Speaker Setup

Tony Go

Hi All,
I am a newbie here and am wondering if someone can steer me in the right direction.
I would like to calibrate my Polk surround sound speakers. (Fronts, rears, center and sub).
Questions:
1) Do I use the Pink noise on my receiver or must I purchase a Test CD or both? If yes on the CD please specify best CD and were to purchase.
2) I am planing to purchase a Radio Shack SPL meter 33-2055 (digital). Will the meter do the job?
Many thanks in advance,
Tony

Frank Z

A set up disc is not essential to getting the system, but it can make a difference. I use the tone generator in my preamp. This link contains some more usefull info.

http://www.audiophilia.com/hardware/spl.htm

Tony Go

Thanks Frank--Good article!

Tony

shiu

I just bought the same 33-2055 sound level meter today. Accouding to the specification, its accuracy is +&- 2 db at 114 db. I wonder if it is good enough. I have not open the box yet.

Sorry I should have read the article Frank provided first. I have not further question but I don't know how to delete my post.

Tony Go

Stupid question: Where to buy Stereophiles Test CD's?

danger boy

you can buy the Avia Home Theater set up disc right here on the Polk website.. go to club shopping, then high perfromance accessories. a lot of the people in here use this Avia disc to set up their speakers.. there are others out there too.

shiu

I tried using my RS digital meter last night. I set my receiver master volume to give 75 dB to calibrate my 7.1 speakers. I found that the sub-woofer (PSW404) was producing up to 87 dB at 60 hz. I moved it around a bit it did not help much. Since the DVD I used has a different tone for its sweep test for the subwoofer, should I be looking for the same 75 dB, if not, what should it be? Thanks

danger boy

it's ok to run your subwoofer higher than the rest of your speakers when using the tone. lots of people run their subs "hot" meaning.. louder than what the Radio Shack meter says .

Tour2ma

True, but you don't run your sub 12 dB hot... maybe 5.

shiu,
What disc are you using? I think it's the Video Essentials that has the "hot" sub track.

Tour2ma

Originally posted by Tony Go
Stupid question: Where to buy Stereophiles Test CD's?

I think Stereophile sells them. I have a couple that came free with past subscriptions...

PolkThug

Originally posted by shiu
I tried using my RS digital meter last night. I set my receiver master volume to give 75 dB to calibrate my 7.1 speakers. I found that the sub-woofer (PSW404) was producing up to 87 dB at 60 hz. I moved it around a bit it did not help much. Since the DVD I used has a different tone for its sweep test for the subwoofer, should I be looking for the same 75 dB, if not, what should it be? Thanks

Sounds like you have your volume knob on the sub set too high. This could be dangerous when Darla starts tappin on your fish tank.

Regards,
PolkThug

shiu

Tour2ma, the disc is "DVD Home Theatre Optimizer" by ALLSOP. I bought it from RS, together with the sound meter. I would have bought the famous AVIA disc if I had visited this forum sooner.

Actually, my sub was only 6 to 7 dB higher than the other speakers, except for the peak at around 60 hz. The response was: 72 dB at 40 hz, 82 dB at 50 hz, 87 dB at 60 hz, 82 dB at 70 hz, 80 dB at 80 hz, 81 dB at 90 hz and 81 dB at 100 hz. The front, center, and surround speakers were all at 75 dB. I turned the subwoofer's volume down to match with the other speakers. The deep bass that I had before seemed to have disappeared. I know before too long I will turn it back up to the way it was before calibration.

Tour2ma

At first glance it does look like a room factor at 60 Hz and a roll-off under 50. Otherwise looks pretty flat...

Couple more questions pop to mind:
What info does the SPL Meter's instructions give about correction factors? (I have the analog meter, and the digital may be different) Are the figures you posted corrected or "raw"?

How are you set up bass management-wise? Are you using your AVR or the sub to set the cross-over point? Are your speakers set to large or small?

shiu

I took a quick look of the instruction manual, there are no mentioning of any correction factor. I used C weighted, slow, as suggested by others in this forum.

My speakers are all set to small and cross over at the Sony DA4ES as follow:

Front L/R RTi38 - 80 hz
Center CSi30 - 90 hz
Surr R/L RM6700 Satellites - 100 hz
Surr back L/R RM6700 Satellites - 100 hz
Subwoofer PSW404 - 110 hz

I did move the sub around a little, including moving it further away from the wall, i.e. from 6 inches to 18 inches away from the wall. Moving it away from the wall did reduce the readings for all frequencies, but not the nasty 60 hz one. I wonder if it is the PSW404's natual frequency. By the way, now that I know the 404 drops off quickly at frequencies below 40 hz, I am going to start saving up for a SVS. Any suggestion of a SVS model that would match up with my other speakers?

Tour2ma

Double checked and correction factors don't kick in until 32 Hz and below. So non-factor here... C, slo is proper...

Strange to me that you'd pick different FQ's to cross different speakers, but I'm not familiar with Sony AVR's and have read here that they are a little different. But all are high enough that I don't think any are contributing to your 60 Hz hump. Continue to play with position along the length of your back wall is best I can recommend there. Can you get to a corner?

As for an SVS choice, it's not a matter of which will blend best with your other speakers. It's a matter of what your room demands are.

Tony Go

Ok...I just purchased the Lasertrak (CD2000) Audio Test CD and the Radio Shack digital SPL meter. I am about to measure the sound pressure of various frequencies as follows:
With the meter located where the head would be while listening and set to "C" and SLOW. Volume to 80dB.
1) Balance speakers with pink noise........... then
2) Measure sound pressure of various frequencies i.e. 1kHz @ 0, 315 Hz @ 0, 50 Hz @ -10, 100 Hz @-10 etc up to 18000Hz @ -10. They are generated on tracks 59 to 75 on above mentioned CD.
Now here are my questions: (keeping in mind that I am a newbie )
1) How do I check (my Sub) below 50 Hz?
2) What does the X Hz 0 and X Hz @-10 mean? In other words what is the significance of the 0 and -10 values?

I totally appreciate you help and many thanks in advance,
Tony

Frank Z

I think 0 is reference level and -10 is 10db below reference level.

Tony Go

Thanks Frank but I still have not clue what that means
Tony

Tour2ma

Originally posted by Frank Z
I think 0 is reference level and -10 is 10db below reference level.

Agree, but why would a calibration disc refer to two different levels?

Tour2ma

Tony,
Find your sub test tones here..
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=16409

Tony Go

Thanks Tour!

Frank Z

Tony,
I copied this from the HTF Beginners Primer.

WHAT THE HECK IS REF LEVEL ANYWAY?

In a nutshell, Dolby specifies an ideal playback level for their theatrical soundtracks and for the mixing envirinments in which those soundtracks are created. So, unlike music, movies are technically created with a standard playback level in mind. Based upon this intended level, dialog and effects are mixed at very specific levels to offer similar sound levels across various dolby soundtracks.

This playback level is basically defined as 105db peak level from any single speaker in the dolby playback system. By using tones on VE or Avia- they are specifically defined to give you this playback level.

Since VE's test tones are exactly 30 steps below the maximum level - calibrating that tone to 75db of SPL in your room means you have calibrated your system to playback 105db when given a peak signal.

Similarly, since Avia's test tones are exactly 20 steps below the maximum level - calibrating that tone to 85db of SPL in your room means you have calibrated your system to playback 105db when given a peak signal.

So, if you calibrate using those tones, and their intended target level (75db for VE or 85db for Avia)- that position on your volume knob will be dolby's ref level, providing you with a system that is now calibrated to offer 105db peak output.

Most home users don't listen at dolby's specified levels- but often it is a good point of ref when seeking help or advice on forums such as this one.