Speakers that have an "Aperiodic" design

[jamiecantar]

Can you help me name some other vintage or new speakers that have the "Aperiodic" enclosure design as the Dynaco A25's. They sound great.

1. Dynaco (60's-70's)

 

[kconnor]

Possibly the Infinity Monitor Jr. speakers of the mid to late '70s. The entire cabinet was stuffed with fiberfill as was the port.

 

[jamiecantar]

i think dynaco used Rock Wool.

 

[Adda]

The Perkins PR-2, it's supposed to be very rare, I haven't even seen a picture of these.
But they are some of the most sophisticated Aperiodic speakers I have seen.

 

[tomlinmgt]

The Perkins PR-2, it's supposed to be very rare, I haven't even seen a picture of these.
But they are some of the most sophisticated Aperiodic speakers I have seen.

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.

 

[tomlinmgt]

Possibly the Infinity Monitor Jr. speakers of the mid to late '70s. The entire cabinet was stuffed with fiberfill as was the port.

My Infinity QLS-1's have a Phillips mid-bass coupler that is housed in a transmission line "tube" that ports to the rear and it's filled with stuffing, as well.

 

[Adda]

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

I don't think they did have any metrics for those things.
I'm quite sure they understood the concept of what they where doing, but I think Aperiodic speakers are always designed through trial and error, rather then calculating and testing.

The rarity of Aperiodic designs are almost certainly a result of the difficulty in developing them (no math or standards for how it's done), and the problems with ensuring the same specs across multiple production runs.

For the DIY'er is different though, we only have to make one pair, so it's much more manageable.

 

[baco99]

Morel MLP-403 uses a Variovent aperiodic filter at the rear of the cabinet.

 

[tubed]

North Creek Audio. supposedly improved upon the aperiodic design and changed the letters around with the (MAPD) Multi-Chambered Aperiod Progessive Damping cabinet.
http://www.northcreekmusic.com/MAPD1.htm

 

[baco99]

Omega A8

 

[baco99]

Scan-Dyna A45x

http://www.audiokarma.org/gallery/showphoto.php?photo=2295&size=big&cat=

 

[Adda]

North Creek Audio. supposedly improved upon the aperiodic design and changed the letters around with the (MAPD) Multi-Chambered Aperiod Progessive Damping cabinet.
http://www.northcreekmusic.com/MAPD1.htm

Are you sure this is not a transmission line? (transmission line speakers are aperiodic, but they incorporate a folded horn rather then just a flow resistor).

Edit: the picture disappeared, as far as I can see, the pic showed something different then the link you posted.
I remember reading about multi chamber aperiodic speakers over at diyaudio, but never saw a real speaker built this way.

Edit2: now the pic returned, that is definitely a transmission line.

 

[tubed]

Are you sure this is not a transmission line? (transmission line speakers are aperiodic, but they incorporate a folded horn rather then just a flow resistor).

Edit: the picture disappeared, as far as I can see, the pic showed something different then the link you posted.
I remember reading about multi chamber aperiodic speakers over at diyaudio, but never saw a real speaker built this way.

Edit2: now the pic returned, that is definitely a transmission line.

Sorry, same company wrong pic.
Here's a pair of aperiodic 8" 2-ways built by a DIy'er from a North Creek kit, (MAPD) specs, North Creek drivers and crossover components.

 

[dc270]

Isn't the "Variovent" an aperiodic principle? I think Dynovox and others used it. Minicus Audio still sells them!
DC

 

[baco99]

Isn't the "Variovent" an aperiodic principle? I think Dynovox and others used it. Minicus Audio still sells them!
DC

Yes. Madisound used to sell them too.

 

[GordonW]

Goodmans made several models of speakers, with their ARU ("Acoustical Resistance Unit) aperiodic vent.

Regards,
Gordon.

 

[Adda]

ScanSpeak makes something they simply call a "flow resistor" it's supposed to be similar to the Variovent.

But how to use them correctly? it's up to you to find out.

Here are the basics, but it's rather crude:
http://diyaudioprojects.com/Technical/Aperiodic/

 

[Adda]

Sorry, same company wrong pic.
Here's a pair of aperiodic 8" 2-ways built by a DIy'er from a North Creek kit, (MAPD) specs, North Creek drivers and crossover components.

Well the MAPD is the first "ready made" DIY aperiodic design I have seen, very interesting indeed.

 

[tubed]

Well the MAPD is the first "ready made" aperiodic design I have seen, very interesting indeed.

Heavily braced and built with the recommended solid 1" birch and 2" baffle.
I wish I still had pics of the insides.
Two chambers with a vent on the inside leading to the low chamber.
Scan speak drivers, Sprague caps, Mills resistors, and very $heavy duty$ coils.
Superb sound.

 

[Adda]

Heavily braced and built with the recommended solid 1" birch and 2" baffle.
I wish I still had pics of the insides.
Two chambers with a vent on the inside leading to the low chamber.
Scan speak drivers, Sprague caps, Mills resistors, and very $heavy duty$ coils.
Superb sound.

Yeah I have heard many many good things about aperiodic designs.

Easy to drive, even for weak tube amps with poor dampening factor, due to the much reduced impedance peak at Fs, compared to other boxed designs.
Low distortion, small size (compared to vented or sealed) and open sound.

The only major problems are unwanted sound leaking out through the port(s), it doesn't provide as extended bass as conventional ported designs, and of cause, the lack of design guidelines and simulation software.

It seems the ideal box design for midbass, wideband and fullrange drivers, especially if you intend to use separate subwoofers.