Hi Derek, thanks for the helping advice.
I have some testing enclosures around which are about 14 liters, mount new baffles on it and test the BMR's in the next weeks, when I have more time.
Meanwhile listening to the OB.
Cheers,
Don C.
I have some testing enclosures around which are about 14 liters, mount new baffles on it and test the BMR's in the next weeks, when I have more time.
Meanwhile listening to the OB.
Cheers,
Don C.
Happy to help if I can!
If you are a perfectionist (like me!) and can be bothered with the hassle, here is a good method to ensure you get the exact cabinet volume that is the best overall compromise for your ears / room, between cabinet size and optimum Q.
(1) Line the cabinet walls with 5mm to 8mm of good dampening material and then test the exact cabinet volume by pouring in dry rice to completely fill the cabinet up to the level the flat BMR cone will be at.
Then pour this rice into an accurate measuring jug and note the exact cabinet volume. (The BMR driver chassis takes up approx 0.1 liter of volume)
(2) Fill 20 soft cotton bags with each bag containing exactly 1 liter of rice, and 10 more bags, each one with 0.5 liters of rice.
Note, the empty cotton bags will also have a "volume"....Compress all the bags and estimate the total volume of the pile, then divide that volume by the number of bags to work out each bags volume.
(3) Now conduct your listening tests, adding / subtracting bags of rice to decrease / increase the internal volume of air the driver will be loaded by....Take your time....!
To help you get a feel for the changes, you can go from empty to almost full as your first comparison and this will give you a handle on the two extreme ends of the scale....Then slowly "home in" on your favorite sound / size compromise.
Please note, before you start your listening tests fully run in the BMR's by running them full range with bass heavy music at high enough SPL to get the BMR cones moving a good plus / minus 1mm or 2mm for at least 20 or 30 hours....This is important!
All the best
Derek.
If you are a perfectionist (like me!) and can be bothered with the hassle, here is a good method to ensure you get the exact cabinet volume that is the best overall compromise for your ears / room, between cabinet size and optimum Q.
(1) Line the cabinet walls with 5mm to 8mm of good dampening material and then test the exact cabinet volume by pouring in dry rice to completely fill the cabinet up to the level the flat BMR cone will be at.
Then pour this rice into an accurate measuring jug and note the exact cabinet volume. (The BMR driver chassis takes up approx 0.1 liter of volume)
(2) Fill 20 soft cotton bags with each bag containing exactly 1 liter of rice, and 10 more bags, each one with 0.5 liters of rice.
Note, the empty cotton bags will also have a "volume"....Compress all the bags and estimate the total volume of the pile, then divide that volume by the number of bags to work out each bags volume.
(3) Now conduct your listening tests, adding / subtracting bags of rice to decrease / increase the internal volume of air the driver will be loaded by....Take your time....!
To help you get a feel for the changes, you can go from empty to almost full as your first comparison and this will give you a handle on the two extreme ends of the scale....Then slowly "home in" on your favorite sound / size compromise.
Please note, before you start your listening tests fully run in the BMR's by running them full range with bass heavy music at high enough SPL to get the BMR cones moving a good plus / minus 1mm or 2mm for at least 20 or 30 hours....This is important!
All the best
Derek.
Hi Derek,
Thanks for the tip. That is a very good way to find out exactly!
I use to do it by adding or removing pieces of stone. But your system is better!
Oh, and I built a slideable back once, which I could check afterwards.
By the way I checked the volume with the parameters and you were right, 14 liters is a Qtc of 0.707.
Although I saw in The Rythem King, they used 7 liters.
Greetings,
Don C.
Thanks for the tip. That is a very good way to find out exactly!
I use to do it by adding or removing pieces of stone. But your system is better!
Oh, and I built a slideable back once, which I could check afterwards.
By the way I checked the volume with the parameters and you were right, 14 liters is a Qtc of 0.707.
Although I saw in The Rythem King, they used 7 liters.
Greetings,
Don C.
Kit Contents
Hi Derek,
I'm sold on the double silk surround BMRs and would certainly like a kit maybe 6 driver line array with DSP, but I already have a Naim N-Sub and 2X Job 225 power amps, which are all rather good, would there be an option to purchase just the drivers cabinet and DSP?
Hi Derek,
I'm sold on the double silk surround BMRs and would certainly like a kit maybe 6 driver line array with DSP, but I already have a Naim N-Sub and 2X Job 225 power amps, which are all rather good, would there be an option to purchase just the drivers cabinet and DSP?
Hi Santa Claws,
Glad to hear you are "pre-sold"....All I need is a few thousand more guys like you and then I can sell the company to Sony!!😀
Happy to set up a demo day where you can bring round your subs / amps ( I am a fan of the high slew rate / high bandwidth Job amps!) and compare them to my subs / amps.
I suspect the silk BMR's will love the Job amps.
I know nothing about the Naim subs.....Are they sealed or ported?
This coming week is a already solid, but next week or the following week will be good.
Must dash at the mo but back on line this evening.
All the best
Derek.
Glad to hear you are "pre-sold"....All I need is a few thousand more guys like you and then I can sell the company to Sony!!😀
Happy to set up a demo day where you can bring round your subs / amps ( I am a fan of the high slew rate / high bandwidth Job amps!) and compare them to my subs / amps.
I suspect the silk BMR's will love the Job amps.
I know nothing about the Naim subs.....Are they sealed or ported?
This coming week is a already solid, but next week or the following week will be good.
Must dash at the mo but back on line this evening.
All the best
Derek.
Taste
No need for a dem, we seem to have similar tastes, rubber surounds yuch! too slow and "rubbery" my last Project used Precision Devices 15", I do have 4 Eminence Deltalite 15" but the Naim N-Sub is good, sealed box and fast, not certain if its foam or rubber surround but Naim always seem to get fast bass out of their speakers. I'm disabled anyway so dem would be impossible, I have to save more pennies and sell some stuff first, think I'll stick those Eminence on swapmeet. right now. Cheers Derek, I'll be in touch.
No need for a dem, we seem to have similar tastes, rubber surounds yuch! too slow and "rubbery" my last Project used Precision Devices 15", I do have 4 Eminence Deltalite 15" but the Naim N-Sub is good, sealed box and fast, not certain if its foam or rubber surround but Naim always seem to get fast bass out of their speakers. I'm disabled anyway so dem would be impossible, I have to save more pennies and sell some stuff first, think I'll stick those Eminence on swapmeet. right now. Cheers Derek, I'll be in touch.
Hi Derek,
I'm thinking about getting one of the PD1550's to have a play with & see how it sounds underpinning my BMR's,what size cabinet would you suggest for this driver ? I have a Behringer amp with with DSP so I could use that to lift the bottom end a bit,I need to get a UMIK or similar so I can measure what frequency response I end with before I start fiddling with that though 🙄
PD 1550 great driver
Hi Jason,
I have used a few PD drivers, they are great off the shelf drivers and built to last a lifetime.
I used the 1550 as a reference driver and it was hard to beat!
My own 15 inch has a slight performance advantage in all the areas I look for:
(1) Mms to Bl ratio is 4.3 for the PD Vs 4.1 for my drivers.
(2) Both have 4 inch voice coils but mine is rated at 800 watts AES continous with 1,600 watt peaks.
(3) PD Ref Efficiency is 3.14%, mine is over 4.5%.
(4) Lastly my driver needs about 25 % less air volume and reaches slightly higher SPL's with slightly lower distortion at any frequency under 200Hz.
Its not really a fair comparison though as my drivers are designed for small sealed box's ....The PD is really a touring bass bin / front horn driver.
Happy to compare them if you build one up and bring it over for a demo.
You will not notice much difference below 100Hz, but between 100Hz and 200Hz the PD gets a bit muddy with male vocals and Cello when compared to my driver.
Got some big demos coming up soon so assembling a killer system, if you liked it the last time you are not going to believe what you'll hear next time.... 😀
All the best
Derek.
Hi Jason,
I have used a few PD drivers, they are great off the shelf drivers and built to last a lifetime.
I used the 1550 as a reference driver and it was hard to beat!
My own 15 inch has a slight performance advantage in all the areas I look for:
(1) Mms to Bl ratio is 4.3 for the PD Vs 4.1 for my drivers.
(2) Both have 4 inch voice coils but mine is rated at 800 watts AES continous with 1,600 watt peaks.
(3) PD Ref Efficiency is 3.14%, mine is over 4.5%.
(4) Lastly my driver needs about 25 % less air volume and reaches slightly higher SPL's with slightly lower distortion at any frequency under 200Hz.
Its not really a fair comparison though as my drivers are designed for small sealed box's ....The PD is really a touring bass bin / front horn driver.
Happy to compare them if you build one up and bring it over for a demo.
You will not notice much difference below 100Hz, but between 100Hz and 200Hz the PD gets a bit muddy with male vocals and Cello when compared to my driver.
Got some big demos coming up soon so assembling a killer system, if you liked it the last time you are not going to believe what you'll hear next time.... 😀
All the best
Derek.
Hey Derek,
I have no doubt that the woofers you have fine tuned will easily outperform the 1550 but I can pick one up for £200 & already have the Behringer,plus I'm in a rented house for a while so until I get my own home again I can't afford to invest too heavily in any new toys 🙁
I know I've already said it a few times but I'm definitely up for another visit to demo your latest kit,I want some money in my pocket when I do though because I don't intend to leave empty handed 😛
I have no doubt that the woofers you have fine tuned will easily outperform the 1550 but I can pick one up for £200 & already have the Behringer,plus I'm in a rented house for a while so until I get my own home again I can't afford to invest too heavily in any new toys 🙁
I know I've already said it a few times but I'm definitely up for another visit to demo your latest kit,I want some money in my pocket when I do though because I don't intend to leave empty handed 😛
Cant go wrong at £200....
Nice one Jason, the PD 1550 is a great driver and it will be way better than the Peerless subs!
My loading requires a big amp.... ie something that wont clip when supplying the PD with all the power it can handle, and thats a lot of power!
Once you have the driver, send me the details of your power amp / crossover and I will work out a good set up for you.
All the best
D.
Nice one Jason, the PD 1550 is a great driver and it will be way better than the Peerless subs!
My loading requires a big amp.... ie something that wont clip when supplying the PD with all the power it can handle, and thats a lot of power!
Once you have the driver, send me the details of your power amp / crossover and I will work out a good set up for you.
All the best
D.
Thanks Derek,that's very cool of you 🙂
The amp is a Behringer NU6000dsp, it can make a continuos 1000w per channel into 8 ohms.
Crossover is done in my Lyngdorf integrated amp,independently selectable filters on high & lowpass,Butterworth or Linkwitz Riley,1st,2nd,4th or 8th order slopes.
Does anyone know if Cotswold Sound Systems is still in business?
Are there anyone else who sell 1.5" (or smaller) BMR drivers?
Are there anyone else who sell 1.5" (or smaller) BMR drivers?
I believe so, but I think you can only generally buy from them as a commercial customer. That said, they do appear to be offering the 2.5" units for general sale, but you have to email them - There is no shop front.
Commercial customer works fine.
I have contacted them but haven't received a reply and heard rumours they are out of business.
I have contacted them but haven't received a reply and heard rumours they are out of business.
I bought 2 from them last month. On their web page there was a special offer on at 50% normal price. I didn´t ask why but service was first class.
Any suggestions for a 8" woofer to use together with the 2.5" BMR driver below?
Cross over anywhere from 300-600 Hz, depending on how the 2.5" BMR performs.
It needs to work well without a subwoofer.
http://www.cotswoldsoundsystems.com/specifications/CSS_Specification_Sheet_BMR46XE_N8R_r1.pdf
Cross over anywhere from 300-600 Hz, depending on how the 2.5" BMR performs.
It needs to work well without a subwoofer.
http://www.cotswoldsoundsystems.com/specifications/CSS_Specification_Sheet_BMR46XE_N8R_r1.pdf
Just got my BMR speakers running again after moving into a rented house a couple of months ago, they sound just as great as I remembered in my previous house & I'm amazed they aren't getting more use, both in commercial & DIY designs.
Check out the new BMR from Tectonics. It has a rather smooth response and will be included in the round 5 lineup for Subjective Blind test.
http://www.parts-express.com/pedocs/specs/297-2157--temb46c20n-4b-2-spec-sheet.pdf
http://www.parts-express.com/pedocs/specs/297-2157--temb46c20n-4b-2-spec-sheet.pdf
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