|Multi-Way Conventional loudspeakers with crossovers|
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
||Thread Tools||Search this Thread|
|19th January 2002, 05:24 AM||#1|
Join Date: Nov 2001
Location: Virginia USA
EQ boost and Q......help
A little help please for an electronically challenged individual....?
(Must admit the whole Q concept is still a bit foreign to me - Any good primers out there on basic circuits, filter orders etc.?)
What's the practical effect of the filter Q of a sub EQ circuit?
For example the "Adjusting EQ bass boost" notes for the Parts Express 250W sub amp lists a "pre amp filter Q" for each of the possible boost settings.
What does this do to the total system Q, and what is the effect on dampening and transient response?
Thanks for any help.
|20th January 2002, 02:15 PM||#2|
Wizard of Kelts
diyAudio Moderator Emeritus
What the preamp does will NOT affect the speaker's Q at all. It has no effect on speaker damping, since there is no passive component, (inductor, capacitor, etc.) between the speaker and the amp. If there is any effect on transient response, it will come from the filter itself-that is, the transient response of the signal will be changed BEFORE it gets to the speaker. The speaker itself will have the same transient response as before
About Q. It measures the size and shape of the impedance rise of a filter. As regards speakers, the speaker's Q tells you high high below-or above-midpoint the speaker is around the resonance point.
The midpoint is the SPL the speaker usually plays at. For most non-PA speakers, it usually around 87-90 dB.
A) In a closed box speaker system with a Qtc of .5 and an Fc of 40 Hz, the response will be 6 dB down from the midpoint at 40 Hz.
B) If the Qtc of that speaker system were .7 instead of .5, the response would be 3 dB down from the midpoint at 40 Hz, (Fc).
C) If the Qtc of that system were 1.0. the response would be exactly at midpoint at 40 Hz (Fc).
In all cases, the response would drop after Fc.
Preamp filters have their own Q's and resonances as well. For instance, a preamp filter for example A might be 6 dB UP at 40 Hz, to compensate for the speaker's response being down by that same amount.
To repeat, the speaker's Q, in both sealed and ported systems, is not affected by any preamp filter. The preamp filter exists only to "fill in" the response where the speaker droops or falls off.
|Thread Tools||Search this Thread|
|Thread||Thread Starter||Forum||Replies||Last Post|
|11.5-12.8v to 13.8-14.4v boost||star882||Power Supplies||16||19th May 2010 03:13 AM|
|to boost or not to boost?||CharlieM||Subwoofers||1||31st January 2009 06:17 PM|
|[enquiry] Treble Boost/High frequency Boost circuitry||elnino86||Parts||2||18th December 2008 12:33 PM|
|1kW Boost||allanon77||Power Supplies||17||4th February 2008 12:18 PM|
|1W Boost||allanon77||Power Supplies||1||22nd January 2008 09:13 AM|
|New To Site?||Need Help?|