ShinOBIWAN
---Anyway what I'd like to ask is would the 2500.1 perform well in a sealed enclosure and what qts value would be acceptable using this driver. I've ran the figures on ISD but the response seems horribly biased to the mid-bass rather than the really low <30hz, which is what I'm after.
Am I doing something wrong?---
I have been simulating closed boxes with very low Q drivers and simple 6 dB/o boosts. Results are impressive on the papers, a Qtb of 0.4 works well.
The question is how to have a very low Q.
An amplifier with negative resistance output can be used. This was all the idea suggested by Russel Breden in Electronics World which had appealed me a lot. I even planned to open a thread about it. I tried it with simple 8' drivers and it worked fairly well. Jeff Macauley published a full project based on the Breden's idea in the same magazine.
The second way to achieve a low Q is the introduction of some kind of velocity feedback, easy to achieve with DVC drivers.
With both the above solutions, you do not need drivers with huge magnets, and they are more efficient than the one below. One must not forget that local efficiency in the bass region near the resonance is higher with smaller magnets.
The third solution is the lazy one as it does not involve complex electronics but it is not efficient : get a driver with an initial very low Q.
I have been looking at many drivers on the market and found that the Volt drivers are good candidates for the Breden's idea. I am happy that a thread about the products of this company has been opened.
---Anyway what I'd like to ask is would the 2500.1 perform well in a sealed enclosure and what qts value would be acceptable using this driver. I've ran the figures on ISD but the response seems horribly biased to the mid-bass rather than the really low <30hz, which is what I'm after.
Am I doing something wrong?---
I have been simulating closed boxes with very low Q drivers and simple 6 dB/o boosts. Results are impressive on the papers, a Qtb of 0.4 works well.
The question is how to have a very low Q.
An amplifier with negative resistance output can be used. This was all the idea suggested by Russel Breden in Electronics World which had appealed me a lot. I even planned to open a thread about it. I tried it with simple 8' drivers and it worked fairly well. Jeff Macauley published a full project based on the Breden's idea in the same magazine.
The second way to achieve a low Q is the introduction of some kind of velocity feedback, easy to achieve with DVC drivers.
With both the above solutions, you do not need drivers with huge magnets, and they are more efficient than the one below. One must not forget that local efficiency in the bass region near the resonance is higher with smaller magnets.
The third solution is the lazy one as it does not involve complex electronics but it is not efficient : get a driver with an initial very low Q.
I have been looking at many drivers on the market and found that the Volt drivers are good candidates for the Breden's idea. I am happy that a thread about the products of this company has been opened.
Hi
I agree the B2500 does not look good when modeled for a ported design, however it is ideal for a passive low pass filiter. If you look at any LC bass filter there is normally a response peak at 100 to 200Hz caused by the series inductor, especially if the inductor has a low DCR. When you combine this with B2500 response it tends to equalise out and give you a nice flat response. You do loose around 2dB of sensitivity in practice but the resulting bass sound is excellent and goes down to 30Hz. This effect makes the low pass filter very simple as you kind of got built-in equalisation. You could equalise for a closed box but you will loose far more sensitivity. (-6db at 60Hz). Velocity feedback is certainly an interesting area but way more complex. Personally I like passive crossovers because I can use a large soldering iron and components I can actual see with my bad eye sight.
I agree the B2500 does not look good when modeled for a ported design, however it is ideal for a passive low pass filiter. If you look at any LC bass filter there is normally a response peak at 100 to 200Hz caused by the series inductor, especially if the inductor has a low DCR. When you combine this with B2500 response it tends to equalise out and give you a nice flat response. You do loose around 2dB of sensitivity in practice but the resulting bass sound is excellent and goes down to 30Hz. This effect makes the low pass filter very simple as you kind of got built-in equalisation. You could equalise for a closed box but you will loose far more sensitivity. (-6db at 60Hz). Velocity feedback is certainly an interesting area but way more complex. Personally I like passive crossovers because I can use a large soldering iron and components I can actual see with my bad eye sight.
Hi
The idea (which may not be very good...) of my project using some servo around a closed box is to use use a dual voice coil driver, one of the coil being a velocity sensor which voltage is reinjected to the amp such as the Qtb is only halved. Some simulation convinced me that, in this case, there is no stability problems, particularly those, well known with servoing or using negative resistance, commonly related to the inductance of the voice coil.
A closed box speaker with a fréquencey around 50 -60 Hz and a Qtb of 0.8. is easily built. The servo would drop the Qtb to 0.4. A boost of 12 dB ahead of the amplifier brings back the response to -5 dB at 30 Hz which I think may be ideal in typical listening rooms.
The idea (which may not be very good...) of my project using some servo around a closed box is to use use a dual voice coil driver, one of the coil being a velocity sensor which voltage is reinjected to the amp such as the Qtb is only halved. Some simulation convinced me that, in this case, there is no stability problems, particularly those, well known with servoing or using negative resistance, commonly related to the inductance of the voice coil.
A closed box speaker with a fréquencey around 50 -60 Hz and a Qtb of 0.8. is easily built. The servo would drop the Qtb to 0.4. A boost of 12 dB ahead of the amplifier brings back the response to -5 dB at 30 Hz which I think may be ideal in typical listening rooms.
i recently built a prototype with a 3143,75/150(non S),& ss9700.
the 3143 was a bad,bad recone that i was able to use untill my new 12s arrived. iam now going with 2-3143's/cabinet at 113l/12
i have sold a pair of PMC IB1's because the ATC mid is more,actually much more to my liking.
i am also going with 2-220.8's,atc mid,and 9700 for center.
never heard the Raal before but there is lots of good comments.
10's and 18's,you have some serious woofer dough($) going on.
2-3143's would be cheaper?????
john
the 3143 was a bad,bad recone that i was able to use untill my new 12s arrived. iam now going with 2-3143's/cabinet at 113l/12
i have sold a pair of PMC IB1's because the ATC mid is more,actually much more to my liking.
i am also going with 2-220.8's,atc mid,and 9700 for center.
never heard the Raal before but there is lots of good comments.
10's and 18's,you have some serious woofer dough($) going on.
2-3143's would be cheaper?????
john
if you take a tweeter like seas(which ever is best with atc) then you add 2 x b2500 with that will you be able to lower the frequency in the woofer,instead of -3 db in 30hz,get -3 db 20 or 25hz?because of the efficency?or it's better to leave as is.
spd that have used this speakers, which of your xovers do you recommend, for this type?
i do have a lot of warmth in the sound already with my set up.what i want more is the slam in all the octaves.
presently i'm using the seas 27tdc because my ss9700 one of them is still buzzing after recone,i'm checking that out to see what is problem with it,but the seas are really suprising.with vifa xt18 (small magnets)in a sealed 1 cubic foot for 2. and 10" 4 ohm x257 peerless in isobaric 3 cubic feet ported (gives me approx 86db of efficency)which made me use 5 db cut on the tweeter and mids.
but i feel i could get much better with the atc mid.
here are a couple of pics:
PS AUDIO preamp and preamp power supply,awsome for the money
excellent cd player emc-1 up warm and detailed
audio research vt 200 outstanding amp one of the best i've heard
diy speakers,always thought you get more when you do it yourself and the help of others
spd that have used this speakers, which of your xovers do you recommend, for this type?
i do have a lot of warmth in the sound already with my set up.what i want more is the slam in all the octaves.
presently i'm using the seas 27tdc because my ss9700 one of them is still buzzing after recone,i'm checking that out to see what is problem with it,but the seas are really suprising.with vifa xt18 (small magnets)in a sealed 1 cubic foot for 2. and 10" 4 ohm x257 peerless in isobaric 3 cubic feet ported (gives me approx 86db of efficency)which made me use 5 db cut on the tweeter and mids.
but i feel i could get much better with the atc mid.
here are a couple of pics:
An externally hosted image should be here but it was not working when we last tested it.
PS AUDIO preamp and preamp power supply,awsome for the money
An externally hosted image should be here but it was not working when we last tested it.
excellent cd player emc-1 up warm and detailed
An externally hosted image should be here but it was not working when we last tested it.
audio research vt 200 outstanding amp one of the best i've heard
An externally hosted image should be here but it was not working when we last tested it.
diy speakers,always thought you get more when you do it yourself and the help of others
An externally hosted image should be here but it was not working when we last tested it.
put them with
www.photobucket.com
you don't have to resize them,the site does it for you ,then all you just have to clic with your left button on img the mouse and a "copied" appears,then right clic the image url paste it in your post and voila!!!
www.photobucket.com
you don't have to resize them,the site does it for you ,then all you just have to clic with your left button on img the mouse and a "copied" appears,then right clic the image url paste it in your post and voila!!!
Hello. An old thread.
Yes i think to use 2 x b2500.1 you need to use the s version for sensitivity wise.
If you have budget. You can clone of proac response D100 (using all 8 ohm 2 x b2500, 2 x sm75 - non s version). Big project! D100 is proac flagship model and better than proac response 4. In case you have a big listening room with good acoustics, you will have a very live sonic performance.
http://www.proac-loudspeakers.com/datasheets/ProAc_ResponseD100.pdf
As an alternative you can also consider Solen design on pyramid uses 2 x RV3143 both 8 ohm wired in parallel but uses sm75-150 8 ohm (non s version). It has a peak in the bottom region.
http://www.solen.ca/pdf/kits/pyramidkit.pdf
actually i was provoked by this thread to use 1 x b2500 to work with 1 x sm75 non s version for my project.
Yes i think to use 2 x b2500.1 you need to use the s version for sensitivity wise.
If you have budget. You can clone of proac response D100 (using all 8 ohm 2 x b2500, 2 x sm75 - non s version). Big project! D100 is proac flagship model and better than proac response 4. In case you have a big listening room with good acoustics, you will have a very live sonic performance.
http://www.proac-loudspeakers.com/datasheets/ProAc_ResponseD100.pdf
As an alternative you can also consider Solen design on pyramid uses 2 x RV3143 both 8 ohm wired in parallel but uses sm75-150 8 ohm (non s version). It has a peak in the bottom region.
http://www.solen.ca/pdf/kits/pyramidkit.pdf
actually i was provoked by this thread to use 1 x b2500 to work with 1 x sm75 non s version for my project.
Revisited for new center channel
It's been a long while since I posted here. I had Wilmslow make a pair of speaker for me with B2500.1, SM75-150 and S/S 97000. I have/had some issues, but now with helps of room correction and digital linear-phase crossover, I am enjoying the sound of these speakers.
I'd like to build a center matching the front, and hopefully a SW later. For center, I'd like to use 2 7" or 8" woofers, SM75-150 and S/S 97000 or similar(Excel Milenium?). Your advices are very welcome for the 7" or 8" woofers to be used for this dual-woofer 3-way center. Thanks in advance!
It's been a long while since I posted here. I had Wilmslow make a pair of speaker for me with B2500.1, SM75-150 and S/S 97000. I have/had some issues, but now with helps of room correction and digital linear-phase crossover, I am enjoying the sound of these speakers.
I'd like to build a center matching the front, and hopefully a SW later. For center, I'd like to use 2 7" or 8" woofers, SM75-150 and S/S 97000 or similar(Excel Milenium?). Your advices are very welcome for the 7" or 8" woofers to be used for this dual-woofer 3-way center. Thanks in advance!
Hi jheoaustin. Did your wilmslow prestige kit speaker? other than room corrections what is your issue?
I also have wilmslow xo using b2500, sm75 & r29 designed for me which following to their prestige (i didn't buy kit but their design service... i paid them GBP 50). Their design was based on netcalc software which look awkward. I want to redesign it with lspcad in order to consider applying equalisation and also allow for baffle step. Anyone input/feedback is very much appreciated.
My application is for audio and not HT. For your center speaker: your 3 way design using sm75 & ss 9700 is more than adequate. If i were you, i would probably go d'apollito using combination of volt bm220 & ss 9700. I like very much volt driver.
I also have wilmslow xo using b2500, sm75 & r29 designed for me which following to their prestige (i didn't buy kit but their design service... i paid them GBP 50). Their design was based on netcalc software which look awkward. I want to redesign it with lspcad in order to consider applying equalisation and also allow for baffle step. Anyone input/feedback is very much appreciated.
My application is for audio and not HT. For your center speaker: your 3 way design using sm75 & ss 9700 is more than adequate. If i were you, i would probably go d'apollito using combination of volt bm220 & ss 9700. I like very much volt driver.
tamariska said:
Tamariska,
Thank you for your input. BM220, and LS201 seem to be good candidates. I also looked at Seas 8" Nextel woofer and S/S 7" carbon paper woofer like 8545 and 8530. Any idea on those options?
Regarding your question, room correction was not an issue, and it actually solved the problem of lack of EQ which would have been done by passive crossover if I didn't do active tri-amplification. I like Audyssey Sound EQ solution a lot, and it made a huge difference.
I think I had an issue with Wilmslow-made crossover and the box as well. The passive system didn't sound very good in my environment and that made me go with active tri-amping.
Then I still see 15+dB dip around 50Hz and 65Hz on left and right speakers, respectively with active solution in a few different room acoustics. I think the box is one of the major causes of those 2 persistent dips.
Then again, this is a customized Forte, so I don't know if Wilmslow's original design has this problem - probably not.