Tune your system the way live pro sound people do for cheap

[nascar03]

i-Touch RTA....

GOYA.....Am I sure of what I or my speakers are doing...NO!
Am I trying something new?...YUP.
For some reason my powered sub wasn't working with the pink noise signal?
Maybe not enough 'content' to activate it?
I am a little skeptical of an i-Touch/built-in-mic being able to diagnose detail issues?
It cost me nothing to try and I think that was the start of this thread.
I will play more soon and compare my other systems as well.
My family room is right next to the kitchen area and the fridge noise always bothered me and now I know exactly how much!!! lol
graham

 

[aabottom]

I am a pro sound engineer, i work large arena and stadium systems and have done for many years.
Love your enthusiasm for the craft, but I feel I have to chime in here.............
You cannot simply fix the sound of a PA system in a room with an RTA and a 1/3 octave iso frequency equalizer, there are more sophisticated ways of doing this now, what you are describing belongs back in the 80's/90's, it would be over 5 or 6 years since Ive used a graphic for that matter................probably 20 years since a 10 band graphic..........

1. We dont use RTA's exclusively to tune systems. Most of us have been using a program called Smaart Live for about 8 years now, it has three functions. One is the RTA, which I only use the spectrograph mode, during live performances, NOT for tuning. The second is to take time snapshots, for time aligning. The third is what we call the transfer function where we look at the actual response of the speaker system by eliminating the room, it also looks at the phase of the system over the bandwidth of the system.

2. The mics I use are made by B&K and cost nearly $2000US per mic. I have two.
You are simply wasting your time with anything less than this.....
My rack of digital processors made by Dolby Laboratories cost in excess of $60,000US, complete with encrypted wireless network to a Motion Labs PC tablet which runs the software for the processors.
So I can wander the venue tweaking the PA system as I go.
In the top of my rack there is a 31 band BSS960 stereo graphic for those old school engineers we get occasionally that like a "grab eq".
.........

Theres a brief overview of system tuning which I do all the time, there is more, but the post I think is long enough.

It takes me about 25 minutes with an assistant running around the various zones with the analyzer mic......

Man thats a lot of typing, I hope somebody finds it interesting

Excellent post kevzep.

Your experience shows that "tuning an audio system" is NOT cheap and NOT easy. Fellow AKers really benefit from posts like yours. Thank you for your contributions.

 

[whoaru99]

Excellent post kevzep.

Your experience shows that "tuning an audio system" is NOT cheap and NOT easy. Fellow AKers really benefit from posts like yours. Thank you for your contributions.

Lest we not forget the considerably different scale as well. One can do a pretty good job in their home for quite a lot less than what's mentioned by kevzep.

Seems like this is one where people tend to view it as an all or nothing deal, but that's certainly not the case.

 

[aabottom]

Lest we not forget the considerably different scale as well. One can do a pretty good job in their home for quite a lot less than what's mentioned by kevzep.

Seems like this is one where people tend to view it as an all or nothing deal, but that's certainly not the case.

Yes, I agree. But there is an extreme at the low end too. I would trust my own ears before I used a cell phone microphone.

 

[kevzep]

Lest we not forget the considerably different scale as well. One can do a pretty good job in their home for quite a lot less than what's mentioned by kevzep.

Seems like this is one where people tend to view it as an all or nothing deal, but that's certainly not the case.

True indeed, I guess Im somewhat like that because I work at one particular end of the scale.......
So to use something at the basic end the the scale for me is more frustrating, but for some people trying to learn and experiment, well thats probably a good place to start
But however expensive gear or not.............or whatever end of the scale you are on, your ears are the common factor that dont change and your ears are certainly more sensitive than any equipment, so on a smaller scale like in an average domestic listening space, I believe if you learn to trust your ears, it will get you a long way, further than you think..........
Use the gear to help train your ears, and soon you will either want better gear or you will just end up doing by ear.............

 

[jimmy mac]

hi, I am new here. I am interested in this from a club sound point of view, I run sound for a few local bands, I have no formal training and most of whay i have learned has been via the internet or trial and error. I normally tune the system by ear and notch out problem feedback frequencies.
If I was to feed the system pink noise and use the iphone RTA would I need the RTA to show a curve similar to that in the first post (low end boosted , dip just above 3k etc) or would I want the RTA to show flat. I was under the impression that Pink noise already accounted for the different frequency sensitivities of human hearing and white noise was truly equal across all frequencies...I may be wrong , like I say I have no formal training and have never tuned a system using noise.
I would be Particularly interested to hear the opinions of the pro sound engineers that have posted.
There is also an ipod app called FFT which looks similar...which is most suitable for this apllication.

 

[Gudstufshevy]

Thanks Barredowl good stuff

I for one appreciate your eagerness to share. Ive been tweaking my listening room for sometime now and would like some data to confirm what my ears tell me. Im looking at a second hand Rane rta, but i happen to have an I-phone 3g, installed the ap:thmbsp: Rather than seeing this as a reason to install an equalizer I hope to use it to tune my room treatments.

Ive damped early reflections, put a rug on the floor (covering concrete in the man cave) and ive found moving anything affects everything... My room being far from ideal, has improved more with a rug than any cables ive tried to date... (insert flames here_____________). Ive also packed more and more gear into the room over the years, some hard, some soft, all has some effect on the sound. Tonight i hope to play with the pink noise a bit.

Also thanks to Kevzep and all the others who have contributed, great insight, any AKer would be dreamy eyed about tuning 300,000 watts. I only wish we could get you down to St Louis to run sound at the amphitheatre. Seriously, the last time I went to a show there the sound was so bad it ruined the show. With what it costs to attend a concert there is no excuse for bad sound, incoherent vocals, time alignment issues etc. The aha moment for me was sitting in the car trying to get out of the parking lot it sounded better in my car... better vocals, tighter bass (still pretty messy its a car) but better than 4th row seats at a live outdoor show... Really...

For those that are sure their ears are better than any cell phone mic, youre probably right. Tools and toys are fun to play with, and sometimes you learn something along the way...

 

[aabottom]

I for one appreciate your eagerness to share.
...
For those that are sure their ears are better than any cell phone mic, youre probably right. Tools and toys are fun to play with, and sometimes you learn something along the way...

Then play on, and have fun.

 

[SPL db]

 

[Deacon Jubal]

I am a mobile DJ who has run sound in quite a number of situations. I have worked in large venue once (Cobb County Civic Center) where pink noise was used for set up. Then the head engineer had the band do a sound check. There was definitely some tweaking going on for the next 20 minutes.

EQ is not merely a small pickup and software. There are certain physical limitations on how sound is picked up. The microphone on a cell phone can not possibly pick up sound in a manner that approximates the human ear, and software is limited on how well it can make up for that.
The type of mics professionals use are much better suited at picking up anomalies in a mix. The trained human ear can also sense feedback at its lower (in terms of volume) thresholds.
For home systems, quality speakers and meticulous placement can make the need for EQ virtually nil, unless your listening room is larger than say, 25' x 25'.

 

[whoaru99]

For home systems, quality speakers and meticulous placement can make the need for EQ virtually nil, unless your listening room is larger than say, 25' x 25'.

Not sure I buy into that. Yes, I agree, that good speakers and good placement certainly help vs. poor of either. The best possible placement is often a deal-breaker for many people. I'll go out on a limb and say most people don't have free reign to place speakers for optimal response. Or, if they do have free reign, they still don't go that way due to aesthetics, etc.

 

[whoaru99]

BTW, forgot to mention that Room EQ Wizard does have an RTA function up to 1/48 octave. Haven't played with it at all though. I think this was new in current v4 release and carried forward into the v5 beta. Anyone interested in playing with this sort of thing really should take a look. There's a LOT of stuff to tinker with/measure using the software package....and it's free.

 

[aabottom]

BTW, forgot to mention that Room EQ Wizard does have an RTA function up to 1/48 octave. Haven't played with it at all though. I think this was new in current v4 release and carried forward into the v5 beta. Anyone interested in playing with this sort of thing really should take a look. There's a LOT of stuff to tinker with/measure using the software package....and it's free.

I've dabbled with REW a bit using an OEM stereo mic that came with my Awia "walkmen" recorder. REW looks nifty. I did not spend a whole lot of time with it because I'm sure the cheap mic is limiting the quality of the results.

I just might get this mic.

AND, you really need a true measurement mic to do this:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=390-801

That means phantom power, but many inexpensive USB preamps are available which provide this.

 

[kirk57]

OK I downloaded RTA lite and played some pink noise through the stereo. The display did show some of what I expected (a peak around 1k and a slight dip around 250) but looking at the website it looks like I need to get the $10 version, which has a lot more functionality.

Also mine is a first generation I-phone with a mic that rolls off above 8k, so not of much use for high frequency analysis. but I think the problems I'm hearing are in the lower frequencies anyway.

cool app, check it out!

 

[whoaru99]

OK I downloaded RTA lite and played some pink noise through the stereo. The display did show some of what I expected (a peak around 1k and a slight dip around 250) but looking at the website it looks like I need to get the $10 version, which has a lot more functionality.

Also mine is a first generation I-phone with a mic that rolls off above 8k, so not of much use for high frequency analysis. but I think the problems I'm hearing are in the lower frequencies anyway.

cool app, check it out!

Download REQW, it has pretty fine RTA resolution and it's free. Attached is a 1/48 octave RTA of basically ambient background noise in my livingroom. I haven't reset/verified SPL levels or anthing yet, it's just a screenshot of what the system was displaying at the moment.

 

[swadd]

hi
barredowl,..nice link shared,..very useful,..nice sharing,..

 

[the-real-mandak]

The REW program has a lot of the stuff that smaart live is made of, it's a great place to start. And using a cheep ECM8000 or a DBX RTA-M mic is fine, don't stop just becurse of a missing $2000 mic! Acutally there has been quite a bit of discussion about using the cheep mic's vs. the DPA 4007 in pro audio forums and the result seems to be that in most cases the cheep ones will do fine. BUT be awhere of change in mic redings due to change in room temperature, cheep mics are not stable when the temp. changes.

whoaru99 try posting the watherfall reading of the run you did with the REW, then you see the room showing it's face (make sure to extend the time line so the response drops into the floor). It will give you an idear about what you are trying to fight with the EQ.

In the first post there was a sugestion about getting the first and best $50 grafic EQ, and then drop it into you're system - BAD idear! It will make you're system sound different, but not better. It will have to be some really heavy problems in you're setup before the EQ will be the better solution. Speaker placement and room treatment is the way to go! And if you need an EQ, go with a parametric one.

kevzep: nice writeup on the tuning of large PA's. And too bad about the Dolby Lake, great produckt at the wrong time. Who the hek got the idear of building processing into the amp's

 

[ev13wt]

:scratch2:.... Interesting points. Wouldn't it make sense to start with an objectively "equally loud" curve, and then modify it by ear, to take into account the psycho-acoustic perceptions? The result should be what "sounds best" to one's own ears... right?

You could measure your ears, and after adjusting to the rooms characteristics, adjust for your ears curve. The thing is, we have different curves at different volumes.


And don't forget something important in this discussion:

If you have room modes that are really annoying, do not try to compensate with an eq! Add bass traps or reposition stuff! The mode takes time to build itself up to resonance- if the (bass) signal is just very short, and you have used your eq to tune that mode down, then you will not hear anything of the short signal anymore.

 

[Fred Sanford]

You could measure your ears, and after adjusting to the rooms characteristics, adjust for your ears curve. The thing is, we have different curves at different volumes.

Good point...

And don't forget something important in this discussion:

If you have room modes that are really annoying, do not try to compensate with an eq! Add bass traps or reposition stuff! The mode takes time to build itself up to resonance- if the (bass) signal is just very short, and you have used your eq to tune that mode down, then you will not hear anything of the short signal anymore.

People often leave time out of the equation...and it's tough to explain the interaction in cases like this.

je

 

[DougMac]

I have a question for kevzep. I know the answer will be subjective, but have you heard a home system with an AVR that's been tuned with built in Audyssey? Any opinions?