLH 17. The tweeter also has an extended pole piece to act as a "phase plug". Crossover is first order electrical to the tweeter, but probably 3rd order acoustic. Very well matched to the woofer, so there is no dip or bump at the crossover.
The woofer has a slotted sheetmetal plate over the front which acts as a mounting for the tweeter, an acoustic resistance for the woofer cone, an acoustical low pass filter, and a dispersion device (acoustic lens) to get broader dispersion at crossover. Bolting the tweeter to the plate and mounting the plate to the woofer frame nicely damps out all resonances in the plate. The tweeter also acts as a "phase plug" for the woofer output. The later A1-401 was the same except the plate was painted gold instead of brown.
Back in the mid 50's the hallmarks of fine quality speakers was massive magnets, cast aluminum frames, and huge voice coils. The GE had none of these, so I looked down on it. (we still make mistakes like that) The ignorance and consumerism of a teenager. It was only later I learned about matching the magnetic circuit to the mass of the cone and the enclosure type. The magnet on the A1-400 was just the right size for the design, the stamped steel frame was more than stiff enough, and the 1.5" VC was big enough; and the "distributed port" enclosure gives just the right Q in the bass.
I had my speaker out on a glassed in sun porch. I can remember playing an RCA recording of Jose' Iturbi, the pianist, with the windows open. People passing by on the sidewalk would stop and look for the piano player inside. The A1-400 had one of the best piano sounds I ever had. It also was on most lists of "best buys" in that era.
I tried removing the sheetmetal front plate and mounting the tweeter separately, I tried a midrange, I tried a more sophisticated crossover, and I tried a bunch of different enclosure types. All were steps backward.
Proper feeding for those is a tube amp with a DF of around 6-10. Higher Damping Factors will result in the bass tailing off a bit.
Jerry
Re: GE A1-400's
• Posted by orthophonic (A) on August 9, 2003 at 23:41:35 In Reply to: Re: GE A1-400's posted by Bold Eagle on August 9, 2003 at 20:31:12:
Agree 100% with Bold Eagle. I have 3 sets of these (
unfortunately I have never been able to locate the
GE factory cabinets, I have the plans, but am lousy at
woodworking!). They are very nice speakers, very detailed,
and exceptionally smooth & sweet. Some people damp
the cone basket, but I haven't tried that, they sound
very good as is. I actually prefer them to the Altec 604.
Paul
Re: GE A1-400's
• Posted by Tubes n' Hornz (A) on August 10, 2003 at 05:57:51 In Reply to: Re: GE A1-400's posted by orthophonic on August 9, 2003 at 23:41:35:
Jerry/Paul - thanks a bunch for the info. I shall leave well enough alone. Will be hooking these up to a pair of W4-MA's or my EL34 amp. Will find out which give me what I'm looking for. Steve
