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Post by jcisbig on Sept 1, 2016 9:47:23 GMT -5
I'm trying to figure out the maximum volume that a subwoofer needs to be able to play to match my normal listening volumes in my HT System. I'm looking at upgrading to dual subs in the future and I want to make sure that whatever I get will have enough headroom to competently handle the bass in movies without distorting, compressing, overtaxing the sub, etc. My question is, what's the best way to figure this out? I can think of two options off the top of my head, but maybe there's a better way? Option 1: Pick a few loud scenes in a few movies and measure the SPL with the whole system up and running. I'd pick scenes like the opening of Master and Commander, Hometree getting destroyed in Avatar, going through the singularity in Interstellar, etc. This will tell me what SPL the whole movie is coming through at and I should make sure to get a sub that can cleanly play above that level. Option 2: Do the exact same thing as above, but after setting my desired listening level, turn off all the speakers except the sub and measure the SPL from the sub alone. Option 3: Just to give current info, I have a single HSU VTF-15h mk 1 (not the current version on the HSU site, which has double the power of my current sub). My room is roughly 15ft wide and 23ft long. See attached pictures. I'm considering the following upgrades after selling my current sub: - Upgrading to dual HSU VTF-15H mk 2s. This should give me a 3db advantage over my current sub, and adding a second will increase that further. This is the most cost effective option. - Going with Dual JTR Captivator 118HTs, they are a little more expensive and not coming out until October-ish. They are also very large and would require me to lift my projector screen a few inches, which isn't the end of the world but it's not ideal. I like the height it's at now. - Possibly going with Dual JTR Captivator S1s. This would give me A LOT more extension, but it's also a VERY expensive option.
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Post by pedrocols on Sept 1, 2016 10:03:35 GMT -5
Just use a SPL meter and some test tones and cover your ears...
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Post by jcisbig on Sept 1, 2016 10:05:03 GMT -5
Just use a SPL meter and some test tones and cover your ears... How can I do that to figure out what I'm needing? A test tone goes louder or quieter based on the volume of the processor, and without a movie playing I'm not sure at what volume I'd need to be at?
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Post by pedrocols on Sept 1, 2016 10:08:16 GMT -5
Well what are your needs. Loud to you might not be loud to me.
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Post by jcisbig on Sept 1, 2016 10:13:00 GMT -5
Well what are your needs. Loud to you might not be loud to me. Exactly, I'm trying to figure out the best way to determine what my needs are. I can pop in a movie and crank it up to the levels that I normally listen at and measure the SPL at the loudest parts of the movie and see what it is. But if I do that, should I measure the SPL of all the speakers and the sub, or just the sub to determine what my overall SPL is? If I recall correctly, I topped out at around 108dB on one of the movies I was watching, but I was measuring that will all speakers and sub playing. Is that the right way to do it? If so, then I need to make sure that I have a sub that can cleanly play at levels over 108dB at my listening position. If that's not the right way to do it, then what is?
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Post by pedrocols on Sept 1, 2016 10:38:05 GMT -5
Firstly 108db is wicked loud. Secondly if I remember correctly, THX standars is peaks of 105db for the low frequencies but I could be wrong.
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Post by pedrocols on Sept 1, 2016 10:39:38 GMT -5
If you need to play any louder than that you potentially have or will end up with hearing issues.
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Post by jcisbig on Sept 1, 2016 10:48:08 GMT -5
Well, I was measuring that with an old analog radio shack sound meter so I can't guarantee that it was super accurate. It was definitely loud at 108dB (if that's what it was), but again that was only for a very short time during one of the loudest scenes of the movie. The rest of the movie was definitely not "loud" just "normal".
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Post by pedrocols on Sept 1, 2016 10:54:49 GMT -5
You will not be able to attain the same loudness throughout the movie soundtracks unless the soumtracks are grossly compressed and that is not how they mix movie sountracks. Yes there are going to be quieter passages throughout the movie.
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Post by Wideawake on Sept 1, 2016 11:03:52 GMT -5
I would use a house curve to integrate the sub and then check at what volume your sub bottoms out using test tones from 20Hz and up. Subs don't play at the same SPL through their entire frequency range. Under 30-35Hz, most subs will output lower SPLs. Then play a movie with some serious LFE and see if your sub holds up at those volumes. Note that the LFE channel runs hotter than the other channels by ~10dbs. Here's a guide to getting your house curve right to integrate your sub. www.hometheatershack.com/forums/rew-forum/96-house-curve-what-why-you-need-how-do.html
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Post by jcisbig on Sept 1, 2016 11:57:19 GMT -5
You will not be able to attain the same loudness throughout the movie soundtracks unless the soumtracks are grossly compressed and that is not how they mix movie sountracks. Yes there are going to be quieter passages throughout the movie. I think I understand what you're saying, and I agree. Some moments in movies will be silent, and others will be deafening, with a range in between those two extremes. I'm trying to figure out the best way to measure how loud a movie gets (and specifically the subwoofer/bass frequencies) at my normal listening volumes so that I can make sure the subs I get will be able to keep up. For example, if my peak SPL in a few movies is 90dB, I need to make sure that my subs can handle outputting sound at at least 90dB, if not 93 or 96 to have some more headroom. If I try and put a pair of subs in my room that can only output 80dB max, then I'm going to run into problems when I try to watch a movie at my "normal" volume of 90dB peaks. The entire purpose of this thread is for me to get ideas from others on how I can find out how loud my sub would need to play to keep up with my normal listening habits.
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Post by pedrocols on Sept 1, 2016 12:15:53 GMT -5
So what are your listening habits and how loud you want the subwoofer to be at your listening position?
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Post by gus4emo on Sept 1, 2016 12:26:57 GMT -5
I'm trying to figure out the maximum volume that a subwoofer needs to be able to play to match my normal listening volumes in my HT System. I'm looking at upgrading to dual subs in the future and I want to make sure that whatever I get will have enough headroom to competently handle the bass in movies without distorting, compressing, overtaxing the sub, etc. My question is, what's the best way to figure this out? I can think of two options off the top of my head, but maybe there's a better way? Option 1: Pick a few loud scenes in a few movies and measure the SPL with the whole system up and running. I'd pick scenes like the opening of Master and Commander, Hometree getting destroyed in Avatar, going through the singularity in Interstellar, etc. This will tell me what SPL the whole movie is coming through at and I should make sure to get a sub that can cleanly play above that level. Option 2: Do the exact same thing as above, but after setting my desired listening level, turn off all the speakers except the sub and measure the SPL from the sub alone. Option 3: Just to give current info, I have a single HSU VTF-15h mk 1 (not the current version on the HSU site, which has double the power of my current sub). My room is roughly 15ft wide and 23ft long. See attached pictures. I'm considering the following upgrades after selling my current sub: - Upgrading to dual HSU VTF-15H mk 2s. This should give me a 3db advantage over my current sub, and adding a second will increase that further. This is the most cost effective option. - Going with Dual JTR Captivator 118HTs, they are a little more expensive and not coming out until October-ish. They are also very large and would require me to lift my projector screen a few inches, which isn't the end of the world but it's not ideal. I like the height it's at now. - Possibly going with Dual JTR Captivator S1s. This would give me A LOT more extension, but it's also a VERY expensive option. Dr Hsu recommends putting a second one next to it for your purpose, I have the MK2 and I MIGHT do it next year, just might...
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Post by garbulky on Sept 1, 2016 13:28:58 GMT -5
How to measure subwoofer headroom. Turn on a song you like. You have to turn the sub up and then measure how far your head bobs up and down. That is your subwoofer headroom. At some point, if you think that your current sub isn't bobbing your head enough, then measure where you want your head to be at its maximum head bop distance. That will be the estimated subwoofer headroom you will need. Always glad to help.
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klinemj
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Post by klinemj on Sept 1, 2016 13:52:17 GMT -5
Call up the companies whose subs you are interested in. They should be able to help you out. I did that after a lot of research on my own, and was finally choosing between a Rythmik F15HP and an F25. I went with the F25...my room is bigger than yours in both dimensions, so I maxed it out. I have no shortage of dB in bass. Your shouldn't either with any move from your single sub to a dual like you list.
Mark
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Post by garbulky on Sept 1, 2016 14:06:13 GMT -5
Also note that say you were listening at a 108 db...that doesn't mean that the sub was going anywhere near that volume. That's your entire system. I've found that overall the subs aren't usually playing ridiculously loudly. I you do want to see what your subs are doing. Listen at the level you want. Then turn off the amps and leave the sub running. That's how loud it's going. But remember that's at listening distance which means the sub has to be louder at say the standard 1 meter measurement.
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Deleted
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Post by Deleted on Sept 1, 2016 14:22:05 GMT -5
you need to download REW and do a compression sweep...it will tell you how much headroom you have
you should be able to have peaks of 115db for full bandwidth for the LFE and 105db for all other channels...but this is for reference...if you only listen at -10 at the loudest...then you just subtract 10 from those numbers
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Post by millst on Sept 1, 2016 18:10:54 GMT -5
Unless your other speakers are all set to large, you actually need more than 115dB because of the redirected bass from the other channels.
-tm
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Post by Gary Cook on Sept 1, 2016 18:23:35 GMT -5
My way (not necessarily the right way or the only way) is based on the output of the other channels' power amplifiers and the efficiency of the speakers. For example if I have 200 watts per channel for the other (non sub) channels with 90 db efficiency speakers, I allow for ~2.5 times the output. So if for example the sub also has 90 db efficiency then I'd look at a sub woofer amp around 200 x 2.5 = 500 watts. I don't completely ignore location as that can add or subtract a few db, especially if, like mine, the sub is placed in a corner.
My system runs 200 watts per channel (2 x XPA-1L's + an XPA-5) for the 5 channels (FR, C, FL, SR and SL) with 91 db efficient speakers and 400 watts with 96 db efficient sub woofer (dual ported and corner location).
I also have a UMC-200 and I have very carefully balanced the SPL's with my trusty Radio Shack analogue SPL meter, then a bit of lightweight frequency tuning. The room is pretty good acoustically (heavy carpet with underlay, double layer curtains and a large acoustic picture panel on the rear wall) so it doesn't need much correction.
Speaking of which, looking at the pictures yours would certainly benefit from some acoustic work.
Cheers Gary
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Post by deltadube on Sept 2, 2016 0:23:59 GMT -5
power sound audio .com
got some great subs for less ...
go duals...
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