SPL meter help

[roboticstar77]

Hi,

I wanted to know what I am suppose to look out for when using a SPL meter. I'm a newbie to the forum and it was suggested a couple of times by members to go out and get a meter. My dilema is trying to figure out why my '93 Quest are faint in sound.


If you would like to find out more about my situation... I started a post titled "Newbie with Quest ML Questions" 6 hrs ago. Thanks everyone! This forum :rocker:


Knowledge is Power

 

[ScottGardner]

Ok, from the brochure the sensitivity rating is 90db 1 watt/meter. So that means your meter will show 90db SPL when held 1 meter from the speaker which is driven by 1 watt.

Because ML's are line source speakers the SPL db drops by 3 for every doubling of distance. 1=90,2=87,4=84. So at about 12 feet your meter should be reading 84 SPL when driven by only one watt.

For each doubling of power you get 3db back. 1=90,2=93,4=96,8=99,16=101,32=104,64=107,128=110, 256=113...

So at 12 feet you have 1=84,2=87,4=90,16=93,32=97,64=101,128=104, 256=107...

(add 3 more if both speakers are driven and the meter is held between them)

It is difficult to know how much power your amps are pushing at any one point but using the numbers above you should be reading somewhere between 84(1watt) and 104(128watts) at 12 feet.

Have fun...

 

[C.A.P]

Rat Shack meters are fine but you do have to know what you are doing to a bit. I would bet your panels are done and neeed replacement. Are the highs gone and sound dull. May be one is louder than the other. If so call ML as its done deal for panels. They are $715 to your door. well worth it. I have been through it a few times and now I am going through it with my CLS. Its the price you pay for the sound you get! Mylar coated panels can only take so many heat cycles and vibrations !

 

[68sting]

I picked up this cd at RMAF. I haven't used it yet but thought it may be of interest.

http://www.rivesaudio.com/software/softframes.html

 

[roboticstar77]

Thanks guys!

I wanted to ask you all something...

Setting my AVR the way I like it. Last night I was playing around with my weak Cambridge audio amp and decided to raise the volume on the amp and the ML's came alive ( testing while watching Underworld on Blue-Ray), but soon after switching to play some PS3 games, the opening scene of one of them has a loud boom and it clipped my amp. So I turned it down and it was fine. Why is that I have to constantly go back and forth on the volume on the amp and on the receiver based on the video source? I never really played with the amps volume because I was getting tired of adjusting the volume constantly, so I kept the amps volume at a low setting to avoid clipping.

If raising the amps volume and getting nice clarity mean that the amp is under powering and a new one is in order or is it still the panels


Found this amp on Audiogon, any opinions?

Rotel RB 1070 power amplifier


Any help would be appreciated :bowdown:

Knowledge is Power!

 

[SteveInNC]

I wanted to ask you all something...

Setting my AVR the way I like it. Last night I was playing around with my weak Cambridge audio amp and decided to raise the volume on the amp and the ML's came alive ( testing while watching Underworld on Blue-Ray), but soon after switching to play some PS3 games, the opening scene of one of them has a loud boom and it clipped my amp. So I turned it down and it was fine. Why is that I have to constantly go back and forth on the volume on the amp and on the receiver based on the video source?

Two things, 1) your amp is underpowered or not suited to driving MLs, which present a difficult load for many amps, and 2) different audio sources have different base audio levels, and typically different degrees of dynamic range compression, which results in an over all "louder" sound - the low levels are pushed up and the high levels are pushed down (this is bad for quality audio in most cases), so the average level tends to be higher/louder - TV commercials are really bad about doing this. The fact that your amp had problems with a dynamic peak is also a sign that you're probably operating at the amp's upper abilities just to drive a normal listening level. You are likely clipping some peaks already, but just don't notice it. If there is a decent high-end audio store near you, see if they'll let you borrow a good amp for a weekend. You might be surprised at how much better your speakers sound without making any other changes to your set-up. Just a warning, don't try out anything much above your price range - you might get sucked in .

If raising the amps volume and getting nice clarity mean that the amp is under powering and a new one is in order or is it still the panels

I'd say it's definitely the amp in this case. The fact that the panels did sound better at higher, non-clipping levels is a good indication of this. When looking for an amp for MLs, you want something that has high-current output and is stable at low impedances. At higher frequencies, the panels on many ML speakers present a 1 ohm load to the amp. Conventional, less-expensive amps are usually designed to drive an 8 ohm load ideally, because that's what cheaper speakers tend to be.

Rotel is a good brand, but I have no personal experience with that model.

 

[roboticstar77]

Thanks Steven

Man, You all are great...

I appreciate all the help. I wish I would have been a member as soon as I got the Quests. Could have saved some money. Now, I know why, we all love ML's.


Thanks!

Sorry I meant Steve.



Knowledge is power!

 

[greg_slo]

i have the 5 ch version (1075) running my aerius i's....you should have no problems...i am bi-amping, but either way its a good amp for logans...rotel is on the brighter side; however, if that matters to you.

 

[JonFo]

A really good match for ML's is the Sunfire line of amps.

Anything from the orginal Sunfire Stereo to any of the multi-channel amps (cinema grand / TGA) will do great on those Quests.

This amp can delvier the current into low impeadances loads of our speakers.

Look around on the 'Gon, you'll find several popping up regularly.

 

[roboticstar77]

Thanks

:bowdown:...thanks! I will keep you all updated.:rocker:

 

[tsmooth]

I went from a Rotel 1075, to a Rotel 1080, and have come to rest on a Sunfire Cinema Grand. Especially since the price is quite similar, the Sunfire took the cake hands down. Or you could buy both and see which one you like, then turn around and sell the loser of the audition. Food for thought.