gain structure

[AlexD]

Because the board I am getting only has pick up and peak meter on each channel I was wondering, could you send only that channel to L&R or any output channel with a meter and use that to set the gain structure to get a more accrete reading (without having to buy an external meter)? I’m sure this will work but I just want to make sure.
If you want to know the board I am getting is the Allen and heath zed-428.

Also, I am going to need an audio analyser so I can set the graphical EQ, I know of the phonic PAA3, way to pricy for us and we only need it once, can you get cheap ones, like £30 that give a true reading?

[museav]

You can PFL a channel to the main meters to look at any individual channel, that's how you would usually monitor the input level for a channel.

On the EQ, an RTA has some limitations to start with and even then the mic and user are likely to have more impact on the results than the analyzer itself. It indeed makes no sense to make a large investment for a one time use and you apparently are avoiding hiring any professionals so you might not even bother with an RTA and just tune by ear, since you have not done anything for the room acoustics or really addressed coverage, etc. in the work done, you'll likely have trouble trying to get the same response throughout the listener area and will probably have to make a greatly subjective evaluation anyways.

[AlexD]

thanks for the PFL advice.

Well no I’m not going to be getting a professional in to do it all, but I am getting a friend to help me out, though he is on holiday at the moment. Coverage isn’t a problem, the two (double) speakers that we have cover most of the area, also the acoustics of the hall is so bad that this is kind of necessary even if it is rough it will help extremely, even if it is set up badly. And yes big exspens for a one off so i will be hireing one.

[Blah067]

Originally Posted by AlexD

thanks for the PFL advice.

Well no I’m not going to be getting a professional in to do it all, but I am getting a friend to help me out, though he is on holiday at the moment. Coverage isn’t a problem, the two (double) speakers that we have cover most of the area, also the acoustics of the hall is so bad that this is kind of necessary even if it is rough it will help extremely, even if it is set up badly. And yes big exspens for a one off so i will be hireing one.

And you think that

a) You can do this better than somebody who does it for a living and gets paid for it?
b) Have you actually walked and analyzed the space and KNOW that the speakers cover everywhere evenly? At all frequencies? I'm sure...

[AlexD]

Wow ok...

I dont belive that i know better than a proffeshnol that gets pain for it, BUT I AM GETTING HELP form a profeshnol who gets payed for it. Im a music tecnolagy a level student so i think i know anouth to know if the volume and sound quality is there or not.

I may not have a lifetime of knolage about sound renforcment but im not stupid.

[SHARYNF]

Stupidity has very little to do with it. In most cases with experience comes not only what to hear but what to do about it. It is one thing to make a judgement call it is another to figure out the remedy.

One of the issues today is that most young people have very little opportunity to actually listen to excellent systems. We have moved from an era when sitting down and listening to a system was something that was done alot. Now that we have moved to mp3's and multitasking and ear buds and Ipods, the mental reference point in my opinion has suffered. Critical Sound analysis is a learned and practiced skill. It is interesting to go back over system reviews of the last 100 years, and read reviewers comments re how excellent the sound was at the time and then compare these systems using today's standards.


Sharyn

[museav]

As Sharyn noted, in the case of system tuning although knowing what sounds good is critical, so is being able to determine the cause of the problem when it doesn't sound good. There are relative time and phase issues as well as room acoustic factors that can affect the frequency response an RTA shows but that cannot be fixed with equalization. Will you be able to recognize when a response anomaly is one of those situations? That is just one factor where knowledge and experience beyond what sounds good and how to use an equalizer can be involved.

In a situation like yours with an installed system consisting using mutliple speaker arrays, I look at system tuning as having up to six general components: 1) each speaker (getting the desired phase and frequency response for each box in a free field condition), 2) the response of each array (addressing speaker interactions to achieve the desired phase and frequency response and the desired coverage for each array in the free field), 3) the effect of nearby surfaces (anomalies caused by reflections from nearby surfaces that affect the resulting frequency and phase response), 4) general room acoustics compensation, 5) tuning for gain before feedback and finally, 6) subjective tuning (achieving the desired subjective sound). When I am using more advanced DSP devices I often try to actually separate the processing related to each step, for example having one 'block' for speaker processing with EQ, crossover, delay, limiting, etc., a second 'block' for the array processing and so forth. That way the first two items can be addressed prior to installing the system if desired and the subjective tuning can be separated and left as user accessible with the other aspects locked out. In many cases all of these components have to be addressed by a single processing device and in a single process, however the tuning is still addressing multiple aspects that affect the resulting sound.

[AlexD]

Yes of curse experience is vital. But I do not have this vast experience, so I am doing as much as I know how to, trying to over come this problem, the gain before feedback is treble and needs to be addressed. So that is what I am doing with the eq, just leaving it really isn’t an option. You need to be there to see how bad it is (my school doesn’t consider function when building buildings. For example our libery has been placed on balconies above music hall where there are people playing a lot, most very badly).

[BNBSound]

Not that you should trust a machine over your ears, but there are several iPhone RTA apps, none more than US$30. Some of them even do real FFT processing and most of them have decent filtering built in to compensate for the tiny mic.

I have one on my iPod that I use with an external mic. It's not the cat's ass but it HAS saved mine once or twice. The key is to remember that it's just a guide line. Any monkey can look at an RTA and poke the graphs until it reads flat. Does it sound good? Likely not.

[TimmyP1955]

I find 31 band RTA to be of little use. FFT on my iPhone (or iPod) is useful, helping me to identify the frequency range that my ears tell me is a problem but that I cannot locate by "hunting and pecking" on the system EQ (because the problem "comes and goes" as the program changes.

For setting up the system - getting the crossover slopes and delays right - one needs Smaart (or the equivalent) and a knowledgeable operator. This is best done outdoors, in an open area. The system can then be installed, and the effects of the room can be determined. One then uses Smaart (or...) to see which problems can be bettered and which must be lived with.