Anyone know about Linn Isobarik speakers?

[DavidR 32]

Not sure this is the correct forum to post but it seemed close enough.

 

There is an audio store in town that carries a lot of high end stuff. They have a pair of  Linn Isobariks (used) for sale.

Does anyone know anything about these? http://www.natural-sound.com/content/used-speakers < 3rd item down the list.

I was going to go take a look. Not sure what they mean by average condition.

[BillD 239]

Well, I know a little about isobaric hookups.  You use two speakers in the same enclosure, either cone to magnet (stacked) in-phase, or magnet to magnet (back to back) out of phase.  It keeps the chamber between the two speakers at the "same pressure" or isobaric.  If they weren't, distortions would arise.  Purportedly, you can double the output in the same size enclosure with this method (especially used in bass configurations.  Here's some more info.

 

http://forums.linn.co.uk/bb/printthread.php?tid=21 

[RichP714 3,163]

Isobaric Applications

Isobaric configurations are not the magic fix for enclosure design. Correctly used, this application does offer some benefits, but at a price. The term Isobaric is Greek in origin. "Iso" meaning constant and "Barik" meaning pressure defines the operational characteristics of this use of multiple woofers. The air space between the to woofers remains a constant pressure and the result is a single drive unit with dual motor assemblies. Figure 10 The difference between a single woofer and an isobaric pair of woofers are...

 

Vas of the isobaric pair of woofers is half that of a single woofer. Fs of the system remains the same. The maximum output capability is the same a single woofer in as enclosure that is twice the size. The efficiency of the system is 50% of a single woofer. The electrical power handling of the system is double that of a single woofer. The mechanical power handling (X-Max) of the system is the same of a single woofer. The moving mass of the system is doubled.

 

There are several performance differences between a single woofer and an isobaric pair of woofers. Following is a brief description.

• The required volume for a sealed enclosure is half that of a single woofer.
• If you need to increase the output of an existing enclosure using a single woofer but need to maintain the same frequency response, addition 3 additional woofer (to create two isobaric pairs) will increase the output by 6 dB if the power is available.
• When using a vented enclosure of 3 or more cubic feet, an isobaric system will reduce the required volume by half. For enclosure volumes less than 3 cubic feet, it is important to consider the needed length of the vent.

 

Two major trade-offs when using isobaric configurations is required vent length and cost versus performance. As the enclosure volume decreases the required vent length increases exponentially. The isobaric configuration reduces the required box volume in half. This results in a drastic increase in vent length required. The increase in cost is a perspective issue. Not so good for the consumer but great for the dealer.

 

There are different ways to configure isobaric applications. Following are the different configurations and the performance characteristics of each different style.

 

 

Cone to magnet

Possible temperature differences between the voice coils dependent on enclosure size Output from front of woofer cone  Can be difficult to construct Uses lots of room for the common pressure chamber Volume between woofer need to be as small as possible for best performance

 

Cone to cone

Output from rear of woofer Possible temperature differences between the voice coils dependent on enclosure size Easiest of all configurations to construct Uses least amount of space for set-up Coupling between the woofers is optimal Benefit of push-pull configuration

 

Magnet to magnet

Most difficult of applications to construct Temperature between woofer voice coils are identical Output from front of woofer cone Uses lots of room for the common pressure chamber Volume between woofer need to be as small as possible for best performance Benefit of push-pull configuration

[DavidR 32]

Thanks Bill and Rich. I had read up on the isobaric feature.

I am looking more for an opinion on the speaker itself. Seems Linn is top notch stuff.

 

I suppose the best thing to do is to go down there with my amp and try them out. I doubt my MkII will have a problem driving them.

[BillD 239]

I believe Scott (dyeraudio) and Mike (Rainman) on the other site have Linns.  Scott has Keilidhs and Mike has Kabers.