KEF modification

Newfie · 24th December 2010, 03:43 PM

I have a pair of Kef c-40s. i believe they're a 3way. they have dual 8s and a 1" tweeter in a sealed box. i enjoy the laid back smooth sound hooked up to a 1978 sony receiver.
but, are they ever lacking in bass. Am i able to add a port? I'm thinking of adding one of those adjustable ports.

Newfie · 24th December 2010, 03:49 PM

here are some specs i just found:

Infinite baffle [ closed box ] design
-:®:- Internal volume : 30lt
-:®:- Power rating : 10W - 100W
-:®:- Drivers : 1 x 25mm dome tweeter, 1 x 200mm polypropylene cone bass / midrange, 1 x 200mm bass drivers
-:®:- Sensitivity : 91dB / 1W / 1m
-:®:- Frequency response : 68Hz - 20kHz -6dB at 58Hz
-:®:- Impedance : nominal 8 ohms
-:®:- Dimensions [ W x D x H ]: 247 x 262 x 650mm
-:®:- Weight : 9.6kg each speaker

frperdurabo · 24th December 2010, 03:59 PM

The short answer is that woofers designed to work in a sealed box of a given size probably won't work in a ported box of the same size. Try placing the speakers closer to the back and side walls. Or investigate digital EQ solutions.

The long answer involves learning about T/S parameters and buying and using test equipment. This can be a lot of fun...

jerome69 · 24th December 2010, 06:01 PM

Add a subwoofer ?

You can easily measure the T/S parameter with your computer and a sound with a line input. You need a cable jack-jack and a resistance less than10$. I wrote a tutorial here (you may need to translate).
The problem when you go to a BR box from a closed box, the volume of the box should be double.

chris661 · 24th December 2010, 06:31 PM

I'd personally think that two 8" drivers per side should be plenty. That said, 30L for both seems a little small. Perhaps adding stuffing will help a little?

BHTX · 24th December 2010, 06:49 PM

Add a pair of adequate DIY subs, LR2 @ 60 Hz.

Inductor · 02:27 PM

Quote:

Originally Posted by Newfie

-:®:- Sensitivity : 91dB / 1W / 1m
-:®:- Frequency response : 68Hz - 20kHz -6dB at 58Hz

Lower sensitivity from original project should have given a little better lower extension to a point, together with a bigger enclosure.

68Hz@-3dB
58Hz@-6dB

(Pic from: KEF C Series speakers on Seattle CL - any good? - AudioKarma.org Home Audio Stereo Discussion Forums)

24th December 2010, 03:43 PM	#1
Newfie diyAudio Member Join Date: Dec 2010	KEF modification I have a pair of Kef c-40s. i believe they're a 3way. they have dual 8s and a 1" tweeter in a sealed box. i enjoy the laid back smooth sound hooked up to a 1978 sony receiver. but, are they ever lacking in bass. Am i able to add a port? I'm thinking of adding one of those adjustable ports.

24th December 2010, 06:31 PM	#5
chris661 diyAudio Member Join Date: Feb 2008 Location: Lancashire Blog Entries: 7	I'd personally think that two 8" drivers per side should be plenty. That said, 30L for both seems a little small. Perhaps adding stuffing will help a little? __________________ "Throwing parts at a failure is like throwing sponges at a rainstorm." - Enzo My setup: http://www.diyaudio.com/forums/multi...tang-band.html

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
KEF 105/3 - Kef Q5	mschafft	Multi-Way	1	28th October 2008 05:36 PM
Modification.....	Actuary	Tubes / Valves	3	26th February 2008 01:34 AM
Kef sub	gareth	Subwoofers	4	5th February 2008 12:48 PM
Kef 103 or Kef 104?	Johnn Wilson	Multi-Way	8	1st February 2008 06:56 AM
X-over modification	hermanho	Multi-Way	1	20th February 2006 06:52 AM

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


	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

24th December 2010, 03:49 PM	#2
Newfie diyAudio Member Join Date: Dec 2010	here are some specs i just found: Infinite baffle [ closed box ] design -:®:- Internal volume : 30lt -:®:- Power rating : 10W - 100W -:®:- Drivers : 1 x 25mm dome tweeter, 1 x 200mm polypropylene cone bass / midrange, 1 x 200mm bass drivers -:®:- Sensitivity : 91dB / 1W / 1m -:®:- Frequency response : 68Hz - 20kHz -6dB at 58Hz -:®:- Impedance : nominal 8 ohms -:®:- Dimensions [ W x D x H ]: 247 x 262 x 650mm -:®:- Weight : 9.6kg each speaker

24th December 2010, 03:59 PM	#3
frperdurabo diyAudio Member Join Date: Sep 2009	The short answer is that woofers designed to work in a sealed box of a given size probably won't work in a ported box of the same size. Try placing the speakers closer to the back and side walls. Or investigate digital EQ solutions. The long answer involves learning about T/S parameters and buying and using test equipment. This can be a lot of fun...

24th December 2010, 06:01 PM	#4
jerome69 diyAudio Member Join Date: Feb 2008 Location: Lyon	Add a subwoofer ? You can easily measure the T/S parameter with your computer and a sound with a line input. You need a cable jack-jack and a resistance less than10$. I wrote a tutorial here (you may need to translate). The problem when you go to a BR box from a closed box, the volume of the box should be double.

24th December 2010, 06:49 PM	#6
BHTX diyAudio Member Join Date: Feb 2006	Add a pair of adequate DIY subs, LR2 @ 60 Hz.

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