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In Reply to: Digital or Analog Meter? posted by Charm on January 05, 2002 at 15:35:54:
Go to radioshack.com and type in 33-2050 in the search section. I've used both and, in my opinion, this meter is easier to read from a distance and is just easier to use in general. Get a set-up disc that has either DD or DTS test signals and put it in your DVD player. There is usually a series of tones that can be generated by the receiver, but the discs are more accurate. You may need to move a sofa or chair, but the best place to set up the SPL meter is: on a tripod, at a 45 degree angle facing forward, at the height of your ears (when you sit). It should also be along the center line of the room. You'll need to set the meter for "SLOW" and "A-Weighted" on the 70dB setting. I will not go into details as to why the "C-Weighted" shouldn't be used, but there are some that will disagree. When you start the set-up disc, pink noise (don't use the 1kHz tone) will cycle through all of the speakers. You'll want to bring up the main volume control so that the left front speaker drives the meter to 75dB (theaters use 85dB, but that may be too loud for you or your system and it won't make a difference here). As the pink noise makes its way around the room, you will want to adjust each channel's level control (not the main volume control) so that it drives the meter to 75dB. The "trip around the room" may take several passes before you get them all right, so be patient. Also, unless all of your speakers are the same make and model, the meter is not going to "match" for every speaker, so just get it as close as you can (usually within 1dB). As for your sub(s), there are several variables -- I don't know whether you have full-range speakers, small speakers, a combination, a powered sub(s) or a passive sub(s) -- so I can't tell you in a sentence or two. Let me know the variables and I'll finish.
Follow Ups:
You guys are too much. Instead of answering this person's question, you criticize my method. Did either of you give a description of a method for setting up the speakers in a home theater? By the way, everyone has a different way of setting up a system. Even the "experts" disagree on what's the proper way on one topic or another. What I have described is what I believe to be the best method for this poster to use in setting up his system without going into the many technical details as to "why" something is or should be done a certain way. I believe I answered his question and I made myself available for further explanation/set-up procedures. Can either of you say this?[I also disagree on the method of setting up subwoofer level, since most method is to use pink noise to
match at 75 or 85dB. If the subs are not placed in the proper location, serious peaks and/or nulls would
occur, and if there are a couple of serious peaks w/o any significant nulls, the sub level would be set too
low, resulting in a uneven transition from the speaker to sub around the crossover freq. I personally
prefer to match the -3dB/-6dB level @ xo freq of the main/sub.][I recommend using the "C" scale, or you will never be able to calibrate your sub correctly in relation to
the rest of your speakers.]#1 Where did I describe how to set up the sub? Please read the second to last sentence in my original response. It's a crapshoot if you don't know the details of his system and his preferences.
[Typically the "A" scale is used to quantify the amount of "damaging to the ear" SPL levels in the
workplace or anywhere else for that matter. Because of this the scale is limited in frequency response
(no bass) to the range -> 500Hz to 10kHz.]#2 The A-Weighting area is where the ear is the most sensitive, therefore, this is the area that you want the most "equality" or "level-match" from speaker to speaker. This area is also where the most "directionality" of sound takes place and relates to the ears response to sound cues and how it perceives the environment.
[Why should it be aimed 45 degree (into the ceiling?) Wouldn't the off axis response cause the result to
be more inaccurate?]#3 I don't believe "45 degrees" is into the ceiling -- that would be 90 degrees. This number is based on 15+ years of personal experience and my own measurements and comparisons using different set-ups, information from several home theater publications and DVD set-up discs/guides. I have observed the results using 0 degrees, 45 degrees and direct line (varying degrees) to the speakers. In my opinion, the 45 degree angle mentioned in my response provides the better sounding home theater experience.
[The "C" scale, on the other hand, measures over a more musical range from 32Hz to 10kHz. Measuring
with the "C" range may also capture room mode peaks when using pure tones as the test signal source,
but this can be corrected by using "warble" tones such as those found on the "Stereophile test CD disk
2 & 3".]#4 Let's be realistic and put this in proper context. The question from the poster -- no disrespect intended -- was from someone that wants know how to use an SPL meter to set up his speakers. Do you really think he needs a lecture on these topics: warble tones, C-Weighting, room nodes and the Stereophile test discs? Do you really think he wants one? I believe the details that you are going into are more applicable to an Audiophile or Videophile "nerd" -- my hand is raised -- or a professional A/V installer. That being said, do you really think a $40 Radio Shack SPL meter is comparable to The Audio Toolbox at $1500?
[Also, I would assume that the meter would have to be aimed at the speaker that is producing the sound,
the 120+ deg off axis response for the ratshack mike would be terrible for the high freq portion of the pink
noise.]#5 No, I said straight forward at a 45 degree angle -- not aimed at the speaker -- and where do you get the 120 degrees off-axis from?
Agree with the 45 degree angle for RS meter.Disagree with "A" weighting because it does NOT correctly calibrate re-directed bass and LFE bass content from the DVD.
The SPL calibration measurement is designed to balance all speakers including the sub.
"A" weighting will mis-calibrate the sub.
bstan
[The SPL calibration measurement is designed to balance all speakers including the sub.
"A" weighting will mis-calibrate the sub.]Your info is correct. But, WHEN did I mention calibration of the sub? The fact is, I didn't -- WHY is that so hard to understand/see/read? My point is this: I deliberately left out calibration of a sub until I knew what speakers were in his system and what type they were (full-range, small or a combination). The sub "how to" chapter can only be explained after you know this information. To set up the sub, you MUST use C-Weighting (the A-Weighting's low end starts at about 500Hz -- not exactly sub territory).
Simply:My advice would be to have a new HT person use one method for balancing all speakers using the "C" weighting so he wouldn't be confused when he gets a sub and goes to calibrate that sub and can't understand why he can't get a reading with the "A" weighting.
bstan
Joe....to give you more details of the system. The room size is in a bedroom at 16 feet by 18 feet with 8 feet ceiling. Speakers are paradigm studio/60 and studio/cc center channel...thats all the speakers for now. I'm using Denon AVR 2802 receiver to power the speakers. When you said I need dvd for test tones...you mean something like Avia cause I hear people talking about it. By the way the speakers are 7 feet apart and 1 feet from the wall behind it. Hope this helps.Eric
#1 If you can, move the 60s out into the room a bit. If they really do go down to 30Hz, you're probably getting some room boom because of their proximity to the wall. You may not be able to do this, but if you can, the sound will be less boomy and smoother.#2 It seems that you are only using 3 speakers (L, R and C). Follow my original set-up "guide" to set up your speakers. I'd recommend setting the L and R speakers as LARGE and the C as SMALL (the CC only goes down to 70Hz). If you haven't done so already, set up the 2802 for no surrounds and no sub. This should direct the sub information to the L and R speakers. Depending on your taste in bass and the speakers' (60s) ability to handle any LFE effects, you may not want to do this. Most AV receivers will direct LFE information automatically to the L and R speakers, while some will just delete the LFE information (it doesn't show up at any of your speakers). I don't know what the 2802 does in this case. If you're not sure, there's always the manual...
#3 There are several DVDs and at least one CD for cycling through pink noise and tones for speaker calibration. On DVD: Video Essentials, Avia and Allsop (this one has DTS and DD movie trailers to play after you calibrate), to name a few. On CD: Technics DTS Surround Set-Up disc.
#4 If you really want to get into Home Theater, I'd advise you to get surround speakers and a sub (or two!). Well, actually, your room may not be all that complimentary for a sub. As for me, a dedicated sub adds impact, dynamics and "physical" emotion that even full-range speakers can't truly realize. I'm sure you realize that your 2802 decodes the current best surround format available -- DTS-ES 6.1 Discrete. Even if you only use the 2802 to decode digital 5.1 sound, these extra speakers will make movie presentaion in your room so much more emersive. And isn't that what Home Theater is about?
#5 The best learning tool is information (ideally, correct information) and one of the best teaching tools is WidescreenReview magazine. Check it out at the 'stand or get a subscription. There are others, but WSR is about 60/40 for video/sound content and they touch on all aspects of Home Theater (technology, acoustics, speakers, HDTV, DVD, movie reviews AND "how to set up a Home Theater"). Hope this helps.
Where can I buy Avia, VE, etc? Media play or places that sell cds have Avia, etc too? By the way about the LFE on Denon AVR 2802 receiver you asked about...for the LFE (subwoofer mode) I can select either "LFE" or "LFE+MAIN". It'll be a while before I get rears but I'll get sub when I get chance.
My dvd player hasn't came yet...can I still calibrate speakers using my cd player for music? If so how do I do that and what disk or cd should I get till my dvd player comes?
The only CD set-up disc that I can think of with surround pink noise is a Technics disc. It's called "DTS Technology Music Demonstration and Set-Up Disc" and the product number is Technics # RFR0005. The disc was made in 1996. If you contact Technics via Panasonic at panasonic.com, they may be able to get you one. There are some other CDs, but I can't think of their specific names right now.
I'm quite interested in your rational for describing the "A" weighted scale for SPL sound calibration. Can you give a bit more detail?Typically the "A" scale is used to quantify the amount of "damaging to the ear" SPL levels in the workplace or anywhere else for that matter. Because of this the scale is limited in frequency response (no bass) to the range -> 500Hz to 10kHz.
The "C" scale, on the other hand, measures over a more musical range from 32Hz to 10kHz. Measuring with the "C" range may also capture room mode peaks when using pure tones as the test signal source, but this can be corrected by using "warble" tones such as those found on the "Stereophile test CD disk 2 & 3".
I recommend using the "C" scale, or you will never be able to calibrate your sub correctly in relation to the rest of your speakers.
Now the meter does have some deviations from flat response, but those can be corrected for by applying well known adjustment figures available here as the "RS SPL meter correction values".
bstan
at the same time, since the pink noise is pretty much random. So for sub adjustment, you would never know the real SPL of the system. Unless you figure out the bandwidth and distribution of the pink noise, do a weighted response drop of the meter for that freq range, and compensate for that. Plus one might have to compensate for the premature rolloff of the sub, since if the sub is not producing any sound below 30hz, the level will be boosted by the person to bring the whole level up to 75dB.
That is why I recommend doing the level matching @ crossover freq, plus plot the whole sub range and maybe mains to 200hz see the integration.
I have another reference (still looking for it) that indicates the low frequency response for the RS SPL meter with pink noise is only 2-3db less than at 1kHz.bstan
If you are only measuring 20-80hz, and the meter starts going low @ 60hz, then the avg as a whole would be off. So if you measure 75dB on the ratshack meter for LFE, it might be actually producing 78-80dB, depending on the sub rolloff & meter inaccuracy.
But you can't accurately measure the pink noise SPL below 500Hz with the "A" weighting on the SPL meter, because the "A" weighting response sensitivity drops off substantially below 500Hz.How do you correct for that?
bstan
This gentleman has done some work with RS spl meter's.
Perhaps it is of help.http://www.gti.net/wallin/
Bill
Thanks,Yes, I have built the calibrated mic-wand and a battery operated mic-preamp displayed on that site and they work quite well.
The mods to the RS SPL meter are designed to correct the response curve for the "C" weighted curve which does measure below 500Hz, but the "A" weighted curve still doesn't measure below 500Hz.
bstan
I'm looking at getting a Behringer DSP 8024 analyzer. might be a ok measuring device with the ability to make some system changes.Bill
Yes, it gets pretty good comments here, but if you are using it to eliminate room peaks in the subwoofer range, just be aware it is limited to only a few parametric EQ filters, unlike the BFD-1124 which provides for 12 filters per channel.bstan
ok, I give. I cant find info for a BFD-1124 anywhere.regards,
Bill
although bfd.com has a pretty cool web page (very off topic)
It is currently being sold as the replacement for the BFD 1100, Behringer just hasn't upgraded their webpage yet for the 1124.Maybe this is a first! Instead of vaporware we have webvapor.
bstan
Why should it be aimed 45 degree (into the ceiling?) Wouldn't the off axis response cause the result to be more inaccurate?Also, I would assume that the meter would have to be aimed at the speaker that is producing the sound, the 120+ deg off axis response for the ratshack mike would be terrible for the high freq portion of the pink noise. Any explaination for your method?
I also disagree on the method of setting up subwoofer level, since most method is to use pink noise to match at 75 or 85dB. If the subs are not placed in the proper location, serious peaks and/or nulls would occur, and if there are a couple of serious peaks w/o any significant nulls, the sub level would be set too low, resulting in a uneven transition from the speaker to sub around the crossover freq. I personally prefer to match the -3dB/-6dB level @ xo freq of the main/sub.
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