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Martin Colloms Offline
#101 Posted : 19 August 2011 11:21:25(UTC)
Martin Colloms


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Off the top,

I have no idea ,

and have never heard these TL speakers

the differences are so diverse I would not know where to begin

25 years of speaker design history might have something to do with it, though I still, in context

admire the BBC LS3/5a 15ohm original of an earlier date

Come and hear the TRK at NAS



http://www.chestergroup....mp;id=81&Itemid=229


Martin C

Martin Colloms Offline
#102 Posted : 24 August 2011 19:22:45(UTC)
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We will shortly post on the site in a TRK section: the enclosure drawings, the crossover, the first feature article, the responses , photos , the driver details, and the designers and suppliers

Martin Colloms
ashleym Offline
#103 Posted : 21 September 2011 18:32:57(UTC)
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At last a website for the BMR driver

http://www.cotswoldsoundsystems.com/index.htm
Matt Offline
#104 Posted : 08 October 2011 14:48:09(UTC)
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Could a BMR be used in a standmount loudspeaker?
Martin Colloms Offline
#105 Posted : 08 October 2011 17:30:01(UTC)
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We have shown that it is a fine low mid to treble driver for the money and a compact two way stand mount is entirely possible

for me a long throw sealed 61/2 inch in 18 litres would be about right

TRK CXover could be quite easily adapted for it

Martin Colloms
Iston User is suspended until 03/06/2039 16:20:34(UTC)
#106 Posted : 12 October 2011 13:30:30(UTC)
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Martin,

I'm curious about possible heat dissipation problems. I've just glanced at the specification and it seems that the chassis of the BMR unit is made of "engineering plastic". I know that ordinary tweeters can have over-heating issues, even with all-metal bodies. The BMR unit is also carrying all the mid-range and some of the bass, so potentially has to dissipate a lot of heat. How does it handle this? Does the sound change much as the temperature increases?
darkmatter Offline
#107 Posted : 12 October 2011 13:40:06(UTC)
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Martin Colloms wrote:
We have shown that it is a fine low mid to treble driver for the money and a compact two way stand mount is entirely possible

for me a long throw sealed 61/2 inch in 18 litres would be about right

TRK CXover could be quite easily adapted for it

Martin Colloms


Now there's an idea for me to play with Wink
Martin Colloms Offline
#108 Posted : 13 October 2011 18:44:29(UTC)
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Iston wrote:
Martin,

I'm curious about possible heat dissipation problems. I've just glanced at the specification and it seems that the chassis of the BMR unit is made of "engineering plastic". I know that ordinary tweeters can have over-heating issues, even with all-metal bodies. The BMR unit is also carrying all the mid-range and some of the bass, so potentially has to dissipate a lot of heat. How does it handle this? Does the sound change much as the temperature increases?









The unit is rated at 12W 50Hz to 20kHz

It comes in at 330Hz and is in addition attenuated by 3dB

that allow for a '24 W' rating , and then allow for the removal of the powerful LF range.

In its working band a fair rating would be 50W

Now it all depends how you drive the system but most tweeters are rated only a few watts yet operate in 200W program rated designs.

The Cotswold driver is rated for IEC continuous pink noise in the defined music related spectrum. Heat is dissipated via the magnet and some air 'convection' around the voice coil.

We rate TRK at nominally 100W programme.
Martin C
schadenfreude Offline
#109 Posted : 24 July 2012 07:23:20(UTC)
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Any chance of this speaker design article being put on the website or can be purchased as a pdf online?
Martin Colloms Offline
#110 Posted : 25 July 2012 09:07:11(UTC)
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I will ask the wizard to post the PDFs
Martin C






its here http://www.hificritic.com/sales/digital9.aspx

Edited by user 25 July 2012 15:31:46(UTC)  | Reason: Not specified

schadenfreude Offline
#111 Posted : 26 July 2012 14:47:08(UTC)
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Fantastic! Thanks Martin!
Martin Colloms Offline
#112 Posted : 01 August 2012 11:35:21(UTC)
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that's about right

Martin Colloms
schadenfreude Offline
#113 Posted : 26 August 2012 15:49:28(UTC)
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Thanks for posting the design online, i've gotten them up over the weekend and have been listening to them.

Posted by the Densen integrated, they give a very impressive performance so far but tends to sound abit etchy & harsh in the mids. The BMR should burn in over time... the lack of a crossover in the mids is telling, vocals and instruments are very coherent.

The bass just kicks ass, very toe tappy!

Pic of my TRKs

Edited by user 26 August 2012 15:50:13(UTC)  | Reason: Not specified

ashleym Offline
#114 Posted : 27 August 2012 12:09:25(UTC)
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Hoo-ray and well done. Keep us posted on how they progress. I see siting them wasnt and problem with the TRKs liking being close up to the rear wall- take note other speaker designers......
Martin Colloms Offline
#115 Posted : 27 August 2012 14:05:58(UTC)
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Originally Posted by: schadenfreude Go to Quoted Post
Thanks for posting the design online, i've gotten them up over the weekend and have been listening to them.

Posted by the Densen integrated, they give a very impressive performance so far but tends to sound abit etchy & harsh in the mids. The BMR should burn in over time... the lack of a crossover in the mids is telling, vocals and instruments are very coherent.

The bass just kicks ass, very toe tappy!

Pic of my TRKs


The BMR's do settle for a little, while the best balance for the TRK is found by carefully angling them inwards a few degrees at a time from a straight ahead position , checking on stereo focus.

They major on clarity immediacy and timing but there is some residual mild roughness in the upper mid and high treble.

If the system and room acoustic seems unsympathetic the series resistor to the mid can be increased in small stages to soften the tonal balance, say 0.22 ohms a time.

More costly crossover parts also improve the sound somewhat

Martin Colloms

Edited by user 22 March 2013 15:16:30(UTC)  | Reason: Not specified

RealityTunnel Offline
#116 Posted : 16 October 2012 22:53:15(UTC)
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I'm curious about building a pair to possibly replace some Quave LS-1s, love the idea of something I can place close to a wall retaining bass timing and rythmn, but trying to get away from a slightly edgy mid/treble in the Quaves. Is this subtle in the TRKs, or quite noticeable? How much can you tame it by the above resistor mod, etc.? If not, any suggestions for something smoother up top, while still retaining clean bass, rythmn and drive, please?
Matt Offline
#117 Posted : 20 March 2013 18:44:12(UTC)
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Just out of curiosity, could the TRK's be built using the smaller 46mm BMR instead?

I expect the treble and midrange would be quieter than the larger BMR?
ashleym Offline
#118 Posted : 22 March 2013 13:21:42(UTC)
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I am sure Martin will have the right answer but I would say no as a drop in replacement. If you have read the spec sheet and seen a lower efficiency then that is one reason. ALso a different BMR might have different bending waves that need filtering differently. And the unit wont fit the cabinets from Wilmslow. I think the best advice is to go with the speaker as it was designed!!
Martin Colloms Offline
#119 Posted : 22 March 2013 15:21:57(UTC)
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hear hear !

the inner balance is to full commercial , rather than 'knock it together kit' standards

If you want to change it , build it first and see where you want to go from there.

Quite subtle technical changes are immediately audible

The BMR is at its best on the end of an amplifer

so the two way active version will have the usual massive active gain plus the happier BMR to boot

Martin Colloms
Matt Offline
#120 Posted : 23 March 2013 15:28:46(UTC)
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Thanks for the reply A+M Smile

Was the 46mm inferior to the larger version, or just not suitable for the TRK?

Edited by user 23 March 2013 15:30:57(UTC)  | Reason: Not specified

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