A little bit of help with my alumni 5.1 crossovers


Active Member
Hi Guys,

Sorry this is prolly a lame question but imma ask it anyway.

THX suggests a crossover setting of 80Hz with all speakers set to “Small” .. which sounds reasonable to me although as some of you will know my alumni have a frequency range starting at 100Hz and this is were i now get confused being new to this whole HT thang.

I'm basically trying to understand what the hell im doing, soooo my alumni 2 and 5 have a effective frequency response starting at 100Hz i know this from the manual if i set my crossover on these speakers to 80Hz I'm now sending low frequency tones that my speakers cannot effectively reproduce(I think if i have got this the right way around). So setting the crossover to 100Hz would instruct the amp or reciever to send anything below 100Hz to my sub thus freeing up the speakers to concentrate on only 100Hz and above frequency tones.

Rather than have the crossover setting set to the minimum is it not better to set it slightly higher than the minimum that my speakers can handle .. maybe 120Hz because from what i understand low frequency information below 120Hz is, for the most part, non-directional, meaning that the effect will still sound like its coming from the surround system and i wouldnt realise it had been crossed over, but does this way of going about things yield other problems?

I'm just trying to get my head round all of this because as i said im new to all of this.



Distinguished Member
Looking at the spec of your speakers which are not far from a set of Missions I own, I would set the Xover to 120Hz.


Distinguished Member
I'd be tempted to agree that 120 sounds about right.

Although why not try both and see if you can actually tell the difference, if you can choose the one you prefer, if not just leave on 120.


Active Member
Although why not try both and see if you can actually tell the difference, if you can choose the one you prefer, if not just leave on 120.

Thanks guys.

yeah i have done this already i personally think that 120 sounds a little better .. it has more ermmm ommmpppphhhh maybe haha ... i didnt know if there would be a down side to this though that was my main question tbh but i think i kinda skirted around it a little and didnt explain myself very well.


Distinguished Member
The THX 80Hz crossover assumes THX certified speakers, which by definition have the ability to accurately reproduce frequencies down to 80 Hz at reference levels. Yours speakers aren't THX speakers and won't go down to 80Hz, so you need to go higher. 120Hz (or even higher, up to 150Hz) seems reasonable. You might wish to get hold of an SPL and measure it out with a test tones source.

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