A401,

I just tried the RealTraps tones with my EP600. The 600 does not cut in until 15Hz where the SPL is up 0.5dB from reference. At 16Hz, it's up 8dB. I have no problem whatsoever hearing and feeling the Introduction to Also Sprach Zarathustra from "Top 20 - The Very Best of Erich Kunzel and the Cincinnati Pops" which according to JohnK is the 16Hz note. This was coming in at 12dB above reference.

The reference level is 58.5dB SPL (this is relatively loud because compressor noise from my aged fridge actually carries down the stairs. This however does not interfere with listening). I had my Denon main gain set to -20 (which corresponds to 1W output per left/right channel at this frequency for my M80s). My 600 is set at ten o'clock, the Denon LFE is set to -6dB (the range is -12 to +12). The cross-over is set to 80Hz, lows out of sub only and the Denon set to stereo. I am in a 4,000 cubic foot, extremely tightly constructed, relatively live room with a large opening going up to my main level. I had the meter at the sweet spot where I normally sit. As you can see from my settings, I have plenty of headroom. When I turn the gain up at 10Hz, it feels like my

BTW, I run my sub about 6dB hot at 81dB SPL.

A more interesting and surprising scenario takes place when I set the M80s to large. At 10Hz, the SPL is up 0.5dB from reference. At 11Hz, it's up 3dB and by 12Hz it's up 8.5dB. I can definitely hear all these tones although I am sure what I am hearing is the room and not the actual tones. I posted about this before and Randy also witnessed it on his system but this is the first time I've posted any numbers.

Now even more shocking. I set the Denon to 7-channel stereo. This set the QS8 and VP150 woofer drivers quaking at 10Hz! Of course they are very small and are hardly pushing any air.

I vote that Axiom releases a mod to remove the so-called brick-wall filter below 15Hz provided it doesn't adversely affect the specifications at higher frequencies.

>>I vote that Axiom releases a mod to remove the so-called brick-wall filter below 15Hz provided it doesn't adversely affect the specifications at higher frequencies.

I think they would have to recalculate all of the speaker parameters and limiting logic to consider cone flapping from those lower frequencies. Not pretty.

Hi Bridgman and all,

Hey, do you all wanna hear air-conditioning rumble from recording studios and other recording venues that have not taken steps to suppress such infra-sonic noises?

You'll also get to hear cutting-lathe rumble on some vinyl recordings as well as inherent rumble from some much-lauded turntables--if you're still playing vinyl.

And I've got a couple of recordings with foot noises from concert pianists pedaling. Those resulted from inadequate isolation of the microphone stands near the piano. The floorboards transmitted the foot noise to the mike stand and up the stand to the mike.

There's a lot of garbage down there that's better left unreproduced.

Regards,

This should be entertaining...

Hi Mojo,

Carol Rosenberger, for one. Back in the vinyl days, this Delos recording, "Water Music of the Impressionists," engineered by John Eargle, who wrote the standard text on studio mike technique, was one of the few audiophile recordings of La Cathedrale Engloutie (The Sunken Cathedral) played on a big Bosendorfer that had authentic 16-Hz content.

I have it on vinyl but it's been reissued on CD here:

http://www.amazon.com/Water-Music-Impres...4067&sr=1-7

I haven't played that disc in years by it's a good recording.

Regards,

The BeachBoys PetSound DVD-A on the ‘God Only Knows’ studio-take track, the bassist hit the pickup(s) while playing a note and there’s this very loud subsonic thump that really shakes the room. It’s kinda of cool because it only happens once … I can see it being annoying if it happens on every other bar, though.

There's a thump like this on the Eric Clapton:Unplugged CD and I thought someone was in my bathroom. No word of a lie...it was downright scary .

I have to agree with Alan that this is one band of the frequency spectrum that we don't want to hear.

Funny.... all my old equipment had infrasonic filters specifically to get rid of those frequencies!

Mark,

Yeah, and it was often called a "Rumble Filter". Later vintage 2-channel preamps changed that to "Subsonic Filter", and it was switchable.

In this age of high-performance subwoofers, an argument could be made for reinstating the switchable subsonic filter on AV receivers so you could engage it when needed with flawed recordings.

Regards,

Alan, thanks for the tip on "Water Music of the Impressionists." I'm going to pick up a used copy and try it out.

I looked at the Bosendorfer New York website and found a list of artists that use Bosies (Tori Amos, Leonard Bernstein, Placido Domingo, Lionel Richie, Arturo Sandoval, Joe Zawinul and Oscar Peterson to name a few. Also, Bosendorfer makes loudspeakers as well.

Alan, I received that disc today, and I listened to that track. Pretty cool! You're right about it being a good recording. I was surprised to find it was an all-digital (DDD) recording from 1983. Anyway, very cool. I'll have to listen to the whole disc later.

Hi CV,

Great! I'm delighted you like it. I knew it was an early digital recording because it appeared in a vinyl audiophile transfer (the one that I'm still digging through my collection to find) before the CD version was available.

Regards,

I hope they're not related to BOSE!