Carlspeak
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Posts posted by Carlspeak
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1 hour ago, ra.ra said:
I keep seeing this discussed in various conversations and I have no reason to doubt it .......... but exactly how does cross-talk present itself in a measurable or perceivable manner; in what ways does re-orientation provide improved performance; and why was this concept not enforced by AR engineers when the crossovers for these loudspeakers were originally laid out for fabrication?
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You've got a high likely hood of inductor cross-talk in a couple of spots due to their same orientation and close proximity to each other. One of the large coils in the left pic should be stood up on edge, In the right pic, stand the blue coil on edge. These changes should be beneficial to your speaker's performance. For more info. on inductor cross talk, visit Troels Graveson's web site. He has a nice chart there that shows recommended mounting of coils and distances.
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With the 0.1 cap the bypass allows signals to pass ~ 1 kHz and above. with the 0.01. not until ~ 4 to 5 kHz. So, with a 2-way speaker there's more benefit with the 0,1 uf and with a 3-way, 0.01 uF.
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If you want to hear more of the effect of the bypass cap, use a 0.1uF. If you want to hear less, use a 0.01 uF.
Vishay makes a good one.
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Seems like no easy DIY fix here. Time to scout out electronic repair shops near you?
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Have you tried disconnecting the woofer itself from the cables and testing it by itself to ensure the woofer is not blown?
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I fixed a powered sub once by opening it up and discovering a fuse inside had blown. Check your sub for fuses.
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OEM Callins and Temple caps are cr&p. They age terribly and drift way out of spec.
I have a pair of 100uF Solen caps F.S. PM me if there's any interest.
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Looking forward to the major update!
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You can pay a fortune for Ohmite 15 ohm rheostats, or go with the prevailing recommendation of an inexpensive 8 ohm L-Pad with parallel 25 ohm resistor that will accomplish the same result. The AR3a restoration document goes into detail about the available options to replace the vintage AP pots. The recommendations are independent of the vintage of the AR speaker.
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Great write up AR surround. Nice spreadsheet!
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I sell a lot of premium linen grille cloth to vintage speaker owners. With it, I provide written instructions on how to install the cloth using a method I used on many cloth installs.
Aileen tacky glue on all four sides, then fold the corners and staple only there.
PM me and I'll be glad to email you those instructions.
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Is there a question there somewhere?
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I would refer you then to the published work of the late, great Roy Allison where he made measurements in a variety of real rooms. I suspect he documented well his measurement methodology. His AES paper is in the library. All others, I suspect, will have a lack of detail or be too variable to have any meaning.
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Could you clarify what you mean by 'age is putting its stain on measurements".?
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I just upgraded a pair of 12's Contour XO's. Didn't go over the top like Kent did with the Auricaps. It was just a basic upgrade that was badly needed after checking the ESR's and uF's on those brown jobs.
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That's the doc. Gene I know existed but couldn't find.
Thanks,
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Here is a link to an earlier thread on oiled veneer. Even Tom Tyson has some advice.
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=581&hl=linseed#entry51242
You can also use the search function to find more threads on the subject. Just enter "linseed" into the search word window, click on "Acoustic Research" to confine the search to AR and click 'search'
I took a quick look in the CSP library but could find anything. I'm sure there was something published by AR about the care of veneered finishes.
BTW, I would be surprised if vintage-AR's linseed oil (don't know if they sell it) is any different from what you'd get from a hardware store. It's pretty generic stuff.
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I would think a local hardware store in your country should carry boiled linseed oil. Have you checked with any in your area?
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What where the AR3a cabinets original finished with?
With that I mean the varnish.
Most were finished with boiled linseed oil. The very glossy ones had a lacquer sprayed on.
The former should be re-oiled once and a while. The latter just dusted.
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Howard F. used to post here regularly some time ago but left after a row with a now deceased troll. Perhaps someone who knows him well could coax him back?
He has a wealth of knowledge about Allison for sure.
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Very interesting, and well done. Undoubtedly many people will find this useful for broken Advents.
Out of curiosity, what causes the 1-2K dip in the OLA's frequency response?
Based on my tested of the one 'prototype' original on hand it was the inductor coil on the woofer. Take it away and away goes the dip.
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Hello,
I was searching for a replacement tweeter for my large Advents, and found this. I have a set of the new Large Advents, and the later 5012/w's. I'd like to have 4 speakers all the same (stackable), and replace the tweeters (especially the fried egg ones) with something better.
I've got the woofers refoamed, and the cabinets of the 5012's braced. I plan on using fiberglass packing. just need a little more information about the crossovers.
Would the crossover you listed Carl work well with the Dayton RS28F-4 tweeters, and the original woofers?
If so, could you post a parts list including brands, and a good place to purchase them?
Maybe, also a wiring diagram, so an electrical noob like me won't mess it up? I can solder though.
Thanks for posting all this info, I'm pretty eager to hear what they're going to sound like.
Dean
The crossover for the tweeter is shown and discussed in post #3. There's a 20 uF cap in series with the tweeter pos post and a 0.5 mH 20 ga. coil attached right after the cap and the other end of the coil attached to the negative wire. After the coil, attach a 3 ohm resistor.
All of those parts are available at Parts Express.
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I've used the kit and found the voice coil to be about right but the cone is too light with the resultant Fs being significantly higher than spec.
I think Roy C. will attest to this as well.
AR90 Crossover Recapping - Taming the UMR
in Acoustic Research
Posted
As you can see in Troels stacked experiments, mH values changed noticeably. I'd be much more concerned if the AR9 had stacked coils in the mid or HF circuits where your hearing is much more sensitive to.