AR 8in. WOOFERS

[lARrybody]

Intrigued by a recent thread about AR18S speakers, I began researching other AR 8 in speakers, especially those from the ADD series. Then 11 days ago on my way home I passed a garage sale sign, and stopped to investigate. There they were, a set of AR25's that looked to be in excellent shape. Of course they needed new foams, but the foam grills were still there and in decent shape. The lady said they purchased them new in 1981, which sounded right. She wanted too much, but I was able to talk her down to fifty dollars. 

I don't know if these are from the ADD series, according to aphenos.net they are from the AR9 series, but the owners manual has them grouped with the AE11,14 and 18 series. The tweeter looks like they are correct for that series.  So I ordered new foams and caps and when they arrived I got started.  To my amazement the woofers turned out to be Realistic replacements. The 6uf cap was not the electrolyte I expected, but a film cap.  Where do I go from here? After reading this post from the aforementioned thread I am really at a quandary.

RobHolt

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Posted August 13 · Report post

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

 

 

 

    

[lARrybody]

Finding the exact woofers for this model may take quite some time. Of course I could use the base drivers from some AR18S speakers, but that would compromise one of my sets. I have woofers in AR7's and AR4X's  that would fit, but would be best left in there respective speakers. I do have a set from some Rock Partners I can use, but these are 10 years newer than the AR25's. 

Or should I just re-foam the Realistic speakers. Comparing them to the Rock Partner speakers they are the same dimensions and within a ounce the same weight. 

Or how about these on the auction site.

http://www.ebay.com/itm/370883235159?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

or these from Parts Express

http://www.parts-express.com/grs-8fr-8-full-range-8-speaker-pioneer-type-b20fu20-51fw--292-430

 

[ra.ra]

The AR-25 does not show up often, and I suspect this model simply got lost amongst the surplus of 8" two-ways that AR offered in the middle to late 70's, or maybe it showed up more often in the Euro market. You have the correct tweeters (p/n 200014, same as AR-17, AR-18 and AR-MST), which should employ a 6uF cap; and the 25 should have woofer p/n 200001 (same as AR-15, 17, 18 and 94). Several of these models are very similar, and soon thereafter marketing jumped into the 'S' series (18s, 28s, 38s.....) and the 'B' series (18B, 28B, 38B.......) again with some similar or identical drivers. Too bad about the woofer replacements - - sounds like another case of someone tossing original parts because the foams deteriorated. Got a pic of the crossover with the film cap?  

 

 

[JKent]

ra.ra. gave you some good leads. I'd be tempted to re-foam the Rat Shack woofers and take my time to see if some p/n 200001 woofers show up at a cheap price. Who knows? The  speakers may sound fine with the RS woofs.

Good thing you didn't pay the full asking price!

Quote

sounds like another case of someone tossing original parts because the foams deteriorated.

Sadly, I've been there myself. Before joining this great forum I didn't know any better. Threw away a perfectly good VMPS 12" woofer and 15" passive radiator (replaced them with genuine VMPS parts but that was a needless expense). Also gave away some Boston A40s. Live & learn......

-Kent

[lARrybody]

Thanks ra.ra for the part number. Here is the crossover. The film cap is labeled Td. 6uf 10% MEXICO  Not the blue electrolyte I was expecting to see.

I forgot to mention a pair of 28S's I purchased a couple years ago already re-foamed. I remember listening to them and not being impressed at all. My 18S's blew them away. I also ordered the 8uf caps for them. Planning on doing them also if I can dig them out.

 Kent, looking at the prices of some replacement woofers I can see why people just replace them not really knowing the difference between apples and oranges.  Then again I have pointed to rotten foams and have picked up some nice speakers for a song.  I will use the Rat Shack (pn 40-1016) woofers and keep a eye out for the 200001's.  I also have a idea to install some l-pads on these.

[ra.ra]

Hmmm, your woofers certainly look to be identical, but is one of them labelled as "Bose"? They might be just fine - - I happen to like lots of R-S products - - but I'd bet you'll be more comfortable with authentic AR woofers. The 200001 woofer, I think, became known as AR's "universal" 8" woofer - - which suggests to me that they found this product to be a satisfactory replacement for several different speaker models - - and I think a pair of them should not be too difficult to locate. 

The woofers in the auction you linked look OK, but they are not AR woofers or factory replacements - - they look much more like replacements for EPI speakers.

Re: the caps in your x-o's - - - I've never seen those in AR speakers, but I have seen them in the early 80's KLH-4, and others. The notion to add an L-pad could be very interesting and a nice simple improvement. 

[michiganpat]

for now I'd use the rock partner woofers, or any spare 8" AR woofer from an AR7 or it's decendants/cousins

if I were buying new replacements, I'd get 2 of the woofers Huw Powell of Human speakers sells for EPI replacement, as they have very similar specifications as far as sensitivity and Fs as the AR 8", plus those speakers run the woofer full range, so you know it has a nice smooth roll of on the upper end much like the AR 8" woofers.

[ra.ra]

mi-pat has a good idea here. The rock partner woofer is p/n 037, and since these (see pic) Tonegen AR-7 replacement woofers of mine have both the 037 and the 001 designations on the stickers, it could be surmised that these part numbers were deemed to be interchangeable from a performance standpoint. Plus, these woofers are visually identical to the woofers in the rock partner.

[Jeff_C]

6 hours ago, JKent said:

Sadly, I've been there myself. Before joining this great forum I didn't know any better. Threw away a perfectly good VMPS 12" woofer and 15" passive radiator (replaced them with genuine VMPS parts but that was a needless expense). Also gave away some Boston A40s. Live & learn......

-Kent

In a strange sort of way I am comforted by your statement Kent.  I have long wondered whether you US hifi people were more clued up than people here in the UK. When my AR speakers first showed signs of foam-rot, I took them to the hifi shop (which had succeeded the original shop where I bought them 17 years earlier. Many of the same staff had moved over to the successor shop).  No one at the shop (and certainly not me) had knowledge that they could be re-foamed.  Replacement woofers were offered, but were considerably more expensive than the complete system I had bought 17 years earlier. I decided to buy new speakers, but fortunately retained the old parts.  It was 20 years after taking the ARs out of use, when I found this site and managed to refurbish them myself with the aid of contributors here.

I often wonder how many easily serviceable speakers find their way to the dump. It is a shame.

I wish the OP good fortune in finding more appropriate replacement woofers, but would concur with Kent's advice to re-foam the Radio Shack woofers. There is very little to lose.

[JKent]

10 hours ago, ra.ra said:

your woofers certainly look to be identical, but is one of them labelled as "Bose"

I think that is a mis-spelling of "Bass" as in "Bass driver (woofer)".

4 hours ago, Jeff_C said:

I often wonder how many easily serviceable speakers find their way to the dump. It is a shame.

Jeff--it's a good thing you were unable to part with those old "ruined" speakers! 

Around here I've noticed the supply of old speakers at the Salvation Army seems to have dried up. I know they check all electronics before selling and discard any that are no good. I wonder if they dump all the speakers with bad foams. Several years ago I just happened to be there when a pair of AR Powered Partners came in. I asked the manager how much and he said they needed to be tested. I convinced him to sell them "as is". Got them home and they didn't work but  after new foams and a new RCA jack they were fine. I'm sure those would have wound up in the dump.

[lARrybody]

On 8/24/2016 at 9:58 PM, ra.ra said:

Hmmm, your woofers certainly look to be identical, but is one of them labelled as "Bose"? They might be just fine - - I happen to like lots of R-S products - - but I'd bet you'll be more comfortable with authentic AR woofers. The 200001 woofer, I think, became known as AR's "universal" 8" woofer - - which suggests to me that they found this product to be a satisfactory replacement for several different speaker models - - and I think a pair of them should not be too difficult to locate. 

 

 

The reason that woofer says "Bose" is because it is a Bose speaker. My thrift store Rock Partners are really Rock Boseners. Looks like I am striking out here. I have no trouble identifying AR  10 in and 12 in woofers, but it is time to go the reeducation camp on the 8 in variety.

I now have a plan thanks to all of your advise. I am going to borrow a set of woofers out of one of my 18S pairs and keep a eye out for some 200001 woofers. I may go ahead and re-foam the realistic woofers and maybe have a A-B listening comparison. Tomorrow I will figure out my modified crossover with the L-pad and post a drawing here before I solder it together.

 

[lARrybody]

Here is what I have came up with for the addition of L-pad to the AR25 crossover. Although the existing binding post are cool, I will be going back with 5 way banana  post  because I swap out speakers often. I am pretty sure everything is correct.

[owlsplace]

Like it ...

[JKent]

So in the 25 the tweeter polarity is reversed relative to the woofer? Or am I looking at this wrong.

Anyway, I like it. I added L-pads to AR-94si's and to some home-brew speakers I built. But did I keep a diagram or photo? Nooooo 

-Kent

[ra.ra]

Wow, I could be way off here, but this is what I see. 

I agree that the 'proposed' sketch is confusing, but it can be seen in larrybody's crossover pic that the original wiring shows similar polarity (red with yellow; blue with black) for the two drivers in the AR-25. Something with this schematic sketch doesn't look right, though, and it's complicated by using designations for original pot terminals (1-B-2) instead of the designations found on new L-pads (3-2-1) that you intend to use. The terminal you have shown as "2" is actually the "1" terminal on an L-pad, and it should connect with the common screw terminal on the masonite. And shouldn't the cap simply run from the "+" screw terminal to the "3" terminal on the L-pad (shown as "1" on your sketch) as the line of "input"? 

Also, since the 25 ohm resistor has typically been added to make an L-pad perform more like the original A-P pot, is it even required here since the AR-25 never had a pot to begin with?

Images below show parts express L-pad wiring, Roy's pictorial comparative for a 4x L-pad installation, and johnieo's schematic comparative for the same speaker model. Clearly, I'm a bit confused, too, but I think this deserves a second look before proceeding too far.

[lARrybody]

Ok here is the revision. The schematic is right on the side of the L-PAD box. The 25 ohm resister is out. This is a simple crossover and I was trying to over engineer it.  Thanks for the clarification.

[owlsplace]

Still like it

 

[ra.ra]

I am far from a crossover expert, but that's exactly how I was seeing it - - you're simply slipping this new control into the existing tweeter circuit. Very nice sketch, too - - simple and clear, but it'd be good if someone else can confirm this x-o arrangement.

What I like about this thread is that it's treading some new ground - - attempting to add a variable tone control to a speaker that never had one originally - - so what is the correct precedent to follow? Driver compatibility? Driver sensitivity? Crossover point? It's a mild madcap adventure, and it will be interesting to see how this turns out, particularly in comparison with your fine collection of AR-18s's.

[ra.ra]

Stumbled upon this image and am just posting it here since it shows a version of the AR-25 that included a 3-position switch for treble control.

[lARrybody]

Got one of the 25's finished after work.today. Will finish the other tomorrow. It didn't take much for the crossover board to fall out. Only held in with 10 staples and dried up glue. Working on classic AR's I always wondered who the guy with the staple gun was, sometimes there being 40 plus staples. I guess he was not around when these were built. Does this mean these cabinets were built November 18, 1980?

Here is the finished crossover with the board re-glued and stapled. I used a 6uf Erse Plus-X cap. The screw holding the nylon cap carriage is showing thru. I will fix that with the appropriate fastener tomorrow. 

A 20037 woofer from one of my 18S speakers is installed. Still have not found the 200001 woofers yet. This listing just popped up on the auction site and probably has the correct woofer, although the tweeters are mismatched. 

http://www.ebay.com/itm/282152049473?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

 

[ra.ra]

Nice work.... will be interested to hear what you think of the balance with these drivers and the effectiveness of the L-pad.

[owlsplace]

14 hours ago, larrybody said:

Does this mean these cabinets were built November 18, 1980?

Looking good ... interesting to see the numbers 18 appear upside down in the date stamp.