AR-6 crossover

[Guest rvisini]

Hi folks,

I have just finished disassembling of my AR-6 models.Woofer foam is good un-expectedly;

Crossover I suppose need some new capacitor as electrolitic caps do not last long;

Are there any special hinds from your experience,which way to do it or just make it step by step

P.S.

The big capacitor (Blue Sprague) have 10uF value for cutting the tw,

anyone knows the other capacitor value, the one in parallel to the Wf.

What value the Indutance?

thanks.

ric.

[dynaco_dan]

Why would you take the crossover board out of the cabinet?

[Rlowe]

>Hi folks,

>I have just finished disassembling of my AR-6 models.Woofer

>foam is good un-expectedly;

>Crossover I suppose need some new capacitor as electrolitic

>caps do not last long;

>Are there any special hinds from your experience,which way to

>do it or just make it step by step

>

>P.S.

>The big capacitor (Blue Sprague) have 10uF value for cutting

>the tw,

>anyone knows the other capacitor value, the one in parallel to

>the Wf.

>What value the Indutance?

>

>thanks.

>ric.

From my AR6 (European version) I read the Resistor//Capacitor combination to be 10//24uF.

INDUSTRIAL Royalite long life 24 uF 50V NP.

The inductor is #4 (0.88mH).

I'm currently using the "Blue" capacitor and the sound is good. I will experiment with a polyPro (NorthCreek)as the crossover is around 2,000 Hz.

I used a 10 Ohm North resistor from North Creek and a cheap 24uF cap until I can replace it. My resistors were damaged due to overheating, I had scorch marks on the fill!

I expect to change the 24uF to polyPro (NorthCreek) when I can.

The pdf shows two crossover circuits which I believe are correctly transcribed from pictures, but no guarantees, ok.

Hope this helps.

[dynaco_dan]

Was there something wrong with the photos?

[Rlowe]

Here's another upload of the PDFs and pictures.

1210.pdf

[Guest rvisini]

Thanks a lot for your info/material very useful;

By the way do you have also x-over schematic for AR-7 and AR-12.

Regards.

Ric.

[Rlowe]

Unfortunately, no.

I wish I had more AR speakers to document and listen too.

[dynaco_dan]

>Why would you take the crossover board out of the cabinet?

[Rlowe]

>Was there something wrong with the photos?

No, same pictures as below.

The link may have been "lost" when the query was shifted from the "News" to "AR" Forum.

[RoyC]

Here are some photos of the AR-6 crossover of the early 70's (serial# 25,500).

The resistor wire measures just shy of 1 ohm.

Roy

http://www.classicspeakerpages.net/dc/user_files/1218.jpg

http://www.classicspeakerpages.net/dc/user_files/1219.jpg

[KlausDK]

Just to complete the story, here is a couple of pictures of a late European AR-6 cross-over, only a two position switch with a resistor and a cap (6 myF) no coils. Only two terminals.

Note that the cap is inserted before the resistor, which means that the Cap is looking at different impedans with the switch in normal and in the increase position.

BRgds Klaus

[RoyC]

>Just to complete the story, here is a couple of pictures of a

>late European AR-6 cross-over, only a two position switch with

>a resistor and a cap (6 myF) no coils. Only two terminals.

Thanks Klaus...

NO coils at all!? Wow, that is interesting! It seems that the European AR-6 is quite different from the US version, AND different than the Australian version Rlowe reported on. I also noticed some of the AR multi-colored polyester stuffing fibers in your cabinet. The US versions I have seen used fiberglass stuffing. It would seem that the drivers would also have to be different to work with such drastically different crossovers.

In two of three US AR-6's I recently worked on, each had coils marked "#4" as shown in the schematics earlier in this thread. They were installed, however, with the # "4" facing down, and actually measured 1.20mh+/- (instead of .88mh). This means they were actually improperly labeled #5 AR coils. I wonder if this was known, and the coils installed upside down to hide the "4"? These were all original with absolutely no signs of previous tampering.

There seems to be a number of varieties of AR-6 floating around out there.

Roy

[KlausDK]

Hi Roy

You are right, they had multicoloured polyester stuffing and the thin edges on the front, like the late European versions of the classics (AR-5, AR-6 and the AR-3a Improved). The woofers have the same part-number as the previous AR-6 versions, these are made in week 47 of 1975.

The Royal Opera AR-6's, also made in Europe, has the early design X-over with two coils, like on the schematic posted by RLowe above. I just checked a cabinet on the inside, and the coils are numbered #4 and #12 and the stuffing is fiberglas.

BRgds Klaus

[RoyC]

>You are right, they had multicoloured polyester stuffing and

>the thin edges on the front, like the late European versions

>of the classics (AR-5, AR-6 and the AR-3a Improved). The

>woofers have the same part-number as the previous AR-6

>versions, these are made in week 47 of 1975.

Your photo shows the later ceramic magnet woofer. I'm guessing that AR changed the original crossover for that woofer. Changes to the AR-2ax and 3a coincided with the introduction of ceramic magnet woofers as well, although the elimination of both inductor coils in the AR-6 design seems a bit drastic. I bet AR saved a few bucks with that move:-).

Do the Royal Opera AR-6 woofers have alnico magnets? I've attached photos of a 1972 US AR-6, and it's alnico woofer. It would seem that the only difference between the Royal Opera AR-6 and the US version is the cabinet style. Other than cabinet style, maybe the AR-6 differences we are seeing are "earlier vs later", and not "US vs European"?

My #4/#5 coils were probably a parts substitution issue or error that could easily have gone unnoticed for 35 years.

Roy

[KlausDK]

The Royal Opera House AR-6's probably had alnico magnet woofers originally, but these were replaced in 1985 with a ceramic magnet woofer. Instead of refoaming the woofers they replaced them. You can only guess what happened to the 20+ alnico woofers they took out!!!

The tweeter's time stamp is January 1972. Here is a picture I posted in the Royal Opera House thread, that shows cabinet style and drivers of those speakers. The drivers has gaskets not putty but the front grill frame was glued on not velcro mounted

Brgds Klaus

[RoyC]

The 1972 Royal Opera version probably originally had alnico woofers, which would make them identical to my 1972 US version (including the thicker-trimmed cabinet style, as seen in your photo). All 5 of the 1972 US versions I have seen used white foam gaskets...no putty here either.

It is obvious that the AR-6 was changed by 1975.

It would be interesting to hear your impressions of the 1975 European version vs the earlier Royal Opera version, since you have both versions equipped with ceramic magnet woofers. If the crossover was later changed for that type of woofer, the 1975 cabinets with the later crossover, should sound "better". Given the radically different crossovers, there is no doubt they will sound different.

I would also be interested in any measurements you take of the many #4 coils you have :-).

Thanks again, Klaus!

Roy

[KlausDK]

If I compare the two versions of AR-6 I have, that is

1) a late version with single cap only crossover with the correct ceramic magnet woofer

and

2) an early version with two coils and a rheostat design crossover, but with a ceramic magnet woofer instead of the alnico.

Both speakers have had the Cap's replaced (polypropylen of same brand). There is a significant difference between the speakers, and the single cap version sounds by far the best. On the older type AR-6 (with incorrect woofer), lacks the dynamic bass response that the coil free speaker can produce. Midrange/high Range differences are less pronounced, with the rheostat correct adjusted.

The AR-6 with the newest version X-over is a marvellous speaker that really surprices most audiophiles. The quality of the bass coming out of that speaker is unbelievable. The Royal Opera House speakers I have restored until now, I have changed crossover to the new style single cap only, since the woofer is the new type.

BRgds Klaus

[RoyC]

It all makes sense...

AR seems to have maintained (or possibly improved) the integrity of the AR-6 with the ceramic magnet woofer, and was able to simplify the crossover at the same time....and there are NO troublesome pots to deal with. I wonder where the "single coil/woofer capacitor" version RLowe discussed fits into the scheme of things?

It is also a perfect example of how using different era drivers (or, especially, new "universal replacement" drivers) in our vintage speaker systems will likely result in disappointment. In fact, it is improbable to get anywhere near originally intended performance when using such replacements without crossover and/or stuffing changes.

We now know where to go for used AR #4 and #12 coils :-).

Great info, Klaus. I believe you are the forum's undisputed king of AR-6 land!

Roy

PS Do you have a suggestion for 8" replacement foam surrounds?

The 10" JBL surround you recommended for 10" AR woofers is the best I have seen.

[dynaco_dan]

Hi there;

>Great info, Klaus. I believe you are the forum's undisputed

>king of AR-6 land!

Roy

I think that this qualifies for the Guiness Book of World Records. LOL

[KlausDK]

>AR seems to have maintained (or possibly improved) the

>integrity of the AR-6 with the ceramic magnet woofer, and was

>able to simplify the crossover at the same time....and there

>are NO troublesome pots to deal with. I wonder where the

>"single coil/woofer capacitor" version RLowe

>discussed fits into the scheme of things?

The three position switch version that Richard reported on, also mentioned in another thred here on CSP, seems to be an interim version between the rheostat and the two switch version, also judged by the serial numbers (all European made):

AR-6 with Rheostat: SN 18644

AR-6 with 3 pos. switch: SN 44770

AR-6 with 2 pos. switch: SN 173924

From the pictures I have gotten (from RLowe and found on Audiokarma)

http://audiokarma.org/forums/showthread.php?t=102634

it looks like the 2 and 3 position switch versions both had square ceramic magnet woofers, but they differ in chassis construction. The 3 switch woofer has a masonite ring both under the foam surround as well as under the spider, where they are glued to the cgassis. This is not the case with the late woofer, also by AR called the 8" universal woofer (see the pricelist from 1979 in the library).

>It is also a perfect example of how using different era

>drivers (or, especially, new "universal replacement"

>drivers) in our vintage speaker systems will likely result in

>disappointment. In fact, it is improbable to get anywhere near

>originally intended performance when using such replacements

>without crossover and/or stuffing changes.

I agree, but as far as my knowledge goes, the absence of a coil between the amplifier and the woofer would lead to better control of woofer movements, which at least partly could explain the better performance of the speaker with the simplified cross-over. The adjustment of the X-over frequency, that happened to the AR-6, could have been made to adjust to the natural roll-off frequency of the AR-6 woofer, thus the only component needed was the 6 myF capacitor for the tweeter (instead of the 10 myF used earlier).

This could indicate, that if you have an "old" AR-6 with newer replacement woofers, the speaker could benefit from an upgrade of the cross-over to the latest single cap version. I think it would be worth a try. According to other posts here on CSP, the tweeter remained the same.

>We now know where to go for used AR #4 and #12 coils :-).

I leave all the original components (except the rheostat) in the speaker, just for the history, but if someone is in desperate need, I can take out a pair.

>Great info, Klaus. I believe you are the forum's undisputed

>king of AR-6 land!

Thanks

>PS Do you have a suggestion for 8" replacement foam

>surrounds?

For the universal type AR-6 woofers (ceramic magnet), I use the standard 8" from Speaker Works Northwest. Replacing the foam surround on the 8" is a little tricky, since the cone is just a little smaller than than the standard, as also noted by others here on CSP, so you have to be very careful to have the surround properly centered when gluing it to the cone.

BRgds Klaus

Here are some pictures of the 3 position switch speaker from audiokarma:

[Carlspeak]

Attached are some photos of an original and upgraded crossover. The particular speakers I worked on for a customer had the 3 position switch, 3 ohm resistors and 10 uF cap and one #4 coil attached to a ceramic magnet woofer #200001-1.

Also included on pg. 2 of the .pdf document are response curves showing the relative changes in the tweeter's response to the 3 position switch. Response changes about plus and minus 2-3 dB. Crossover point appears to be in the 1200-1400 hz range.

Vintage is 1970's. Ser. #041326. This speaker had 425 grams of FG stuffing. Cabinet vol. calculated at 0.68 cu. ft. yielding a rather high stuffing density of about 1.4 lbs/cu. ft.

This .pdf document is offered to add further information to the AR6 discussion.

It's all about the music

Carl

Carl's Custom Loudspeakers

[JLM2230]

Information Please

The AR Model History Spreadsheet refers to the AR-6 and AR-7 Tweeter as DOME/CONE. I have AR literature from 11/73 that refers to the tweeter as CONE. The speaker was produced until 1976, did it perhaps evolve to a different DOME tweeter. I am attaching a copy of the .jpg that was in the Post to which I posted this reply. Is this tweeter so unique that it was refered to as a DOME/CONE.

Any information would be aprecciated.

Good Listening

Jeff

http://www.classicspeakerpages.net/dc/user_files/2621.jpg

[Rich W]

Jeff,

Whatever the nomenclature was, this is basically the same tweeter used in the AR-6, AR-7 and the later "Truth in Listening" series AR-17 and AR-18. The only variation that I'm aware of is that the 17/18 versions were ferro-fluid cooled and had slightly larger magnets. At no point did it ever evolve into something other than what your photo shows for these model numbers.

As far as I know, the cone/dome naming derives from the fact that the central "nipple" of this tweeter has dome radiating characteristics. However, from a construction standpoint, it is built like a cone(i.e. has radiating area outside the central voice coil).

It is one of the finest high-frequency drivers ever designed for a two-way system.

Best Regards,

Rich W

[JLM2230]

Thanks for your response. The sheet uses the tweeter type PRESSURE to describe the 17 & 18 tweeters. I take your response to be in favor of considering the DOME/CONE as an accurate description of an unusual design.

Thank Again for your input.

Good Listening

Jeff

[Rich W]

Yes, I rememember . . . yet another terminology for this tweeter, "Pressure".

Does anyone know what is meant by this term? Does it describe how the tweeter disperses sound?

A tweeter by any other name would sound just as sweet.

Rich W