I have a set of what is best described as AR3 clones. I got them in 1998 from my father as a birthday present, so I suppose that makes them "precious" to me. They were sort of a kit, in that I soldered and installed all the individual drivers and crossovers, etc.
Anyhoo- 20 plus years later everything has failed and I would like to rebuild them.
I tried, before I knew anything about AR3s, they sounded like garbage, then I learned a bit about acoustic suspension, etc.
The drivers need to be completely / very well sealed, right?
Is there anything needed inside the cab, like wool or foam?
Anyhoo- 20 plus years later everything has failed and I would like to rebuild them.
I tried, before I knew anything about AR3s, they sounded like garbage, then I learned a bit about acoustic suspension, etc.
The drivers need to be completely / very well sealed, right?
Is there anything needed inside the cab, like wool or foam?
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"everything has failed" is a bit general. How are the surrounds? Is there any sound from the drivers?
I have restored AR-2Ax, which are rather similar, several years ago. I don't remember if woofer surround were already replaced, everything else was mostly OK. But:
-dual capacitor deteriorated, 8 and 5.5 uF instead of 6 and 4. Replaced with MKP and PE caps.
-attenuators slightly corroded. Cleaned and greased them.
-cabinets need A LOT of stuffing. I had to literally stuff enclosure to the brim with heavy kaolin wool, otherwise one-note midbass was unbearable, 80 Hz at +10 dB. With enough damping material I was able to get woofers into +-2 dB in 65-600 Hz range.
Sadly, I didn't save measurements of a complete speaker. I remember listening window mostly flat with about +-3 dB variation. Mostly narrow band deviation, overall trend flat, driver levels balanced. On-axis had a lot of diffration nulls and peaks. Overall impression was mostly positive - not a quite "high fidelity" speaker, but I guess more than OK for the 60s. Way more listenable than some Klipsches of the same vintage. Drive units, while very cheaply made, are mostly linear with well-suppressed resonances and rather clean sound. I guess a new low-diffraction baffle and proper crossover can elevate those old ARs to another level.
Here are driver frequency responses for reference. Yours should be similar:
-tweeter nearfield (1 cm on axis) w/o crossover (green), through 4 uF cap (yellow):
-same tweeter in cabinet on axis (yellow) and at 45 degrees off-axis (green). Lots of diffraction from raised baffle edge:
-two woofers overlaid, 35 and 31 Hz Fs, 1.6 and 1.35 Qts. Really weak motors. Nearfield measurement w/o enclosure:
-woofer 1+midrange 1, in box, no stuffing, refurbished X-over:
-midrange 1 FR at 0 and 45 degrees:
I have restored AR-2Ax, which are rather similar, several years ago. I don't remember if woofer surround were already replaced, everything else was mostly OK. But:
-dual capacitor deteriorated, 8 and 5.5 uF instead of 6 and 4. Replaced with MKP and PE caps.
-attenuators slightly corroded. Cleaned and greased them.
-cabinets need A LOT of stuffing. I had to literally stuff enclosure to the brim with heavy kaolin wool, otherwise one-note midbass was unbearable, 80 Hz at +10 dB. With enough damping material I was able to get woofers into +-2 dB in 65-600 Hz range.
Sadly, I didn't save measurements of a complete speaker. I remember listening window mostly flat with about +-3 dB variation. Mostly narrow band deviation, overall trend flat, driver levels balanced. On-axis had a lot of diffration nulls and peaks. Overall impression was mostly positive - not a quite "high fidelity" speaker, but I guess more than OK for the 60s. Way more listenable than some Klipsches of the same vintage. Drive units, while very cheaply made, are mostly linear with well-suppressed resonances and rather clean sound. I guess a new low-diffraction baffle and proper crossover can elevate those old ARs to another level.
Here are driver frequency responses for reference. Yours should be similar:
-tweeter nearfield (1 cm on axis) w/o crossover (green), through 4 uF cap (yellow):
-same tweeter in cabinet on axis (yellow) and at 45 degrees off-axis (green). Lots of diffraction from raised baffle edge:
-two woofers overlaid, 35 and 31 Hz Fs, 1.6 and 1.35 Qts. Really weak motors. Nearfield measurement w/o enclosure:
-woofer 1+midrange 1, in box, no stuffing, refurbished X-over:
-midrange 1 FR at 0 and 45 degrees:
I guess it's more like a three way with a 12" woofer and no ports. I think it's based on the idea of acoustic suspension
That's what the company was based on, definitely no ports.
https://auralfetish.com/pages/acoustic-research
https://auralfetish.com/pages/acoustic-research
So my two questions I think fit.
1. Do I need to super make sure that the drivers are sealed against / in the wood?
2. Should I stuff the cabinet with anything? Right now I have large blankets stuffed in there.
1. Do I need to super make sure that the drivers are sealed against / in the wood?
2. Should I stuff the cabinet with anything? Right now I have large blankets stuffed in there.
1. Just a regular foam gasket would do. It doesn’t have to be super-sealed and sniffed with helium leak detector.
2. Absolutely, unless you are a fan of one-note mid bass. Replace blankets with a lot of mineral wool.
2. Absolutely, unless you are a fan of one-note mid bass. Replace blankets with a lot of mineral wool.
Yes, just like AR-2Ax. The difference is that 2Ax uses 10” woofer and simplified crossover.
Yeah, that's my whole point. I've stuffed them with random drivers over the years and hodge-podged my way through some sort of crossover. I'd like to start from scratch and find something that works well with the cabinets.
These are the woofers for sure GRS 12PR-8 that are currently in it.
These are the woofers for sure GRS 12PR-8 that are currently in it.
There's pretty much nothing in that box close to an AR3. Except maybe the 3.
That woofer surely doesn't.
High Qts, weak motor, minimal Xmax. May be useful as a passive radiator, I guess.
https://www.parts-express.com/Dayton-Audio-DS315-8-12-Designer-Series-Woofer-295-434?quantity=1
No Qt, no sensitivity, no Fs, no VAS. No frequency chart. Roll the dice, it looks like a woofer. For $109 I would expect more info.
For sealed cabinets, eminence suggests woofers with Qt >0.4 Delta-12a is in stock at PE, $125
400 W AES, sensitivity 98 db 1w1m, Qt 0.43, Vas 2.8 cuft, Fs 55 hz, Xmax 2.4 mm. Bl 13.5 tm (motor power)
For less wattage, Beta-12a-2 $119 at PE. 250 W AES, sensitivity 98 db 1w1m, Qt 0.46 VAS 4.2 cuft, Fs 47 hz, Xmax 4.4 mm, Bl 10.8 tm
With those numbers you can start designing a cabinet or see if either can fit your cabinet. Delta frequency response is pretty flat 130 hz - 1800 hz. Beta frequency flat 130 hz-700 hz.
No Qt, no sensitivity, no Fs, no VAS. No frequency chart. Roll the dice, it looks like a woofer. For $109 I would expect more info.
For sealed cabinets, eminence suggests woofers with Qt >0.4 Delta-12a is in stock at PE, $125
400 W AES, sensitivity 98 db 1w1m, Qt 0.43, Vas 2.8 cuft, Fs 55 hz, Xmax 2.4 mm. Bl 13.5 tm (motor power)
For less wattage, Beta-12a-2 $119 at PE. 250 W AES, sensitivity 98 db 1w1m, Qt 0.46 VAS 4.2 cuft, Fs 47 hz, Xmax 4.4 mm, Bl 10.8 tm
With those numbers you can start designing a cabinet or see if either can fit your cabinet. Delta frequency response is pretty flat 130 hz - 1800 hz. Beta frequency flat 130 hz-700 hz.
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If you scroll down, there are TSP listed
https://www.parts-express.com/Dayton-Audio-DS315-8-12-Designer-Series-Woofer-295-434?quantity=1
Should work in a large closed box, better may be vented
https://www.parts-express.com/Dayton-Audio-DS315-8-12-Designer-Series-Woofer-295-434?quantity=1
Should work in a large closed box, better may be vented
For anything even remotely approaching AR woofer specs, Fs should be around 18Hz (and not 28 or higher) and Qt should be around 0.3. Vas is supposed to be some 290 Litres, although I vaguely recall having seen different Qt (higher that is) and Vas specs.
That's why I'm thinking about starting from scratch with these cabinets. Lets say a budget of around $300 for each speaker.