Bump at 120 Hz with large inductor before woofer?

mhd204 · 9th February 2011, 05:56 PM

I've been modeling a 2-way design with PCD using the U16RCYP and 27TDFC drivers, in an 11L vented box. The FRD and ZMA files are fully corrected for the box/baffle conditions. When I implement a full BSC design, using a 4 mh inductor before the woofer, there is a 3dB bump centered around 120 Hz. Is this a normal feature of implementing a full BSC design? Attached is an image of the frequency response.

crazyhub · 9th February 2011, 08:11 PM

Hi,

It's the second impedance peak of the vented system which alters the working condition of the 4mH self; you may flatten this peak by adding a notch LCR network // to the woofer.
edit: 4mH seems relatively huge even for a full BSC. Just my opinion.

mhd204 · 9th February 2011, 08:37 PM

I played around with some values for a circuit that would flatten that peak, it seems like I would need some huge caps to do it, so instead a reduced BSC with around 3DB of BSC seems to line up the rest of the FR curve with the 120Hz bump. Looks like a more elegant solution. The room reinforcement should help below that bump correct?

What do you think?

crazyhub · 9th February 2011, 09:04 PM

Sure 84dbs efficiency should give a balanced speaker with this woofer in standard rooms and placement.

9th February 2011, 05:56 PM	#1
mhd204 diyAudio Member Join Date: Jan 2008 Location: Brookline, MA	Bump at 120 Hz with large inductor before woofer? I've been modeling a 2-way design with PCD using the U16RCYP and 27TDFC drivers, in an 11L vented box. The FRD and ZMA files are fully corrected for the box/baffle conditions. When I implement a full BSC design, using a 4 mh inductor before the woofer, there is a 3dB bump centered around 120 Hz. Is this a normal feature of implementing a full BSC design? Attached is an image of the frequency response.

9th February 2011, 08:11 PM	#2
crazyhub diyAudio Member Join Date: Nov 2005 Location: alsace	Hi, It's the second impedance peak of the vented system which alters the working condition of the 4mH self; you may flatten this peak by adding a notch LCR network // to the woofer. edit: 4mH seems relatively huge even for a full BSC. Just my opinion. __________________ crazyhub

9th February 2011, 09:04 PM	#4
crazyhub diyAudio Member Join Date: Nov 2005 Location: alsace	Sure 84dbs efficiency should give a balanced speaker with this woofer in standard rooms and placement. __________________ crazyhub

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
C-C spacing between woofer and tweeter with 500 hz XO	Defo	Multi-Way	2	3rd July 2010 02:31 PM
FS large transformer and inductor	woody	Swap Meet	2	10th March 2009 12:20 PM
WTB in Oz: modest $ midrangers/ midwoofer (c. 120 - 2400 Hz)	rick57	Swap Meet	4	9th March 2007 11:50 PM
120 Hz Buzz Unplugged	dr._sleep	Tubes / Valves	4	17th September 2005 02:47 AM
woofer up to 3000 Hz ?	promitheus	Multi-Way	5	28th August 2002 05:03 PM


	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

9th February 2011, 08:37 PM	#3
mhd204 diyAudio Member Join Date: Jan 2008 Location: Brookline, MA	I played around with some values for a circuit that would flatten that peak, it seems like I would need some huge caps to do it, so instead a reduced BSC with around 3DB of BSC seems to line up the rest of the FR curve with the 120Hz bump. Looks like a more elegant solution. The room reinforcement should help below that bump correct? What do you think?

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read