The speakers look like Alnicos to me.
From a quick search on, Sonora - it has quite a history. Started out making phonographs (The Sonora Phonograph Co.), then moved on to tube radio in the 30/40's.
I think they'll look great refurbished. Very nostalgic.
What kind of drivers you plan on using in them? Going to seal it up in the back?
From a quick search on, Sonora - it has quite a history. Started out making phonographs (The Sonora Phonograph Co.), then moved on to tube radio in the 30/40's.
I think they'll look great refurbished. Very nostalgic.
What kind of drivers you plan on using in them? Going to seal it up in the back?
They are not open backed, they are reflexed.
From the days reflexing only considered the panel thickness.
(For such small lengths there is a large correction factor)
I notice both units are open backed.
Not as as big a problem as you'd imagine.
Midrange unit suspension can easily handle bass frequencies.
Replacing the units would make a entirely different speaker.
(I absolutely say you should keep the original units, also other
the terminals it should look like it was made when it was)
I'd suggest listening to the drivers seperately, if the larger unit
is louder then a 1st order series croosover at the baffle step
frequency will improve matters no end.
(this is the only upgrade I'd consider)
Block the section in the back and add terminals and a port,
I'd say around 55hz tuning frequency for an overdamped
alignment. Use a cardboard tube, a varnished tiolet roll tube
sounds good to me.
Line the back and side sections with fibreglass/ rockwool.
🙂 sreten.
From the days reflexing only considered the panel thickness.
(For such small lengths there is a large correction factor)
I notice both units are open backed.
Not as as big a problem as you'd imagine.
Midrange unit suspension can easily handle bass frequencies.
Replacing the units would make a entirely different speaker.
(I absolutely say you should keep the original units, also other
the terminals it should look like it was made when it was)
I'd suggest listening to the drivers seperately, if the larger unit
is louder then a 1st order series croosover at the baffle step
frequency will improve matters no end.
(this is the only upgrade I'd consider)
Block the section in the back and add terminals and a port,
I'd say around 55hz tuning frequency for an overdamped
alignment. Use a cardboard tube, a varnished tiolet roll tube
sounds good to me.
Line the back and side sections with fibreglass/ rockwool.
🙂 sreten.
that material that the grill cloth is, is that tweed? i thought i saw similar stuff on parts express. am i wrong there? when the speakers were inside the box, the "tweet" frame was overlapping onto the woofer, they don't fit perfectly, i am almost convinced that these aren't the origional speakers. but if i put them in a new baffle then i can make it all fit, and be air tite. this'll be fun.
Care to give us the dimensions of the box, the thickness of the wood, and the size of the slot in back?
Just curious what they were actually tuned to.
And yes, it does look like fun! 🙂
Just curious what they were actually tuned to.
And yes, it does look like fun! 🙂
i will measure it out tonite, i am at work right now... shhhhh, the boss might hear! I am planning on doing an almost exact replica of the front baffle, except i am going to make the "bar" going over the woofer a hair thinner, and i will move the tweet up 3/4 of an inch or so. of course i will flush mount the speakers on the front, they were mounted on the inside!? that is all for now, gotta go!
A friend of mine's dad has some Bose 901s from the 70's or something like that, or it could be the early 80's for that matter. Anyway, he had them down for refoaming, and I noticed the same sort of cone construction on them - where the circle of paper is cut and then rolled to form the cone.
A cut-'n-roll cone like that is a sure sign of a cheap driver. Given that the cone looks clean and the basket of the woofer doesn't look tarnished, I'd say it's unlikely that the woofer is original. Can't tell much about the other driver from the picture.
My guess is that the old driver(s) died and someone replaced them with something inexpensive. The original crossover was probably jettisoned at the same time.
To the extent that you're talking about putting new drivers in, you'll have a difficult time matching them to that particular box volume/tuning. That's not to say that it can't be done, just that you'll burn a lot of hours trying to find a driver with the right characteristics. The only helpful hint that I have to offer is that it's easier to make a box smaller than it is to make it larger. I'm not talking about cutting the box down. I'd leave that alone. If you want to reduce volume, think in terms of putting in bracing. You can burn off a surprising number of cubic inches with bracing, and make the speaker sound better in the bargain.
Grey
EDIT: After looking at the pictures again, I'm willing to bet that the opening in the back is where the hookups went, probably on a piece of Masonite that also held the crossover. In other words, it was originally an acoustic suspension (i.e. infinite baffle) design. Chances are good that the original woofer had a foam surround which rotted. That, in turn, lead to the replacement driver.
That's waaaay too large a hole for a box that size to be a ported design.
My guess is that the old driver(s) died and someone replaced them with something inexpensive. The original crossover was probably jettisoned at the same time.
To the extent that you're talking about putting new drivers in, you'll have a difficult time matching them to that particular box volume/tuning. That's not to say that it can't be done, just that you'll burn a lot of hours trying to find a driver with the right characteristics. The only helpful hint that I have to offer is that it's easier to make a box smaller than it is to make it larger. I'm not talking about cutting the box down. I'd leave that alone. If you want to reduce volume, think in terms of putting in bracing. You can burn off a surprising number of cubic inches with bracing, and make the speaker sound better in the bargain.
Grey
EDIT: After looking at the pictures again, I'm willing to bet that the opening in the back is where the hookups went, probably on a piece of Masonite that also held the crossover. In other words, it was originally an acoustic suspension (i.e. infinite baffle) design. Chances are good that the original woofer had a foam surround which rotted. That, in turn, lead to the replacement driver.
That's waaaay too large a hole for a box that size to be a ported design.
the slot in the back was covered from the inside with a black cloth with the same type of staples as were holding the grill cloth on. the speakers themselves are quite tarnished, it didn't show up too well in the photo though. there is a white residue that is grimy on most of the frame. there is lots of rust on the tweeters magnet, and on the woofer magnet there is some type of corrosion also. but i have a hard time believing that these are the origional drivers..... they didn't really fit in there well. the tweeter overlapped on top of the woofer!? well here are the measurements i got.
all panels are 1/2 inch thick.
box:
18" tall
5 1/4" deep
9 1/2" wide
slot:
7"long
2 1/2" wide
tweeter cutout 3"
woofer cutout 7"
the drivers are indeed old. i haven't even tried the speakers out yet. well they are apart now and it is tooooo late. i am going to refinish the nice wood and re-do the baffle and back panel. anyone have any idea what kind of wood that is? teak (teek?) or walnut maybe?
all panels are 1/2 inch thick.
box:
18" tall
5 1/4" deep
9 1/2" wide
slot:
7"long
2 1/2" wide
tweeter cutout 3"
woofer cutout 7"
the drivers are indeed old. i haven't even tried the speakers out yet. well they are apart now and it is tooooo late. i am going to refinish the nice wood and re-do the baffle and back panel. anyone have any idea what kind of wood that is? teak (teek?) or walnut maybe?
Got a picture of the woofer/full range from the back? I'll be able to get a better idea of the OEM from that -- from what i can see i'd say it is probably original and Japanese. The corrision is typical of drivers open to the ocean... a paper towel with some windex on it does a pretty good job on cleaning most of it off.
The box is classic Japanee construction. I find it surprising that you think they are solid wood. Much more likely well veneered particle board or 3 or 5 plu plywood -- from the edges of the baffle cleats -- one looks like particle board -- i'd guess the same. Sometimes i'll reuse the nice pluwood ones for speakers but most often these get used for shelving units (if they don't hit the fire-pile).
Typically these were a full-range driver with a tweeter added primarily so they could sell them into a North American market convnced more was better. I've seen a lot of units with the tweeter XO set at 20k.
I'd guess you are right on the tweeter -- it looks like USA manufacture (and probably not particularily useful for anything -- you could salvage the alnico thimble for picking up nails 🙂)
Any numbers on the drivers would be useful too.
XO on these was invariably a single cap. What size is the one in there (it may be the original -- what kind is it).
The cone construction isn't really indicative of quality, my lowthers were built the same way, and it is an honoured technique for some limited production exotic drivers -- the test is in the listening.
dave
The box is classic Japanee construction. I find it surprising that you think they are solid wood. Much more likely well veneered particle board or 3 or 5 plu plywood -- from the edges of the baffle cleats -- one looks like particle board -- i'd guess the same. Sometimes i'll reuse the nice pluwood ones for speakers but most often these get used for shelving units (if they don't hit the fire-pile).
Typically these were a full-range driver with a tweeter added primarily so they could sell them into a North American market convnced more was better. I've seen a lot of units with the tweeter XO set at 20k.
I'd guess you are right on the tweeter -- it looks like USA manufacture (and probably not particularily useful for anything -- you could salvage the alnico thimble for picking up nails 🙂)
Any numbers on the drivers would be useful too.
XO on these was invariably a single cap. What size is the one in there (it may be the original -- what kind is it).
The cone construction isn't really indicative of quality, my lowthers were built the same way, and it is an honoured technique for some limited production exotic drivers -- the test is in the listening.
dave
GRollins said:
Good call.
Assuming the measurements Speekergeek gave were for outside dimensions, with ½" material I just subracted an inch from each measurement. This left me with an internal box volume of 0.355 Ft³, (10 liters).
A woofer hole of 2½" x 7" by ¾" deep tunes the box to 175 Hz. I cannot imagine any design tuning that high.
Maybe the grill cloth changed the tuning from an unobstructed vent-I don't know.
The woofer cutout is 7", meaning an 8" is needed. Finding an 8" to fit into a 10 liter box might take some doing. I did see a Peerless CSX 8" which would fit into there in a sealed box with an Fc of 95 and a Qtc of 1.2-which could be treated with an aperiodic vent. Maybe that was what the cloth was over the vent for-dunno.
But I am sure there are better choices out there, if you want to replace the drivers.
i said they were solid wood because i already checked. i made sure that the cabinets were solid wood by drilling a nice 1/4" hole on the inside about 3/4 of the way through the wood and the grain runs all the way. and by drilling it i would say it is probably walnut because i had a hell of a time drilling it! i think the hole in the back of the speaker may be there for the same reason a lot of guitar amp/speakers have open backs. the speaker wire was run through a hole in the back panel. here is the only identifying mark; 62-1108
and that is on the woofer itself on both. the tweeter says nothing on it.
and that is on the woofer itself on both. the tweeter says nothing on it.
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Hmmm... doesn't look like any japanese alnico i've run across (and those number in the hundreds of units). The 62-1108 is possibly a date code (ie 8 Nov or 11-Aug 1962), which if it is means they are not American (or Canadian), so perhaps obscure Japanese or Tawainese.
Solid wood is very unusual -- makes them pretty special.
Any numbers on the tweeter? Cap size? Impedance?
dave
Solid wood is very unusual -- makes them pretty special.
Any numbers on the tweeter? Cap size? Impedance?
dave
the tweeters have no markings as far as i can tell. the woof and tweet are very similar though... the gasket looks about the same color and type, and the dustcap on both are extremely similar. on the back of the tweeter there are two screw holes that i cannot tell what they were for. maybe a tweeter xover mount? here is a good shot of the "mount".
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speekergeek said:
It is not really a tweeter, but another full-range. the screw holes are for mounting an output transformer.
dave
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