Sacriledge. AR93Q

[Jab]

All good advice and suggestions.    Aadams suggestion of the https://www.humanspeakers.com/e/parts/001.htm  woofers seems the path of least hassle.   Though maybe at some point I'll get motivated to pack these up and send them off for re-foaming.  I think I just got too used to enjoying my leisure to do it myself.

I'll mull this all over, then post a pic or sound file once these are operational again.

Thanks All.

[Jab]

OK, y'all convinced me.   Surround kits are on the way from Simply Speakers.   Nice folks.  Super helpful.   But....

I forgot to order dust caps, so this aint over yet!  Could someone please post a link to the re-building video?   It's been years since I did this on a set of infinities, and damn if I can remember what was involved in getting the dust cap off! 

Thanks in Advance.

[Stimpy]

38 minutes ago, Jab said:

OK, y'all convinced me.   Surround kits are on the way from Simply Speakers.   Nice folks.  Super helpful.   But....

I forgot to order dust caps, so this aint over yet!  Could someone please post a link to the re-building video?   It's been years since I did this on a set of infinities, and damn if I can remember what was involved in getting the dust cap off! 

Thanks in Advance.

 

I've followed the techniques in this video, and didn't have to remove the center dust cap.  Actually, with my M&K sub refoam, shimming the voice coil, still left a rub.  Following the advise in the Simply Speakers video worked even better, since I could adjust the centering by feel.

Simply Speakers Refoaming Technique

[Jab]

Thanks Stimpy.     Forgot all about Ren and Stimpy.  Loved them.

[Aadams]

On 4/16/2023 at 12:32 PM, AR55 said:

The specs for the AR93’s drivers (8” woofer – 200035, 8” midrange – 200036 & 1¼” cone tweeter – 200034/200038) are attached.  Also attached is some research on AR 8” woofers/midranges & AR 1¼” tweeters.

AR55 those PDFs you posted are library worthy.  I recommend you post them in the library section.  Not many people can get into the drawings as you do.

[giovanni56]

On 4/19/2023 at 6:50 PM, Jab said:

OK, mi avete convinto. I kit surround sono in arrivo da Simply Speakers. Gente simpatica. Super utile. Mamma....

Ho dimenticato di ordinare i cappucci antipolvere, quindi non è ancora finita! Qualcuno potrebbe per favore postare un link al video della ricostruzione? Sono passati anni da quando l'ho fatto su un set di infiniti, e dannazione se riesco a ricordare cosa è stato coinvolto nel togliere il cappuccio antipolvere! 

Grazie in anticipo.

I would not change the dust covers, especially the creamy white oneswhich, if I am not mistaken, have a calibrated weight to achieve the desired resonance frequency.

[giovanni56]

On 19/4/2023 at 07:11, Jab said:

Tutti buoni consigli e suggerimenti. Il suggerimento di Aadams dei woofer https://www.humanspeakers.com/e/parts/001.htm   sembra il percorso meno problematico. Anche se forse a un certo punto sarò motivato a impacchettarli e inviarli per la schiumatura. Penso di essermi abituato troppo a godermi il mio tempo libero per farlo da solo.

Rifletterò su tutto questo, quindi pubblicherò una foto o un file audio una volta che saranno nuovamente operativi.

Ringrazia tutti.

The drivers as has already been said are all original Ar, changing them with others, Dayton or any other, makes no sense. The 8" foams can also be found in Italy.

[nefertem]

On 4/16/2023 at 2:29 PM, genek said:

If what you want is to skip the work and potential screwing up of drivers if you do it wrong, I'd just order some of the "AR replacement" drivers being offered by Simply Speakers. A halfway decent 8" woofer from Parts Express is only going to be $20 or so cheaper, and while the SS replacements won't be exactly "right," they'll likely be closer than anything you'll find after spending hours comparing no-name drivers to the old AR specs.

That is the same thing I did with my original AR93 after my cat sprayed on the woofers and destroyed the woofer I actually bought scanspeak midwoofers from Denmark ps I only have female cats now

Edited May 17, 2023 by nefertem
Added some more information

[spazmoch]

On 4/19/2023 at 5:50 PM, Jab said:

OK, y'all convinced me.   Surround kits are on the way from Simply Speakers.   Nice folks.  Super helpful.   But....

I forgot to order dust caps, so this aint over yet!  Could someone please post a link to the re-building video?   It's been years since I did this on a set of infinities, and damn if I can remember what was involved in getting the dust cap off! 

Thanks in Advance.

Highly recommend a 1.5v battery to centre then whilst you glue the surrounds. The 8" drivers are pretty forgiving, you'll feel when it easily when it's rubbing Vs when it's not. The dust caps on the 93s and all the AR woofers with flat or inner dustcaps are impossible to cut cleanly, I leave them alone on all AR speakers now.

[Jab]

They should indeed easily tolerate the 1/3 watt a 1.5V battery would produce.  I can also apply a low frequency sinusoid, which should (if I am thinking this through correctly) keep the travel at the center of it's range on average. 

The surrounds are still in transit.   No fault of Simply speakers.  They have been marvelous.   The point is I have plenty of time to get set up properly.  My former workshop must be restocked.   

[ReliaBill Engineer]

Interesting topic and comments here. I’m sure a great many others have had the same thoughts about using new drivers to replace legacy AR drivers, because they fit. 
 

In 1982 I rebuilt my dads Wharfdale W70Cs. When I removed the rear panel, I saw where he had sealed off the port by glueing a block of plywood over the hole from inside of the cabinets. They never sounded correct; chesty, wooly bass. Bass reflex woofers truly do not sound correct in a sealed enclosure! Once I removed the wood blocks, the bass sounded so much better!! But I still completed the rebuild, new crossovers I designed to perform well with the new drivers. 
 

Bass reflex woofers “can” be made to sound good in a sealed enclosure, if you have the modeling software and test equipment on your bench. It’s definitely NOT a plug-n-play scenario, though.

[Jab]

Thanks Bill, Understood.  Not an acoustics engineer here, but retired EE.   From back in the day when we had to take our maths in the math department, similar with mechanics and physics.   Remember?

The thought occurred to me that if I had found a path to acoustically "similar" drivers, there is PC based software out there to test assembled performance with nothing but a calibrated microphone, then perhaps fiddle with the crossover.  Bring the crossover outside the cabinet for tuning, then the whole process might provide a "reasonable" state.   

Something like this https://www.daytonaudio.com/product/1116/umm-6-usb-measurement-microphone (for which you can download serialized calibration files) (if you can trust them?)  could take advantage of this wonderful age we live in where the cost of reasonable test equipment has come down.  

But sourcing replacements with some assurance of similarity proved to be a PITA, so, it looks like this winter I'll just replace the surrounds and call it a day.  😉  Though, the process of confirming basic performance might be fun.   Advanced performance characterization I would argue, with sadness, requires exceptional hearing, ear training, and sound field experience.   This is why it only makes sense for me to take it so far.

[ReliaBill Engineer]

I don’t have that software either. Tempted to get it. A buddy of mine locally does have it. I had him test my woofers when I removed them. Gives a plot of impedence and T/S parameters. After I butyl-doped the magnet side of the woofer surrounds, I had him perform another test, to see if my butyl rubber “wash” changed any of the parameters. It did not; same as when he first tested them. The software did expose a problem with one tweeter in a pair I bought on eBay for another project; it showed one tweeter was centered badly. The impedance plot was skewed on one. Good software! He rebuilds speakers now that he’s retired. The software is very good at exposing flaws, or for matching drivers. It measures the “DNA” of the drivers. I would think it to be a good way to find a replacement driver that matches the “DNA” of an original vs replacement.

[Jab]

I can't find it now, but that software was public domain.   Perhaps someone will remember. 

These https://www.trueaudio.com/    all have a modest price, but none ring a bell.  

 

[genek]

It has been well established that there are no "similar drivers" to AR woofers being produced new. Even woofers being offered as "AR replacements" don't meet the specs required to produce original performance.

Yes, you could redesign the cabinets and crossovers to work with new drivers. You could also rip apart the spiders and voice coils of new drivers and try to rebuild them to meet original specs. But unless you are an inveterate tinkerer doing it all for fun, that's a lot of time, effort and money to avoid refoaming an old woofer.

It'll also get your discussion moved to the Mods, Tweaks and Upgrades forum.

[Jab]

Searching, I found re-discovered this.  That the "replacements" are cheap junk.   

I am indeed an inveterate tinkerer, but have agreed with the advice that the best path forward with these is new foam surrounds.   I may go so far as to purchase a reference microphone and see how close to the original the rebuild came, and will post results.   

Don't hold your breath though,  😉 this rebuild isn't going to happen until the shop is suitably re-equipped to do the job well.    If it suits any administrative purpose you can close this thread, and I will re-open one to share the rebuild and solicit any tips. 

[JKent]

8 hours ago, Jab said:

this rebuild isn't going to happen until the shop is suitably re-equipped to do the job well. 

Jab,

I've been following this and I think you think re-foaming is much more complicated than it is. It's really very simple and you don't need a well-equipped shop, just a table.

You've said you don't plan to shim (btw, I always shim) so it may be even simpler. And you don't need a lot of tools or supplies: an X-Acto knife, some alcohol, maybe a few small clamps or clothespins.

One word of advice: DON'T USE THAT AWFUL SOLVENT-BASED GLUE IN THE SIMPLY SPEAKERS KIT.

Plain ol' white glue works. Aleene's Tacky Glue is perfect but may not be available in Italy. White glue works. It can be spread with your finger. It cleans up with water. And it's very forgiving--if you make a mistake just pull it apart before the glue sets, wash it off and try again. 

The solvent-based glue is necessary if you have a plastic cone but it is not needed for paper cones and it is very likely to produce terrible results.

...just my 2 cents.

Kent

[Jab]

Thanks Kent, excellent information.   The reason I plan to wait until the shop is "just so", is for me rather than the speakers.  Lighting is now reasonable, but not what I want.  I have a fairly nice 8X illuminated magnifier.  I need to pick up an array of cutting and clamping devices.   The last time I did this was like 30? years ago with a set of Infinities, and the project came out very well.   Will look closely into the various parameters of the glue.  Not to disagree, but I'm not convinced it would adhere well to the foam.  The paper, certainly.

Will put an exacto knife set on my list.  

There is another factor in play...it's summer.  By winter I'll have the shop in good shape, and not be distracted with outdoor projects. 

Thanks man,

John

 

[genek]

Jab, there's no time limit. What determines whether a discussion stays here or moves to Mods, Tweaks and Upgrades is whether it's about repairing, restoring and maintaining original speakers or about redesigning them into something else.

[JKent]

On 7/6/2023 at 9:57 AM, Jab said:

Not to disagree, but I'm not convinced it would adhere well to the foam. 

John,

I certainly respect and understand your desire to set up your shop. Not necessary for a simple re-foam but satisfying in its own right. And summer certainly offers other sources of enjoyment.

On the subject of glue, PVA (white glue) works perfectly on foam. I buy my surrounds from SpeakerWorks. They offer both types of adhesive and you can read about them here: https://www.speakerworks.com/SearchResults.asp?Search=glue&Submit=.  

White glue is very easy to use and very forgiving. Cleans up easily with water, can also be thinned with water and is non-toxic. Many speaker manufacturers use it. Nitrile-based adhesive OTOH is smelly, toxic, and very unforgiving. If you are a meticulous worker you "can" use it on paper cones but why go through the hassle? When I press a surround into the glue on a cone some inevitably oozes out. With white glue it's easily wiped off (I just use my finger) and cleaned with a damp rag. The nitrile-based stuff is much more difficult to use. Think Elmer's glue vs contact cement.

Literally thousands (hundreds of thousands?) of DIYers have used white glue on foam surrounds for paper cone drivers. Adhesion is not an issue.

Kent

[Jab]

Excellent glue information, Thank You Kent!