Accurate subwoofer levels - Page 8 - Home Theater Forum and Systems -

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post #71 of 116 Old 08-03-08, 12:41 PM
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Re: Accurate subwoofer levels

I did not read all of the postings here but it seems there are many theories and opinions as to what the proper sub settings should be. Here is mine:
From my experience of almost 20 years of using subwoofers for HT, I have found many things come into play; room construction i.e. walls and flooring, apartment or house, carpeting or not, symetrical room shape, and many others.
With subs it can be like chasing your tail trying to get a nice setting in some rooms. I avoid the use of the words 'right' or 'correct' on purpose. Theatre systems are set up to achieve a certain frequency response at a specific volume level which is not always possible in the home environment. First of all many people have neighbors that would prefer not to hear movies thundering through aprtment or duplex walls. I can't tell you the number of times I have had neghbors come pounding on my door or start banging on the walls or ceiling. Ughh... Thus, I have to find a good overall sound level with reasonable sub settings that allows me to enjoy a movie without disturbing my neighbors.
I have found that sub amps with built-in EQ, or crossovers with built-in EQ -the Audio Control Richter Scale that comes with calibration mic. and a bridged Hafler Dh500 is what I started with in the 80's and is still made- will help you get a nice sound from your subs. Also try to find one with phase adjustment. I am using the O-Audio 500W BASH plate amp and single 12" Infinity driver.
I can get relatively flat response down to around 28Hz. But as some previous posts stated that left the system with plenty of low end rumble but no real punch. I finally played around with EQ settings to account for room modes around 30-40HZ EQ'd down by about 6-7db. This left the rumble that seems to come out of nowhere at the right times and lots of punch and definition when the soundtrack kicks in.
Also remember that the human ear does not hear with a flat response. I also use acoustical absorption panels on front and side walls. The Fletcher-Munsen Curve or Equal-Loudness Contour that defines how humans actually hear what frequencies and how loud they are percieved. I have played drums since I was 7 years old and been in rock bands since I was 15. Cymbals at close proximity will have a profound affect on the hearing. After some shows my ears would ring for weeks. I had to give it up and now wear headphone monitors when playing but that is all another story.
My main point is that regardless of the alleged correct or right settings, or what you measure with SPL meters, in the end all that goes out the window and it will come down to tuning the sub to integrate with the room and your personal taste.

Last edited by Synthsayer; 08-03-08 at 01:07 PM. Reason: more info-citations
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post #72 of 116 Old 08-03-08, 05:31 PM
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Re: Accurate subwoofer levels

Like many posts have said, listen to your ears and adjust accordingly. This is geared towards any bedroom full of the usual furnishings for a college student. My experiences have led me to using this method, fine tuning by ear, using a galaxy cm-140 spl meter, rives audio test cd2, and running through this procedure anytime I've changed my furniture layout . I first begin by placing my sub as close to the exact ear listening position I will be in, because I am almost always the only person using and watching. Then I crawl around the room in the space I can place the sub, with spl meter in upright position, marking with coins where I get the "best sound" or highest spl reading using slow weighted c response. Then I set the sub, facing toward my listening position closest to that spot with the speaker cone. Next, I use a test cd (rives test cd 2) ,set to the crossover point preferred to check for phase, and run a test tone at that or around 60-80hz. While incrementally moving the phase from 0-180 degrees, i have the spl meter in my listening position, again set to slow c response, and find the setting where I get the highest spl reading and leave this. Next, Since I have a sunfire true subwoofer signature eq, I run it's automatic eq with it's supplied mic set in my listening position, and vouch it does a pretty good job, instead of running through setting a flat tone with test tones from rives test cd. Next, I proceed to turning off the sub, and running audyssey eq with all the other speakers through my onkyo 805 receiver, with supplied audyssey mic in listening position(s). After letting it calculate, I save, turn on the sub, recheck for accurate speaker distance, and use the reciever's pink noise to also reaffirm the speaker levels (with sub on) with spl meter in listening position, set to c weighted slow response, and level every speaker but the sub to around 80-85db (neighbors don't mind), and have the sub around 90-95db. I'm one step away from the end! Then a I run a familiar cd with lots of bass guitar at low levels from 40-80hz (primus, pork soda cd), and just use the sub gain knob to further integrate while going back and forth to my listening position. Again, crossover frequencies for your speakers to your sub can differ depending on yours. I use to think my main speakers could hold 50-60hz well with past test cd playing, but recently set them to 80hz cutoff and set the sub to 80hz low pass cutoff, and it made a huge difference and obviously took even more of a load off the other speakers while sending the rest to the sub, which is it's purpose after all. That is a general outline without going into too much details I could include, and should work well with the recievers of today with automatic eq setups.

Last edited by pnutbutter81; 08-03-08 at 05:43 PM.
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post #73 of 116 Old 08-04-08, 07:53 AM
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Re: Accurate subwoofer levels

I checked out the Sunfire True Sub Web Site and it looks very impressive. I really like the idea of the various EQ settings and built in test mic. I bet it rocks.
I tried to find some pricing info but will have to contact dealers I guess. I can't afford it right now anyway.
It sounds like you have a very nice system and found a nice method for setting it up. Mine is a bit more convoluted.
I place a studio condensor mic. on a boom stand in the listening position and run it into a Tascam TM-D1000 digital mixing board on an XP Pro system running Nuendo3 recording software with Waves Diamond Edition .VST plu-ins. All mixer EQ set flat. This goes through a fibre digital converter into the EMU1212 Sound Card on the Digital Audio Workstation PC. I then connect audio output of my Acer laptop running Vista to spare inputs on my Harmon-Kardon AVR 154. I use WinISD BETA on laptop to generate a slow sweep from at 10HZ-10kHz. I know the approximate response of the studio mic (cheapy but decent MXL 990 from musician's friend) and it is fairly flat from 30Hz-20kHz according to manufacturer . I record the sweep tone onto an audio track using the recording software at increasing levels until it is just beyond what my normal listening level would be. This gives the sweep tone frequencies running through the sub and as fr. increases, out of the front center and rear satelites. I then use a frequency analyzer plug-in and play back the tone to see where the peaks and dips are and look for possible phase problems.
Like I said, it is a really convoluted ( Rube Goldberg ) process but it seems to give a fair indication of the system response overall. I make most of my speakers except the small rear and center units.
O-Audio sub amp is actually running a leftover Infinity 1230W Reference Series Auto Sub in 1.7 ft. cu. sealed cabinet that is weighed down with a leftover power amp that weighs about 40 pounds and on spikes. I compared the driver response plots to many other high end units costing ten times as much and even though it has an f3 of 42Hz. I get reasonable flat response measured down to 30HZ. I had the driver in a ported cabinet that was supposed to be flat to 30 Hz but liked the sound of the sealed system better. The front main speakers are HiVi Research 8" woofers and Scanspeak Revelator Series D2905 1" tweeters w response from45Hz-30kHz. Crossover in Harmon-Kardon is set to 80Hz and is 12db per ocatave and I bypass the internal one on the sub amp to avoid phase issues. I may experiment with changing this.
The system sounds okay but I miss my old powerhouse stereo system. I used a Superphon SP100 Signature series pre-amp going into Behringer CX-2300 crossover and a Ramsa P1200 running EV DH1012 compression drivers mounted on HR9040 horns; BGW 250 driving JBL short-throw bass bins (popular concert cabs for many years); and QSC-RMX 1450 running the sub. It had a total of over 2000 watts into 8 ohms and could make your pants legs move with the air pressure. It was crystal clear at the highest levels. Those things could get loud.
I switched to the lower power system so it would take up less space and give me 5.1 surround and remote control flexibility features. I am fairly happy with the system even though it is far from perfect.
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post #74 of 116 Old 08-04-08, 08:15 AM
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Re: Accurate subwoofer levels

Like I said, it is a really convoluted ( Rube Goldberg ) process but it seems to give a fair indication of the system response overall. I make most of my speakers except the small rear and center units.
Wow that is involved. I'm impressed.

But I personally find that REW with a calibration mike (LinearX M31) plus a RS SPL meter is fairly simple to use. I also use TrueRTA with my cal mike to look at various speaker responses in detail.
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post #75 of 116 Old 08-04-08, 08:34 AM
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Re: Accurate subwoofer levels

Thanks B,
I will check those out when I have some time later today. I am sure there are much, much simpler ways to analyze the system but I am kind of stuck using what I have for the moment. When I can afford to, I will get some different test gear. I would really like to have something to more accurately measure the response of my DIY speakers that I build. I'm pretty happy with what I have right now, but I am sure I will have new ideas to modify the system in the future.
Thanks again.
Have a nice day.
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post #76 of 116 Old 08-05-08, 06:27 AM
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Re: Accurate subwoofer levels

In answer to the original question, do we like the sound of house curve / flat responses?

My answer is no.

I have previously had a 12" sub driven by a 240watt plate amp tuned to 20hz and now have 2 x 18"ers tuned to 15hz powered by an EP2500 which gives 750 watts per channel (at 4 ohm load).

In both cases I prefer the un-EQed sound, basically for the massive room gain peaks - as soon as I flatten eveything out, I get less shaking, and so it's less exciting for me. I should note that for the 2 x 18" subs, in order to get a flat room response, I have to add a whopping -12db filter at about the 40hz mark.

Re the flat response - the way I figure it, let's assume I'm running the EP2500 at full power (750watts/channel) and that you need twice the power for every increase in 3db gain. If I have to knock 12 db gain off around 40hz to get a flat response, that would work out to about 47watts of power being supplied in the 40hz region (47 x 2 x 2 x 2 x 2 = 750) - no wonder I'm not getting much happening!

I should note that I only use my subs for home theatre and not music. I doubt that you would want massive peaks in the bass when listening to music. However, for me, subwoofers in home theatres are all about feeling the action so for my taste - more, anywhere (at any frequency), seems better.

Also, I have just started to play around with my new setup so I may change my mind in a few months but for now, that's my 2 cents worth.

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post #77 of 116 Old 08-05-08, 08:08 AM Thread Starter
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Re: Accurate subwoofer levels

Thanks for contributing Blueeyedfrog. Don't you find that when you watch a movie that has a musical score (99.99% of the time) that it sounds bass heavy if you don't EQ ? Do you have bass traps in your room ?

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post #78 of 116 Old 08-05-08, 09:55 AM
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Re: Accurate subwoofer levels

Watts don't mean much. I run my four subwoofers using only 180W. 180W X 4 = 720W so all of my subwoofers combined do not run on as many as one of your subs. I would almost be afraid to put that much power in my little HT. The first time I sat a sub in my bare concrete room (before it was built) and played a wal-mart 25$ subwoofer in my plywood box with one of my amps my ears were ringing for about 20 minutes. I think you would have fun with room treatments. It doesn't sound the same as equalization.
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post #79 of 116 Old 08-05-08, 11:34 AM
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Re: Accurate subwoofer levels

I also dont like the sound of a "flat" system, I like to add some lows and highs to it My EQ usually has a bit more boosted in the 20-40Hz range and again in the 12-15kHz range.

Home theater:
Onkyo 805, Yamaha YDP2006EQ, Samson Servo 600 amp
3 EV Sentry 500 monitors across the front, 4 Mission 762i's Surrounds, SVS PB13U sub, Panasonic BDT220, Harmony 1100, Nintendo WiiU
Panasonic PT-AE8000 on a 120" 2,35:1 fixed screen

Living room system:
Sherwood/Newcastle R972, Mission 765's, SVS SBS02's, A/D/S MS3u sub, Yamaha YDG2030EQ
Yamaha KX-393 Tape deck, CDC 805 CD changer, Panasonic BD60, Sony turntable PS-T20
Panasonic TC-P50ST60, HD-PVR & WDTV Live, Harmony 900

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post #80 of 116 Old 08-05-08, 03:13 PM
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Re: Accurate subwoofer levels

thewire wrote: View Post
I think you would have fun with room treatments. It doesn't sound the same as equalization.
Room treatment can do a lot to improve the sound of any home theatre or listening environment. It does not have to cost much either. I used 3" wedge and pyramid foam, glued it to 2'X4' sections of 1/8" Masonite board, then experimented with placement until I was satisfied with the results.
It was well worth the trouble.
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