Pete B
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Posts posted by Pete B
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Also, with regard to this thread the AR-3 had just a .4mH inductor to the woofer,
without any capacitor. It is first order electrical, and given the inductive input
impedance it is actually less than first order.
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This thread is also interesting, note Tom Tyson's posts, not that I agree with them all:
https://community.classicspeakerpages.net/topic/1156-ar-3a-two-woofers-two-crossovers/
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Yes, number 7 inductor 1.88mH was used early on, and #9 2.85mH later. Many years
ago I simulated the AR-3a in CALSOD and compared the results to the many published
impedance curves from AR. At that time schematics showing the 2.85mH were the only
ones while I pointed out that something closer to 1.9mH was required for agreement.
Many denied that there was ever a value other than 2.85mH, then I think it was Roy
who pointed out that he had worked on several that had the #7 inductor.
Many say now that the #7 was used with the Alnico woofer and #9 with ceramic, but
I believe that it was simply a minor change in the voicing of the design as a result of
the extensive work done by Roy Allison about the in room acoustical environment.
I have no proof but it makes sense.
Some of these old threads could be found with a google search just a few weeks ago
but now I can't seem to find them.
Here's the one covering my early simulation in 2005:
https://community.classicspeakerpages.net/topic/1270-anyone-have-ar-3a-measurements-system-drivers/
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Hi Adams,
If you think about it, on the floor away from the rear wall as in an audiophile listening
position is similar to up at ear level on a shelf because both have the woofer close to
one boundary. On the floor against the wall has the woofer close to two boundaries.
From what I understand the 58S and the 91 have the same crossover except for level
controls. Given that the woofer to mid crossover is around 500Hz raising/lowering
the mid and tweeter level should provide some adjustment to the amount of baffle
step. I have AR-11 s and they sound best in the audiophile position with the mid at about
-6 dB and the tweeter at -3dB. The 58S and 91 have less baffle step with a smaller
woofer inductor. The shape of the electrical response of the woofer would be easy to
simulate in Xsim with a woofer .ZMA file.
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Good to hear that you're back Scottie, just get better nothing to worry about here!
I went through my pile of drivers and found one that made sense to open up. I expected
to find more of a difference but not much. I'll report on it when I can find some time.
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@twinsig I have not bought any yet, rather it was @genek who you should ask.
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@scottie munoz Scottie, I have opened two of my round magnet woofers and therefore will
not need yours. Save your money as the shipping has gone way up.
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As most of you know, AR put a lot of emphasis on power response and perfected dome
drivers as a means to provide wide dispersion for improved power response. The AR-3
had a large 1 3/8" dome tweeter and 2" mid, whereas the AR-3a had the much smaller .75"
dome tweeter and 1.5" mid. These further improved the power response by having wider
dispersion at the top end of their operating range, and therefore from this perspective I
view the AR-3a as an evolution in the design. However, power response does not tell the
whole story, there are obviously other factors such as on axis response, distortion, thermal
compression and more. There are also psychoacoustic factors related to the in home listening
experience that effect how we rank a give speaker with regard to realism. It is completely
possible that some people prefer one design over the other but that might be due to one
speaker being a better match to the listener's room, forced speaker placement, or subjective
preferences. The AR3 has less baffle step than the late production AR-3a and that might
make it sound better in certain positions and rooms, of course the opposite may also be true.
Edit: Reading Roy's post where he provides a quote from CR, they state that the .75" tweeter
is not efficient enough to keep up with the rest of the system to provide the same, preferred
balance, as with the AR-3. This makes sense since smaller drivers tend to be less efficient
than larger ones. The CR observation seems to be an honest one. However, if you use tone
controls, then one's preference may change.
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Hi Scottie,
Woofer still has not arrived, hope that you are well and no rush at all.
Pete B.
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On 2/1/2022 at 7:16 PM, genek said:
I ordered a yard of my best pick from Ulster Linen. It arrived this week and if I can figure out what I did with my staplegun (which I haven't seen since before we packed up to move to Portland eight years ago!) I have a spare pair of 3a frame boards I can mount it to.
It's undyed, unbleached natural flax linen. We figured out a while back that it's 20ct. Here's what the loose yardage looks like.
Why does it look tea colored on the right? Is the left the color as sent to you?
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Just curious, do the rubber surrounds that you bought match the originals very well?
Where did you buy them?
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Hi Scottie, That would be great I've been wondering about this for a very long time!
I'll send you my address by email.
Thanks, Pete B.
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I've measured the in system, small signal, T&S parameters for OLA, NLA square,
and 5012 round magnet woofers and they are all nearly the same. I'm very curious
to find out the wind height on the round magnet version but have never had one
apart to do it. There might easily be large signal differences.
If anyone has a blown round magnet woofer I'll pay shipping to me and report back
on the findings.
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I think it sounds great, we ran them with 200W/ch and I think they could have used
more power. One young guy at the show put it that they kicked ass and had a big
smile while he listened to them. He also said that he just heard music and it didn't
sound like it was coming out of speakers which I take as a significant compliment.
That is how many described the SL6 s when they came out. He does a lot of restorations
on vintage gear and has owned some big impressive speakers.
I plan to build a full 3-way in the box and once that's done I'll compare them to the AR-11.
I could obviously use the plate that I 3D printed with the mid and tweeter but I might
want to try other drivers.
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I did a passive crossover at about 250 Hz, using junk box parts but it would have
been even easier to biamped it with a MiniDSP. I did 1st order to the top end and 2nd
order with a bit of damping in the cap shunt.
I came up with this configuration about 20 years ago, others use it also.
The top end is Celestion SL6, these are the first version in the series with the copper
dome tweeter that provides a depressed top end that some like. Thread on AK:
https://audiokarma.org/forums/index.php?threads/celestion-sl6.992260/
I bought them knowing that one tweeter was blown. The copper tweeter has a high Q
resonance in the top end that must be notched so the crossovers are tuned to match the
tweeters. Also the output at the very top end is matched to the design spec by another factory
tuning. The next revision of the system, the SL6S, and following 6Si and SL700, all used a newer
aluminum tweeter that pushed the resonance above 20K, but JA's measurements in
Stereophile showed a large notch at 15K that is not acceptable IMO. All systems with the
aluminum tweeter do not have any factory tuning of the crossover. There was only one version
of the 1.25" copper tweeter and one of the 1.25" aluminum tweeter used in these systems as
far as I know, and no other tweeters.
I decided to adapt the Dayton RST28F large 1 1/8" tweeter which I had on hand, to it as a reasonable
replacement. There is also an aluminum dome Dayton version that shouldn't be difficult to fit.
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Dayton 12" 4 ohm woofer in 1.6 cu ft having as low or better Fc and Qtc as the AR 12" woofer:
Old Advent OLA Utility boxes are cut for a 12" so they drop right in for evaluation purposes.
The nicer real wood veneered boxes will not take a normal 12" because the trim reduces the
width too much. The NLA woofer opening is smaller so it also will not fit without cutting.
A pair of them playing as 3-ways at Frankenfest this past weekend:
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There was an older style, usually Butyl, rubber surround that were quite thick
and are hard to find these days. If those were rubber, they were more like foam
that was covered with a very thin rubber layer and I've never seen these for sale
anywhere and that's why I suggested foam. But you should call some of the suppliers
and see what they say. I'm fairly sure that the owner of Springfield Speakers is on
AudioKarma and there are several pros there that do a lot of work.
I'm not a pro, and what I offered is how I would do it, you should ask your questions
on AK and you might get some better answers.
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I worked on my friend's pair probably 10 years ago and they didn't need refoaming back then.
I try to clean off old material the best that I can but you have to judge if you are going to
do more damage. A couple of tips:
I've used a tiny wire brush on a Dremel tool with very good results, go slowly of course,
and I usually stuff old plastic bags under the cone so that all the force doesn't go to the
voice coil to counter the wire brush. You should also put something directly behind the spot
where you are using the wire brush, I very carefully use a finger.
You could try slicing it off with an Exacto but I'd had mixed results with it.
Last resort is to glue on top of it.
That was regarding the cones, the metal frames are not a problem to clean, scraping with
Goo Off or sometimes Nail Polish remover is better.
I'd call Simply Speakers or one of the other US companies and ask for their advice.
I don't think that, if those were rubber, that type of rubber is generally available and
therefore I'd go with foam.
There are guides as to what measurements to take to get the correct foam, also tell
them if the cone side edge is flat, angled, or filled fillet.
I fairly sure that those are coated paper cones, and I'd use Aleen's Tacky glue since it
gives you time to adjust things.
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I had a hard time finding several of my very old threads and I believe that the
built in search engine is defective. I was able to find them by searching through
Google. You can enter your search string, then add site:community.classicspeakerpages.net
and it will only look here.
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It is a lot of money for the White Oak rebuild so that is easy to understand.
Where you able to access the docs at AudioKarma, if not PM me your email address
and I'll send them. There were a lot of warnings and several updates to the PL700 design.
I think the thing about a single large amp is that when a huge bass peak comes along
you have ALL of the amp power to drive it.
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Thanks everyone for the interesting comments!
@AR55 I had no idea that the folks at AR read the review and actually improved them.
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You can find the 700B and 700 Series 2 service manuals, and many others here in the AudioKarma data base:
http://akdatabase.com/AKview/thumbnails.php?album=94
Many of the service bulletins are included in those docs.
I'm not sure if you have to sign into AudioKarma to have access to the documentation.
Frank, do all of your amps have the White Oak upgrades?
https://www.whiteoakaudio.com/estore.aspx
Pete B.
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@frankmarsi Have you seen the service bulletins for the PL700 from the factory? I have
several of them somewhere on my computer.
Advent/1 and Large Advent square vs round magnet
in Advent
Posted
All of my NLA square magnet woofers are in good condition and therefore I don't want to open
up any of them. If anyone has a blown one, I'd like to take a look at it for analysis, preferably in
the CT area.