575 is EIA source code for Heppner Speakers
relatively well known for affordable horn loaded tweeters.
But also did various woofers etc etc
Believe Fender used them and various others.
Mainly sound cabinets from Organs
Here is photo of another Heppner speaker with similar basket and 575 code
The Horns appear to be Heppner as well
relatively well known for affordable horn loaded tweeters.
But also did various woofers etc etc
Believe Fender used them and various others.
Mainly sound cabinets from Organs
Here is photo of another Heppner speaker with similar basket and 575 code
The Horns appear to be Heppner as well
I dont know exactly how the date codes work.
usually if only 3 numbers following EIA , means its a single digit year code, then week number.
So with single digit you would have to know the era.
575629 = 575 (6) year 29 week
575723 = 575 (7) year 23 week
575 is manufacture EIA source code
its likely
1976 29th week
1977 23rd week
single digit years is usually very old stuff from 1940 to 60's
but some companies used single digit up to the 70's
so don't hold me too it LOL
Heppner I believe was bought by Cerwin Vega in late 70's
So these speakers you have were probably made towards the end
usually if only 3 numbers following EIA , means its a single digit year code, then week number.
So with single digit you would have to know the era.
575629 = 575 (6) year 29 week
575723 = 575 (7) year 23 week
575 is manufacture EIA source code
its likely
1976 29th week
1977 23rd week
single digit years is usually very old stuff from 1940 to 60's
but some companies used single digit up to the 70's
so don't hold me too it LOL
Heppner I believe was bought by Cerwin Vega in late 70's
So these speakers you have were probably made towards the end
I was able to put one of the cabs' 3.3uF caps (looks to be a polypropylene) on a vintage Heathkit tester without having to separate it from the rest of the crossover. The tester found it to be just above 3uF by its scale (it's a 10% tolerance cap) and leakage was nil. it's a 100V-rated cap; at its 25V setting the tester actually puts 38V across the cap. The next higher setting is 150V so I left well enough along with the 25V setting. I'll test the other cap at some point but I'd already put that cabinet back together. Now waiting for the two replacement horns to arrive.
The Parts Express horns came and they look great; much more substantial than either the original Heppner horn or the replacement Gem Sound horn that the previous owner put in - but its mounting flange is about 1/8"-3/16" too high to get past the wood at the very front of the cab. If they were shaved down a little top and bottom, they'd fit just fine. ARGGGH!
If the edge of the plastic is flat and thin, I would cut off 1/8-3/16" until it fit. A shop shear would be great but I lost my access to one 15 years ago. Next best is a power nibbler but you have to control it . https://www.ebay.com/itm/403359174916?hash=item5dea149104:g:XBkAAOSwdW5hu2US
New Makita nibbler is $361.
Alternate is taking a wood chisel to the cabinet to open it out a little.If partical board it would not make a smooth edge.
New Makita nibbler is $361.
Alternate is taking a wood chisel to the cabinet to open it out a little.If partical board it would not make a smooth edge.
These horns are aluminum. A machinist could do a perfect and very clean job of it using a mill or a shaper, I'm sure.
If you go back and look at the photo, it's not the hole that the horns fit into that's the issue; it's the wide rectangular opening in the front of the cab that the horns are set back a few inches from that they won't quite fit past. I have a table jigsaw that might be able to handle it without making a mess of things.
Here's the latest. Before I trimmed the long edges of the Studio Z T-122 horns from Simply Speakers and making them unreturnable, I wanted to hook them up and verify that they worked. To my disappointment, they didn't sound the same at all with white noise running through them, so I set up a large-diaphragm mic and recorded white noise output so I could get spectra.
Here's "left:"
and here's "right:"
By comparison, here are the two horns (the plastic-horned Gem Sound replacement and the original Heppner) that these T-122s were supposed to replace:
The Studio Z horns are awfully peaky - and how about the I-got-nuthin' -45db-down notch at ~12.4kHz?? But even down where things are more audible (and in the post-crossover range they would receive) that's really uneven and not consistently so between the two speakers. I thought maybe it was due to the metal horns ringing (if you strike them or even rub the edge with your hand they "sing" at about 6k) but I tried again with alternately grabbing the horns with both hands and releasing them and it made no difference. So I think I need to get in touch with Simply Speakers and ask for a recommendation. Getting the blown original back from the original owner is looking better and better.
Here's "left:"
and here's "right:"
By comparison, here are the two horns (the plastic-horned Gem Sound replacement and the original Heppner) that these T-122s were supposed to replace:
The Studio Z horns are awfully peaky - and how about the I-got-nuthin' -45db-down notch at ~12.4kHz?? But even down where things are more audible (and in the post-crossover range they would receive) that's really uneven and not consistently so between the two speakers. I thought maybe it was due to the metal horns ringing (if you strike them or even rub the edge with your hand they "sing" at about 6k) but I tried again with alternately grabbing the horns with both hands and releasing them and it made no difference. So I think I need to get in touch with Simply Speakers and ask for a recommendation. Getting the blown original back from the original owner is looking better and better.
How many watts do you put into this speaker?
A eminence PSD2002-16 ($45) bolted to a H290b horn ($15) would take 80 AES watts. That is 11.7" X 6.6" x 6.8" . They have smaller horns.
Assuming 1/3 watts go to the tweeter that would allow to run your speaker at 240 AES Watts. That fraction may be high, depends on the crossover. Pispeakers is using this down to 1200 hz. Part-express has the 16 ohm in stock today. Eminence ASD1001b is cheaper and lower watts, but PE only has the 8 ohm one.
BTW, what software did you use to do the charts in post 25? Windows PC compatible? I need to do that.
A eminence PSD2002-16 ($45) bolted to a H290b horn ($15) would take 80 AES watts. That is 11.7" X 6.6" x 6.8" . They have smaller horns.
Assuming 1/3 watts go to the tweeter that would allow to run your speaker at 240 AES Watts. That fraction may be high, depends on the crossover. Pispeakers is using this down to 1200 hz. Part-express has the 16 ohm in stock today. Eminence ASD1001b is cheaper and lower watts, but PE only has the 8 ohm one.
BTW, what software did you use to do the charts in post 25? Windows PC compatible? I need to do that.
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I'd already looked at Eminence's horns; they don't make a 4x10. PE is the only other ready source I've found so far and is probably my last resort shy of trying to get another one of the original horns, to include the blown one from the previous owner.
I don't ever expect to flat-out these speakers but I do expect to run a keyboard rig through them at performance volumes (somewhat down from stage volumes but higher than I'd run them in my music room at home).
The spectrum plots were made in Audacity which is available for Windows, Mac, and Linux at no cost. The white noise came from a Denon test CD by way of a Crown Class D power amp that I recently bought. I ran the horns at a level just loud enough that I wore ear protection when sitting on the floor right in front of them.
It seems as though any search on the Internet that I try - to include just going on eBay, Reverb, or Amazon - yields 4x10s that are all coming from the same source as the ones I bought from Simply Speakers. They may be labeled this or that but they all seem to be the same.
I just got an automated email from Parts Express saying that the Pyle PH391 4"x10" horns are back in stock. Thing is, though, when you go to the product listing at PE, the photo you're shown looks just like the ones I bought from Simply Speakers. It appears that at least in the United States, all new-production 4"x10" horns are coming from a single manufacturer. The guy I bought the cabs from has offered to trade me the removed broken original horn in trade for the GEM Sound one that he replaced it with, so I may be doing that with an eye toward either getting the broken one rewound or perhaps even doing it myself. I can just jumper-clip the horns I got from Simply Speakers and sit them on top of the cabs in the meantime.
Here is an electrovoice 4" x 10.5" horn on ebay $35 + freight . Wolverine SH-10 8 ohms
https://www.ebay.com/itm/313854177564?hash=item49132ab11c:g:5ekAAOSwHMVhq6rMDoesn't look modern at all.
https://www.ebay.com/itm/313854177564?hash=item49132ab11c:g:5ekAAOSwHMVhq6rMDoesn't look modern at all.
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I appreciate this info; thank you. Per this document, EV MR-10 would seem to be a physical drop-in fit in the Acoustic 807 cabinet. Even the screw hole locations seem to line up. However, the power handling seems low at 20W and the frequency range narrow (1000-3500). Apparently the MR-10 was part of the MF1 "step-up" kit. Certainly worth keeping in mind if other paths fail me.
UPDATE: I've obtained the broken original horn from the cabs' seller. The connectors are indeed open-circuit. I have found that after Klipsch bought Heppfer, they continued the horn in their KG4 speaker and searching on that, I see that Simply Speakers sells a replacement diaphragm for that and it has the same measurements (I still need to check voice coil diameter) as the ones in the Heppfers.
My objective at this point, since I tried going down the "rework" course of action involving a new (but not cognizantly-crossover-pointed) crossover and winding up with little confidence that I was doing myself any favors, is to trust the cabs' original designers and just assure that all of the original components are working to spec as best as I can tell. I reassembled them with the GEM Sound replacement 4x10" horn in the "left" cab (last weekend I got the broken Heppfer back for it in a straight trade). I've been running my keyboard rig through them at up to low-moderate volume via a Crown class-D amp (that has too high a noise floor for home use but I've been grinning and bearing it). I'm kind of treating these cabs as "vintage instruments" in their own right and by working with the keyboard equipment in terms of designing patches and setting EQ and levels on instruments while auditioning the results through those speakers, I do think I'm moving toward having a good-sounding arrangement. So if I have both these Heppfer horns with new and matched diaphragms in them I think I'll be pretty close to meeting my objective.
UPDATE: To recap, I ordered a pair of D-417 diaphragms to put in these Acoustic 807 cabs' circa-late-1970s Heppner horns, one of which has an open-circuit voice coil. I've tried one of the new diaphragms and it's unusable; the horn sounds like a kazoo at low volume. But when I took the horn back apart and just fit the diaphragm assembly onto the magnet and apply signal it behaves just fine. Now, in order to get the new diaphragm to fit I needed to slightly drill out the index holes, but I did not drill them so big that the diaphragm can slide around; it's staying centered so the voice coil is not rubbing on the magnet. The best I can tell is that the dome is making contact with the phase plug and using my digital calipers I've found that the height of the D-417 assembly (as measured from the bottom of the voice coil to the top of the dome) is almost exactly 0.05" more than that of the original assembly and subsequent measurements show that that height difference is partially due to the dome and partially due to the D-417's surround being slightly thicker. The two diaphragms' voice coils seem to protrude below the surround by almost exactly the same amount, so I'm not worried about the voice coil bottoming (and by the way, I was careful to clean out the magnet gap before installing the D-417 diaphragm). I'm hoping Simply Speakers can tell me how far the dome of the titanium version protrudes from the surround; if it doesn't stick out as far as the dome on the D-417, maybe that's what I need to do; it's either that or fab a pair of spacer plates to go between the phase plug and the magnet so the two don't collide.
On these horns, what I'm calling a "diaphragm" is an assembly consisting of a voice coil, a dome, a flat surround with a gasket cemented to it, and a pair of spade lugs. Shaped roughly like a keyhole. The ends of the voice coil are brought out to the spade lugs and lacquered down. Best I can tell, the ends were intact on the bad diaphragm.
UPDATE: Simply Speakers suggests I make spacers out of gasket material sourced from an auto parts store to fit between the diaphragm and the phase plug. Sounds reasonable to me. SS also says that the titanium version of the diaphragm has a dome that would stick up even farther and would sound too harsh regardless. So it looks like I can use the soft dome diaphragms I've already bought once I make some spacers. I need to provide about 1/20" of spacer.