Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

B&C 21SW152 clone
B&C 21SW152 clone
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th June 2019, 07:43 AM   #11
Matthew Morgan J is offline Matthew Morgan J  United States
diyAudio Member
 
Matthew Morgan J's Avatar
 
Join Date: May 2011
Location: Arizona
Quote:
Originally Posted by TBTL View Post
[SIZE=2]Could you please explain? I thought motor force scales to BL^2 / Re.





TBTL,

BL^2/Re is an oversimplified method when it comes to drivers with high relative inductance like the Chinese driver, because using BL^2/Re alone to compare a driver with high relative inductance to a driver with much lower relative inductance (like the 21SW152) gives the driver with high relative inductance an unfair and misleading advantage when in fact it may have less motor force in the real world (as is the case here).....

For drivers with high relative inductance like the Chinese driver you can use the "Lossy Inductance" feature on Hornresp to adjust the BL down for you and then use that adjusted figure in the BL^2/Re formula in order to give you a better idea about how much "effective" motor force the driver really has ...

The community of builders/designers i have been working with lately have used the "Lossy Le" feature many times with drivers that have high relative inductance and our results do correlate well with the models (in term of predicted curve shape and damping behavior) .........NOTE: The feature is not required with most PA drivers (only certain ones like the iPALs , DS115 series and that Chinese driver...............High Excursion Car Audio subwoofers and Home Theater style subwoofer drivers will require the "Lossy Le" feature in most cases .. )

With Lossy Inductance feature applied (so the BL adjusted accordingly) the Chinese driver ends up with a BL^2/Re of around 150 ....

The 21SW152-8 (for which the feature is not required) has a BL^2/Re of up around 250 as you pointed out .... So in reality the 21SW152 is considerably stronger than the Chinese 21" .. .
  Reply With Quote
Old 19th June 2019, 01:16 PM   #12
mark100 is online now mark100  United States
diyAudio Member
 
Join Date: Dec 2010
Quote:
Originally Posted by ICG View Post



No, it isn't that easy. You have to compare and look very closely at the excursion. A correct sum does not say how much mechanical and aswell electrical (power) stress is on them. I've seen it several times at some firends event parties, they said "ah, that works suprisingly good" and an hour later half of their mixed subs died. Oversimplifying things isn't helping you at all. You often don't even recognize when the power compression on one of the sub types starts. That's actually the prototype on 'how to fry my subs'.



Well, how did you place the subs? How many subs? Just two? Monostack, 2 stacks r+l, tooth-row, end-fire, cardioid? How/where did you measure it?
To me 'separately powered' means all the concerns you mentioned have been addressed....that is, amps are sized appropriately for each sub, limiters are in place if needed.
I take all that as a given when combining subs, but you do make a good reminder for those who might not.

How placed/how measured ? Really ??
I placed two banks of 8 subs of each type in a inter-weaved hyper-cardiod mobius array, with antimattermerretmerizer phase processing

Or should I say one sub of each type out on the driveway, each alone, and then the pair side-by-side. 8m using Smaart as previously shown.
  Reply With Quote
Old 19th June 2019, 07:50 PM   #13
ICG is offline ICG  Germany
diyAudio Member
 
ICG's Avatar
 
Join Date: Jul 2007
Location: I had a Dj Moo - I've seen that BS before!
Quote:
Originally Posted by mark100 View Post
To me 'separately powered' means all the concerns you mentioned have been addressed....that is, amps are sized appropriately for each sub, limiters are in place if needed.
I take all that as a given when combining subs, but you do make a good reminder for those who might not.
Well, limiters are a very good tool to keep your subs alive. It depends on the dsp but most limiters aren't RMS limiter but just peak limiter, which doesn't care about how much the average. On ~47Hz you've EQ'd +3dB. That doesn't sound much but it still is double the power. It looks like you really know what you are doing but that 'bit' EQing is something someone else with less experience will very likely overlook. That frequency is well 'populated' and low enough to not notice the distortion, double the power there can very quickly mean exceeding the xmax. The twice the power is bad for someone with less experience because a peak limiter won't catch that, it's simply not possible for it, especally at music genres like dubstep, raggae or others with long duration, low attack, low frequency tones because it will not trigger. Because it likely doesn't even show the limit led you don't have any feedback on the actual power.

Quote:
Originally Posted by mark100 View Post
How placed/how measured ? Really ??
I placed two banks of 8 subs of each type in a inter-weaved hyper-cardiod mobius array, with antimattermerretmerizer phase processing
That's bad. You obviously didn't use a laser aligned non-phase impacting measurement microphone, only the Binford 9000 hyperlinear GTS-X Mk II mic can do that correctly.

Quote:
Originally Posted by mark100 View Post
Or should I say one sub of each type out on the driveway, each alone, and then the pair side-by-side. 8m using Smaart as previously shown.
So outside with low to no reflections and the same distance. I was asking to exclude room influence on the measurement or a phase difference because of close mic placement and high runtime difference of a longer row of subs. Sorry for asking that offensively, I wanted to avoid a chat-like series of posts, asking in each for more additional informations because x or y are missing, annoying each other more and more while doing so.
__________________
I had a Dj Moo - I've seen that BS before!
  Reply With Quote
Old 19th June 2019, 08:00 PM   #14
TBTL is offline TBTL  Germany
diyAudio Member
 
Join Date: Oct 2013
Quote:
Originally Posted by Matthew Morgan J View Post
TBTL,

BL^2/Re is an oversimplified method
[...]
Thank you for your elaborate explanation
  Reply With Quote
Old 19th June 2019, 08:27 PM   #15
mark100 is online now mark100  United States
diyAudio Member
 
Join Date: Dec 2010
Quote:
Originally Posted by ICG View Post
Well, limiters are a very good tool to keep your subs alive. It depends on the dsp but most limiters aren't RMS limiter but just peak limiter, which doesn't care about how much the average. On ~47Hz you've EQ'd +3dB. That doesn't sound much but it still is double the power. It looks like you really know what you are doing but that 'bit' EQing is something someone else with less experience will very likely overlook. That frequency is well 'populated' and low enough to not notice the distortion, double the power there can very quickly mean exceeding the xmax. The twice the power is bad for someone with less experience because a peak limiter won't catch that, it's simply not possible for it, especally at music genres like dubstep, raggae or others with long duration, low attack, low frequency tones because it will not trigger. Because it likely doesn't even show the limit led you don't have any feedback on the actual power.



That's bad. You obviously didn't use a laser aligned non-phase impacting measurement microphone, only the Binford 9000 hyperlinear GTS-X Mk II mic can do that correctly.



So outside with low to no reflections and the same distance. I was asking to exclude room influence on the measurement or a phase difference because of close mic placement and high runtime difference of a longer row of subs. Sorry for asking that offensively, I wanted to avoid a chat-like series of posts, asking in each for more additional informations because x or y are missing, annoying each other more and more while doing so.
Dang ! Gotta get me one of those Binford 9000's

Thx for the kind explanation re questions.

Yep, regarding RMS and Peak limiting. I routinely keep both in play on all drivers.
And I'm beginning to play with side-chain triggered limiting. I'd like to emulate a sliding frequency high-pass filter for subs, that I've seen in the Linea Research dsp's.

@ Matthew Morgan J
I second TBTL's thank you!
  Reply With Quote
Old 19th June 2019, 09:43 PM   #16
ojedadavid is offline ojedadavid
diyAudio Member
 
Join Date: Dec 2015
so, there is phase change, using 2 different drivers, in example,
2 dayton PA465 and 2 PRV 2200.
but under 100hz and outdoors wont be noticeable?
anyways the roof vibrates and sounds like a trunk of a car with high power subwoofers.
  Reply With Quote
Old 20th June 2019, 04:01 AM   #17
Matthew Morgan J is offline Matthew Morgan J  United States
diyAudio Member
 
Matthew Morgan J's Avatar
 
Join Date: May 2011
Location: Arizona
No problem TBTL and Mark100, you are welcome.

Glad to be helfpul
  Reply With Quote
Old 20th June 2019, 05:34 AM   #18
diyuser2010 is online now diyuser2010
diyAudio Member
 
Join Date: Jun 2018
Quote:
Originally Posted by ICG View Post
1. Don't mix different subs! The phase will be different and that will cause more or less cancelling.

2. One of the 21" got 1750 cm cone surface. Two of the 18" got 2x ~1200 = 2400 cm cone surface. That means, you lose roughly 30% of cone surface. That's really bad, outdoors that's exactly what counts, cone surface. That gives you much less headroom instead of more!

3. Don't buy noname drivers from china which aren't sold anymore in a year. Why? Not because they might be bad. Okay, that may or may not be the case.. anyway. No, if you kill one, there are no recone kits, you are unable to get a replacement which usually means you have to throw the enclosure away too and a single one remaining is practically useless for you.

The best would be to buy more 18" (maybe 6) which are not too expensive.

I agree with most of this, especially throwing money away at a product with questionable quality control, no support. What happens when you get a driver with a coil rub, the Qes is way out to lunch, and a coil that isn't centered?



Multiple drivers are always a better idea than one or two good drivers, especially outdoors.



(6) 18's would be a good start for outdoors, and placing the boxes together in a center cluster would give you some forward directivity.



If you bought 6 at a time, the B&C 18TBW100 could be had for around ~ $ 320 street price, maybe a bit less. Sure, it's more boxes, and more money, but the efficiency and headroom gained by running 6 enclosures will offset that somewhat. Perhaps you can sell off your existing set up once you have replacement boxes built and running, which would lower the cost of ownership.



There are less expensive, less capable drivers out there and it all comes down to your choice.
  Reply With Quote
Old 25th June 2019, 05:39 PM   #19
Crashpc is offline Crashpc  Czech Republic
diyAudio Member
 
Join Date: Nov 2008
The basic Bl force "ratio" cannot be discarted just like that, as in 30-60Hz range, the inductance is low. Also 21DS115 is stronger than 21SW152. But I do agree that I would be worried about these copies.
  Reply With Quote
Old 25th June 2019, 06:14 PM   #20
multi is offline multi  Australia
diyAudio Member
 
Join Date: Jan 2011
I have used lots of Hiwell speakers only problem is DHL the cost is crazy; i use an agent who sends by China surface. I f no one has tried them how do you know they are duds ?
  Reply With Quote

Reply


B&C 21SW152 cloneHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Generic Asian Clone driver board RE and Clone jacampb2 Car Audio 26 3rd July 2018 08:01 PM
Cleaning sub cones of mud (B&C 21SW152) Infinite Audio NZ Subwoofers 9 23rd February 2018 05:10 PM
FS: Drivers for JBL 250Ti clone (LE14, 108H clone, 104H-2 GordonW Swap Meet 10 20th May 2014 08:19 PM
FS: 1 pair of B&C 21SW152-8 21" Subwoofer Drivers. opc Swap Meet 14 6th February 2012 04:49 PM
Ricci's dual B&C 21SW152 build thread. Josh Ricci Subwoofers 22 12th April 2010 09:39 PM


New To Site? Need Help?

All times are GMT. The time now is 08:21 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki