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Re: Sub level- adjust at sub vs let Denon/Audyssey1909
GregLee #257818 04/22/09 06:47 PM
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Greg, Sirquack needs those subs just to keep the LFE even and powerfull let alone mid bass etc. He has a HUGE open room not a "listening" room.


Jason
M80 v2
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QS8 v2
PB13 Ultra
Denon 3808
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Re: Sub level- adjust at sub vs let Denon/Audyssey1909
GregLee #257819 04/22/09 06:56 PM
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It seems to me what Dr. Lee is saying is that it is important to smooth out the response in the 50-150Hz region and relatively unimportant below 50Hz.

If that is the case, then using multiple lower cost subs for the above 50Hz stuff seems to make sense.


Fred

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Re: Sub level- adjust at sub vs let Denon/Audyssey1909
fredk #257828 04/22/09 08:42 PM
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The above is exactly what he is saying.

From the thread:

"The one thing about room response at LF that I feel gets missed in these discussions is how the response varies arround the room at LF. At near DC there is NO variation of the response arround the room, it is everywhere the same. As the frequency goes up it gets greater and greater. But a sub operating from 25-50 Hz will se virtually NO spatial variation in either its response at the seating location or its sensitivity to location. Usuing more than one will thus only increase the output, but do little to nothing to smooth the response as there basically is nothing to smooth."


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: Sub level- adjust at sub vs let Denon/Audyssey1909
GregLee #257836 04/23/09 12:44 AM
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Yes Greg, I assumed you were saying it takes expensive subs to follow the methods I use, that is not the case. I've saved up through the years. Started with a EP350v1, then EP500, then EP600, then added 2 EP350v3's.

Keep in mind, my room is around 8,000 cubic feet. Cheap, wussey subs just can't cut it to preasurize that space.


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: Sub level- adjust at sub vs let Denon/Audyssey1909
fredk #257844 04/23/09 01:47 AM
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Fred, the quoted statement appears to be incorrect, at least in part. "Near DC" is one matter, but frequencies such as 25-50Hz, which are subjected to room modes in listening rooms of typical dimensions, are another. For example, in a room with a 20' length dimension, the first mode is at about 28Hz(1130/(2x20) )and certainly varies at different locations within the room, as all modes do. The benefit of placing two subs at mode minimum locations and/or where the mode frequencies are opposite in phase and tend to cancel, would exist down to the lowest mode frequency of the room, although not to "near DC".


-----------------------------------

Enjoy the music, not the equipment.


Re: Sub level- adjust at sub vs let Denon/Audyssey1909
SirQuack #257850 04/23/09 02:25 AM
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 Originally Posted By: sirquack
Yes Greg, I assumed you were saying it takes expensive subs to follow the methods I use, ...

No, that's not what I was saying. I was saying that the example you give purporting to show that other methods work better than Geddes' doesn't show that, because your subs are expensive, and Geddes method applies only to inexpensive subs. The response curve you give for your three subs, though interesting in itself, doesn't show anything one way or another about Geddes' theories. Maybe, as you suggest, Geddes is all wet, and Toole's and others' theories work better, but the specific evidence you gave doesn't show that. That's all I was saying.


Greg
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Re: Sub level- adjust at sub vs let Denon/Audyssey1909
GregLee #257856 04/23/09 03:21 AM
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I never said one method works better, please don't put words in my mouth. Your the one that said "I'm not sure he should be doing that". I was giving Dave ideas on how to manually calibrate his subs, then you jumped in. So one persons ideas rule out others that have been around much longer? I studied and practiced the Geddes method as I like to tweak things to get the best results. Although he makes it sound easy, it is not if you follow Mark's website. Most people do not have the equipment required in an FFT Real Time Analyzer, those cost money and you can't use REW or other free products, they are not the same.

I also never referenced my subs in my statements or said you had to have expensive subs to calibrate them. I was only telling Dave how to calibrate multiple subs manually, prior to running Audyssey. These methods weren't born yesterday, and have been referenced by true AV experts for years and can be used on any subs, no matter the cost.

My graph shows the end result after calibrating each sub individually, and placing them centered on the walls per Welti's Harmon papers. Can I see a graph of your room that has less deviation, less than 10dB?

Below is a "before" graph with just the EP600 and no room treatments, I see a huge improvement to FR by adding the additional subs and a few FRZ's and basstraps. All that was done was calibrate the subs to 75dB's with an spl meter and place them at the midpoint of opposite walls, pretty easy. At least I don't have to put one above the center line like Geddes suggests, or not use treatments like he disregards.




M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: Sub level- adjust at sub vs let Denon/Audyssey1909
SirQuack #257858 04/23/09 03:34 AM
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 Quote:
Your You're the one that said "I'm not sure he should be doing that".


Ahem....


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Apostrophe Bot is a free service, but is not affiliated with Axiom Audio.
Re: Sub level- adjust at sub vs let Denon/Audyssey1909
JohnK #257868 04/23/09 05:46 AM
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John. I noticed that as well. If you read through the thread at all (its quite interesting after you wade through the troll droppings) he acknowledges that his room has one mode below 50 Hz, but still sticks by his original asertion.

His point is that, compared to the 50-150 range(where there are increasingly more), there are none.


Fred

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Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
Re: Sub level- adjust at sub vs let Denon/Audyssey1909
fredk #257876 04/23/09 06:23 AM
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Well, after reading page 5 of this thread, I can see I will stay out of 'sub tech talk'. A guy could get hurt. ;\)

After weeks of theorizing about speaker choice, then ordering, waiting, getting and trying many Axioms... I am tired. I need a break to just be a listener/watcher of HT for a bit. When my batteries get recharged, I'' do the individual sub calibration that Randy and Jay outlined. Jay, From your comments, I will try unplugging the Servo 15 to see what the 2 KLH's are actually doing. I never thought of that. Thanks. Then I'll try with just the Servo15. After I do the individual sub calibration, I will repeat the above process, noting differences I hear (or don't ;o).

Thanks to all here for the great ideas. It will likely be a week (or maybe a few days ;o) before I get back into testing mode.

Cheers to all.

Last edited by davekro; 04/23/09 06:23 AM.

Dave

"In theory, practice and theory are the same. In practice they're not."
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