Spectrum analyzer?

Depends on your needs. In general, RTA is not the best tool for speaker/room interactions. The starting place for RTA is TrueRTA.

However, the best combination of capability and price is RoomEQ Wizard which is a freeware program. You will need a mic, a preamp/soundcard and a PC, though.

There are other options if you have specific requirements.

Kal

1/10 octave or better can be achieved by both TrueRTA and by REW.

The reason that RTA is not useful is that it has little memory while the major room influence is in the delayed reflections and their interactions. For that, you need to see "waterfall" plots or similar that show how the sounds at different frequencies decay in the room. Generally, one wants uniform decay of all frequencies.

For more info, I recommend Toole's new book "Sound Reproduction - Loudspeakers and Rooms." I am about half way through it now.

Kal

I have no experience with the Behringer. Does it show you a time-decay response?

Kal

I would be able to match the filter configuration to it and then check the results.

Kal

IMHO, the most pernicious effect of the room acoustics is the extended decay at certain frequencies. These frequencies are not necessarily those that show up as instantaneous magnitude peaks nor, if they do, is simply reducing the magnitude going to reduce the decay time appropriately. Ideally, one would like to have a room with a uniform decay time (analogous to RT60) for all frequencies but this is more difficult with small rooms (at home) than it is with large ones (concert halls).

Kal

Juanpablocuervo wrote:

but the best RTA its your ears,
make everything as silent as possible , then clap real hard
if you listen something other than your hands clapping, thats what you need to fix.

Actually true since no RTA will give you that information about ringing and decay that your ears detect. Of course, REW will do it graphically and tell you how to filter it.

i dificult room could need +-24dB of EQ in some bands,
a good treated room needs less.

How true.

Kal

There are many devices that attempt this with varying degrees of success. These include the usual suspects such as Audyssey, TacT, ARC and a slew of PEQs when coupled with RoomEQ Wizard. The one I like best is the Meridian MRC which measures the broadband decay above the Schroder frequency (~200-300Hz in most domestic rooms) and then calculates filters for band below that frequency. What is nice is the ability to adjust the decay target, to modify/delete/create filters and the ability to graph the results.

You are right about concert halls since there are effects there which are different from those in small rooms (short latency reflections, distance effects on frequency, etc.). Nonetheless, there is a definable RT-60 across most of the audible frequencies well into the bass in concert halls but small listening rooms have their low frequencies dominated by room modes below the Schroder frequency.

In addition, if you want to reproduce the concert hall acoustics when you play a recording of them, you do not want to superimpose the acoustical characteristics of the small room on them.

BTW, there's a great new book on all this from Floyd Toole.

Kal

"the spectrum analyzer is useless is you cannot alter the anomalies of your room. In other words, the analyzer will show you the peaks, nulls in your room but thats it."

The RTA can only show you the frequency response in your room. It cannot identify variations in FR as peaks and nulls due to room modes since it cannot show you the room response with respect to time. Corrections based on RTA, only, are chancy.

Kal

I said "chancy" intentionally; it does not mean that they never work. Besides, flattening the bass response, by itself, is advantageous.

Many people have had excellent results with the DEQ2496 using REW as the tool for setting up the filters. I do not know what tools for measurement are built into the DEQ2496, itself.

Kal