The mystery has been solved

[HarryM]

The mystery of the 6uf cap in the AR9 schematics that is. My new to me 9x's have the 6uf cap instead of the 8uf cap that the 9's have. I wonder if the change in the caps is why these are 9x's.

I am taking pictures as I go and will post them at a later date. These were modified by a speaker shop and I plan to bring them back to what they once were. Luckily they left the original xovers alone, they just added to them. They didn't even recap them when they did the modes.

Harry

[HarryM]

All done but the cabs. Modes removed, recapped and sounding great. Well worth the 12 hours of driving to get them. I will post pics later, I'm tired now and the dog wants food. She doesn't like the 9x's as much as I do. LOL

Harry.

[HarryM]

Here's the pics.The upper mid in this pic was a spare that I put in, the mids that were in them were non AR'sSome of the damage done by the speaker shopThey also had vented dust caps on the lower mids.

Wow the second pic is out of focus. I didn't realize the new camera wasn't on auto focus.LOL I'll see if I can find a better one.

Harry.

[ar_pro]

Harry, those are easily the worst, most hacked-up mods I've ever seen on an AR-9.

You were really lucky that the speaker shop didn't "improve" the original crossovers while they were at it!

[HarryM]

Here's some more. You can see the hole from the horn tweeter they had installed.It's alot easier to remove the woofers on the floor before putting the speaker on the work table.Here they are all finished and sounding great.

My first impressions are that these have a more detailed sound in the high end then the 90's and more umph in the bottom end on higher volumes.

[HarryM]

Yes, I was very happy to see they had not touched the xovers. You would think they would of at least recapped it before doing the modes though.

[frankmarsi]

Yes, I was very happy to see they had not touched the xovers. You would think they would of at least recapped it before doing the modes though.

Finally, someone who may be more bizarre in everyday living, face to face with his multitude of AR big speakers barely without having only room to fart, more than I do!

Your freak'in place is almost, and I insist, please, let me have this one; almost looks as bad as my place once did. This might be why I never got anything done, I was so immersed in my own life of collecting and feeling that insane pride of ownership, laced with greed for the way AR let us hear! The wanting to have things as they once were...................... At least God give it to my ears and eyes!

And Carl, you gotta be there too for this almost --- -----, that you proposed, not that there's anything wrong with that. You guys might ruff me up and steal my speakers? Screw dat!

I mean I may give the impression of being dumb and sounding stupid, but why would you think I have all the great speakers, components, parts and multitude of vinyl records that I do.

fm

P.S. With only 6 replies and 116 views, at 11:57 NYC time 9/3/13, watch this post go big and with the millions and millions of views it will now bring about.

fm

[HarryM]

Thanks for the reply Frank. It's a good thing I've given away about 10 pairs of speakers in the last couple of months. LOL.

My brother just left here with my 91's. I gave them to him on condition he doesn't sell them. They were my first AR's, they have to stay in the family.

It is starting to dawn on me that I can only listen to so many speakers at once and now with the 9x's I'm not in a hurry to listen to any of the rest. I did still reply to an ad last night for 12" AR woofers. You do have to have spares just in case.

Harry.

[HarryM]

I need some help with these 9x's.

I'm getting a kind of ringing sound from the upper mids when playing any kind of music in both speakers.

I can tone it down by putting the switch at -6.

I borrowed the mids from the 90's that never had this sound and it didn't fix it.

Can anybody give me an idea where to look for the problem?

Thanks, Harry.

[ar_pro]

@harry -

Try your AR-90s in the exact same setup that you have with the AR-9s, just to be sure that it's not an amplification or source problem.

If that doesn't prove to be the case, and since you've already substituted a pair of upper mids from your AR-90s that you know to be good, my hunch would be that it's either a crossover issue, and/or another modification that the speaker shop made that you haven't found yet.

Two other thoughts: is all of the original cabinet stuffing still present, and are you getting tight seals on all of the original driver gaskets as well as the cabinet holes that were cut by the previous owner?

[HarryM]

Thanks for the reply ar_pro.

The things I can tell you is the stuffing is all there and I did the test with the woofers for air leaks and that checks good.

I had the 91's running the other night and they sounded normal.

They are set up right where the 90's were.

I guess I'm going to have to open them up again.

Thanks,Harry.

[HarryM]

So after opening them up again and not finding anything wrong I had a real close listen to the front facing drivers and found the LMR's were having difficulties.

It seems when the PO had new surrounds installed, they used the wrong ones and the cones could do little more then vibrate.I switched them out for

a pair of woofers from my AR 25's that have the boston fillet surrounds. The improvement it quite noticeable but not right yet. The original mids will

get new surrounds and see if that gets everything balanced. The woofers also need to be done, they only have the 1/2" roll surrounds. As you

can tell I still have work to do but they will get back to what they once were.

Harry

[HarryM]

With the new surrounds on the LMR's the difference is huge. I'm glad I had a couple of surrounds left from my last order from Msound. These are

very close to sounding like the 90's now. New surrounds on the woofers should have them sounding better at higher volumes then the 90's.

Lesson's I've learn so far with these speakers is,

1 just because a driver doesn't sound right doesn't mean that it's the one with the problem.

2 make sure all drivers have the correct surrounds.

3 a 200001-1 is NOT a good substitute for a 9, 9x or 90 LMR.

4 I'm going to need another Crown XLS 1000. One is just not enough for the 9x's. LOL

Thanks, Harry.

[Mach3]

HarryM,

Sorry but the plot - at least as far as I am concerned - only thickens. Where did you get the information that the original AR-9 had an 8 uF cap in parallel with the MR dome? Your picture - which is an originally installed cap - and I know because of the old glue - is a 6 uF - same as my original, same as the "official schematic".

I have heard many people suggest that the cap in question should be an 8 uF - but nobody has been able to tell me why this cap should be an 8 uF. The ONLY information supporting this change has been one fellow who measured his "original, old" caps and found that particular cap to be - at the time of measurement (almost 30 years later) to measure at 8 uf (old electrolytic caps tend to show MORE capacitance with age - which may explain the rising value).

I am ready to do some other mods to my Nines - and while in there would like to go ahead and change the cap - IFF (if and only if) somebody can tell me why the cap should be an 8uF.

can anybody explain the mystery of that particular capacitor.

[Robert_S]

My understanding is that the 'official' schematic (drawn by Barry Dorobkowski?) which is in the library, and shows a 6µF (upper mid-range) capacitor – is incorrect (and should at best not be considered as official, or indeed sanctioned as such by senior members of this site).

I would hazard a guess that the ambiguity stems from a misreading by Barry of the AR-9 Crossover Assembly Blueprint, where the stated value of the capacitor in question has been rendered partially illegible, possibly due to close proximity to a fold in the paper, and may at first glance be mistaken for a 6. Having paid close attention to the handwriting style of Rich, on this and several other of his technical blueprints, it is to my mind – definitely an 8 – not a 6, in this particular iteration.

This is not to imply that there were no variants throughout the production run.

Some previous mention of the schematic:

• AR-9 Schematic now online! Started by administrator, Jan 07 2002

• AR 9 schematic has error Started by Bret, Jul 11 2005

• AR9 restoration Started by Mafia1976, Mar 31 2013

AR-9 Crossover Assembly Blueprint:

8µF Detail:

Full Scan (low resolution jpeg):

Full Scan (high resolution tiff):

AR-9_Crossover_Assembly_(Scan15sm).tiff

Robert_S

[HarryM]

Thanks for explaining that Robert_S, you did a much better job at it than I could of.

Mach3 I also may change the 6 for an 8 just to see what happens. If I like it I'll keep it. If the cap difference isn't why mine are 9x's, I wonder what the

difference would be. Everything else seems to be the same as 9's are far as I can tell.

Harry

[Robert_S]

. . . a 6 uF - same as my original, same as the "official schematic"

In the interest of bringing further clarity to the discussion, you say above that the value of your original capacitor was 6µF, but previously you have mentioned finding an 8µF, and replacing it with a 6µF?

As for the 6 uF versus 8 uF in the cap in parallel with the UMR (large dome) this has been attested to in a number of articles - and when I removed my "original" it was an 8uF - but since the schematic called for a 6 uF I went with the published value - and to my ears brought some brightness to the region (around 7 KHz I have a 3 dB bump - which means that my upper crossover limit is not falling as steeply as it should - which the larger cap value will/should ameliorate).

Generally, I would replace like for like, unless other changes have been made, such as accommodating for a replacement driver, where it was known to be an earlier/later variant that called for such changes.

Robert_S

[Robert_S]

If the cap difference isn't why mine are 9x's, I wonder what the difference would be. Everything else seems to be the same as 9's are far as I can tell.

Still staying in guesswork territory, it may simply be vanity (or humour) on the part of whoever modified your AR-9 speakers. It's difficult to see detail in the pictures that you have posted, but if the only indication of an 'x' designation is in the badges, these were perhaps custom made by/for the modder(s) in question.

If this is the case, at least they vaguely referenced AR's previously implemented naming convention, as outlined below by Steve F:

The subject of AR’s early product naming scheme has always been a focal point of confusion and fascination for audio historians.

[. . .]

So, in a nutshell, here it is:

- An ‘x’ suffix designated a change concerning a cone mid or high frequency driver.

- An ‘a’ suffix designated a change concerning a dome mid or high frequency driver.

The AR-3 went to the AR-3a—changes in the dome drivers, from 2-inch and 1 3/8-inch to 1 1/2-inch and 3/4-inch.

The AR-2 went to the 2a—the 1 3/8-inch dome tweeter was added.

The AR-2 became the 2x—the dual 5-inch cones were replaced with the single 3 1/2-inch cone

The AR-4 became the 4x—the 3 1/2-inch cone was replaced with the 2 1/2-inch cone.

The AR-1 became the 1x—the 8-inch cone was replaced with the 2 1/2-inch cone.

The AR-2a became the 2ax—the dual 5-inch cones were replaced with the single 3 1/2-inch cone

Robert_S

[ar_pro]

I've never come across any reference to an AR-9x.

As Robert has noted, it's quite possible that whoever did the modifications also assigned it an "X", and made up a nameplate for good measure.

Doesn't it say "AR-9" on the vinyl sticker below the 8" midrange?

[HarryM]

You guys are good, the sticker says AR9. All the looking at these and I never noticed. So a mystery has been solved just not the one I thought. LOL.

Knowing that I do not have the original UMR's, I think when I do the woofer surrounds I'm going to switch the 6uf for an 8uf cap. That may clear up that

little bit of harshness in the upper mid that I've been hearing.

Thanks guys, you've been a great help.

Harry

[RoyC]

You guys are good, the sticker says AR9. All the looking at these and I never noticed. So a mystery has been solved just not the one I thought. LOL.

Knowing that I do not have the original UMR's, I think when I do the woofer surrounds I'm going to switch the 6uf for an 8uf cap. That may clear up that

little bit of harshness in the upper mid that I've been hearing.

Thanks guys, you've been a great help.

Harry

Hi Harry,

Have you identified the other 6uf cap in the tweeter circuit? Just making sure we are discussing the correct 6uf cap.

Roy

[HarryM]

I was going to check that Roy. It seemed to me that the 6uf cap was in the tweeter circuit. Is that standard for the 9's. The list of caps that's been posted a few times doesn't have a 6uf cap on it. I'm only a little more confused then I was. LOL

Harry.

[RoyC]

I was going to check that Roy. It seemed to me that the 6uf cap was in the tweeter circuit. Is that standard for the 9's. The list of caps that's been posted a few times doesn't have a 6uf cap on it. I'm only a little more confused then I was. LOL

Harry.

The schematic shows a 4uf and 6uf cap in line with the AR-9 tweeter.

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=3797&p=70218

The controversial cap on the schematic is an 8uf cap (which some people believe is a 6uf cap) in parallel with the upper midrange. If you actually do have a 6uf cap instead of the 8uf cap in this location, you will have two 6uf caps in each of your crossovers. You may want to take a closer look before replacing anything.

Roy

[HarryM]

Ok Thanks Roy