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What happens when non-functional AR2s end up at Zilchlab?

wiredbecker

wiredbecker

...jams ECONO!
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They end up as ZL2s :thmbsp:

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We don't know yet. Tonight, probably, biamped, at least.

The cabinet construction is very good, and well worth the $20 we paid for the pair.

I'm thinking we'll do one closed-box with AR2 woofer and one ported with JBL 127H-1 (shown) and A/B compare.... :yes:
 
Those don't look anything like my AR parts... :scratch2:


(OK, OK - so how do they sound? Will they make me have wild desires to rip my AR's apart? :D )
 
ozmoid said:
Those don't look anything like my AR parts... :scratch2:
Click to expand...
We've got a bunch of AR pots to send. PM me your mailing address, please.... :thmbsp:

ozmoid said:
Cool... don't forget the stuffing for the sealed box! :music:
Click to expand...
Not gonna be what came out of them, I guarantee.... :no:

SPL db said:
Cool... what are you going to run for a crossover?
Click to expand...
Behringer CX3400 plus the BMS HF compensation filter we developed for Valencias, for starters.

I've never tried that on these DDS horns, but it usually gets to something listenable in fairly short order here.... :yes:
 
Here's some measurements on the stock AR2s as they arrived. Three of the four mids (two per unit, cross-fired,) were not operating. Still investigating why; it's not the pots.

The mids have MUCH wider response than is used in AR2s. The highpass filter rolls most of that down and off at a fairly high frequency, violet vs. cyan, both +10 dB, for a net acoustic crossover in the region of 2.8 kHz, red cursor. Nobody's home above 12 kHz, green cursor. I'll document the filters and then compare to specs.

On RTA, the bass is rolled off below 50 Hz, and effectively gone by 40 Hz (-10 dB). In the MLS curves, a significant notch in both woofers' responses is revealed at 1.5 kHz. We'll get a better look at bass response if I remember to measure the test boxes nearfield.... :yes:
 

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Zilch said:
On RTA, the bass is rolled off below 50 Hz, and effectively gone by 40 Hz (-10 dB). In the MLS curves, a significant notch in both woofers' responses is revealed at 1.5 kHz. We'll get a better look at bass response if I remember to measure the test boxes nearfield.... :yes:
Click to expand...
Only 40Hz? Is that typical for a sealed system like this that uses 10" drivers? Or could it be the age of the AR drivers?
 
RadShak1251 said:
Only 40Hz? Is that typical for a sealed system like this that uses 10" drivers? Or could it be the age of the AR drivers?
Click to expand...
I won't know until I investigate further with nearfield measurements; RTA is in-room response. The best I can say is that it's been nearly 50 years since I owned a pair of AR2s, easily exceeding the span of my own sonic memory. ;)

Here's a bit of prior work I did with 10" JBL drivers in acoustic suspension alignment in a slightly larger (+0.2 cuft.) box:

http://audioheritage.org/vbulletin/showthread.php?p=132152#post132152

I'd say it looks similar.

RadShak1251 said:
Are you referring to the midrange driver's response, or the system as a whole?
Click to expand...
The cross-fired midrange drivers are used as a tweeter in the AR2 system, so it applies to both, at least insofar as this one sample is concerned. Whether this is representative of the class, either originally or as aged, would require looking at a broader sample, of course.... :yes:
 
O.K. thanks.

Didn't know these particular ARs used the mids to reproduce the higher frequencies also - I just ass-umed :) there was a dome tweeter in there. Well since most guys that are over 35 or so have hearing that craps out past 12kHz anyway, maybe this is not such a big deal.
 
RadShak1251 said:
O.K. thanks.

Didn't know these particular ARs used the mids to reproduce the higher frequencies also - I just ass-umed :) there was a dome tweeter in there. Well since most guys that are over 35 or so have hearing that craps out past 12kHz anyway, maybe this is not such a big deal.
Click to expand...

The AR-2Ax and AR2A used dome tweeters. The AR2 and AR2x did not.

As for hearing- we just did some impromptu testing here, and I had no problem hearing 17.4KHz, and could still detect 18KHz, albeit at perceived lower volume (though, we hadn't RTA'd the test setup- it might actually be down a bit at 18KHz, so I might actually be better at 18KHz than first indications might imply). Not bad for a 40 year old, I guess!

Regards,
Gordon.
 
RadShak1251 said:
Only 40Hz? Is that typical for a sealed system like this that uses 10" drivers? Or could it be the age of the AR drivers?
Click to expand...

Typical for a 10" driver of that era. The Xmax is probably pretty short, 3-6mm I'm guessing (if you tried to get lower than 40-50 hz the speaker will lose it's power handeling), and the Fs is probably in the 40hz range, so it should come as no surprise.
Most of those old speakers had a bit of "60hz bass"
 
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