SPL meter results relative to Magnepan's (supposed?) craving for power/current

Thanks for your help. I'm using 3 different apps to measure that claim +/- 2 Db accuracy including Decibel X. I do not know why so inaccurate now when my old house read 35 Db ambient with same apps? Please excuse my errors. Highest I get is 28 Db with HVAC running in this new home so it must be my microphone.  Srry. 

phcollie : "My listening room measures at 12-14 Db ambient (Hvac Off)."

I don't believe your taking measurements correctly as that's unrealistically low for any room. 

My listening room is an interior room of a brick home, there is just no noise going on except the Hvac System. It certainly isn't anything special except the fact that there are multiple walls between the outside and the interior space that is my room. Perhaps my SPL software is reading low?
I downloaded another program and am getting the same 24-25 with the Air system engaged.  

phcollie, congratulations on your listen room noise levels. They are astonishingly low.  As points of reference -- 40dB is a moderate background level (louder than a library, but softer than an office), professional recording studios are in the 20 to 25dB range and 15dB is the sound of your own breathing.

45dB ambient SPL sounds completely normal for someone living in the city without special windows. I live on golf course and I just measured 45dB SPL ambient with no TV or radio on in the house, no HVAC.  I think the ambient level in many apartments in large cities would be much higher than that-60-65 dB SPL is not crazy.

Studios need to get the noise floor down so they can deliver noise floors of 10 to 20 dB SPL. They use floating floors, sealed doors and properly treated HVAC. Pretty difficult to achieve especially at low frequency (a truck driving by leaks into everything). In a home its almost impossible because no one wants to spend that much money on doors, windows and HVAC. A nice quiet door in a studio can be $30,000.

The point of all this is dynamic range. If you have a noise floor of 50 or 60, you need enough system power to get over that by a significant margin- at least 10dB but more is better. Its when you cannot get over the ambient noise that your system doesn’t work well and you still hear the ambient noise when the system is playing.

Its pretty hard to imagine you don’t want more dynamic range. It doesn’t make a lot of sense to reduce this, as just about no one has a system that mimics real life. Here’s a case where high efficiency really helps deliver a high dynamic range system.

Brad
Lone Mountain

With 400wpc whatever Maggies you have, they will sing. I'll assume that is 400wpc at 8 ohms. If not YMMV.

I agree that your ambient noise level does not sound right. My listening room measures at 12-14 Db ambient (Hvac Off). Using Tin Pan Alley as a test track, they "fill out" in a rich way at around 50 Db. My listening average is 60-65 Db. Interesting question, but I can not say how much of this is my getting slightly older ears :). @ 85 Db you almost want to leave the room and the amp isn’t close to clipping. 300W Bryston 4B3.

Edit: HVAC System finally came on and it measures 23-25 with air running.

An ambient noise level of 40 dB is very high!

My ambient noise level is 28 to 33 dB.

My Magnepan 3.6 "wakes up" at at around SPL peaks of about 75 dB.

But that depends on amplifier quality, 

A very high quality power amp can sound very good, late at night, when ambient noise is low, even at low volumes.

so the amp is loafing at 75db 9’ away at listening position. You should try to improve the noise in room IF possible. I have a 20 db fan outlet that is clearly audible. You should also try to demo a lower power amp, consult to Maggie crowd..

@bdp24 will have excellent advice, he can hear and knows tge value of an spl meter..

Thanks for the help!
To answer your questions, I don’t know the frequency range of my meter. But it was inexpensive.

and the maggies are about 9 ft away..
        and thanks, MC! It explains a lot knowing that was logarithmic

Let’s sort it out with real help.

40 db of background noise in the room, at what frequency?

chances are it’s not broadband noise, so your real music signal to background noise is probably better than 35 db, which is not awesome. At this listening level, you are probably overpowered….but

How far away from the maggie are you taking the SPL measure ?

You’re looking at a meter to see the difference between music and noise? I can’t hear your system. Does it sound like noise to you? If you can’t hear the difference what are the odds the meter will?  

Anyway technically no, not even close. Sound pressure levels are logarithmic. 40 is more than half of 75 in linear terms. In log terms 40 is closer to a thousandth of 75. In other words not even close.