AR 11 rebuild project

[Guest audioslave]

From original topic: AR 11 parts, schematics

" With the help of the AR-11 schematic (belated thanks to Tom

>for sending and Mark for posting), some pictures of the AR-11

>crossover we pulled off eBay, and some messages we exchanged

>about the schematic vs the actual wiring, Jeff was able to

>build his own crossovers for his AR-11s. He e-mailed me a

>picture of the completed crossover. He did a great job.

>

>Rich Laski"

Thanks, Rich for you complement on the crossovers. I have attached a picture of the same pict I sent Rich which was taken while the glue was still drying and the crossover(s) were in one of their many test phases.

Thanks to Tom Tyson, I had the schematic which was a valuable source!!!! However, I ran into a few problems with the crossover schematic that I received from Tom Tyson.

Rich Laski, again a valuable source of information for my restoration compared the crossover schematic to the crossovers in his AR 11's... Here's the quote from his email:

" I've done a quick comparison between the schematic and my AR-11B crossovers. There are several significant differences:

Tweeter circuit -

1) The 3 Ohm resistor (attached to the switch) is a 5 Ohm resistor.

2) The 10 uF (almost looks like 101 MFD (uF) but that is a 10) cap is wired on the + side of the tweeter. It is actually soldered to the + terminal post and one of the terminals of the switch.

3) I think the "dot" (indicated the + terminal) is on the wrong side of the tweeter. It would put is out of phase with the midrange and woofer. I can look into this some more and let you know what I find if you'd like.

Midrange circuit -

1) The .5 Ohm resistor (attached to the switch) is a 10 Ohm resistor. That may have been a "15" that got cut off in a page fold or pasting two pages together. At any rate it is a 10 Ohm resistor.

2) The 40 MFD (40 uF) cap is also soldered directly to the + terminal post and the other lead is soldered to the two midrange coils. It is not on the - (negative) side of the driver.

Woofer circuit -

1) Looks like a 2.85 MH to me as well.

2) The two caps (72 MFD and 50 MFD) are replaced by a single 120 uF cap.

3) There is no 2 amp fuse."

My first layout of the crossover was basically the same as the schematic supplied by Tom. This layout caused my old Pioneer SX-780 to go into protection. After a few minor tweaks to the crossover circuit, the Pioneer went into protection for the last time, never to return to "normal" operation.

The final crossover incorporated the "changes" that Rich pointed out in his email. The main difference being the switches, which were robbed from old advent and epi cabinets. The way I wired the switches makes the far left position 0db, center -9db and far right is -3db. I knew this was incorrect but the urge to listen to them was too great, and I figured I could change this later.

The drivers I used to fill the empty cabinets includes:

2) AB Tech replacement tweeters received as a birthday present from my Wife, with some help from my father.

2) "reworked" AR 1.5" midrange drivers (200010-1) These have the black metal screen and a yellowish ring. They also have the AR logo on the frame. Thanks to Dale for selling me the mids!!! (I believe his forum ID is dogmeninreno)

2) actual AR 11 woofers, re-foamed.

The coils were wound by a company in New York State, not far from where I live. Because of their machine limitations 14ga wire had to be used with the two smaller coils. The larger coils were wound with 18ga. If ever you need coils wound, email me and I'll send you the company's phone number. Some other companies wanted twice the amount to wind the same coils. These guys were great!!

I'd like to thank Tom Tyson, Rich Laski, Dale in Reno, my Father and this site for all the help along the way. My 11's do sound great!

I am still looking for one silver screened AR mid, the ones that are more commonly seen in the 10pi and 11. Let me know if anyone out there has an extra one they'd like to sell.

[r_laski]

Jeff,

I’m glad I could help you out. Good to see you back on the forum.

Just to clarify something that you and I resolved. I originally stated:

“3) I think the "dot" (indicated the + terminal) is on the wrong side of the tweeter. It would put is out of phase with the midrange and woofer. I can look into this some more and let you know what I find if you'd like.”

The AR-11 tweeter is wired “out of phase” of the midrange and woofer, like the AR-3a. I had been comparing the AR-11 to the AR-91 schematic and noticed it shows the AR-91 tweeter wired "in phase".

Rich Laski

[Guest Bret]

>The AR-11 tweeter is wired “out of phase” of the midrange and woofer, like the AR-3a. I had been comparing the AR-11 to the AR-91 schematic and noticed it shows the AR-91 tweeter wired "in phase".<

Whoa. Whoa. What color wire is supposed to be to the "+" side of the tweeter?

I'm so easily confused.

Bret

[r_laski]

>Whoa. Whoa. What color wire is supposed to be to the "+"

>side of the tweeter?

>

>I'm so easily confused.

Bret,

The YELLOW wire is supposed to the “+” side of the AR-11 tweeter. However, if you trace the YELLOW wire back to the crossover, you will find it is soldered to the NEGATIVE terminal binding screw along with the BLACK (woofer negative), and BROWN (midrange negative). That is what makes the AR-11 tweeter “out of phase”. BTW, If you still have good foam on the front of your AR-11 tweeter, the foam covers the embossed “+” on the front mounting plate. The “+” terminal can also be identified as the one closest to the PN sticker on the back.

Rich Laski

[Guest Bret]

>However, if you trace the YELLOW wire back to the crossover, you will find it is soldered to the NEGATIVE terminal binding screw along with the BLACK (woofer negative), and BROWN (midrange negative). <

That's what I hoped you meant. I knew when we were talking about the crossover that it was entirely possible for the crossover to have to be "wired backwards" so that the drivers end-up in phase.

Which is what I understand was "discovered" in the 3a, not that it was decided to run the driver out-of-phase at the driver, on purpose.

Or do I STILL have it wrong? (for academic purposes, only. I have no plans to rebuild a 3a anytime soon)

Bret

[r_laski]

>That's what I hoped you meant. I knew when we were talking

>about the crossover that it was entirely possible for the

>crossover to have to be "wired backwards" so that the drivers

>end-up in phase.

>

>Which is what I understand was "discovered" in the 3a, not

>that it was decided to run the driver out-of-phase at the

>driver, on purpose.

>

>Or do I STILL have it wrong? (for academic purposes, only. I

>have no plans to rebuild a 3a anytime soon)

>

>Bret

Bret,

Would it clear everything up if I stated AR “reversed the POLARITY” (“wired backwards”) of the tweeter instead of “phase”. I admit I used the wrong word. All I wanted was to make sure Jeff wired his tweeters correctly. My apologies for creating confusion.

Rich Laski

[Guest Bret]

>Would it clear everything up if I stated AR “reversed the POLARITY” (“wired backwards”) of the tweeter instead of “phase”. I admit I used the wrong word. All I wanted was to make sure Jeff wired his tweeters correctly. My apologies for creating confusion.<

No no ! lol Nothing to apologize for at all! Gee, I'm sorry if I made you think I was being critical.

I didn't mean to say anything to even remotely imply I thought you did/said/implied anything wrong. I was just hoping that I hadn't been wiring stuff backwards for years and years.

My fear of being wrong panicked me for a minute. You know the neurosis -> "I've been driving on the wrong side of the road for how many years? I married an alien and haven't noticed? You mean underwear don't go on with the split in the back? This isn't the line for driver's license renewal? Why wasn't I informed!?"

In this case that old sinking feeling expressed itself like this: "How many replacement drivers have I installed backwards over the years!? Did I really do that? Oh, man! Okay, okay, think. . . What are all those people's names and addresses?"

Wouldn't St. Peter's discovering I installed tweeters out of phase during a life-review disqualify me, an AR-fan, from entering heaven?

Like I said, "easily confused." Besides, you used the perfect words.

It does bring a possibility to mind, though. Without any gear to measure the phase at the driver (or just failing to test) a bunch of shadetree speaker builders have probably built many a system with something ultimately out-of-phase.

I'm sorry if my self-doubt came across like a challenge or critique.

Bret

[r_laski]

>>No no ! lol Nothing to apologize for at all! Gee, I'm sorry if I made you think I was being critical.

I didn't mean to say anything to even remotely imply I thought you did/said/implied anything wrong. I was just hoping that I hadn't been wiring stuff backwards for years and years.

I'm sorry if my self-doubt came across like a challenge or critique <<

Bret,

You have nothing to apologize for either. I was not offended by and didn’t take anything you said as a challenge or criticism. Your questions were all valid and taken as another academic exercise. The AR Owner’s Instruction Manual talks about the importance of maintaining POLARITY when removing and replacing drivers. I erroneously used the terms “phase” and “polarity” synonymously. My Bad!

I know exactly what you mean about wiring drivers “backwards”. I’ve had that neurosis since the first time I pulled dead drivers out of my AR-11s to replace them. When I recently pulled the tweeters out of my brother’s AR-11s to refinish the cabinets, I noticed they were in fact “wired backwards”. They had been worked on years ago by an “AR authorized” shop that replaced the tweeters. Did it make a difference in how the speakers sounded? Absolutely.

One thing I recently learned that is a wiring “rule of thumb” among speaker builders is that the lighter colored wire going TO THE DRIVER is connected to the positive (+) terminal AT THE DRIVER (red, orange, yellow, and white for AR speakers). That’s why the Yellow wire (lighter color than Blue) is connected to the “+” terminal of the tweeter even though the other end is connected to the negative binding post. If you were to follow the wiring from the “+” binding post, it is very likely you would end up connecting the blue wire to the tweeter “+” terminal. If you did this, you would be wiring the tweeter “backwards.” The correct wiring can be found in the notes on the AR-11 system assembly drawing on this web site.

>> It does bring a possibility to mind, though. Without any gear to measure the phase at the driver (or just failing to test) a bunch of shadetree speaker builders have probably built many a system with something ultimately out-of-phase. <<

You are exactly correct. That’s why its best if I leave discussion and explanation of speaker/crossover design, phase response, and time and phase coherence in multi-driver speaker systems to experts in this field like Jim Thiel (Thiel loudspeakers) and Brian Cheney (VMPS).

>> In this case that old sinking feeling expressed itself like this: "How many replacement drivers have I installed backwards over the years!? Did I really do that? Oh, man! Okay, okay, think. . . What are all those people's names and addresses?" <<

Bret, I know what you meant to write, but I just can’t resist this:

Its one thing to wire drivers backwards. It’s something completely different to install a driver backwards. The magnet structure goes INSIDE the cabinet. The cones/domes face the outside. Besides sounding better, it makes it easier to get the grill cover on. (LOL)

Sorry, when I read this paragraph, I got an image of an AR-11 with the driver magnets all sticking out of the front baffle. Dementia caused by some of the calls I took when doing tech support for Compaq. “Ma’am you need to reconnect the SCSI cable to your hard drives.” “Is that the thing that looks like a belt?”

Rich Laski

[Guest Bret]

>Its one thing to wire drivers backwards. It’s something completely different to install a driver backwards. The magnet structure goes INSIDE the cabinet. The cones/domes face the outside. Besides sounding better, it makes it easier to get the grill cover on. (LOL)<

LOL - Rich, that's the first belly-laugh anyone's gotten out of me in MONTHS. Thank you.

Talk about direct/reflecting loudspeakers!

I had to wipe the tears out of my eyes before I could reply.

Or did I enjoy that entirely too much and we can add "easily amused" to "easily confused?"

Bret

[Guest Bret]

>You are exactly correct. That’s why its best if I leave discussion and explanation of speaker/crossover design, phase response, and time and phase coherence in multi-driver speaker systems to experts in this field like Jim Thiel (Thiel loudspeakers) and Brian Cheney (VMPS). <

I wonder if I'm related to Jim Thiel? There aren't that many of us.

Do you recall the speakers called, DCM Time Windows? Wasn't their "thing" time coherence done at the crossover rather than trying to do it physically a la ESS (AMT 1a/b/c) and those pyramidal things Technics tried to pass-off as loudspeakers? (those were almost as sad as the plastic-boxed honeycomb things Technics made)

I recall they were a "big deal" but I couldn't find anyone who actually heard them that liked them. I can't recall ever auditioning a pair, although I find that hard to believe considering how much time friends of mine and I used to spend in audio stores.

Maybe they were highly forgettable?

We REALLY need to get together for AR's 50th. I'll have to find a speaker switcher and we'd need to agree on a reference amp/preamp/CD system. We could get Ken to suggest a combination that isn't broken.

And then. . . well, we'd have to fight about what to play.

Shoot, let's publicize the event and sell tickets (that's a joke).

Bret

[Guest Bret]

>I am still looking for one silver screened AR mid, the ones that are more commonly seen in the 10pi and 11. Let me know if anyone out there has an extra one they'd like to sell.<

If you find two I'll split the pair with you. I've got one black and one silver, also.

There was a guy in B.C. with original 10pi tweeters and midranges on eBay. The tweeters he wanted $70 for (a pair) and the midranges were $90 (a pair).

So I thought and walked around and slept on it and finally decided that this was just too good to pass-up. I picked-up the laptop, fired it up, and although I had shut-down properly Win2000 decided I needed to run scandisk. And it ran and ran and ran. . I put it down, went and did some things, came back, it was "verifying free space" and it ran, and ran, and ran.

When it finally booted completely I went immediately to these midranges and clicked on "Buy It Now." The reply screen said, "The bidding for this item has ended."

Missed it by that much.

Bret

[Guest audioslave]

>If you find two I'll split the pair with you. I've got one

>black and one silver, also.

>

Sounds like a plan to me. I'll be in touch if I find a pair of them.

Jeff

[r_laski]

>Do you recall the speakers called, DCM Time Windows? Wasn't

their "thing" time coherence done at the crossover rather than

trying to do it physically a la ESS ...

>

I recall they were a "big deal" but I couldn't find anyone who

actually heard them that liked them. I can't recall ever

auditioning a pair, although I find that hard to believe

considering how much time friends of mine and I used to spend

in audio stores.

>

>Maybe they were highly forgettable?

Bret,

I’ve saw and listened the DCM Time Windows when they first came out – 1974. DCM is still making loudspeakers and they have a web site. I thought they sounded pretty good, although a little too odd looking for my eyes. Sort of like plant stands with speakers in them. If you want to see what they look like, there’s a pair of DCM Time Window 3s on eBay right now: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewI...&category=14993

“Time coherence” was done through a combination of the physical shape of the “cabinets,” layout of the drivers, and a crossover that included spectral balance controls. Kind of like a combination of the (forgive me) Bose 901s and the AR LSTs in a columnar transmission line speaker. They had to compete with the traditional “box” speakers from Advent, AR, and Klipsch of that time and the early electrostatics from Magnepan. Once I read about, saw, and listened to AR LSTs about this same time, I never gave the Time Windows another thought.

Rich Laski