ar-3a wiring: what's under the tape?

[Guest packrat]

I have a pair of AR-3a speakers and looking under the tape they are wired differently. One of the wires crosses over to meet the tabs, on the other they don't. Which one is correct?

I've looked through every picture I can find on the net, and they all have the tape covering them up so I can't tell which way it is supposed to be! The mids also look slightly different - one has a raised AR logo and the other doesn't.

They sounded out of phase when I first got them and checking inside I found the woofers to be wired out of phase with each other. The crossovers seem to be wired the same. After getting the woofers straight, they still sounded out of phase on a mono test, and so I discovered this with the mids.

To try them out I rewired them the same way (uncrossed) and have been able to listen to them - they sound great! The level pots do need cleaning, but I don't want to open them up too often so I'm leaving them as-is. But, I just don't know if I've got the mids wired in correctly or not.

[johnieo]

Greetings packrat:

I believe the correct mid and tweet wiring is shown in the attached gif file. The two fine driver wires connected to the center terminal go to the #1 terminal on speaker backside via the common yellow wire.

This out of phase wiring was AR's designer. The + woofer terminal (or red dot) should go to the #2 terminal on speaker backside.

http://www.classicspeakerpages.net/dc/user_files/1141.gif

cheers,

[dynaco_dan]

>I have a pair of AR-3a speakers and looking under the tape

>they are wired differently. One of the wires crosses over to

>meet the tabs, on the other they don't. Which one is

>correct?

>

>I've looked through every picture I can find on the net, and

>they all have the tape covering them up so I can't tell which

>way it is supposed to be! The mids also look slightly

>different - one has a raised AR logo and the other doesn't.

>

>

>They sounded out of phase when I first got them and checking

>inside I found the woofers to be wired out of phase with each

>other. The crossovers seem to be wired the same. After

>getting the woofers straight, they still sounded out of phase

>on a mono test, and so I discovered this with the mids.

>

>To try them out I rewired them the same way (uncrossed) and

>have been able to listen to them - they sound great! The

>level pots do need cleaning, but I don't want to open them up

>too often so I'm leaving them as-is. But, I just don't know

>if I've got the mids wired in correctly or not.

Hi there;

You have an older AR-3A cabinet with the front wired tweeters which is ok, actually great.

The mids are both later and different versions, rear wiring connections, and one with the AR logo.

Possibly they are each replacement drivers.

Tom or Steve perhaps, can provide you with more information later.

John is also very good with historical data.

[johnieo]

Packrat:

I made an assumption in looking at your speakers that they were the old style, front wired units, because the cabinets are old-style and contained the terminal block designed for use with front wired drivers.

The tweeter appears to be wired incorrectly in both your speakers.

If the midranges were first or second generation (orange- or white-eyeball) drivers, then they would be wired correctly. However, the one illustrated in your Attachment #1 is a third-generation, black-eyeball mid; I am not sure how that should be wired to the early terminal block. My gut feeling says it should be wired opposite to that shown in the gif file, because the phase reversal in that later unit was done internally.

Tom Tyson, could you comment? I believe you mentioned that the later midrange had its phase reversal done internally, so the crossover schematic would show it to be wired in-phase (see for example, the X-O of the AR-11).

If that is true, then the crossed wires on the black-eyeball mid are correct, and the uncrossed wires on the white-eyeball mid are also correct; only the tweets are incorrect!

Forward-backward; cross-eyed: It would appear that St. Paddie's day is coming not quite soon enough!

[RoyC]

The dot on the mid in John's diagram is + side of that driver in both the back-wired and front-wired versions. The + side of the tweeter remains the same in the back-wired version as well.

All drivers are wired + to + (cabinet inputs "T" and "2") and - to - (cabinet input "1"). I have not found any 3a's from 1967 to 1975 to have the tweeters' and mids' polarity reversed relative to the woofer, although it has been rumored to be the case at some point in the 3a run.

The 3a drivers are wired in phase as it relates to polarity wiring in all those I have worked on.

It can be deceiving as all the mid and tweeter series crossover components are wired in series on the negative side of the circuit originating at cabinet input "1"(- input terminal).

In the later back-wired 3a's there are two yellow wires instead of one common wire originating from the pots. They each connect to the + sides of the tweeter and midrange. See attached.

Roy

[RoyC]

Packrat,

Your mids are the later back-wired version adapted for front-wiring. No matter, you have it right now. The mid wires were never supposed to be crossed like the tweeter wires are. That was probably an installation mistake made by the person who also wired your woofers out of phase.

The left sides of both the tweeter and midrange, as you face them, are always the + sides.

Roy

[johnieo]

>Packrat,

>

>Your mids are the later back-wired version adapted for

>front-wiring. No matter, you have it right now. The mid wires

>were never supposed to be crossed like the tweeter wires are.

Roy: I think we each misssed one point. I said the yellow went to terminal 1, not so; it indeed goes to the + terminal (2) as you note. Thus the tweet wires need to be crossed--problem it is not possible to tell if they are currently, unless the tape is lifted--hopefully they are crossed.

look carefully at Packrat's two attachments: I think you missed a detail.

Attachment #1: The mid wires are crossed.

Attachment #2: The mid wires are not crossed.

cheers, I think...

[Guest packrat]

Thanks for all the advice, and the tip that '+' is the left terminal on the drivers. I checked the one mid with the AR logo and it has a '+' label on the left side wire, and this goes to the middle tab on the terminal block. I'm going to leave them with no crossed wires on either mid or tweeter, as it seems that is the correct way.

The SNs on these are in the 48xxx range, so I suspect that none of the drivers are original. The woofers have regular paper cones, foam surrounds, and no wire mesh on the basket. They look to be in fine condition, so I think these were 'rebuilt' within the last ten years, but by someone with not so great wiring skills.

Next step is to re-cap the crossover and rebuilt the rheostats (or replace with L-pads).

thanks again!

edit:

I just re-read everything....now I'm wondering if the tweeter wires should be crossed! I thought it was the AR-3 that had these crossed?

[mluong303]

Hi Tom, I don't know how far off am I on these details? So please feel free to correct me or add in details since I can only remember so much!

I would say both wiring are correct. One is the original AR-3a wiring and the other one is new version such as the AR-3a Improved. Base on the picture it might have happened when one of the AR-3a was sent out for repaired with the front wired AR-10Pi midrange (silver grill) installed. The technician had wired it base on the new version.

So as long as you connect them to either way but identical for both, you should be OK to go.

Minh Luong

http://www.classicspeakerpages.net/dc/user_files/1146.jpg

http://www.classicspeakerpages.net/dc/user_files/1147.jpg

[RoyC]

I agree with Minh. The most important thing is to have both speakers wired the same way.

Minh's photo of the original 3a is consistent with all that I have seen through 1975.

It would appear that the 3a Improved reversed the midrange polarity relative to the tweeter and woofer. Of course that accompanied crossover changes as well.

I have experimented with reversing the polarity of the original 3a mid and tweeter and found the effects to be subtle. A case could be made for keeping the original 3a tweeter reversed, as I believe Packrat has his wired. It smooths out the upper midrange somewhat at the expense of some detail.

Roy

[Guest packrat]

>I agree with Minh. The most important thing is to have both

>speakers wired the same way.

>

>Minh's photo of the original 3a is consistent with all that I

>have seen through 1975.

>

>It would appear that the 3a Improved reversed the midrange

>polarity relative to the tweeter and woofer. Of course that

>accompanied crossover changes as well.

>

>I have experimented with reversing the polarity of the

>original 3a mid and tweeter and found the effects to be

>subtle. A case could be made for keeping the original 3a

>tweeter reversed, as I believe Packrat has his wired. It

>smooths out the upper midrange somewhat at the expense of some

>detail.

>

>Roy

>

Thanks for the clarification on all this - especially confirming that the tweeter wires are to be crossed over on all AR-3a's.

I'm going to have another look at the tweeters - if the wires are crossed over under the little bit of tape that is there I'll leave them alone. If they are not crossed, I'll cross them over.

Although the phase change may not be audible, a response dip might occur if the tweeter is not wired correctly relative to the mid. I also want them as they were from the factory, at least to start with.

[RoyC]

>Although the phase change may not be audible, a response dip

>might occur if the tweeter is not wired correctly relative to

>the mid. I also want them as they were from the factory

Agreed...

Be extremely careful when lifting the tape! The hair-like voice coil wire is soldered to the tinsel lead and is VERY easy to break. After taking another look at your photo, your tweeter wires could very well be crossed in that delicate area near the dome.

Good Luck

Roy