AR48s Rebuild and Reverse Engineering - Crossover Schematic

[Pete B]

AR48s Rebuild and Reverse Engineering page, will add more measurements in time:

http://members.aol.com/basconsultants/AR48s.html

Pete B.

[dynaco_dan]

Hi Pete;

Very nicely done!

[Guest Eunomians]

I enjoyed the reading.

Now I'd like to hear the speaker in person!

Cheers

[Pete B]

Thank you gentlemen!

I've added some pictures and driver measurements.

http://members.aol.com/basconsultants/AR48s.html

AR tweeter followers should take a look at Figure 3 for

an interesting repair.

Pete B.

[dynaco_dan]

Hi Pete;

First class, my friend, first class.

[Pete B]

Thank you again Vern,

Added a picture of the Advent Legacy woofer,

looks even better than the older Advent 10/12".

Would have to measure the specs and listen to

be sure.

Have you seen Frank M. around,

I want his job, lol!

[frankmarsi]

>Thank you again Vern,

>

>Added a picture of the Advent Legacy woofer,

>looks even better than the older Advent 10/12".

>Would have to measure the specs and listen to

>be sure.

>

>Have you seen Frank M. around,

>I want his job, lol!

9-3-06

Here I am, Pete B. Staying low until I make some progress that I can photograph and post on the site here. I feel as though I ‘shot myself in the foot’ by buying seven AR 12” used woofers when I already had 8 waiting to re-foam.

I’m left here just listening to half assembled speakers begging me to get on with the show and start working. I’m a lazy son of a gun I’ll admit. With 15 of these bad boys, I’ve overwhelmed myself and find it easier to sit around and eat and start putting on some winter weight in preparation of the season- what a darn excuse! I also have 18 tweeters to install. I have to admit again I put myself in a hole here and find it easier to test new interconnects and listen to some old vinyl and new CD’s. What a joker I’ve become in this vintage AR bliss. I know once I finally get started, it’ll all move fast, but I like the dragging out of things sometimes. I also realize that once I get everything assembled and functioning, I wonder what I’ll do then?

Will it give me the opportunity to spend more money I really don’t have on vintage stuff, or get back into listening more than I already do?

I guess I’ll take the easy way out again and playfully blame all of you nuts for sharing with me information about this insane hobby.

By the way I listed my main system’s components on the Stereophile-site.

If anyone’s interested, under ‘insane hobby’ thread. I didn’t want to be too much of a bragger as I know there are systems out there that can beat mine of course and I sometimes come off as being too proud of my system. You see there goes that little kid mentality of mine again.

I just wish I’d get off my ass already so I’d have something more to talk about.

Has anyone come up with some sort of ‘assembly-line’ way of re-foaming?

Frank Marsi

[Pete B]

Hi Frank,

15 woofers! Sure you have enough?

Don't know what to say, what's that saying enjoy the

journey, so why rush and spoil it, it should be enjoyable

and relaxing, they are toys after all.

I've got a backlog myself.

How about a refoaming party!

I was wondering, have you ever tried, your stacked LSTs

plus a pair of AR-3a woofers for a total of 4 woofers

per side? Looks like you've got enough woofers anyway.

All the best to you!

Edit: If you mount the woofers in the 3a's magnet out it

would tend to cancel some of the harmonic distortion.

[Pete B]

Sorry, forgot that the LSTs do not allow the woofer section to be driven independently, which makes this a bit difficult. Also the 3a's would run woofers only.

[frankmarsi]

>Hi Frank,

>

>15 woofers! Sure you have enough?

>Don't know what to say, what's that saying enjoy the

>journey, so why rush and spoil it, it should be enjoyable

>and relaxing, they are toys after all.

>I've got a backlog myself.

>How about a refoaming party!

>I was wondering, have you ever tried, your stacked LSTs

>plus a pair of AR-3a woofers for a total of 4 woofers

>per side? Looks like you've got enough woofers anyway.

>

>All the best to you!

>

>Edit: If you mount the woofers in the 3a's magnet out it

>would tend to cancel some of the harmonic distortion.

9-3-06

Pete B. I know I’m a little crazed when it comes to AR-3a woofers. Most others obviously think what I have is over-kill and frankly it is, but these guys are special and becoming very scarce. I’ve loved these drivers since I first heard them in 1970, bought a set AR-3a’s new in ’72 and have never felt any need to own or use any other brand name of woofer. Regarding speakers needing repair I have 4 LST’s and 4 AR-3a’s that need work, my four 2ax’s is another story for much later. I operate with four LST’s full time, the four AR-3a’s can wait, but I did have the thought of using 2 AR-3a boxes along side the LST’s as you suggested, but room for them is limited. Am I more demented than I thought I was?

Can this be done and still have credible sounding music?

Would I have to use some sort of cross-over to the AR-3a boxes or simply disconnect the tweeters? I do have a couple of spare amps available to me, one Phase Linear 400@ 400RMS per side and a B&K ST202 @ 160RMS into 4 ohms per side. I was using the PL400 for a set of 3a’s,(another system with 4- AR-3a’s and 2- PL400’s, is in the works) but I could consider this ‘super-bass’ set up you suggest. Any comments from any one else out there in space? I must say I was astonished when I first heard my stacked LST’s with double PL400 amps, but this idea about an additional 2 AR-3a woofers assisting the LST’s is inconceivably a great one.

I would no doubt be the proudest former bass player I know if I had all 6 woofers going with 3 amps.

Well Stanley, here’s another fine mess you got me into! Now I’m afraid I may have to re-think my whole system over again. One more set-back and I’ll start using an Ipod.

Frank Marsi

[Pete B]

I thought of this because stacked LSTs have all those mids and tweeters, why not a few more woofers!

What would make this all easy, is if the LSTs allowed bi-wiring. Then remember that the 3a with the mid and tweeter disconnected has nearly the same woofer XO as the LST, 2.85 mH vs. 2.6 as I recall, close enough. If the LSTs could be bi-wired you could put one 3a strapped for woofer only in series with one LST providing an 8 ohm

load to the Phase, the LST high end would go in parallel with this.

The woofers in series will have equal sensitivity as a single even

at the higher impedance as a result of the 3dB efficiency increase.

OK just had another idea, put each LST in series with one 3a strapped for woofer only. Then put a big cap across the 3a woofer box to shunt the mid and high end to the LST. This would work and provide an easier 8 0hm load in the bass to the Phase Amp. No new amp needed.

I'm sure you've thought of 4 Phase Linears 2 for the 4 LSTs and 2 for the 4 3a's, probably a bit of overkill.

Just noticed that you wrote 6 woofers above, I'm talking about 4 per side for a total of 8.

[frankmarsi]

9-3-06

Pete B. Sounds glorious, but what would do to arrange such a ‘wall of sound’?

Think of the size of this monster? I felt one woofer per side with a separate amp driving just the AR-3a’s. This still would be a bundle to figure out placement of each box. You’ve got my head spinning though I can be resourceful when challenged.

Frank Marsi

[Pete B]

We have something in common, I also like big systems!

Have you seen my setup, I also use 2 400W amplifiers as

you do, load is 2 ohms in the bass so they put out a lot

more, about 1150W total:

http://members.aol.com/basconsultants/spkrs.htm

Most people have not heard low distortion bass, it

sounds different, very clean and effortless.

What I suggest is keep the normal LST stack, then place

one AR-3a horizontally, could act as a stand, below the

stack, woofer lined up with the LST woofer. The other

3a at the top of the stack, woofer also close to the LST

woofer. How tall would the stack be, I'd have to go look

up the dimensions. Do you have 1-W boxes those would

make more sense in not having the mid and tweeter go to

waste. Would want similar woofers in all the boxes.

Wanted to mention that I have a friend with a PL 700, last

I heard he was not using it.

All the best to you Frank, I'm out for the night!

[Kencat]

AR48s Rebuild and Reverse Engineering page, will add more measurements in time:

http://members.aol.com/basconsultants/AR48s.html

Pete B.

Hello Pete,

If you are still around the site - the links don't work anymore, the hosting site has been shutdown.

[Pete B]

Hello Pete,

If you are still around the site - the links don't work anymore, the hosting site has been shutdown.

Are you looking for the crossover schematic or anything in particular?

The site is down and I'm in the process of looking for a new host.

[Kencat]

Are you looking for the crossover schematic or anything in particular?

The site is down and I'm in the process of looking for a new host.

Nothing in particular Pete. I came across the old post and found the link not working so posted to let you know in case you didn't know.

Since you are "still around" though , I'll ask a question or two. A set of tweeters that I picked up, supposedly from AR14 speakers, are marked as 200024, instead of the originals that were marked 200024-1. The AR14 was supposed to have the -1s as well based on the engineering prints from this site. Do you know what the non-dashed versions would be and are they different from the -1? Physically they are identical. I still have the dead originals.

Pics of the AR14 tweeters attached.

You seem to be one of the few people in the world to give this model any consideration. What is it about them that intrigues you? Too bad they have the vinyl covering, but from a few feet away they look fine. The rubber or GPS (?) surround on the mid is cool and was perhaps a technical innovation, but we can't enjoy the original sound without a proper replacement. One of mine still has the OEM surround intact but it's yellow and I've read they go brittle. Still seems to work well, but is it like it was new? Does using a foam replacement alter anything do you think? Perhaps making a doped cloth surround would let the driver work closer to intended parameters?

[Pete B]

Nothing in particular Pete. I came across the old post and found the link not working so posted to let you know in case you didn't know.

Since you are "still around" though , I'll ask a question or two. A set of tweeters that I picked up, supposedly from AR14 speakers, are marked as 200024, instead of the originals that were marked 200024-1. The AR14 was supposed to have the -1s as well based on the engineering prints from this site. Do you know what the non-dashed versions would be and are they different from the -1? Physically they are identical. I still have the dead originals.

Pics of the AR14 tweeters attached.

You seem to be one of the few people in the world to give this model any consideration. What is it about them that intrigues you? Too bad they have the vinyl covering, but from a few feet away they look fine. The rubber or GPS (?) surround on the mid is cool and was perhaps a technical innovation, but we can't enjoy the original sound without a proper replacement. One of mine still has the OEM surround intact but it's yellow and I've read they go brittle. Still seems to work well, but is it like it was new? Does using a foam replacement alter anything do you think? Perhaps making a doped cloth surround would let the driver work closer to intended parameters?

These were given to me, and I was mainly interested in how they

fit into the AR2 - AR5 evolution. I actually like the idea of using a

small cone midrange and the 1" dome allows for a lower and more

reasonable crossover point. Not impressed with the woofer and I

think that the Large Advent or New Large Advent woofer would be

better.

I don't know what the dash numbers mean with AR drivers; perhaps

someone here will offer some insight. It is usually a revision for

improved performance or lower cost.

I would be very surprised if that surround is not brittle. I'm using

foam replacements but I've not measured the final response of the

system. The edge does strongly influence the breakup behavior of

a cone, however the only way to know is to try it and measure. I'm

not sure which would be closer but given that foam is available that

is what I'm going to use.

Mine are on hold as I slowly collect parts to finish them. I'm probably

going to substitute a low cost tweeter, recap them, and call it done.

[Pete B]

This page was hosted at AOL, then moved to google after AOL shutdown hosting,

now hosted at my own domain since google stopped free html hosting - hopefully to stay:

http://baselaudiolab.com/AR48s.html

[Kencat]

Thanks much Pete.

Keep looking for tweets on the sale sites, might get lucky.