Jump to content

Achieving a flat frequency response?


Recommended Posts

  • Members

I know from reading other threads here that a "trained ear" can't be beat for dialing in a system. I have a descent ear and usually get our system sounding reasonably good; but since I'm not overly experienced, I would still like to have a method to use as a guide for acheiving a flat response without spending the $$ on an RTA.

 

Here's my questions:

 

1. Does putting a vocal mic out in front to ring out a system get you close enough to be beneficial, or does the frequency curve of these mics render this option useless? Would picking up a calibrated mic and using this method be a good option?

 

2. I was thinking about picking up an SPL meter to have for other purposes; can these be used with a tone generator to dial in a system, or is this just a stupid idea? If it can, could you suggest a proper method?

Link to comment
Share on other sites

  • Members

 

no a SPL is for measuring the over all volume it won't measure the frequencies.

 

 

I understand what an SPL meter is made to do and that it doesn't measure frequencies. However, the manual it describes a method of using a tone generator and going through a series of frequencies so you can read the SPL of each tone, and using that information to adjust the EQ. Wouldn't this be similar to using an RTA with pink noise, only one frequency at a time?

 

I'm just wondering this method has any real use, or if it would be nothing more than a tedious pain in the butt?

 

 

Thanks JRBLE. I'll bring a car jack to the next show!

Link to comment
Share on other sites

  • Members

Ringing out attenuates resonant frequencies in a hostile acoustic environment. It does not yield a flat response. There's a difference.

 

I have found that a soundcheck CD with several tunes selected for things I listen for does the trick for getting a system to sound good. The tunes are stuff I have listened to for years on an optimal reference speaker system.

Link to comment
Share on other sites

  • Members

 

I understand what an SPL meter is made to do and that it doesn't measure frequencies. However, the manual it describes a method of using a tone generator and going through a series of frequencies so you can read the SPL of each tone, and using that information to adjust the EQ. Wouldn't this be similar to using an RTA with pink noise, only one frequency at a time?


I'm just wondering this method has any real use, or if it would be nothing more than a tedious pain in the butt?



Thanks JRBLE. I'll bring a car jack to the next show!

 

 

From what distance would you measure out ?

Link to comment
Share on other sites

  • Members

Who wants it flat?

 

Really, the tools to get a flat response are used to get a starting point. Then the system is tuned to be "musically pleasing".

 

Studio monitors must be flat so the engineer can hear exactly and accurately what has been recorded. Flat PA speakers give you a tool to shape them to get your desired sound and not the "JBL Sound" or the "EAW Sound" or the "British Sound".

 

Just my $0.02

Link to comment
Share on other sites

  • Members

 

I understand what an SPL meter is made to do and that it doesn't measure frequencies. However, the manual it describes a method of using a tone generator and going through a series of frequencies so you can read the SPL of each tone, and using that information to adjust the EQ. Wouldn't this be similar to using an RTA with pink noise, only one frequency at a time?


I'm just wondering this method has any real use, or if it would be nothing more than a tedious pain in the butt?



Thanks JRBLE. I'll bring a car jack to the next show!

 

This will definitely NOT work, at least not with a tone generator. In a room the sound pressure varies wildly with position at any given frequency. So if you move by a couple of inches the SPL at 1000 Hz may increase by 6 dB but may go down by 8 dB at 1003 Hz. It kind of averages out over small frequency areas.

The way to do it would to use 1/3 octave narrow band noise, which is spectrally wider than a single tone but narrow enough to allow for proper EQ resolution. You would also have to have an SPL meter that can be set to "unweighted" (neither "A" or "C" weighting). That's in essence the same thing that a RTA does.

Link to comment
Share on other sites

  • Members

 

This will definitely NOT work, at least not with a tone generator. In a room the sound pressure varies wildly with position at any given frequency. So if you move by a couple of inches the SPL at 1000 Hz may increase by 6 dB but may go down by 8 dB at 1003 Hz. It kind of averages out over small frequency areas.

The way to do it would to use 1/3 octave narrow band noise, which is spectrally wider than a single tone but narrow enough to allow for proper EQ resolution. You would also have to have an SPL meter that can be set to "unweighted" (neither "A" or "C" weighting). That's in essence the same thing that a RTA does.

 

 

I see... I wasn't neccesarily setting out to use this method; just read about it in the manual when I was looking around for SPL meters and wondered if it could be useful in that way.

 

Prosigna- A starting point is exactly what I'm looking for - not necessarily to keep it completely flat.

 

I guess I just don't really trust my ears yet and I would like to know if I'm way off with something and just not hearing it.

Link to comment
Share on other sites

  • Members

 

This will definitely NOT work, at least not with a tone generator. In a room the sound pressure varies wildly with position at any given frequency. So if you move by a couple of inches the SPL at 1000 Hz may increase by 6 dB but may go down by 8 dB at 1003 Hz. It kind of averages out over small frequency areas.

The way to do it would to use 1/3 octave narrow band noise, which is spectrally wider than a single tone but narrow enough to allow for proper EQ resolution. You would also have to have an SPL meter that can be set to "unweighted" (neither "A" or "C" weighting). That's in essence the same thing that a RTA does.

 

 

My comments exactly.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...