AR3a Crossover Rebuild (Long)

[Guest lmrosenthal]

Greetings to everyone on this fine forum!!

I thought I'd take a few moments and share my experience with you in rebuilding the crossovers for my 3a's.

I've had my 3a's since 1970 (purchased new), and they have been my only speakers in my system. I had the woofer surrounds replaced in 1996, and have been very happy with the sound for all these many years. Late last August, I noticed that one of the speakers sounded kind of distorted in the midrange, plus the mid and hi freq pots were getting scratchy for the first time. I removed the woofer, and noticed that the 2 can capacitors were leaking.

I ordered the crossover rebuild kit from Layne Audio for my pair of 3a's. It consisted of new capacitors, pots, hook-up wire (18ga Vamire for the mids/tweeters; 12ga Van Den Hul for the woofers), and schematic. Total cost for both speakers was about $80.00 plus shipping. Steve was very helpful in answering my questions, and the parts were delivered within a couple of weeks (he was on vacation for 1 of them).

What follows is a brief description of the steps I took:

1. I removed the woofer, and wore goggles and a mask while removing all the fiberglass damping inside the cabinet. Very important. That stuff gets all over and is very irritating.

2. I found impossible to remove the crossover component mounting board without causing damage to the board itself. I removed the staples, and tried everything I knew to heat the glue holding the board down, but nothing seemed to work. I was especialy worried about breaking the board, as well as damaging the reverse side (the outside surface you see from the rear of the speaker). I wanted to keep it cosmetically perfect. What I finally ended up doing was purchasing 1/8" thick masonite type board, cut to the same dimensions as the original (6.5" x 11.5"). More on this later.

3. I removed all the crossover components from the cabinet, unclipped the retaining clips from the coils, and pried up the riveted solder connections.

4. I then carefully measured the location of the holes in the original crossover mounting board, and drilled holes into my new boards.

5. I mounted the coils onto the new board using 2" x 1/8" flat head machine screws. I used 1" outside diameter washers underneath a nut and lock washer for holding down the coils. I did not re-use the original retaining clips or original posts for the coils.

6. Following the schematic supplied by Layne, I soldered the compenents together, re-wired the speakers with the supplied hook-up wire. I should also note that I was thinking of wiring the midrange drive in-phase with the woofer and tweeter, but after reading several of the posts here, I decided against it. I felt that I've been so happy with the sound for over 30 years, why change that critical aspect of it. I was already somewhat nervous about what the new crossover caps would sound like. Would it be better, the same or worse?

7. I was going to upgrade the screw-type terminal posts to new 5-way binding posts, but decided against that, as well.

8. At this point, I was ready to test my work before putting everything back together. Lo and behold - my speaker made music - rather anemic music since the woofer wasn't in the cabinet, but all three drivers worked! I mounted the new crossover board using wood screws and washers through pre-drilled holes, plus some Blue-Tak under the new board for vibration control. Mounted the new caps on the new board using 1" and 1/2" round retaining clips plus Blue-Tak. Re-filled the fiberglass, installed the crepe sheet between the woofer and the fiberglass, and remounted the woofer using non-drying caulk (The original gasket material was too stretched out to re-use), and I was set to go!

I originally was going to rebuild the crossover of the second speaker, but decided to wait until I could determine what, if any, difference the new caps made to the sound, since I now had 1 speaker with the original crossover and the other speaker with the rebuilt crossover.

I ran my system pretty much continously for 3 weeks or so, mostly as background music, before I tried to see what the differences were. I listened closely, at my normal listening levels (approx 85-90 db), with several mono albums in my collection (Dave Brubek, Getz & Gilberto, Wes Montgomery, Jimmy Smith, Miles Davis, Dvorak, Shostakovich, Mussorgsky, Beethoven, Sinatra, Ella Fitzgerald, Glenn Miller, Beatles, Stones, Beach Boys, etc) and discovered the following comparing the rebuilt to the original:

-A definite improvement in the mids and highs. It's hard for me to explain this but the word 'cleaner' is the best adjective I can use. The tonal balance between the bass, mids and highs are the same, but there seems to be much more detail in the highs - things like cymbals and triangles are much better defined.

-The low mids and bass are slightly more defined, more noticeably so in the low bass. As an example, on Jimmy Smith's albums, when he uses the pedals of his Hammond B3, the rebuilt crossover's bass notes seem much more defined. That is, you can more clearly hear the start/stop of each bass note. On the orginal speaker, the bass notes seem to blend together slightly.

As a result of my admittedly low-tech, amateurish listening tests, I rebuilt the second speaker in early December. I'm very happy I did. I'm getting wonderful music from my 3a's.

Finally, I must thank the writers of the many posts I've read here about the 3a's. Such a great group of people, especially Brett Thiel, Ken Kantor, Steve F, Tom Tyson, AR_pro, among many others. I've learned so much. Thanks to all of you!

Regards,

Larry

[ar_pro]

Great work on the 3a...really true to the spirit of restoring that classic!

One way to get a tighter connection for the binding posts is to replace the knurled nut with a hex nut - you'd be able to use a nutdriver to tighten (careful!) beyond finger-tight. I always liked the 3a's posts because it provided for the use of ring terminals on my speaker wires. I'm using spades with my AR-9's, and although I've tightened the heck out of my replacement nylon 5-way posts, I'll bet that it would still be possible to rotate the wire's spade terminal with my bare hands!

[Guest lmrosenthal]

Hey, good to hear from you!

Yes, I know what you mean. I kept the original posts for the 3a as well, and changed the knurled nuts to hex nuts and a lock washer, for that very reason. My speaker cables terminate in ring terminals and the connections work very well. I found that with the knurled nuts I had to check and re-tighten the connections every couple of weeks. Now, with the hex nuts/lock washer combo, they have yet to need re-tightening.

Larry

[Guest]

>As a result of my admittedly low-tech, amateurish listening tests, I rebuilt the second speaker in early December. I'm very happy I did. I'm getting wonderful music from my 3a's.<

Thanks for posting your results. Nobody who has been listening consistently to the same set of AR3a's since 1970 can say their observations are amateurish. No sir. Indeed I'd say we're hearing the voice of considerable experience.

You're helping me whether you really know it or not. I am hearing strange and unusual stuff out of my 9's and I am not pleased. I have replaced drivers, I have experimented, I have. . . switch channels on the amp and moved them to the opposite positions. Grrrrrrr.

One is more transparent than the other which, paradoxically, is louder (brighter, but not really).

I assume that something in the crossovers is shot. I don't know what, but something. I've been very hesitant to fool with crossover components. I'm less fearful after reading your post.

Bret

[Guest lmrosenthal]

Hi Bret,

I really appreciate your kind words. Thanks. For me, rebuilding the crossovers was a labor of love.

I'm not at all familiar with the 9's, so I can't really offer you any specific advice - however, if you happen to be familiar with the 3a's (particularly ways the 3a's are similar to the 9's), and think I can help you, I'd be more than happy to assist in any way I can.

You said: "I have. . . switch channels on the amp and moved them to the opposite positions. Grrrrrrr."

Question: when you moved the speakers to the opposite positions, did you move the speaker cables as well, or just switched the speakers?

Larry

[Guest]

>familiar with the 3a's (particularly ways the 3a's are similar to the 9's<

I am familiar with the 3a's, but there is essentially nothing the same in the 9 and 3a. The 9 is almost its own universe sharing, as far as I can tell, only a close kinship with the 90s and I'm taking other people's word for that since I haven't been inside 90s. (I'm talking crossover here.)

No, I didn't move the wire so if the wire were a factor it should have stayed with the wire and it stayed with the cabinet. I've even swapped the tweeter and upper midranges in the cabinets and it stays with the cabinet. X-over trouble. I have the speakers "bi-wired" with 7' bits of 12 gauge wire. Ever try to get that much wire in a single banana plug?

By the way, you know how to make a pair of AR speakers sound completely clinical and extremely unmusical? Stick 'em in a mostly empty room with stone on that wall, glass on this wall, and bare gypsum (sp?) board over firring strips over panelling on the other two, with wood-on-concrete floors; connect to Adcom preamp/amp, turn-up volume. Oh my, does that ever stink! Gotta get more furniture and another rug or two.

Bret

[ar_pro]

Hi, Bret -

Are your 3-position level control switches working properly?

[Guest]

"Are your 3-position level control switches working properly?"

Yes, they seem to be.