Recapping AR-4X

[RayW]

But I settled on a simple JBL topology: first order LP with tuned Zobel and second order HP with bump. That got me within +/- 2.5 dB, nearly as close as I achieved with any of the other approaches.

Hey Z, how about curves with the tweeter adjustment at the extremes so we can see the range?

Hi Carl. Welcome to the AK world of speaker geekers. Sounds like an interesting study. I usually just laze out and get the PE black grill cloth. I'll send a PM in a minute.

Ray

 

[Fedallah]

I just wanted to pop in and say that this is a great thread, even though much of it is utterly incomprehensible to me. Look at the nice flat frequency response graph, smile, nod, pet the kitty... I'll be in much better shape when I have time to go plow through the XO section of my newly delivered Loudspeaker Design Cookbook.

 

[RayW]

I just wanted to pop in and say that this is a great thread, even though much of it is utterly incomprehensible to me.

Ask questions about the incomprehensible parts and we'll see if we can fill in the gaps for ya. I love this stuff.

Ray

 

[Zilch]

Hey Z, how about curves with the tweeter adjustment at the extremes so we can see the range?

Sure, Ray, they're still set up. See below. Org is where they were set for last night's testing. There's just enough headroom to allow additional "brightness," if desired.

[Sound just as good this morning, BTW.... : ]

I just wanted to pop in and say that this is a great thread, even though much of it is utterly incomprehensible to me. Look at the nice flat frequency response graph, smile, nod, pet the kitty... I'll be in much better shape when I have time to go plow through the XO section of my newly delivered Loudspeaker Design Cookbook.

It's well documented there. Some of what's in this thread will be familiar ground.

I still do it the hard way, learning more each time.

Glad you got "The Book;" new perspectives and much fun abound therein.... :thmbsp:

About a year ago I undertook a brief study on grill cloth. Coincidentally, the study involved the use of an AR4x speaker.

Did you also conclude the stock "Linen" was not optimum for acoustic transparency?

 

[RayW]

Looks like orange is the way to go but that wouldn't work for me. My 2 year old is sleeping at 3:00 and I can't really listen to music.

What's with the cyan? Does that turn the tweeter off completely?

Ray

 

[Zilch]

What's with the cyan? Does that turn the tweeter off completely?

Yup, revealing how the woofer and LP behave. :

With 8-Ohm L-Pad at minimum setting, series R is 8 Ohms, and parallel R is 0 Ohms; the tweeter is off.... :yes:

******

That graph should objectify the scale of what these measurements describe for some readers. Violet is "Virtually off" at -8 dB. If any given response curve has a broad 10 dB peak, as I've shown in some measurements of systems here, the rest of it might as well not even be playing. That's HUGE, and it matters....

******

Any derelict AR4xs out your way? 116H and 116A show up frequently on eBay for cheap, just needing refoam, typically. The T/S parameters are the same. "A" is for alnico, in this instance. "H" distortion is lower.

[You'll have to set up your measurement gear, tho, to be certain the Zilchster's not making this stuff up..... ]

 

[spkrdtr]

"Did you also conclude the stock "Linen" was not optimum for acoustic transparency?" Quote - Zilch

No, I didn't conclude that. It's fine if it's open enough and not too fuzzy. Most of the cloth I sell for grilles is part or all linen. Burlap on the tight side is definitely no good. It will diminish the highs.

 

[Zilch]

I can't say the stock linen diminishes the highs, either, but it sets up interferences in them I don't much like.

I'll recover a set of these frames in contemporary polyester double-knit for comparison for the next AR4x iteration.... :yes:

 

[Duffinator]

They're mighty good; good enough I'm moving them to edgeless PE stock cabs with mirror imaging. (Auditions by arrangement in the interim.

Duff's AR4x cabs will then experience a more radical upgrade.... :yes:

Zilch, what have you done to my speakers?

I stopped by the top secret ZilchLab yesterday and listened to these speakers and all I can say is WOW! I was blown away by the bass they put out. I never heard the AR4x speakers at their original full potential but I'm certain they don't sound as good as the modified ones.

 

[Zilch]

Zilch, what have you done to my speakers?

Heh, heh. :thmbsp:

And I ain't done with them yet, even.

[You'll see; gonna get radical soon.... : ]

 

[Zilch]

18 Sound XT120

http://www.eighteensound.com/index.aspx?mainMenu=view_product&pid=179

1) Gasket outlines the cutout; comes with the horns.

2) Sparing y'all the gory spectacle, AR4x again succumbs to the will of the Barbie SawZall.

3) "What's behind the grilles, Zilchster?"

["I'll hafta check my notes...." ]

 

[Aage]

An AR with a horn tweeter...? Say, you should show this to the new AR company, they might sense a winner here, if they could find a way to make it in China...

 

[Zilch]

An AR with a horn tweeter...? Say, you should show this to the new AR company, they might sense a winner here, if they could find a way to make it in China...

Horn's made in Italy, actually.

Inspiration:

http://www.jblpro.com/products/recording&broadcast/LSR6300/lsr6328p.html

I'm running active crossed at 2 kHz right now, with just some preliminary tweaks.

+/- 2 dB, I'd say it has potential.

Sometimes, stuff just works.

[Tweeter's a bit pricey, tho.... : ]

Edit: BMS 4540ND with throat adapter works as well, saving $100 per pair (second curve). Specs say it's playing to ~30 kHz:

http://www.bmspro.info/index.php?show=item&usbid=10278&id=54358

Looks like JBL 2408H ($80/pair, used) works too, but requires different compensation (violet, third curve). Green is nearfield (1/4") low frequency response.

 

[RayW]

Edit: BMS 4540ND with throat adapter works as well, saving $100 per pair (second curve). Specs say it's playing to ~30 kHz:

Sweet! I'd love to hear those. Care to send them to the center of the continent for a listening session?

Ray

 

[Zilch]

Sweet! I'd love to hear those. Care to send them to the center of the continent for a listening session?

Could happen, Ray, but only if we don't blow 'em up at the Sacto AK Fest.

I've got two months to work up a passive XO for these.... :

With boundary reinforcement, just near the wall:

 

[wiredbecker]

Hey Zilch, if you want more tweeter data I have 2 pairs of AR4s we could open up.

 

[Zilch]

I DO have another mod idea, if you're willing to give up a pair to "Science."

They won't be AR4s anymore, tho, which seems to be a recurrent ZilchLab theme.

[Holy CRAP, look at those curves! I've got to put the Presidians away and get back on AR4s here, obviously.... :yes: ]

 

[wiredbecker]

Which parts are gonna get the heave-ho?

I was just about to put these 4 AR4s into a new HT rig. One pair is a FrankenBose. Tweeters were dead so I stole some replacements from a free pair of Bose bookshelves that screwed right in. Thanks Laney College flea market junk pile!

 

[Zilch]

Which parts are gonna get the heave-ho!

Woofers, tweeters, crossovers, rockwool.... :

 

[RayW]

Let me first say I very much like the TB tweeters. Thank you for the suggestion, Ray.

Brought back as a public service announcement. That tweeter (Tang Band 28-847SE) is on sale at Parts Express for $12 each. link

Ray