Meridian - The Art Of Loudspeaker design
One area of speaker design which is often overlooked is the speaker driver/cabinet interface. Ensuring a uniform clamping force to control resonances and seal the driver against the cabinet is a major part of any loudspeaker design.
The majority of loudspeaker drivers utilise bolts locating through the driver mounting flanges and into threaded inserts or even into the bare wood. This design has a number of weaknesses, firstly the clamping force of the bolt is transferred to a small areas of flange around the hole. This can lead to an over compression of the cabinet mounting wood flange around the bolt hole with eventual relaxation of the wood and a potentially loose driver. Owners are then encourage to tighten their drivers. Over tightening can lead to further problems with the potential for distorting the speaker driver flanges between the mounting holes leading to poor sealing and subsequent air leaks. We have seen this problem on a number of early DSP5000 loudspeakers.
Meridian addressed this design issue with the introduction of clamp rings, initially implemented on the Legacy DSP8000.
DSP8000 - Clamp Rings since launch at CES las vegas 2000
What is not generally appreciated is that all DSP8000’s have clamp rings since their launch in Yr 2000. Technically, the legacy and Speaker Link version clamp rings (8 Holes) are mounted with their bolts through the clamp ring, the driver mounting flange holes and into the cabinet threaded inserts. The clamp ring spreads the external clamping force on the driver mounting flange over the whole of the driver/cabinet interface.
The 'Ruby' and SE Clamp Rings
The first use of the ‘enhanced clamp ring’ was first introduced on the 40th Anniversary ‘Ruby’ Limited Edition Loudspeaker in the Autumn of 2011.
This also coincided with the change of driver chassis from the previous CA21 (8 hole) chassis to the CA22 (6 hole) chassis for the bass drivers, the mid range had a similar change. Specification and performance wise they are the same, the only difference being a larger diameter driver mounting flange on the replacements.
For aesthetic balance, Meridian does not orientate driver to cabinet along vertical bolt lines. This has an effect on the Legacy and SL DSP8000. The original DSP8000 mid range driver uses a T17 Chassis (8 bolt). This driver orientates the driver connecting coil wires to a bolt position. This can be clearly seen through the mid range poly driver. This means the coil wires can be seen offset by a bolt pitch (nominally to the left in the examples we have seen).
With the larger chassis T18 mid range driver (6 bolt) used in the Ruby/SE models the wires are orientated between bolts pitches, allowing the wires to be orientated vertically.
Technically the alternate driver chassis sizes T18 and CA22 were first introduced with the launch of the DSP7200 pre dating the DSP8000 Ruby introduction, With the SE range these new driver chassis sizes were consolidated across the bothe DSP8000SE (and DSP8000.2) , DSP7200SE and SE Centre variants.
Jewel in The Crown
The 'Ruby' DSP8000 is therefore quite literally a jewel in Meridian's crown giving us the design elements that shaped the both the SE and .2 product ranges. A true celebration of achievement.
An SE upgraded Ruby would be the finest speaker Meridian ever produced.
clamp rings - Evolutionary Design enhancements
Meridian’s engineers realised that they could enhance the clamping aspect of the original DSP8000 clamp rings further
In place of the cabinet threaded inserts, internally mounted extended curved and pressed steel pieces are placed around the internal circumference held in place with ‘through’ screws from the cabinet mounting flange. These individual steel peices are used as a complete ring would not fit through the finished speaker driver hole.
The clamp rings then clamp through using bolts into threaded portions of the pressed steel. This design enables an increased clamping force to be achieved across the driver/cabinet interface from both sides.
Another enhancement included a thin gasket added to the internal surface of the SE clamp ring avoiding any metal to metal interference with the drive unit.
This resulted in a superb design which is why the clamping ring configuration across the entire SE range adds significantly to the magnificeant sound quality of the SE range.
The DSP8000SE X-Ray
If you look at some of Meridian’s recent promotional 'x ray skeletal ’ material of the DSP8000SE you can clearly see the clamp ring arrangement.These images were created by eminent x-ray artist, Nick Veasey,
We have in the recent past modified a legacy DSP8000 with the SE design elements using complete internal threaded pressed steel rings. However we would not recommend this undertaking as it requires precise cabinet modification and design considerations.
Changing The Colour
If you require an SE silver clamp ring appearance, you can always polish or paint your DSP8000 clamp rings but be careful with polishing as you can potentially loose edge detail. Changing the clamp ring colour by re anodising involving stripping off the original anodising and re-applying, this can result in variable colour finish, loss of detail and dimension.
We have been asked if you can add clamp rings to other Legacy products, well not easily and not economically. Here we have an example of a DSP5500 showing a CA21 chassis driver (same driver used in original DSP8000, DSP6000 and DSP7000) bolted directly to the loudspeaker cabinet.
There is not enough inner circumference on the cabinet to accommodate a clamp ring. A major cabinet modification would be required for an unquantifiable gain in performance.
Please note that the driver mounting flange is also sometimes and rather confusingly referred to as a clamp ring, i,e the ring of the driver which clamps to the cabinet.
This actual image perfectly demonstrates how and why Meridian developed clamp rings for this driver with the original DSP8000. The drive mounting flange is narrow and not unduly thick making it difficult to clamp uniformly around its circumference without mechanical distortion. Clamp rings solved this design consideration.
ALL DSP8000 variants have clamp rings.
The Ruby and SE variants added additional internal clamping elements. Note the DSP8000.2 can be upgraded to the full SE specification as it already has the 6 bolt SE clamp ring ring arrangement.
SE clamp rings are not interchangeable with legacy or SL models (bolt hole configuration with change of chassis) which is why Meridian are unable to offer them as part of the SE upgrade.
The longevity of the DSP8000 and it's ongoing worldwide enduring appeal is supported by an amazing design, through to the finest detail. Whatever flavour of clamp rings you have, you own one of the finest sounding loudspeakers in the world, enjoy the music!
The views and facts presented here have been collated by observation of Meridian products and publicly available information. No reverse engineering in any form has been undertaken. This blog is an extract from 'Meridian Evolution' a blog to be presented soon..