AR's Biggest Little Speaker? AR-18s

[owlsplace]

Just curious if the Teledyne era AR-18/s was AR's biggest little speaker?

I grabbed a pair of the "s" version today locally for the drivers -- the cabs are very marginal.

Some fun old posts from the archives:

I wonder if he had any issues with the AR-7 reverse phasing ...

I'm not very impressed with the refoam job and it seems there are or have been some caveats from the past regarding 8" foams:

Robert (ra.ra), any reservations about dropping these drivers into AR-7 cabs with the appropriate crossover components. It looks like a slight reduction in cabinet volume.

Roger

[ra.ra]

Roger, there are more than a few members on this site who know the intricacies of these models better than me (michiganpat, Robert_S, maybe?), but yes, the AR-18, 18s, and 18b all used excellent drivers worth salvaging if all else is beyond repair. Not sure if any of the earliest of the 18's had real wood veneer cabinets, but even the 18 and 18s (see pic) had at least three differences: driver placement, tweeter (both had FF, but different lead-out wires), and woofers. Some '18' models use a 6uF cap; others have a 5uF cap, I think.

I have some literature that lists the AR-7 and AR-18 as both having identical cabinet volume (9.77L), whereas it appears the AR-18s is listed as just a tad larger (9.86L). Close enough for government work, and they all have the same x-o frequency (2000 Hz) and use a 5 or 6uF cap, so my guess is that this 18s woofer might serve as a very reasonable substitute for an AR-7 woofer.

The 18s woofer should be p/n 200037, same as in this 18b I recently re-foamed. I did not like working with this flimsy, shiny dust cap, but I just slit it, folded it back and shimmed, and delicately glued it back in place. Your question about driver polarity is a good one since the AR-18s has consistent polarity and the AR-7 has drivers reversed. I dunno - - - am still curious about the AR-7 wiring - - - why not try it both ways and report back.

[owlsplace]

Caps are Unicon 5mfd NPE on these that measure within 10%. I will replace with (4) of the old Madisound 10mfd surplus which will boost output a bit due to half ohm lower esr and zero voltage loss compared to the Unicons. If I don't like the sound I'll order some new NPEs.

Interesting to note the "mechanical" xover specs in AR's literature for the AR-18s:

I will go ahead and correct the AR-7 xover polarity to match all of AR's other speakers since I have a tendency to play speakers in multiple pairs. The next person who gets these can scratch their head if they sound out-of-phase with their other AR-7's.

Roger

[lARrybody]

Oh yes the AR 18S, now there is a subject dear to my heart. In fact these are my favorite small bookshelf speaker. Did you know there are are two different varieties of the 18S.  The original version on top and the newer one on the bottom.

Here are the differences I can see.  The newer version is 1/2 in wider. Has a terminal cup instead of a standard spring strip and the plastic woofer ring is outbound instead of recessed like the original. They all come with the 5uf NPE cap, fiber fill instead of fiberglass, and vinyl covered cabinets. Why not drag all my 18S examples out.  Two of each variety.

The first thing I do is re-foam the woofers with surrounds supplied by Rick Cobb. I believe they are the correct foams. Replace the 5uf with 5.1uf Daytons. Replace the spring clips with binding post from Parts Express. I have the binding post terminal cups for the newer version, but haven't got around to it yet because it will require slightly larger holes and re-positioning the caps. Did I say I really like these speakers.  I have a 18B and Rock Partner example.  Have not run across the 18 model yet. Not interested in the the other versions. I like the way the 18S model has inline drivers. 

 

 

Edited October 10, 2019 by lARrybody
image url

[ra.ra]

Fantastic collection and great photos - - - the AR-18 (and 18s) does have a fervent following, and I always love to see the enthusiasm for AR's small two-ways. I'm wondering if that small dimensional change accounted for the minor bump in internal volume, and I'm also curious about the change in cap value from 6uF to 5uF. I, too, prefer the aligned drivers in the 18s, but it's too bad they abandoned the two-way tweeter switch from the earlier 18. Thanks for sharing.

[owlsplace]

Yes, nice collection of 18s models ... on the set here one of the cabs had some heavy water damage hence the driver donor status.

The cabs have an internal stamp showing they were made in Brooklyn.

Roger

[DavidDru]

On 8/5/2016 at 1:32 PM, owlsplace said:

I will replace with (4) of the old Madisound 10mfd surplus which will boost output a bit due to half ohm lower esr and zero voltage loss compared to the Unicons.

Roger, clarify this for me please.  I don't understand the math I guess.

[owlsplace]

4 hours ago, DavidDru said:

Roger, clarify this for me please.  I don't understand the math I guess.

I don't have any 5mfd caps around so two 10's in series makes 5mfd.

[DavidDru]

Ah, okay, missed that.

[michiganpat]

the cap difference came with the revised tweeter (0038 I think are the last 4 digits in the PN)...it was a tad more sensitive...it has the S shaped vs, straight leads of the older (0014 pn I believe) tweeter in the 18....

 

[DavidDru]

Here is my pair, or I should say my sons.  New surrounds.

 

[ra.ra]

1 hour ago, michiganpat said:

the cap difference came with the revised tweeter (0038 I think are the last 4 digits in the PN)...it was a tad more sensitive...it has the S shaped vs, straight leads of the older (0014 pn I believe) tweeter in the 18....

Sounds very plausible, thanks, mi-pat.

[lARrybody]

I agree with what michiganpat says. Here are some extra tweeters I acquired when collecting and restoring my 18S models.

Looking for some Model 18 speakers from the ADD series and I am coming across different versions. The 18AU and 18J. Maybe one has the tweeter switch and one does not. Maybe the woofers are slightly different. They both appear to have the same tweeter and 6uf cap. 

Edited October 10, 2019 by lARrybody
image url

[michiganpat]

my uncle gave me 2 pair of ADD series 18's and a marantz 2265 that he bought while in the air force in 1977....one pair has the tweeter level switch, the other doesn't....both were bought at the same time, and both have the same woofer....

[RobHolt]

The 'S' designated models are about 2dB higher in sensitivity so some care is needed when mixing and matching 8" bass drivers with tweeters.

The paper classic tweeters from the 'S' series appear to lack damping compared to the non 'S' versions and the paper looks lighter in colour as a result. This would lower moving mass and give slightly higher output at the expense of response smoothness.

The 'S' bass drivers have around 2dB more output in the upper range - one reason why the tweeter series capacitor was reduced from 6uf to 5uf as you need less output from bottom of the tweeter range.

I have measured these differences myself but AR reflected the difference in the published specs with S series models rated at 89dBw.

Rob

 

[owlsplace]

Good to know, Rob.

[ra.ra]

Great info from m-pat and RHolt. For those of us who aren't skilled enough to fully understand the mutual inter-workings of driver sensitivities, crossover slopes, and the subsequent effects of caps and coils that go into the design of any speaker model, this is all interesting and helpful information to consider. It makes me want to possibly experiment with adjusting some cap values on some speaker projects where I have transplanted similar, but not entirely original, drivers due to availability.  

[adam2434]

Hi, first post here.

Picked up a pair of 18s at a thrift store for a few bucks.  Heard pretty good things about them.

Woofers need to be re-foamed (this will be my first re-foam job).  I just tested the speakers and the tweeters work and have no signs of damage.  Also, the woofer voice coils do not rub, so I assume they are ok.

I’m looking for foam recos that will replicate the stock foam as much as possible.  Larrybody's post above mentions Rick Cobb surrounds.  Are these the best option?  If so, how does one order them?

I also found the options below.

http://www.simplyspeakers.com/acoustic-research-speaker-foam-edge-repair-kit-fsk-8.html#

http://www.parts-express.com/parts-express-speaker-surround-re-foam-repair-kit-for-8-speaker--260-920

I will also replace the tweeter cap, so would appreciate recos for that too.

Thanks in advance!

[owlsplace]

3 hours ago, adam2434 said:

Hi, first post here.

Picked up a pair of 18s at a thrift store for a few bucks.  Heard pretty good things about them.

Woofers need to be re-foamed (this will be my first re-foam job).  I just tested the speakers and the tweeters work and have no signs of damage.  Also, the woofer voice coils do not rub, so I assume they are ok.

I’m looking for foam recos that will replicate the stock foam as much as possible.  Larrybody's post above mentions Rick Cobb surrounds.  Are these the best option?  If so, how does one order them?

I also found the options below.

http://www.simplyspeakers.com/acoustic-research-speaker-foam-edge-repair-kit-fsk-8.html#

http://www.parts-express.com/parts-express-speaker-surround-re-foam-repair-kit-for-8-speaker--260-920

I will also replace the tweeter cap, so would appreciate recos for that too.

Thanks in advance!

Rick Cobb should be here: http://www.ebay.com/itm/BEST-Speaker-Foam-Surround-AR-Acoustic-Research-4-4AX-6-7-8-9-9LS-10-15-16-18-/172316450385?hash=item281edc5e51:m:mXXu7fItk-EzydhfglnYpfw

The last foams I got on ebay were from Audiodogs.

Not sure if Boston FF surrounds are recommended for the 8" woofers. I know Audiodogs will have a strong opinion but I've never dealt with Rick ... maybe someone will chime in here. The link to Rick's auction does not show Boston FF foams so they may be JBL's.

Madisound is good source for the Carli caps that I use.

Roger

[michiganpat]

either the JBL or the 8" filled fillet for boston acoustics are the recommended surrounds

 

[lARrybody]

On 8/13/2016 at 6:28 PM, RobHolt said:

You can email Rick direct at rcobb@tampabay.rr.com   You want part number 610-365. He can supply you with a kit or just the surrounds. These are correct for your 18S speakers.  Peace

 

 

[adam2434]

Thanks for the recos, guys.

Seems like there are several recommended surrounds (Rick Cobb, JBL, Boston FF, Audiodogs), and not a unanimous winner.

Perhaps some of these are one in the same?

I will email Rick Cobb.

 

 

[JKent]

Welcome Adam

1 hour ago, adam2434 said:

Seems like there are several recommended surrounds (Rick Cobb, JBL, Boston FF, Audiodogs), and not a unanimous winner.

Perhaps some of these are one in the same?

Rick Cobb and Audiodogs are sellers. Add to those http://www.speakerworks.com/speaker_repair_kits_s/65.htm

JBL and Boston filled fillet are the type of foam. For that reason you are better off with one of these specialists (sellers) than with Parts Express or Simply Speakers who, I believe, sell "generic" 8 inch foams. Not all 8" foams are the same.

As a first-timer you are better off with a kit, which will come with the stuff you need and instructions. The Speakerworks site I linked has a video to watch.

There is some disagreement about whether you should remove the dust caps and install shims. IMHO (and that of many members here) shims are the way to go. Also, check to see what kind of glue comes with the kit you order. I'm a big fan of the white glue. It's like Aleene's Tacky glue (which can also be used). Some sellers have solvent-based glue that's like contact cement and VERY unforgiving. DO NOT GET THAT STUFF. The white glue can be smeared around with your finger and washes off with water. If you goof you can peel the foam off and try again. Use white glue.

Roger recommended Madisound for Cali caps and I second that. You want film caps (Carlis are mylar film) for long life but there is no reason to buy expensive caps. I don't know the values of the caps in your 18s but you can combine caps if needed and you don't have to have the exact value (3.9 is fine for replacing 4.0). The 18 used a 6uF cap so maybe the 18s does too (some versions of the 18 series used a 5uF). Here's the 6uF https://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-6-mfd/  If you need 5uF you can use a 4.7uF Carli, https://www.madisoundspeakerstore.com/carli-capacitors/carli-mylar-4.7-mfd/ or if you want a 5 here's a Solen https://www.madisoundspeakerstore.com/solen-capacitors/solen-5-mfd-fast-cap-400v/

Hope this helps.

-Kent

PS:  Rob says

Quote

The 'S' bass drivers have around 2dB more output in the upper range - one reason why the tweeter series capacitor was reduced from 6uf to 5uf as you need less output from bottom of the tweeter range.

So either the Carli 4.7 or the Solen 5.0 should work fine. If you're compulsive about the cap value you could even add this Bennic in parallel with the Carli to make 5.03uF  https://www.madisoundspeakerstore.com/pmt-poly-cap-630vdc/bennic-pmt-0.33mfd-polypropylene-630v-cap/

Parallel caps are not as silly as it may seem:

• The Carli/Bennic combo costs less than a Solen
• The Carli has an ESR that is closer to the original electrolytics and therefore could sound more authentic.
• Some people think "bypassing" a tweeter cap with a small value cap has sonic benefits, so "it couldn't hurt".

[DavidDru]

Rick for the surrounds.  Maybe Tom at myaudioaddiction.

I used Ricks test tone for centering the VC on these.  Easy peazy.  Or remove the dust cap and shim.  Both are fine on this smaller woofer.  Cleaning off the old surround stuff is annoying at best.

[DavidR]

13 hours ago, larrybody said:

  On 8/13/2016 at 6:28 PM, RobHolt said:

You can email Rick direct at rcobb@tampabay.rr.com   You want part number 610-365. He can supply you with a kit or just the surrounds. These are correct for your 18S speakers.  Peace

Larry,

Does this surround work for all AR 8" woofers or just this particular p/n woofer from the AR18S ?