Question regarding SPL findings in my HT(great advice thanks!) provided more INFO

[Fishboy]

Hello, looking for some input regarding the results for my SPL meter findings for my home theater. Firstly my set-up is as follows

1. Yamaha RXV1081- only surrounds run off the receiver which are Polk RTIA1,s (110 W 2 channels) driven)
   
2. Emotiva Basx700, 80w RMS all channels driven- 4 channels used to power Polk RTIA9 biamped(fronts)
3. Polk Audio RTI A3s for rear surrounds (powered by emotiva)
4. Polk Audio CSIA6 center channel (powered of emotiva)
5. 3 sub-woofers all Polk PSW505'
6. All speakers set to small (use bass management)

So my results were this, with the receiver at a volume of -15db which is loud and crisp for me, i do bring it up to -10db as well on occasion. But at minus -15db in the main seating area which is smack dab in the middle of the set up the SPL meter (good quality one I borrowed for work, I know it works well and accurate) it read 82db (10 feet from the fronts and rears and center) at the seating position. when i brought it roughly one meter form the front left RTIA9 it read about 93db. I expected the SPL reading to be much higher at the -15 volume on the receiver (which to me is loud). Basically my question is this- with the reading of 93db one meter from the speaker at that -15db volume on the receiver, I am only using 2 watts to drive that speaker at that point? oh sensitivity of all the polks are 90db 1W@1meter. In fact all speakers read about 93db as i put the SPL one meter in-front of each speaker at that same -15db volume on the receiver. Have I misunderstood all this time of how little watts i was actually using at the -15 db volume o the receiver. I am astonished, I was worried about insufficient power to drive my speakers. Is it safe to say I can bring the volume to -5db and not even be concerned about clipping? I'm still learning folks. Do my results make sense? I followed the proper procedure for measuring.
ALSO, what percentage less do the speakers use in terms of wattage when set to small (80Hz)?
One more thing, I want to upgrade my surrounds form RTI A1's to RTI A5,s, and I was considering getting the Emotiva basx300(150W RMS) per channel to power them. right now the surrounds run off the yamaha (only speakers) which has 110W per channel (2 channels driven). Is it even necessary to buy the emotiva given my findings or is the Yamaha more than enough to run them?
Thanks Folks
What a great hobby!

 

[Bucknekked]

Basically my question is this- with the reading of 93db one meter from the speaker at that -15db volume on the receiver, I am only using 2 watts to drive that speaker at that point? oh sensitivity of all the polks are 90db 1W@1meter. Is it safe to say I can bring the volume to -5db and not even be concerned about clipping? I'm still learning folks.

What a great hobby!

Fishboy
Welcome to the AH forum and we do share a great hobby. I hope you have a lot of good posts and lots of interaction.

I did something similar last year is measuring my SPL at a fixed distance from the speaker and at the listening position to try and learn how many watts I was pumping out. I was stunned to find out that with the speakers I was running at the time I wasn't even using a whole watt yet to generate my standard listening level. At increased SPL, I was barely turning less than 2 watts

There are guys on the forum, @PENG for instance, who have the formulas down cold and can give you the in's and out's of SPL vs distance vs power. I can't say that your method will produce highly accurate results, but, you are definitely in the ballpark. I found it to be an eye opener how much power I wasn't burning. I thought for sure I was using big watts. As I remember it the only way to accurately measure the power consumption is with an O'scope with high impedance probes, a signal generator, and a whole bunch of time.

Sounds like you are safe. The ultimate guide is your volume control and what you hear. Take it easy with the volume control and pay attention to how things sound. Your system will let you know if you're walking to close to the line

Enjoy

 

[lovinthehd]

What sounds/tones were you using to measure with? What weighting scale on the spl meter (and which meter)? You might also try this spl calculator to get some confirmation.

If you calibrated the volume on your receiver via YPAO to the relative scale, as it appears you have, which would be relative to the movie recording standards, then -15 on the volume scale for playback of a movie should yield approximately average levels of 70 dB and allow for 20dB peaks (0 on the volume scale would be average levels of 85dB with allowance for 20dB peaks). Your LFE level would be 10dB higher than that for the speakers.

Keep in mind to gain 3 dB in spl you need to double amp power, and to swing 10dB you need 10x the amp power (and 10dB is roughly considered a doubling of apparent volume).

 

[shadyJ]

You can't know what kind of current you are feeding your speakers until you measure it. Do you have a multimeter handy? I would not make any assumptions about the power use or speaker sensitivity unless you have measured it. Speaker sensitivity specs from manufacturers can very often be meaningless, so don't put too much stock in whatever the manufacturer reports on their spec sheet. You can't judge anything by what they report. you are also trying to measure loudness indoors, which is not going to tell you anything about the speaker's sensitivity since that only applies to that specific acoustic scenario.

What is likely happening is you are not using nearly as much wattage as you would think. Unless you are a headbanger or like to watch all your movies at reference level, you probably do not need anywhere near 150 watts per channel.

 

[Bucknekked]

You can't know what kind of current you are feeding your speakers until you measure it. Do you have a multimeter handy? I would not make any assumptions about the power use or speaker sensitivity unless you have measured it. Speaker sensitivity specs from manufacturers can very often be meaningless, so don't put too much stock in whatever the manufacturer reports on their spec sheet. You can't judge anything by what they report. you are also trying to measure loudness indoors, which is not going to tell you anything about the speaker's sensitivity since that only applies to that specific acoustic scenario.

What is likely happening is you are not using nearly as much wattage as you would think. Unless you are a headbanger or like to watch all your movies at reference level, you probably do not need anywhere near 150 watts per channel.

remember, you can't use a regular multimeter on those speaker terminals. It has to be a high impedance meter and probes. Most folks that have access to a multimeter have garden variety stuff that won't give an accurate measure. That's what I did to get my garden variety numbers. I believe it was TLS Guy that told me I was wasting my time because my meter wasn't of the caliber necessary to actually do these measurements. I was still in the ballpark, and I still learned something. But, accuracy? Who knows?

Your comments on manufacturers numbers being highly suspect is perfect.

 

[Fishboy]

Thanks Lovin the HD and Shady J & Bucknekked, thank you for the input firstly. When I did the SPL measuring I thought playing a blue ray (Rush live in Cleveland) because of the loudness and dynamic range of the Blu-ray it would yield the best material to measure, Its a tacklife SPL meter fairly new and calibrated. I understand how 3db and doubling the amp power numbers to do so. I have confidence in the SPL meter, I am still amazed at the unused wattage im actually not using at those volume levels. Can I safely say that if at -15 db on the receiver im only using 1-2 watts its crazy. Power was my biggest concern from all the things I have researched when i built this system. Is it safe to say that at 0db on the knob( which is rare)that I have ample power to run the system properly? Like I said I want to upgrade my Polk RTI A1s(surrounds) to A5s, the only speaker that is powered off the receiver 110w(2 channels driven). -5db to-15db are my loudest volumes ever. My next upgrade was this as follows before my findings:
buy 2 Emotiva Basx300 to run the front RTI A9s ( 300 watts RMS to each one)
Run the upgraded Polk RTI A5s surrounds with the Emo bas x700, bi amped so they get 160 W a piece. Bi amp the center channel 160 W to it. and run the A3s rears off the receiver at 110 W to each. Am I wasting my money? would the Yamaha support the RTI A5 upgrade and not even buy anymore power leave the set up as is? Do I have enough headroom with my current set up for peaks and dynamic burst of sounds in music and movies at a -5 db volume level on the knob. Will I see a significant improvement in the speakers with the upgraded juice?
I Just want this thing to be perfect!
Thanks Folks

 

[lovinthehd]

Using music to measure with not a very good way to go. Pink noise would be better. What weighting scale were you using on the meter?

Just think about a typical speaker sensitivity rating of say 87 dB (2.83V/1m, or 1 watt at 8 ohm). At one meter distance that's 87 dB with using one watt. Double the distance to your seat and lose 6dB. Boundaries can reinforce. Use that spl calculator I linked with various parameters and see how it works as you make changes....as to whether you need an additional amp, are you hearing distortion/clipping now at the volume levels you indicate?

As to passive bi-amping (and how the wattage isn't additive) you might want to read this http://www.audioholics.com/frequent-questions/the-difference-between-biamping-vs-biwiring

 

[yepimonfire]

Music is a lot less demanding than home theater (outside of some classical recordings). Movie tracks played back at reference level (0dB on the volume knob) have a per channel peak of 105dB. If you listen at - 10, then it would be 95dB per channel. The LFE channel is 10dB higher than this (115dB).

Personally, I prefer to run the numbers for a worst case scenario to ensure my system will be capable of handling those peaks. Plenty of action movies do indeed hit 0dBfs regularly, across multiple channels. Spl drops about 6dB per doubling of distance, so at 10', you lose about 10dB. The Rti a9 are rated 91dB @1m, so at 10', 1w translates to about 81dB. To achieve a 95dB peak (-10 on the volume), you'd only need about 20w.

If you decided to watch a movie at full reference level (0dB), you'd need about 240w to achieve 105dB peaks.

Sent from my LM-X210(G) using Tapatalk

 

[PENG]

I have confidence in the SPL meter, I am still amazed at the unused wattage im actually not using at those volume levels. Can I safely say that if at -15 db on the receiver im only using 1-2 watts its crazy. Power was my biggest concern from all the things I have researched when i built this system. Is it safe to say that at 0db on the knob( which is rare)that I have ample power to run the system properly?

Was it measured in C weighting? It sounds like you don't need to add any amp if you set the speakers to small and XO at 80 Hz. That little Emotiva you are thinking won't do much other than keeping the AVR cooler. You can just spend a few dollars on a good quiet fan.

To use a multi meter to get reasonably accurate and meaning current and voltage readings you need to spend some good money and have to know what to do with it. I used a $500 Fluke meter for the job and I would use both music, movies and test tones. I think the calculator HD linked is good enough for the job.

That online calculator shows you should be getting 105 dB peak with about 150 W output, one channel driven. There is an ongoing all channel driven controversy, but in real world movie watching it is practically irrelevant, though it doesn't hurt to have the short term (seconds) ACD capability.

 

[shadyJ]

remember, you can't use a regular multimeter on those speaker terminals. It has to be a high impedance meter and probes. Most folks that have access to a multimeter have garden variety stuff that won't give an accurate measure. That's what I did to get my garden variety numbers. I believe it was TLS Guy that told me I was wasting my time because my meter wasn't of the caliber necessary to actually do these measurements. I was still in the ballpark, and I still learned something. But, accuracy? Who knows?

Your comments on manufacturers numbers being highly suspect is perfect.

This is interesting Buck, can you point to me the post where he explains this idea?

 

[PENG]

This is interesting Buck, can you point to me the post where he explains this idea?

haha, TLSG could be a little extreme at times, to make his points. I guess I know what you may be thinking, that multimeters should have high output impedance anyway (typically > 1 MOhm), but I do feel you need something much better than a $30 RS meter to do a decent job. Actually not so much for accuracy but for build quality, features, such as the ability to measure fast rising peaks, true rms, maximum hold, bandwidth/accuracy etc etc..

 

[Fishboy]

I opened up a real can of worms didnt I!

 

[Fishboy]

I do appreciatte the help however

 

[Bucknekked]

I opened up a real can of worms didnt I!

oh no. this isn't a can of worms. this is a gentlemanly conversation.
If you want worms, just bring up magical properties in your cables or some such nonsense about your tube amp being superior to all other life forms.
then you'll see worms. @shadyJ and @PENG are being nice (as always) and taking it easy on me.

 

[Bucknekked]

This is interesting Buck, can you point to me the post where he explains this idea?

shadyj
It turns out it wasn't TLS Guy, but highfigh that mentioned the simple meter wasn't up to the job.

"A VOM or DMM isn't going to be accurate at most frequencies and when you have multiple frequencies at the same time, it just kind of takes its ball and goes home."

In additional posts the o'scope gets thrown in to the tool mix as the best idea. In additional posts someone then suggests the quality of the meter needs to be way better than my Simpson analog.

The thread ran about 6 or 7 pages and was pretty informative to me. I think I got out of it what I needed: I wasn't burning hardly any watts (much to my surprise).

I may have defamed TLS Guy by naming him as suggesting my meter wasn't up to it. Looks like highfigh or a revisionist memory of the thread did the job. TLS Guy is innocent in this case.

 

[PENG]

shadyj
It turns out it wasn't TLS Guy, but highfigh that mentioned the simple meter wasn't up to the job.

"A VOM or DMM isn't going to be accurate at most frequencies and when you have multiple frequencies at the same time, it just kind of takes its ball and goes home."

In additional posts the o'scope gets thrown in to the tool mix as the best idea. In additional posts someone then suggests the quality of the meter needs to be way better than my Simpson analog.

The thread ran about 6 or 7 pages and was pretty informative to me. I think I got out of it what I needed: I wasn't burning hardly any watts (much to my surprise).

I may have defamed TLS Guy by naming him as suggesting my meter wasn't up to it. Looks like highfigh or a revisionist memory of the thread did the job. TLS Guy is innocent in this case.

I remember now and iirc I disagreed with highfigh, to some extents.

 

[Fishboy]

Hey Folks, Can any body recommend a good quality RCA y cable male to 2 male, 5-6 feet". I read some reviews that the amazon basics series are actually pretty decent, any thoughts......

 

[lovinthehd]

Amazon basics work fine, so does Monoprice. Or use a shorter y adapter and supplement with other rcas cables from existing supplies?

 

[Fishboy]

Thanks LHD, i will get the basics or the y adapters not sure. Just a question, how long can they be from receiver to power amp before signal is degraded. Does the extra connection points using y adapters affect the quality of the signal as well?

 

[Fishboy]

Also I looked on monoprice and cant find a y cable male to 2 male rca, 6-8 feet, whole cable pre assembled i mean.