I am not familiar with the Devialet so I can't really say. I am also no expert as there are many ways to setup subs.
But a high pass is just a crossover on the sub side and you do not want to use the low pass filter when using a high pass. The high pass will have a given slope (12 or 24db usually) and when it tapers off the sub it brings the mains in at the same slope. Some crossovers even correct for phase in side the crossover. Mine does not correct for phase and has a Manal phase adjustment. If you measure a dip or peak at the crossover point the phase needs adjusted.
Now the Devialet might not cut the sub/mains at the same frequency and could set the high and low pass at different frequencies as desired.
Hi James:
My last post was referring more to my primary system's pre-pro (Theta) which includes high and low pass settings for each individual speaker. There are also slope settings as you note above for each speaker and phase as well. The Devialet also has similar setting options but they are universal, not per speaker.
So that I fully understand what you are saying, it appears you are telling me that the high pass filter and low pass filter both apply to the sub, is that correct? I thought the high pass filter applied to limiting how low the mains will play (and pass only higher frequencies along), while the low pass filter applies to limit how high a frequency the sub will play by (passing along only frequencies lower than the setting). It appears I misunderstand this according to what you are saying so please be patient with me.
If I adjust my high pass filter and still have a setting option for the low pass filter, should i leave them set at the same frequency? That's what I've done so far.
I think some people find a bit of overlap in frequency works best while others may find setting high and low pass filters at the same frequency works best. Why else would they provide the option?
Here is a definition of the high pass filter I found:
A high-pass filter is an electronic circuit that removes all the notes above the filter's frequency setting. A high-pass filter set at 100 Hz, for example, will allow all the signal above 100 Hz in frequency to pass through, but block all those under 100 Hz. High-pass filters are primarily used to block bass notes from distorting through car speakers and tweeters.
Comment: If I want to block the woofer from operating higher than a certain frequency, wouldn't I use this filter to accomplish that? Why would I want to limit higher frequencies from the mains? I don't think I would. I would want to keep my mains from having to produce frequencies that are too low for them to handle properly. That's why I thought this filter applied to limiting how low the mains will play. But you are telling me that the high pass filter applies to the sub.
Here is a definition of a low pass filter I found:
Low-pass Filter
A low-pass filter is an electronic circuit that removes all the notes below the filter's frequency setting. A low-pass filter, set at 100 Hz for example, will block the notes above 100 Hz and allow those under that to pass. Low-pass filters are primarily used to keep high notes from subwoofers.
Comment: If the low pass filter will allow only frequencies below what I set it at, why would that apply to the mains? I want them to play higher frequencies. The definition implies that the low pass filter will allow me to limit how high a frequency will be played by the woofer.
So I am confused then and looking for you to help me get this straight!
Thanks, James!
popspin
PS: High and low pass filters were used for the 1st time commercially in the 1920's when Bell Labs Acoustics Division dealt with an issue of trying to use conical speakers in theaters instead of horn speakers. They had all kinds of distortions and couldn't get the conical speakers to sound clean. The eventual solution was to increase the power of the tube amps they were using and apply high pass filters. I know this because my mother's uncle was in charge of the Acoustics Division of Bell Labs at that time and he was the guy who made the conical speakers work in the RKO theater in Rochester, NY. This information is available on line on the IEEE site (interview with Dr Irving Wolff).