Reflex vs sealed - Page 4

audiokinesis · 4th November 2008, 08:26 PM

Infinia, I don't do exactly the same thing that simon5 does - I just use the same approach.

It's not quite an EBS tuning, as the target response is a curve that slopes gently downward at about 3 dB per octave, then of course rolls off rapidly below the tuning frequency. Perhaps this approach deserves its own acronym. I propose "RGC", for "Room Gain Complimentary" tuning.

It's not really all that difficult, but like anything else you have to do some modelling to find woofers that will do what you want in a box size you can live with.

Duke

simon5 · 4th November 2008, 10:18 PM

Here's an example...

This is an example, using Dan Wiggins ShivaMKIV.

I will post the FR curve shortly.

simon5 · 4th November 2008, 10:21 PM

Here's the FR curve measured in room. It was measured by hand and plotted in Excel. It's not perfect but it does give an idea.

infinia · 4th November 2008, 10:34 PM

Nice... gets very loud also, no subsonic filter needed.
How did you measure in room?

simon5 · 4th November 2008, 11:03 PM

It was measured using a simple Ratshack dB meter on the C weighted rating and using a compensation chart.

As I said, not perfect, but it gives an idea.

audiokinesis · 5th November 2008, 07:43 PM

Simon5, thanks for posting an example. I didn't have time to yesterday.

Regarding your posted in-room measurement, I would have expected to see a peak-and-dip pattern at the microphone position due to room interaction. Is that a spliced close-miked measurement, or an average of several microphone locations? Or, were you using warble-tones?

Thanks,

Duke

simon5 · 6th November 2008, 11:23 AM

Quote:

Originally posted by audiokinesis
Regarding your posted in-room measurement, I would have expected to see a peak-and-dip pattern at the microphone position due to room interaction.

It's not what you would call a professional FR curve hehe ! It was measured with a computer frequency generator, using a Creative Audigy 4, single sinusoidal frequency at a time. Input 16 Hz, take a measurement, repeat at interval of 4 Hz or so, up to 125 Hz. So it was about 20 discrete measurements...

That's why I stated several times that it's not perfect, but it gives an idea.

You could post a better design with a better FR curve, I'm sure !

4th November 2008, 10:34 PM	#34
infinia diyAudio Member Join Date: May 2005 Location: Californication	Nice... gets very loud also, no subsonic filter needed. How did you measure in room? __________________ like four million tons of hydrogen exploding on the sun like the whisper of the termites building castles in the dust

4th November 2008, 11:03 PM	#35
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	It was measured using a simple Ratshack dB meter on the C weighted rating and using a compensation chart. As I said, not perfect, but it gives an idea. __________________ DIYaudio for President !

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
Audio Reflex CE-431	rpapps	Everything Else	0	30th October 2005 05:31 AM
Sealed midbass vs BR, why not sealed ?	mbon	Multi-Way	3	16th June 2004 10:50 AM
Port reflex or sealed	mark.carline	Multi-Way	7	11th May 2004 07:08 AM
Bass Reflex	Guss	Multi-Way	1	15th December 2003 02:33 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

4th November 2008, 08:26 PM	#31
audiokinesis diyAudio Member Join Date: Oct 2007 Location: Preston, Idaho	Infinia, I don't do exactly the same thing that simon5 does - I just use the same approach. It's not quite an EBS tuning, as the target response is a curve that slopes gently downward at about 3 dB per octave, then of course rolls off rapidly below the tuning frequency. Perhaps this approach deserves its own acronym. I propose "RGC", for "Room Gain Complimentary" tuning. It's not really all that difficult, but like anything else you have to do some modelling to find woofers that will do what you want in a box size you can live with. Duke

5th November 2008, 07:43 PM	#36
audiokinesis diyAudio Member Join Date: Oct 2007 Location: Preston, Idaho	Simon5, thanks for posting an example. I didn't have time to yesterday. Regarding your posted in-room measurement, I would have expected to see a peak-and-dip pattern at the microphone position due to room interaction. Is that a spliced close-miked measurement, or an average of several microphone locations? Or, were you using warble-tones? Thanks, Duke

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