2. tech-talk
  3. 132814-2005

Filter Slope Question

My Emotiva preamp has bass management features that incorporate a 12db/octave slope for both the high and low pass filters.  I like using this feature to keep the low bass out of my main speakers.  I am going to purchase two Rythmik F12 subwoofers but the plate amps in these subwoofers do not have an option to switch the built in filter out of the circuit.  It has both 12db and 24db slope options.  What would be the result of having both the preamp and plate amp filters in the circuit?  What would be the result if I used the 24db option on the plate amp along with the 12db filter in the preamp?  Will a 12db high pass filter and a 24db low pass filter impede proper integration?  I plan on crossing the mains over to the subs at 50HZ. 
danoroo
bdp24's avatar
bdp24
10,248 posts
 

If you get the "G" version of the F12---the F12G, obviously!---Danny Richie of GR Research (the reason for the G designation in the sub's model number) is a great source of advice. So is Brian Ding of Rythmik, but he can be hard to understand over the phone, due to his heavy Asian accent. Another great source of info is the Rythmik Audio Forum.

almarg's avatar
almarg
9,670 posts
 
The PEQ3 version of the plate amp, which is the version that is supplied as standard with this sub, provides an LFE input which removes the sub’s filter from the signal path. Have you considered purchasing that version?

Also, when providing bass managed inputs to the Line In connections of both the PEQ3 and the PEQ (non-"3") version of the plate amp (the latter does not provide an LFE input, providing 80 Hz high pass filtered line outputs instead), the corresponding manuals and the rear panel markings appear to recommend setting the sub’s filter to 12 db, not 24 db. That would seem to make sense, as having two 12 db low pass filters in the sub’s signal path would of course come closer to being complementary to a single 12 db high pass filter in the signal path to the main speakers than the 24 + 12 low pass alternative that was cited in your question.

Regards,
-- Al

danoroo OP
239 posts
 
Thank you guys for your responses.  I am embarrassed to admit that I created a problem where one does not actually exist.  After I created this thread an astounding revelation came to me (duh!).  Just disable the low pass filter in the preamp, run the full audio signal to the subs and use the low pass filters in the subs.  I can still use the preamp's high pass filter to keep the frequencies below 50hz out of my mains.  I wish the filters in my preamp were 24 db/octave instead of 12 db/octave slope.  It seems that a steeper roll off would make for better integration.
bdp24's avatar
bdp24
10,248 posts
 
The A370PEQ version of the Rythmik plate amp includes 12dB/octave high-pass filtered (at 80Hz) outputs on RCA jacks. You can set the sub’s low-pass filter to 24dB (at either 50 or 80Hz), then combine the A370PEQ’s 12dB high-pass filter with your pre’s 12dB high-pass filter to achieve 24dB of high-pass filtering. I think! Call Danny Richie and ask him---he’s a x/o expert, and a really nice guy.
More to discover