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

gkimeng · Mar 12, 2008

Zilch said:
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.

The midrange driver is 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:

The specs for the original AR-2 claimed response from 42Hz to 18KHz. The woofer sounds like it's still up to snuff (not surprising); the highs have definitely deteriorated, but whether that's the driver or the crossover...maybe some new caps are called for here?

Duffinator · Mar 12, 2008

I wonder how these will sound compared to the AR4x spearkers you operated on? The bass was amazing in those with the JBL auto speakers or whatever they were. :yes:

Zilch · Mar 12, 2008

gkimeng said:
The specs for the original AR-2 claimed response from 42Hz to 18KHz. The woofer sounds like it's still up to snuff (not surprising); the highs have definitely deteriorated, but whether that's the driver or the crossover...maybe some new caps are called for here?

The violet curve is the "tweeter" run full range, so it's the driver. I doubt if those ever played to 18 kHz.

[Well, this one DOES play out to there, but at -20 dB.... :yes: ]

Edit: Ad says 42 Hz to 14 kHz (+/- 5 dB) and down 10 dB at 16 kHz:

http://audiokarma.org/forums/showthread.php?p=1562908#post1562908

Duffinator said:
I wonder how these will sound compared to the AR4x spearkers you operated on? The bass was amazing in those with the JBL auto speakers or whatever they were.

WB's doing a pair of those for himself, as well. We've listened to the versions with Tang Band and 18 Sound HF and he wants to hear the OASR ("Dr. Seuss" horn) variant before deciding. It's going to be horns for certain, looks like, tho, with the same JBL 116H woofers as are in yours. We're still acquiring data on his AR4xs and AR4xas for the record in another thread here.

The AR2s will be ducted, so it'll be an interesting comparison. We auditioned them last night (still need to cut in the ducts,) and concluded that the HF is "Done." It's BMS 4555 on 1.5" DDS vertical-format CFD 1.5-70 horn. There may be other HF driver/ horn/waveguide options; later for that, by others, probably.

AR2 LF drivers are actually 11" diameter so we chose the wide-flange JBL 127H-1 as upgrade. The cone diameters are the same 8.25". T/S parameters indicate it can be used either closed-box or vented, but the box models suggest vented will provide much better bass in this size (~1.4 cuft.) enclosure.... :thmbsp:

vinyldavid said:
Hmmm....this would look GREAT in a vintage setup!

Inspiration:

http://www.jbl.com/array_series/specs.aspx

You buy AR2s for 20 bucks; dump the funk and fast-forward. JBL 2342, DDS Engebretson, 18 Sound XT1086, others. Just DO it. Keep the AR2 woofers if you must:

gkimeng · Mar 12, 2008

Zilch said:
The violet curve is the "tweeter" run full range, so it's the driver.

Ad says 42 Hz to 14

I guess I must have been thinking of the 2a or 2x. 12k from a driver originally spec'd at 14k is actually not that bad after this many years.

Zilch · Mar 14, 2008

AR2 woofers nearfield response, below.

Compare to original spec here:

http://www.classicspeakerpages.net/...rochures/ar-2_brochure/ar-2_brochure_pg3.html

Apropos of earlier discussion above, note:

H.F. response derived from on-axis curve of one tweeter.

Measurements @ #13 taken on-axis of the array with one tweeter active.

Stock AR2s are crossed at 2 kHz, but we determined 1.2 kHz is more appropriate; substantial coloration at and above the 1.5 kHz notch is quite audible....

wiredbecker · Mar 14, 2008

Whoa guys you need to hear these speakers! :drool:

I wish I had the cash right now so I could tear into my spare pair of AR2s and swap out the cross-firing mids with the horn tweeter like Zilch's. The dialed in ZL2s are jaw dropppingly amazing. Seriously. I was originally planning on refurbing my dad's AR2s but after hearing these, I just can't bring myself to do it. My dad deserves better.

wiredbecker · Mar 14, 2008

double postage

wiredbecker · Mar 14, 2008

Zilch said:
Stock AR2s are crossed at 2 kHz, but we determined 1.2 kHz is more appropriate; substantial coloration at and above the 1.5 kHz notch is quite audible....

Indeed a fair assessment. Running both the JBL as well as the vintage AR2 woofer in stereo, gave me hope that I might actually be able to afford to do these modifications in a few semi-affordable steps. The AR2 woofer wasn't that bad--getting rid of the tired mids and XO is the most important issue here. The AR2 woofer would greatly benefit from a re-doping, as it seemed to have a difficult time keeping up with transient sounds (at least to my ears) whereas the JBL rocked the house with ease. :banana:

Zilch · Mar 14, 2008

wiredbecker said:
Running both the JBL as well as the vintage AR2 woofer in stereo, gave me hope that I might actually be able to afford to do these modifications in a few semi-affordable steps.

The 18-Sound oval horn and Selenium driver Jack and I are working with in the EconoWave thread may be a more affordable approach.

I would envisage that horn mounted on a rotatable plate such that it could be used either horizontally or vertically.

This is premature, however. I haven't worked with that combination yet and only know the horn by reputation, but will take a closer look along with the Selenium driver on the others I have shown above.

BMS on DDS is virtually a slam dunk, of course, but double the cost.... :yes:

wiredbecker said:
JBL rocked the house with ease.

I had them cranked all day today. They certainly aren't wimpy weenies....

:

RadShak1251 · Mar 14, 2008

wiredbecker said:
The AR2 woofer would greatly benefit from a re-doping, as it seemed to have a difficult time keeping up with transient sounds (at least to my ears) whereas the JBL rocked the house with ease.

Those AR woofers use cones that are heavy, rather soft and IIRC incorporate quite a bit of felt vs. the JBLs which seem to be much lighter & stiffer, so even when brand new I guess their transient behavior would naturally be different.......right?

RadShak1251 · Mar 14, 2008

wineslob said:
Most of those old speakers had a bit of "60hz bass"

You mean a purposely built-in frequency response "hump" to maybe give the speaker some excitement for rock/pop music?

I owned a pair of the original Baby Advents & back in 1984 had read a review of them in Stereo Review and they said they had a hump around the 100Hz region to give an illusion of more low bass, which was weird because they said the Baby actually had "usable" bass all the way down to 45Hz, which I can personally confirm (their low 86dB efficiency is a clue to this aspect of their performance).

Zilch · Mar 25, 2008

UT, oh:

geaugafletcher · Mar 25, 2008

What is this iconoclastic butchery?! You will burn, sir, burn right dreadfully!!

!

Sorry, don't know what came over me...carry on...

Zilch · Mar 25, 2008

The hardboard backing broke when removing the grilles.

They're trash now, right?

gkimeng · Mar 25, 2008

Zilch said:
The hardboard backing broke when removing the grilles.

They're trash now, right?

Yeah, don't bother trying to fix them, just use it as a template to cut a new one.

Zilch · Mar 25, 2008

Inspired by this post from Stegnick:

http://audiokarma.org/forums/showthread.php?p=1742099#post1742099

I dragged these up from the dungeon in quest of the mythical mid-bass thump. Nearfield measurements reveal it's there, bigger'n Godzilla poop, at least in this one sample, (the other one appears to be dead,) between 100 and 300 Hz (Red), no less artificial than L100's exaggerated "West Coast" hump at a somewhat lower frequency.

Of interest, what it says on the label affixed to the rear of the cabinet:

AR1 SN 15707

AMPLIFIER CONNECTION
(See instructions for complete information.)

1) Input terminals are Nos. 1 and 3.

2) The speaker is shipped with terminals 1 and 2 strapped for the normal 4-ohm connection. For 8-ohm connection (to be used only when the cabinet is mounted unfavorably with regard to bass performance -- out in the middle of the floor in the center of a large wall,) remove strap.

MOUNTING POSITION

One excellent location for the AR speaker is cater-cornered (touching each wall), at least 3 or 4 feet above the floor.

It smells like there's a 4-Ohm resistor behind that strap, Green:

How does the AR 12" woofer compare with the AR 10"? See Cyan. I normalized the curves between 500 Hz and 1 kHz by +2 dB for the comparison, i.e., the 10" is a bit less sensitive in this region:

What's it mean? Used with boundary reinforcement, such as by floor, wall or corner location, a mid-bass hump dominates this 12" response @ 4 Ohms in AR1 alignment; the AR 10" provides more accurate and somewhat deeper bass.

Solid-state, one sample only, folks, mileage may vary, and subject to verification.... :yes:

Edit: "HA! Got any TOOBS, Zilchster?"

EICO HF-87 knocks it down ~1 dB, black:

grateful · Mar 28, 2008

Interesting Roy Allison identified that loudspeakers installed close to a back wall have a loss at exactly that frequency range because of standing wave cancellation. Can be as much as 10 db. I wonder if the speakers have flat bass response into a real room

wineslob · Mar 28, 2008

RadShak1251 said:
You mean a purposely built-in frequency response "hump" to maybe give the speaker some excitement for rock/pop music?

I owned a pair of the original Baby Advents & back in 1984 had read a review of them in Stereo Review and they said they had a hump around the 100Hz region to give an illusion of more low bass, which was weird because they said the Baby actually had "usable" bass all the way down to 45Hz, which I can personally confirm (their low 86dB efficiency is a clue to this aspect of their performance).

Yes :yes: but that dosent mean that a speaker would not have, as back in the day they would say, "usable" output. The problem was what they considered "usable", many times it was -10db, virtually gone in relation to the rest of the speakers output.

Zilch · Mar 28, 2008

I've always considered nearfield low-frequency measurements as representative of response in a 2-Pi, i.e., hemispherical, alignment, the same as if reinforced by one boundary, such as mounting against a wall.

AR recommends a corner location for these, a 1-Pi alignment, further enhancing the bass below 100 Hz.

My take on the "8-Ohm" connection is that it damps the peak when the speakers are used in free space, with no boundaries, so that they don't sound boomy.

I don't know what AR did in AR3, but assuming it's the same woofer, the same issues would arise.

Again, this is a sample of one. If some AR3s would come calling, we could get more definitive data.... :yes:

Edit: Here's some curves from a JBL subwoofer datasheet illustrating how boundary loading alters the response. 4-Pi is freespace, 1-Pi is wall/floor or corner reinforcement:

Corner ceiling or corner floor placement, half-Pi, would kick the VLF differentially up even more....

grateful · Mar 28, 2008

AR developed several speakers designed to deal with the bass loss problem at 200 HZ on later models. Most of these speakers were strongly influenced by Roy Allison. The first speakers were the Ar LST and 10 Pi. Both of these speakers used elaborate crossover networks that had specific curves to optimize the speakers whether they were free standing, against 1 wall, 2 walls, or in a corner. Later the AR-9 was developed and solved this issue in a different way. The crossover to the low freq drivers was 200 hz, too low for the standing wave to develop. They also placed those drivers very close to the floor. They added a 8 inch mid bass driver from 200 hz up and mounted it high in the cabinet. This was too high in freq for the standing wave to develop. The result very smooth bass from 40 hz - 700 hz. Later the Allison 1 came out and also employed all of these tricks for smooth bass output in a room.

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

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