And it should be much wider in the highs compared to a pistonic driver like the ScanSpeak 10F/8424, you have experience with. 😉
That implies a more uniform power response. 🙂
Size matters....!
The little Tectonic BMR is good for small speakers / TV's / portables etc but it's tiny Sd severely limits its SPL and dynamics.
It might be classed as a 3 inch driver, but its Sd is only 19 square cm.
Compare this to the CS 4.5 inch rubber surround BMR which has an Sd over 3 times this, 60cm square from memory.
My silk surround 4.5 inch driver has an Sd of 70cm square.
If you are seeking anything more than background levels you will need to cross the Tectonic BMR over around 800Hz to 1,000Hz to a good bass / mid.
It does have an excellent power response, way better than any comparable cone or dome and this "room filling" sound does help compensate for its other limitations.
Overall its a great value driver and it will be interesting to hear your panels thoughts on how it compares to the other drivers.
All the best
Derek.
The little Tectonic BMR is good for small speakers / TV's / portables etc but it's tiny Sd severely limits its SPL and dynamics.
It might be classed as a 3 inch driver, but its Sd is only 19 square cm.
Compare this to the CS 4.5 inch rubber surround BMR which has an Sd over 3 times this, 60cm square from memory.
My silk surround 4.5 inch driver has an Sd of 70cm square.
If you are seeking anything more than background levels you will need to cross the Tectonic BMR over around 800Hz to 1,000Hz to a good bass / mid.
It does have an excellent power response, way better than any comparable cone or dome and this "room filling" sound does help compensate for its other limitations.
Overall its a great value driver and it will be interesting to hear your panels thoughts on how it compares to the other drivers.
All the best
Derek.
Hi Derek,
Do you have any measurements of those drivers? And do you know how BMRs look in the time domain (CSD)?
Seems like the bigger BMRs have a more uneven response vs the smaller ones. Perhaps not worse than it can fixed be EQ though. I would like to see off-axis response of the different sizes. Although BMRs are wider in the highs, I assume the bigger ones also here becomes narrower compared to the smaller ones.
You haven't tried a 6.5" BMR by the way?
Do you have any measurements of those drivers? And do you know how BMRs look in the time domain (CSD)?
Seems like the bigger BMRs have a more uneven response vs the smaller ones. Perhaps not worse than it can fixed be EQ though. I would like to see off-axis response of the different sizes. Although BMRs are wider in the highs, I assume the bigger ones also here becomes narrower compared to the smaller ones.
You haven't tried a 6.5" BMR by the way?
No doubt Overkill is right but on the other hand where else can you buy diy BMR drivers? Parts express has the Tectonic's neo drivers. Seems at least some potential for an on wall line array with these and subwoofers.
Yes indeed, I now also believe that onwall arrays is the best way to go with BMR drivers. I have tried it on multiple open baffles setups in the last year with a lot of fine tuning but it just didnt work.
Newest plan is as Derek mentioned; onwall arrays with digital EQ.
Newest plan is as Derek mentioned; onwall arrays with digital EQ.
A few updates
Hi Don,
You are right, the BMR's (any size) just dont work in open baffle....
I have found that BMR's are very sensitive to loading & they need a very specific sealed box volume tuned to the TS spec of the driver in order to deliver their full potential.
This does make tuning the design a lot more time consuming but hey thats half the fun in DIY!
For those seeking an off the shelf BMR kit which has had all the R&D done and just needs assembly I now have some options.
I am not sure if there is enough demand to make a production run viable so I might open a group buy to hit a minimum of say 15 pairs....?
First I am going to invite a few DIY guys round for a demo so they can post their impressions....PM me if anyone is interested😉
Cheers
Derek.
PS Omholt -
I had a demo of a Tymphany 6.5 inch BMR and it sounded muddy and lacked detail in the low midrange.
The top end was lacking in resolution.
I think the clue is in the heavy cone / weak motor, 13.5 g / 3.95 Bl = 3.4.
Combined with a rubber surround this driver will have a very poor CSD plot.
But its cheap so might be worth buying a pair?
Hi Don,
You are right, the BMR's (any size) just dont work in open baffle....
I have found that BMR's are very sensitive to loading & they need a very specific sealed box volume tuned to the TS spec of the driver in order to deliver their full potential.
This does make tuning the design a lot more time consuming but hey thats half the fun in DIY!
For those seeking an off the shelf BMR kit which has had all the R&D done and just needs assembly I now have some options.
I am not sure if there is enough demand to make a production run viable so I might open a group buy to hit a minimum of say 15 pairs....?
First I am going to invite a few DIY guys round for a demo so they can post their impressions....PM me if anyone is interested😉
Cheers
Derek.
PS Omholt -
I had a demo of a Tymphany 6.5 inch BMR and it sounded muddy and lacked detail in the low midrange.
The top end was lacking in resolution.
I think the clue is in the heavy cone / weak motor, 13.5 g / 3.95 Bl = 3.4.
Combined with a rubber surround this driver will have a very poor CSD plot.
But its cheap so might be worth buying a pair?
Last edited:
CSD plot....Mmmmn!
Hi Omholt,
The attached should give you a warm feeling inside....!
Its easy flatten the frequency response as I use DSP for crossover anyway.
Also "flat" is not a pleasant sound, best to have a gentle downwards by about 4dB to 6dB at 20KHz...Basically following the Fletcher Munson curves.
Cheers
Derek.
Hi Omholt,
The attached should give you a warm feeling inside....!
Its easy flatten the frequency response as I use DSP for crossover anyway.
Also "flat" is not a pleasant sound, best to have a gentle downwards by about 4dB to 6dB at 20KHz...Basically following the Fletcher Munson curves.
Cheers
Derek.
Attachments
Hi Derek, great to hear some of your new kit is ready for demo & can be bought as a kit, I am very much looking forward to hearing the silk surround BMR's, still loving my ol' rubber jobbies though
Kit options
Hi Octavia,
There are so many options and possibilities with different kits I need to get some idea of what price points / designs will be the most popular, so I need to get some DIY guys round for a listen and gather some feedback.
One thing I am confident about is that my BMR kits will blow away any kits from the mainstream suppliers....I have spent some time checking out a range of kits from various European suppliers.....£ for £ they cant come close to what I have already.
Jason, always happy to hear from your good self😀
Just let me know some dates last week in October or first week in Nov and I will set up a killer demo. How is the new house by the way?
Cheers
D.
Hi Octavia,
There are so many options and possibilities with different kits I need to get some idea of what price points / designs will be the most popular, so I need to get some DIY guys round for a listen and gather some feedback.
One thing I am confident about is that my BMR kits will blow away any kits from the mainstream suppliers....I have spent some time checking out a range of kits from various European suppliers.....£ for £ they cant come close to what I have already.
Jason, always happy to hear from your good self😀
Just let me know some dates last week in October or first week in Nov and I will set up a killer demo. How is the new house by the way?
Cheers
D.
Cheers Derek, one day during the last week of October could work for me, I'll find out & check what works with you.
New house is working out great thank you, only renting for now so my BMR's are only fixed up in a temporary fashion but still sounding superb.
I'm really pleased for you that all your work on these things is now coming together for you.
So what does your home system look like these days? I recall you building line-sources with these drivers and seemed very happy?
Or did I mix it up with someone else?
//
Hi Derek
It looks nice, but would you mind posting something with around 50dB headroom and 3ms time window?
Have you made some on and off axis FR measuements yet?
Home system....
Hi TNT,
My home system constantly changes depending on who is coming for a demo.
Varies from stereo near-field studio monitors (under 15 litres) to full on 7.2 home cinema with up to 43 of my silk surround BMR's (Front L / R / centre with 9 drivers each ) plus a pair of singles for rears.
We still use the 1.8 meter tall line arrays ( rubber surround BMR's) as they are great in commercial environments like gyms and bars, crossed over at 80Hz to subs they really kick ***!
We have finished our power amps and DAC's and are still waiting on the DSP, this is way behind schedule so we are using a DSP board OEM'd from a very well respected supplier.
Also use off the shelf Yamaha AV amps a fair bit, they are great value and their DSP / Eq sound quality is very good.
Cheers
D.
Hi TNT,
My home system constantly changes depending on who is coming for a demo.
Varies from stereo near-field studio monitors (under 15 litres) to full on 7.2 home cinema with up to 43 of my silk surround BMR's (Front L / R / centre with 9 drivers each ) plus a pair of singles for rears.
We still use the 1.8 meter tall line arrays ( rubber surround BMR's) as they are great in commercial environments like gyms and bars, crossed over at 80Hz to subs they really kick ***!
We have finished our power amps and DAC's and are still waiting on the DSP, this is way behind schedule so we are using a DSP board OEM'd from a very well respected supplier.
Also use off the shelf Yamaha AV amps a fair bit, they are great value and their DSP / Eq sound quality is very good.
Cheers
D.
Measurements....Just a sneak preview!
Hi Snickers,
I have only released this sneak preview CSD as a teaser....There is no way I would publish any of my home measurements or any of the UoM measurements on a DIY forum.....That opens up a whole can of worms!
Only when the whole system is complete and ready for its commercial launch will we publish the full suite of independent measurements including full anechoic chamber polars, CSD, impulse, step and all the usual THD and frequency graphs.
All these measurements will be carried out by a very well respected & totally independent third party with state of the art equipment....That is the only way to avoid the can of worms where all the DIY armchair experts complain about poor quality or fake measurements /results.
The DIY market is the smallest and least profitable of all the audio markets but there are still a million plus of them and they all think they know best and are only too happy to post their opinions....So, "for the avoidance of doubt" our measurements will only be posted on our website when we have the finished system boxed and ready to ship.....It will be well worth the wait!
Until the whole system is ready we are happy to give demo's as even conventional electronics drive our speakers beautifully.
All the best
Derek.
Hi Snickers,
I have only released this sneak preview CSD as a teaser....There is no way I would publish any of my home measurements or any of the UoM measurements on a DIY forum.....That opens up a whole can of worms!
Only when the whole system is complete and ready for its commercial launch will we publish the full suite of independent measurements including full anechoic chamber polars, CSD, impulse, step and all the usual THD and frequency graphs.
All these measurements will be carried out by a very well respected & totally independent third party with state of the art equipment....That is the only way to avoid the can of worms where all the DIY armchair experts complain about poor quality or fake measurements /results.
The DIY market is the smallest and least profitable of all the audio markets but there are still a million plus of them and they all think they know best and are only too happy to post their opinions....So, "for the avoidance of doubt" our measurements will only be posted on our website when we have the finished system boxed and ready to ship.....It will be well worth the wait!
Until the whole system is ready we are happy to give demo's as even conventional electronics drive our speakers beautifully.
All the best
Derek.
Hi Derek
Thanks for you feedback.
I am really not used to be called an DIY armchair expert. Not sure what to make of that.
The members opinions are probably not damaging, unless you are not sure how to respond. However, allow me to remind you that you have allready chosen to post this on a DIY forum. It is probably not a good idea to present your negative view on the members general knowledge and agenda. I suspect you will end up getting more critical views on this with a 20dB CSD than you would have had on a more revealing measurement.
My document holder is stationary....
Hi Snickers,
I have seen a lot of the small commercial vendors fall into the bottomless pit of trying to satisfy a thousand different requests for different measurement types and parameters....It always ends in a mess.
I will not make that mistake and as I explained, the CSD plot is just a sneak preview, not a definitive suite of results.
When the measurements are published on the website I will post a link and then all the DIY guys and commercial guys can make informed decisions and comment on the products based on accurate data and results which conform to AES standards.
I believe this is the best approach and it will benefit the majority of the DIY guys.
If some individuals prefer to have a particular type of measurement taken in a different way or to meet a different standard I can arrange for this....I get charged £800 per day for the hire of the anechoic chamber / equipment and the acoustic engineers time.....I am happy to pass this on at cost to meet any DIY members requests....Payment in advance please!😉
Cheers
Derek.
Hi Snickers,
I have seen a lot of the small commercial vendors fall into the bottomless pit of trying to satisfy a thousand different requests for different measurement types and parameters....It always ends in a mess.
I will not make that mistake and as I explained, the CSD plot is just a sneak preview, not a definitive suite of results.
When the measurements are published on the website I will post a link and then all the DIY guys and commercial guys can make informed decisions and comment on the products based on accurate data and results which conform to AES standards.
I believe this is the best approach and it will benefit the majority of the DIY guys.
If some individuals prefer to have a particular type of measurement taken in a different way or to meet a different standard I can arrange for this....I get charged £800 per day for the hire of the anechoic chamber / equipment and the acoustic engineers time.....I am happy to pass this on at cost to meet any DIY members requests....Payment in advance please!😉
Cheers
Derek.
Hi Derek,
Will the electronic Xover/DSP unit be just devoted to the BMR system or will it be useful for other applications, and uses friendly?
Will the electronic Xover/DSP unit be just devoted to the BMR system or will it be useful for other applications, and uses friendly?