Speakers that have an "Aperiodic" design

[frommerstop]

A firm by the name of Digital Phase used to sell speakers that used an "acousta-reed" base loading - back in the early nineties. As far as I could tell, they were basically an aperiodic design. It's been years since I've see, let alone heard one, but I remember them sounding quite good.

 

[voyager12]

Celef (predecessor Proac) used tubes with small straws in them, as you can see below. I can remember that Celef explained
that will make it harder to displace the internal volume of air, which has a dampening effect. Question is if you don't achieve
the same thing by stuffing foam in your speakers' ported tubes. I can see three effects of aperiodic damping:
1. Limit a woofer's excursion
2. Limit bass response of a BR speaker
3. Muffle sound from inside the speaker

 

[baco99]

Here's an example most people forget:

Naim SBL. Untraditional in every way. The woofer resonates into two chambers, the first directly behind the driver like normal, and the second lower chamber connected via an aperiodic screen. Very similar in concept to the Dynaco A35.

 

[baco99]

Someone also mentioned Audio Concepts. The Model G2 was also an Aperiodic design. This version featured three small holes on the lower back of the speaker, about 1" in diameter each, with charcoal foam packed over the openings from the inside.

 

[opnly bafld]

Not a lot of them out there, but Omega made one using Viston B200 drivers and scan-speak vents.
Picture here https://6moons.com/audioreviews/redwine3/system.html

 

[karik57]

Urei studio main monitors 811, 813 and 815 were all aperiodic designs.

 

[2tec]

Adda, you and I have discussed this a bit as we both share similar interest in the concept...but I wonder how the hell they went about establishing performance metrics for "high drag", controlled drag", and "fixed impedance lossy"? Gas flow resistance of the absorption media is about all I can come up with. :scratch2: :headscrat

Oh, and Dynaudio has utilized aperiodic venting.

https://peI arl-hifi.com/03_Prod_Serv/PR2/PR2_Content.html

 

[loudnoises]

Oh, and Dynaudio has utilized aperiodic venting.

I have a highly customized set of dynaudio xennon, and this totally explains the bracing inside the cabinet. Multiple chambers and a big ol port. I wonder where they got the cabinet plans from...

Some of the nicest deepest base I've ever heard from a smaller driver.

 

[Frbock]

Interesting reading thru this thread.
Back in the early 70s, I bought a stereo with Dynaco a25s, and my friend had bought a system with Large Advents.
Given the size and price difference, the Dynacos put up a good fight. Similar efficiency, very similar sound. The Dynaco's just couldn't match the low bass of the Advents.
I always wondered why the design wasn't used on other speakers. I suspect there's a maximum box size that aperiodic would help, but I felt that A35s (also bookshelf) could have been serious contenders if they'd continued the aperiodic design to the larger box.

 

[GordonW]

Interesting reading thru this thread.
Back in the early 70s, I bought a stereo with Dynaco a25s, and my friend had bought a system with Large Advents.
Given the size and price difference, the Dynacos put up a good fight. Similar efficiency, very similar sound. The Dynaco's just couldn't match the low bass of the Advents.
I always wondered why the design wasn't used on other speakers. I suspect there's a maximum box size that aperiodic would help, but I felt that A35s (also bookshelf) could have been serious contenders if they'd continued the aperiodic design to the larger box.

I have seen aperiodic design, used on some subwoofers. IIRC, custom-rebuilt 15" drivers. They were super-soft suspension, with very low Fs, (well below 20Hz) but had too high of a Qts to work well in a reasonable size infinite-baffle enclosure (and by reasonable, I mean "a box that, while still huge, physically could be made to fit in the space it needed to go" ). So, a few Scan-Speak aperiodic vents were added to each box. Fixed the boominess/ lack of "tightness" (actually, it was more like a "sluggishness" like the bass had poor decay, it kind of "lingered" before the aperiodic vents were installed), post-haste. Lost a little bit of extension- but the difference was like from 18Hz in an optimal enclosure, to 23Hz or so, for F3. Still acceptable!

EDIT: And, actually, the Dynaco A35 DID have aperiodic damping. It was just BETWEEN the two otherwise sealed chambers inside the enclosure, instead of vented to the outside like in the A25. The A35 was a very interesting design. I don't know if anyone has modeled that design... it would be very enlightening to try and reverse- engineer that tuning scheme!

Regards,
Gordon.

 

[Frbock]

I have seen aperiodic design, used on some subwoofers. IIRC, custom-rebuilt 15" drivers. They were super-soft suspension, with very low Fs, (well below 20Hz) but had too high of a Qts to work well in a reasonable size infinite-baffle enclosure (and by reasonable, I mean "a box that, while still huge, physically could be made to fit in the space it needed to go" ). So, a few Scan-Speak aperiodic vents were added to each box. Fixed the boominess/ lack of "tightness" (actually, it was more like a "sluggishness" like the bass had poor decay, it kind of "lingered" before the aperiodic vents were installed), post-haste. Lost a little bit of extension- but the difference was like from 18Hz in an optimal enclosure, to 23Hz or so, for F3. Still acceptable!

EDIT: And, actually, the Dynaco A35 DID have aperiodic damping. It was just BETWEEN the two otherwise sealed chambers inside the enclosure, instead of vented to the outside like in the A25. The A35 was a very interesting design. I don't know if anyone has modeled that design... it would be very enlightening to try and reverse- engineer that tuning scheme!

Regards,
Gordon.

I did see the A35 and a50 both had internal aperiodic enclosures. Unfortunately, I saw it after I posted.
I'm no engineer, so basically creating a second box with a different resonance just seems counterintuitive. The a25s only had 1 resonance to work around.

 

[Nat]

Frbock: I tend to agree with you about the dubious value of the second enclosure. I am a big fan of the A25 (and have heard many), but the A35s and A50s I have heard impressed me less. Maybe my expectations were too high.

 

[bolero]

Ortofon with Scanspeak drivers

Thread 'Ortofon 445'

Jun 16, 2008

Ortofon 445 SPEAKERS

Just got a pair of Ortofon 445 speakers. Anybody out there know anything about these like value, pecking order, etc...

• RocknRollBen
• Replies: 29
• Forum: Speakers