Axiom Home Page Forums General Discussion Advice from Axiom Owners Crossover Frequency Confusion

grunt,

Your explanation is excellent. I wish I had written it myself. I am not sure I would want to boost my surround channels by 3 dB but it is a great example of using the manual calibration settings to customize things to your liking and your room. I am a big fan of living with your various experiments for a while to experience different content being played before landing a final decision. Adjusting channel volumes and x-over points is not affecting the tonal balance and therefore not causing the sort of potential damage that things like Auto Room EQ can cause, certainly above 300 Hz. One of these days we will take some actual measurements of what Auto EQ devices are doing to the amplitude response. It would be interesting to see the effects, measured in the anechoic chamber, after the correction had been applied in a room.

The above said I do think JohnK brought up a valid point though. If you don’t have, at a minimum, a decent SPL meter to play around with the manual calibration settings, the auto calibration may be the safest bet.

i use the Audyssey "Flat" curve, since my room is treated and if i didn't use "flat", the high frequencies would be weak and lacking.
"flat" is just right to my ears.

careful setup like this is what permits me to listen to movies at around 0dB without cringing; it's like in the cinema, wide, crisp, clean, smooth and "natural".

i listen to the music stations on Galaxie at around + 2dB; this gives me a realistic level on those stations i listen to.

I have probably asked this before - If I have not, I'm sure someone else has. I have M60's and an EP 500. The crossover on the 500 is all the way up - 150 hz, I think. Crossover on the receiver is set to 80 and is not configurable by speaker. Is there any harm in setting the mains to Large rather than Small?

Any harm setting them to large will be largely dependent on the amplifier, source material, volume (which is largely dependent on your seating positions and personal loudness preferences).

Having the speakers set to large with highly dynamic blu-ray soundtracks could cause stress or compression due to some low-frequency content at loud volumes being sent to the mains or possibly inducing amplifier clipping damaging the tweets. Mid to low frequencies is what could really cause the current demand to ramp up, particularly problematic with a run of the mill AVR (clipping, overheating). Having the speakers set to large will require more power than having them sent to small. Your EP500 with its own dedicated internal amplifier and woofer designed to handle content between 20hz to 80hz is better suited than the mains.

Thanks Ian!

Just to clarify I only boost the rear speakers by +3dB but leave the side surrounds at the same level as the front speakers.

For the untrained ear (meaning most people) I agree that auto calibration is better than nothing if someone doesn’t have an SPL meter. However, in my experience once a person hones their critical listening skills they can get pretty close to the same settings as auto calibration or an SPL meter gives for sound level (distance at some frequencies if you’re really good) by ear alone. Though I totally understand that for most people auto calibration is far more practical.

A perfect example of the ear sometimes being better than auto calibration was when in my apartment I invited over a friend who use to master demo tapes for local bands. When I demoed the opening battle in Master and Commander he immediately said that my subwoofer distance was off. He adjusted it by ear and I ended up with the best sounding crossover from the mains to the sub I have ever had.

One of the reasons I keep bringing up this topic is that I fell prey to thinking that auto-cal and auto-EQ would do all the work for me and because they are machines will be more accurate than my hearing. Only by accident did I realize that speaker/seating placement and eventually things like room treatments played a much greater role in the quality of sound I’m getting from my system than whether or not I was using EQ or the auto calibration settings. I think the best example of this is that despite all the science and experience Axiom puts into their speaker designs you still put things through double blind listening tests to make sure it works in practice.

Another time I only realized by accident what furniture did to in room sound when I added a futon (previously just had a matrass on the floor) and suddenly had all the “life” sucked out of my music. Later I found that by elevating my mains it returned much of the ambiance I had lost when I put that giant sound absorbing futon in the middle of my room. Most people will never experience this because the room they put their speakers in is likely laid out and furnished before adding the speakers.

In more general terms living abroad especially in “third world” countries I learned that human perception is far more powerful than most Westerners (steeped in the “scientific method”) realize. We’re taught to trust our instruments and distrust our senses. I’m a trained interrogator and can say without a doubt that I can detect a lie better than any polygraph machine I’ve seen. There is a reason El Al Air Lines uses trained interviewers as their primary means of detecting terrorists boarding airplanes . . . they work better than baggage and body screening machines. Pacific islanders were able to navigate between islands by being able to feel the reflected swells on their legs hanging in the water coming off islands as far as 30 miles away. The list of seemingly amazing things human perception is capable of is almost endless but most people, especially Westerners disregard them because it’s what our cultures teach us. Yet audio, especially music, is IMO very much about perception. (steps off soap box)

Those measurements of what auto EQ does would be very interesting to see.

Cheers,
Dean

I can attest to this about BD audio. The new Star Wars Blu-rays kept overheating my Onkyo despite the mains being set to small but with a 40 Hz crossover. So they don’t even have to be set to large in my experience. Note that this happened to a receiver that I tested at 100dB for one and a half hours playing very bass heavy trance music.

My main reason for using the auto calibration features, isn't for speaker playing levels. It's for setting the frequency response for each speaker to gain a more balanced tonal match for the room. I've adjusted furniture around the room and haven't re-calibrated. I need to do that.

Apparently it's useful to point out yet again that Drifter wanted help with "Crossover Frequency Confusion". That confusion about crossovers isn't likely to be lessened by instead discussing the separate and much more complex question of room eq. Randy's reply covers the question asked quite well.

Rob, on your crossover related question, it'd be probably be too much to suggest that "harm" would result from setting the M60s "Large", when a sub as good as the EP500 is available. However, by not setting a crossover for the M60s advantage wouldn't be taken of modern bass management which has been paid for in the sub and HT receiver. The capability of the EP500 would be wasted in part by having the M60s play low bass frequencies that the EP500 is designed to do a better job of. Cleaner M60 response above the crossover is one benefit, less load on the amplifier is another.

On the amplifier load point, however, it should be pointed out that this is sometimes exaggerated in the form of claims that bass frequencies are inherently "power hungry". Of course, basic audio technology is that power requirements are related to loudness and unrelated to frequency. For example, playing a 400Hz note at 80dB requires ten times the power that playing a 40Hz note at 70dB does.

The bottom line is to set even large tower speakers with an appropriate crossover, most likely 80Hz.

Thanks for all the responses - I am going to switch over to small on the mains and as "Ivan" suggested to "High Plains Drifter" listen and experiment.

I don't think it is that simple. If you factor in the speakers impedance (assuming a constant phase angle for now), that is directly related to frequency. So what would demand more current? Let's say a speaker has an impedance of 4 ohms at 400hz and 40hz and playing at 80dB. But volume isn't constant either. Movies and music are filled with dynamics. Dynamic peaks in blu-ray movies especially range from the midbass to subsonic frequencies.