Expert moving coil speaker

[streetmechanic14]

I assume this speaker had a gasket or some resilient flange between the driver and its pyramidal wooden stand. The hole in the stand measures 5-7/16", the driver 5-⅛" so the fit is quite sloppy- not at all like the old post card photo! The driver appears to have been "ported" through the hollow pyramid so something close to an airtight seal was probably intended, but then EMG-Expert people will know far better than I and, I hope, be able to describe the missing gasket.
-Dave

[chunnybh]

Knock me over with a feather!
That's the most exciting thing I have seen in ages. Yes, I need to get a life.
I imagine the stand was used with a smaller horn and just for connecting up to a radio. An Expert Junior or Senior horn would be far too big. I am confused at the size of the hole, 5-7/16". The Expert Senior horn slides into a ~ 3-½" hole.

Does it work?

[streetmechanic14]

Chunnybh-
It does work- not much to go wrong I would think though some letters accompanying it suggest the original owner had some sort of trouble. As you suggest, a smaller horn might make more sense but in fact it came with the Senior horn in place which leans forward a good deal more than the old photo shows. Maybe Mr. Ginn employed the 1930 equivalent of Photoshop.
Since these things don't seem terribly common I thought you might like a few more pictures.
-Dave

[chunnybh]

Wow!. Now that is beautiful.
Thanks so much for sharing. Can we get some measurements?

[emgcr]

My goodness, that is wonderful. We have seen these items in the literature but an actual example has never come to light in modern times as far as I know.

It would seem your photo of the post card detailing two sizes of Type A is also "new" information as is the pyramid type support. As Chunny says, the measurements appear to be curious and confusing so full details/dimensions and more photos would be very gratefully received. Many thanks for the postings so far.

How did you come across this item ? Photos of the correspondence/history would also be fascinating. There appears to be a Patent Number for 1931 ?

In which continent are you ?

[fran604g]

Fascinating! Was this manufactured "in house" do you think? I've consulted my copy of High-Quality Horn Loudspeaker Systems (Kolbrek & Dunker, 2019), but find no information.

Cheers,
Fran

[streetmechanic14]

Very embarrassing! Substitute "3" for the "5" in the dimensions I gave. My combination of myopia and stupidity can create mysteries where none should be. In another piece of stupidity it seems never to have occurred to me to investigate what is obviously a British patent number; Ginn or Phillips explanation of the rear port on the driver should make interesting reading. Apropos of that, Chunny's old photos are a little confusing. The driver on the HMV is straightforward enough- its case may plausibly be either sealed or open, but placing the driver on an Expert gramophone as shown in the other picture would vent the back of the speaker into the tone arm and sound box (at least if the case is open in back as mine is). I can't claim to have tried this arrangement, but I'm not really tempted.
In answer to other questions: (1) I'll be happy to provide measurements but I'm guessing that they may not now be necessary with my "3" for "5" corrections. Let me know. (2) I am in the northeast USA. (3) More paperwork- interesting to see how courteous and personal was the attention Ginn gave his customers. The speaker design shown was new to me- do any of these exist? Modern enthusiasts might find Ginn's comments concerning horns a bit heretical.
-Dave

[fran604g]

I'm impressed by the claimed FR of 30-15,000 Hz. If true this speaker might make a fun build in a full range single driver "frugle horn" cabinet, just to play around with. Although with lack of comprehensive specs for other critical measurements, it would require some experimentation.

[Orchorsol]

Absolutely wonderful and astonishing to see this impossibly rare bird, thank you so much for posting about it!

Fascinating! Was this manufactured "in house" do you think? I've consulted my copy of High-Quality Horn Loudspeaker Systems (Kolbrek & Dunker, 2019), but find no information.

Cheers,
Fran

Some years ago Bjørn Kolbrek visited several of us EMG owners at length here in the UK and made very detailed scientific measurements of various EMG and Expert acoustic gramophones, both playing frequency tones and gliding frequencies from 78s, and injecting reference tones into the acoustic systems. He seemed very excited to be able to investigate them, and it was really fascinating for us too. He said that the designs are pretty much as valid and high quality as so many super-expensive hi-fi horn designs of recent years - just a different approach, one of many radically different approaches possible and existing. However, only a small passing reference is made to EMG and Expert horns in the book.

[chunnybh]

Hi Dave,
Can we have a picture of the whole horn on the stand. I'm having problems seeing a Senior horn on the stand, surly it would topple over?
Thanks also for sharing the paperwork, such a boon having it from the horses mouth.

I'm impressed by the claimed FR of 30-15,000 Hz

. Yes, well Ginn was prone to "self promotion". That is some letterhead.