AR3a improved tweeter diagnosis

[dls123]

Hi

I just finished re-capping my AR3a improved speakers. All drivers seem to work, but as before the re-capping, output is slightly louder from one speaker. You have to set the balance to about 1 or 2 o'clock to center a female vocal. I have done some experimenting and it appears that one tweeter has less output. All resistors in the crossover are pretty much on spec and it does the same with the switch in the A position which has no resistor to tweeter. The 6 uF caps are new Solens and read almost exactly the same on my meter. The tweeter is AR part no. 200013-1. Is it common for a tweeter to slowly loose output rather than fail? I suppose I can pull it and check the connection or change the wire on that side, but all the wires looked good in the crossover end of things. Resistance across strong tweeter is 3.1 ohms, and 2.5 ohms across weaker one. Is tweeter going? I guess so. If you swap tweeters the problem moves to the other speaker...... Any good sources of 200013-1 tweeters....?

cheers,

Don

[Guest rbrumett]

Hi

I just finished re-capping my AR3a improved speakers. All drivers seem to work, but as before the re-capping, output is slightly louder from one speaker. You have to set the balance to about 1 or 2 o'clock to center a female vocal. I have done some experimenting and it appears that one tweeter has less output. All resistors in the crossover are pretty much on spec and it does the same with the switch in the A position which has no resistor to tweeter. The 6 uF caps are new Solens and read almost exactly the same on my meter. The tweeter is AR part no. 200013-1. Is it common for a tweeter to slowly loose output rather than fail? I suppose I can pull it and check the connection or change the wire on that side, but all the wires looked good in the crossover end of things. Resistance across strong tweeter is 3.1 ohms, and 2.5 ohms across weaker one. Is tweeter going? I guess so. If you swap tweeters the problem moves to the other speaker...... Any good sources of 200013-1 tweeters....?

cheers,

Don

[

We have a had a few threads about this lately. There is a low(lower cost) solution with a pair of Carl's tweeter rings, a pair of special AR tweeters and a pair of coils(available at "Parts Express")-time to go to work-good luck

Thanks,

Rick Brumett

[dls123]

We have a had a few threads about this lately. There is a low(lower cost) solution with a pair of Carl's tweeter rings, a pair of special AR tweeters and a pair of coils(available at "Parts Express")-time to go to work-good luck

Thanks,

Rick Brumett

Hi,

Thanks, I was reading a thread on that last night. Seems like a sub-optimal solution given the wonderful dispersion of the original tweeters. Guess I will join the ranks trolling ebay for a tweeter and if no luck will go the Carl's or AB-tech route. Do you know if you can sub an older AR tweeter from the 3a series in there? Or do you need a pair of older ones? I guess I will keep searching the old threads for people's experiences.

cheers,

Don

[Robert_S]

Do you know if you can sub an older AR tweeter from the 3a series in there? Or do you need a pair of older ones? I guess I will keep searching the old threads for people's experiences.

cheers,

Don

Hello Don,

The AR-3a Improved used the same tweeter as the AR-3a, so you should be fine with any of the front- or back-wired design variations (see Fig. A.19, A.20 and A.23 in the 'Restoring the AR-3a' guide document). The back-wired flavour would, in your case (obviously!), be easier to fit.

For more information regarding the AR-3a Improved, see the following topic/post:

http://www.classicspeakerpages.net/IP.Boar...ost&p=73706

Good luck with your internet auction search, it shouldn't be too hard to find a suitable unit (or two).

Robert_S

[genek]

Thanks, I was reading a thread on that last night. Seems like a sub-optimal solution given the wonderful dispersion of the original tweeters. Guess I will join the ranks trolling ebay for a tweeter and if no luck will go the Carl's or AB-tech route. Do you know if you can sub an older AR tweeter from the 3a series in there? Or do you need a pair of older ones? I guess I will keep searching the old threads for people's experiences.

Premature conclusion, as I have yet to compare the tweeters with grilles on. Similar design tweeters in my AR-2ax's lose some dispersion due to grille frames and fabric, and I presume the 3a's will as well.

There's a front-mount 3a tweeter coming up in four days. I'm planning on going after it myself and will probably drive you into the $100+ range for it before I give up. Fair warning. I also have a second tweeter coming from Carl so I'll have a matched pair.

[dls123]

Premature conclusion, as I have yet to compare the tweeters with grilles on. Similar design tweeters in my AR-2ax's lose some dispersion due to grille frames and fabric, and I presume the 3a's will as well.

There's a front-mount 3a tweeter coming up in four days. I'm planning on going after it myself and will probably drive you into the $100+ range for it before I give up. Fair warning. I also have a second tweeter coming from Carl so I'll have a matched pair.

Hi

Thanks for the auction warning. If it hits $100 you can have it! I will find one or a pair eventually. I will keep reading about your dispersion experiments..

thanks.

[genek]

Thanks for the auction warning. If it hits $100 you can have it! I will find one or a pair eventually. I will keep reading about your dispersion experiments..

Another alternative you might want to consider is 3/4" domes from the AR-10pi/11. These are ferrofluid cooled drivers like ones Carl has and the current ABTechservices replacements, and like them would need an inductor across the terminals, but their domes more closely resemble the 3a's.

The AR-11 used a .10mH coil and a 10MFD cap instead of the 3a's 6MFD cap and no coil, and Ken Kantor has determined that the AB service replacement on a 3a with its original cap would require a .07mH coil. There are currently two pairs of those and a single unit up for bid, and these do seem to appear more often than 3a tweeters. I think you'd definitely want to swap out both tweeters if you went this route.