Spectrum Analyzers

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Jason M Hancock

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Have I got the name right for this piece of equipment? The one that shows all the frequencies present in a room? Some questions:

1. What are they for?
2. How are they used?
3. Can they show all the freq's present in a given song?
4. How much do they cost?
5. Where can I find one?


Thanks!
 
Jason, sometimes they're built into audio software (Cool Edit's got one, for instance), sometimes they're their own (expensive) program. They show you which frequencies are really standing out, so you can narrow in on that frequency more easily and do something about it, like cut that frequency or make sure another instrument in the same range isn't hitting the same frequency. And yes, they can show all the frequencies present in a song or track. If you do a search for 'spectral analyzer' in the mixing forum, you'll come up with a thread by Igormeister, and ideas about how to use them, plus a link to downloadable ones I think, can be found there.
 
Thanks!

Thanks, Dobro. Thanks, Blue Bear Sound.

I've gotta say that I'm writhing in pain at 4-5 grand. 1-2 is closer to my threshold of pain, but still! I saw an analyzer once that appeared to be a simple black box with LED indicators for each freq range. Of course I could be wrong, but I just can't imagine that unit was more than $1,500.

Maybe it's like asking for the holy grail, but any idea of manufacturers offering something for less than $1,500?

Thanks again!
 
What got me thinking about this...

Can anyone explain:

I was hanging out at a recording studio a little over a year ago. (The only experience I've had in a real studio and it was limited to a few visits.) The owner/engineer had an analyzer (very much like this one: Audiocontrol Industrial SA-3051) working/monitoring in the control room. It was constantly on and the LEDs were forever bouncing whenever anyone spoke. Occasionally, a nearby train would go rolling through town and well before you could hear it, he'd point to the analyzer's low freq's and say, "Hey, there's the train coming!"

So, why have an analyzer like this working in the control room? Does it help to adjust the near fields for mixing/tracking or something???
 
It is useful during tracking/mixing to get a visual sense of the frequency ranges an individual track is working around. If there's something you want blend more easily between 2 tracks, you easily see where to cut or work on.

Also, it's useful to determine the workings of your gear - just how much does your EQ slope as you move the knobs - you can even stuff that's part of the signal that may not be audible. ie, spurious < 20hz blips...

All kinds of useful info that help you work your gear. It's probably used the least to "tune" a room with, since tuning a room with an SA and a graphic EQ is a band-aid solution at best.

However, I have used it to successfully adjust my sub's crossover point and level relative to my nearfields so that the sub acts as an extension to the bass response of my PS6s, rather than superseding it.

They are a very useful tool, but yeah - ya gotta pay to play! Even the SA-3051 you mentioned comes in at around the $2300 new, if I'm not mistaken.

Bruce
 
"All kinds of useful info that help you work your gear. It's probably used the least to "tune" a room with, since tuning a room with an SA and a graphic EQ is a band-aid solution at best."

Are you suggesting a parametric would prove more effective?
 
I think what he was referring to is that you shouldn't be tuning your room with EQ, as that is just a "band-aid" or "patch". You should tune your room by actually tuning the room. Placement of monitors, room shape, surface treatments, diffusors, bass traps, etc...

Queue
 
Gargamel said:
"All kinds of useful info that help you work your gear. It's probably used the least to "tune" a room with, since tuning a room with an SA and a graphic EQ is a band-aid solution at best."

Are you suggesting a parametric would prove more effective?
Click to expand...
No - EQ'ing monitors to tune a room doesn't really work at all - period. You need to use room design, or failing that, acoustic treatment....

Bruce
 
Will it work if your using nearfields? I read a very ineresting article in electronic musician regarding this topic. It covered axial modes and room modes, how the length width and height of your room affects the frequencies that may be problematic.

f=1130'/2(d)

F= Frequency Mode

1130'= speed of sound per second

d= several things (height of your room, length and width)

Measure the lenghth of your room. Call it d1

Measure the width of your room. Call it d2

Measure the height of your room. Call it d3



example room:

mode HZ for Lenghth(16.5') Width(10.5) Height(7.7)

f1 34.2 53.8 (73.4)

f2 (68.5) (107.6) 146.8

f3 (102.6) 161.4 (220.2)

f4 137 (215.2) 293.6

f5 170 (269) +300

f6 205.2 +300 +300

f7 239.4 +300 +300

f8 (273.6) +300 +300

This table shows room modes for a room that is 16.5' long, 10.5' wide and 7.7' high. Any frequency within 5 Hz of another frequency is shown in paraentheses to denote the potetially worst modes. Here, the four worst modes occur between 68 and 73 Hz, 102 and 107 Hz, 215 and 220 Hz and 269 and 273Hz.

You should now hook up a Parametric EQ (2 channel, preferably a 5 band) between the power amp and speakers. Dial in the problematic frequencies listed above that were derived from the table. Boost/Cut where necessary, use your ears.......

I reccomend checking the article out........
 
By adding EQ into the monitoring chain, you add phase anomalies that will be more detrimental to your sound than the gain you might have acheived with the EQ adjustment.....

It is simply NOT a good idea to EQ your monitoring chain.

Bruce
 
But....aren't we adding the eq to remove the anomalies of the room we are working in? If we only adjust the problematic frequencies of the room, wouldn't that help us achieve a better mix?
 
Hey, Bruce- I have just 3 words for you: "Terrasonde Audio Toolbox".

http://www.terrasonde.com/audio.htm

$750 brandy-new. Still pricey, but a damned sight less than an Amber or the Klark-Technik stuff. Mine will be arriving today, and I'll post a review when it gets here and I get it running. I just discovered it a few weeks ago, and as soon as I saw what it would do, I had to have one...

I don't have a lot of analog machinery that I have to align any more (thank Gawd!), but this thing looks like it'll do everything my old Amber did. And it really will fit in my toolbox for roadwork...
 
Gargamel said:
But....aren't we adding the eq to remove the anomalies of the room we are working in? If we only adjust the problematic frequencies of the room, wouldn't that help us achieve a better mix?
Click to expand...
No... because by EQing at all you are introducing phase problems that will supersede any positive effect you might have had.
 
skippy said:
Hey, Bruce- I have just 3 words for you: "Terrasonde Audio Toolbox".

http://www.terrasonde.com/audio.htm

$750 brandy-new. Still pricey, but a damned sight less than an Amber or the Klark-Technik stuff. Mine will be arriving today, and I'll post a review when it gets here and I get it running. I just discovered it a few weeks ago, and as soon as I saw what it would do, I had to have one...

I don't have a lot of analog machinery that I have to align any more (thank Gawd!), but this thing looks like it'll do everything my old Amber did. And it really will fit in my toolbox for roadwork...
Click to expand...
Yeah -- I saw that - a good tool but also has some testing limitations that the bigger, more expensive units do not...

But it is a very cool tool regardless... really an engineer's swiss army knife...

I might just put it on my Christmas wish list!

:)

Bruce
 
Prices in US

Audio Control SA3051 $995.00 New List

Gold lIne DSP-30 $1625.00 New List
30M8 $822.50 New List
For your purposes even the Gold line Loft Model TS-1B might be enough at $489.00 New List.

IM deaf in one ear and can't see out the other!


Peace,
Dennis
 
Blue Bear Sound said:
No... because by EQing at all you are introducing phase problems that will supersede any positive effect you might have had.
Click to expand...

Even more important than this is the fact that you are altering the direct response of your monitors.

A spectrum analyzer averages the signal over time. Usually on the order of about 0.25 seconds. When you measure a room you are then getting an average picture of the direct, first reflected (wall), and ambient (room) response [see attachment] at the position of the test microphone.

So you use the EQ along with the spectrum analyzer flatten the "room response". The problem is your monitors are designed to have flat DIRECT response. If you EQ to level out the room, you un-flatten the direct response. This would be all fine and good if your ears and brain worked like a spectrum analyzer, but they don't. In a normal size room (not too small) you can actually distinguish the direct and reflected sounds which arrive at your ears at different TIMEs.

Your sense of tonal balance and spatial placement is heavily influenced by the DIRECT response. But if you have un-flattened the monitors with EQ you will be getting an incorrect impression of your music.

Direct and reflected sound combines to form your sonic picture of your music. But since your ears can discern these signals in time, you can't just fix one at the expense of the other. The only way to properly get accurate monitoring is to make the room acoustically flat as well.

barefoot
 

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Good point BF... I hadn't considered the difference in response time of the measuring device vs. the "time to ear" response of the speakers and the room....

Bruce
 
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