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Designing an Audio Test
Kmarshall
Posts: 17
Greetings everyone! Long time reader, first time poster!
I play in a 4 man Irish band in Central Illinois, 6 years ago we started out with a huge setup that took 3 vehicals to get to a show. Portability and simplicity have been a driving force in reworking our system. We now have it down to 1 minivan! It is hard enough to make money at this, why spend it on gas!
Reducing most of our gear has left me working to get a wide range of features in the smallest package possible, which led me to the yamaha powered board and now to the DRPA.
Here is our setup (I agree with most everyone about the Bose 802 speakers, truth is, they are ideal for MOST of our needs)
Mics: 4-SM58 and 4 AT85 clip-ons
Board: Yamaha EMX5016cf
Monitors: Wharfdale Titan8 passive
DRPA
Amp: Crown 802
Mains: 2 Bose 802II
We run the monitors through the powered board and the Bose through the Crown 802.
We just bought the DRPA and the Crown, (still in boxes) and I am looking forward to setting up our small system and getting it tweaked. I am sure you are seeing my problem coming. When we lost most of our outboard gear, we lost a lot of control for all of the little problems we have from time to time. (feedback, EQ, Limiting, etc) So I got the DRPA.
Of course we have Bose 802's so there is that wonderful little black box in the chain. From all of my reading, I have accepted that the DRPA cannot truly replace the box so I am looking to do some experiments to figure out what works best.
1. The Bose Controller Alone
2. The DRPA replacing the Controller
3. The Controller between the DRPA and the AMP (some PSW postings suggested this would be the best way)
In the end I always go with what sounds good, but in all the reading I have done recently, I am convinced that until I get a \"technically\" correct setup, I won't really know what sounding good is. So I am looking for some advice on how to determine what is really \"the best\" setup.
This is mostly just me wanting to have fun with my new toys, but I might as well make it useful!
My plan is to take a baseline with just the controller and then compare the two other setups. For measurement, I have only the DRPA with the RTA mic, my radio shack DB meter and of course my ears. I have downloaded Pink noise, Log sweep, and the full spectrum of tones from Bink (thank you for that) and was going to run all those through the system.
While I am convinced I can make either way sound good, I want to have the control, headroom, and flat response I need to do this right.
Might be a completely off topic post, but I know there are some things I haven't taken into consideration and was hoping for some input.
one last thing. I am assuming that I can use the RTA feature without actually having the DRPA in a signal chain.
All the best!
Kevin
I play in a 4 man Irish band in Central Illinois, 6 years ago we started out with a huge setup that took 3 vehicals to get to a show. Portability and simplicity have been a driving force in reworking our system. We now have it down to 1 minivan! It is hard enough to make money at this, why spend it on gas!
Reducing most of our gear has left me working to get a wide range of features in the smallest package possible, which led me to the yamaha powered board and now to the DRPA.
Here is our setup (I agree with most everyone about the Bose 802 speakers, truth is, they are ideal for MOST of our needs)
Mics: 4-SM58 and 4 AT85 clip-ons
Board: Yamaha EMX5016cf
Monitors: Wharfdale Titan8 passive
DRPA
Amp: Crown 802
Mains: 2 Bose 802II
We run the monitors through the powered board and the Bose through the Crown 802.
We just bought the DRPA and the Crown, (still in boxes) and I am looking forward to setting up our small system and getting it tweaked. I am sure you are seeing my problem coming. When we lost most of our outboard gear, we lost a lot of control for all of the little problems we have from time to time. (feedback, EQ, Limiting, etc) So I got the DRPA.
Of course we have Bose 802's so there is that wonderful little black box in the chain. From all of my reading, I have accepted that the DRPA cannot truly replace the box so I am looking to do some experiments to figure out what works best.
1. The Bose Controller Alone
2. The DRPA replacing the Controller
3. The Controller between the DRPA and the AMP (some PSW postings suggested this would be the best way)
In the end I always go with what sounds good, but in all the reading I have done recently, I am convinced that until I get a \"technically\" correct setup, I won't really know what sounding good is. So I am looking for some advice on how to determine what is really \"the best\" setup.
This is mostly just me wanting to have fun with my new toys, but I might as well make it useful!
My plan is to take a baseline with just the controller and then compare the two other setups. For measurement, I have only the DRPA with the RTA mic, my radio shack DB meter and of course my ears. I have downloaded Pink noise, Log sweep, and the full spectrum of tones from Bink (thank you for that) and was going to run all those through the system.
While I am convinced I can make either way sound good, I want to have the control, headroom, and flat response I need to do this right.
Might be a completely off topic post, but I know there are some things I haven't taken into consideration and was hoping for some input.
one last thing. I am assuming that I can use the RTA feature without actually having the DRPA in a signal chain.
All the best!
Kevin
0
Comments
No hi's, no lows, must be Blose...
Being as how I don't like them and haven't used them, but have seen them in the past...I guess I'd get a baseline with the controller in place close proximity mic, outdoor if possible, one speaker only. Then I'd remove the controller and see what the DR can do EQ wise... if you get a \"not finished\" message and you look at the EQ curve and see more than 4 bands (above the HPF) fully cut or boosted, that is what happened then....and the speaker requires more attention than the DRPA can give it...If not, see what it sounds like and then, if you like the sound, try and mimic the GEQ with the PEQ's, and re Auto EQ... till you get essentially flat.
Much info in the READ ME FIRST BEFORE POSTING sections
If your hoping to run the mains AND monitors off the DRPA, don't open it.. take it back...get the 260...WAAAYYYY better $680 at NSL... ut well worth twice the difference
G
I am not in love with the bose but they get the job done. But we don't have many lows except for the Irish Bodhran so generally the 802's do just fine. I always tell the audio guys who give me a hard time about them that if there was a 32lb speaker that sounds as good, I would buy it!
We often rent gear for larger venues, which is a big reason I need the DRPA. For when we need to BiAmp bigger
speakers, or at least split the signal up.
Now that I rethink it, the DRPA would have to be in the signal chain. It doesn't just listen, it listens and adjusts so it would have to be in control of the speaker. I am going to have to find some other way of measuring the frequency response of the bose with the controller alone. Mostly just out of curiosity.
I have found a printout of the EQ curve the controller puts out, it is pretty dramatic.
The DRPA will just control the mains. The monitors are controlled by the onboard eq and AFS on the board.
Thanks again for this great forum and all your help. I have read pretty much everything on this site and feel like I can already use this thing and it is still in the box.
Kevin
There is a way to do the speaker plot with the controller attached... simply get a plot of the speakers without the controller, this will be your control.. then add the controller, and see what the DRPA does to the speakers sound and you'll have an idea what the controller does...I bet a TON of mids will be cut and lows/hi's boosted... its a parlor trick that can be done with most any speaker...Bag end does the same thing...but at the expense of efficiency. My portable rig consists of a pair of the tops .. powered (with and experimental amp package my son designed cigarette size amp that puts out 500 watts, plus 100 watts, which adds a total weight of 4 lbs to the 1 1/2 cubic foot multi purpose speakers.. and a 60 lb powered sub that will do 35 hz total weight 220 lbs, capable of frequency response from 40-20khz +-3db..and capable of 125 db peaks, Substitute the HO tops and a second sub and cover a live heavy metal band in a small club...I have had bands LAUGH at the setup, till I rip their faces off... :shock: and with the driverack I have been able to have no feedback issues even with a singer standing in FRONT of the mains (like RIGHT in front of the HO tops) and screaming his brains out.. and the FBX unit doesn't even excite...I do set the system to stupid loud levels and let the fbx latch onto some really narrow surgical (very narrow hi frequencies), or leave ALL the bands to roam or it latches on to some fairly broad guitar feedback frequencies. No sense letting the FBX kill a bunch of useful frequencies with broad filters... I wish the FBX had a setting below 5 seconds actually...
So it can be done.. I call them the LBD series (Little but deadly):shock: very high on the WOW factor
Hey I'd like to have you send me that EQ plot.. ok? tzone42@paulbunyan.net I'm curious just HOW MUCH eq is necessary ..I know 8 PEQ bands are more than enough to make my speakers ROCK LIKE CRAZY. Keep us informed what happens with the driverack on those speakers... even if I don't like em.. I may be able to help others with the info...
G
I love 802's.
For what they are, the weight and the fact there is only 8 x 4inch speakers they were ahead of there time when released
Have done a A - B test with the SX300 (Double blind test) and Bose sounded better. (We had 5 Sound men voting)
In the right setup and musical genre they are perfect
Love the EQ plot as well please
Will send you a PM with email
Thanks
DRA
Carols by candle light followed by a week of orchestral music
Just perfect. Bass freq's was outstanding
out of 4 inch speakers!!!!!
Mark
I need to come up with a third party, comprehensive frequency response analysis to individually test all configurations. I wish I had Smaart or something like it to do some more professional measurements but I think I have come up with a good solution.
Per Gadget's advice, I am going to test using only one speaker. I will setup my Db meter on axis a few feet from the speaker. Once I have the system optimized (depending on what I am testing) I will play each of the 36 tones provided by Bink http://www.binkster.net/extras.shtml#cd
This will give me full range frequencies to test from 16hz to 20k. With each frequency I will measure the dB and then record data.
Essentially a 36 band RTA, just one band at a time.
Once I have the data, I can break it down into +/- dB and develop a plot from that. While it may not jive with a pro setup, it will at least be consistent within itself and meet the needs of the test.
I think I will also test the Bose speakers without the Controller in place, just to see the actual response of the speaker.
If I am at a reasonable volume, do I risk doing any real damage pumping 16hz through something that claims to only go to 55hz?
All the best!
Kevin
The cone is going to attempt to make the sound (move at 16 cycles / min) but nothing is going to happen (except for you possibly being able to hold the cone in your hand while the frame and magnet are still in the cabinet). I would not do it.
DRA
I will just start my test at 60Hz.
Isn't Pink noise just full spectrum sound at equal dB? If so, doesn't that contain the 20Hz tone? Will Pink Noise cause similar damage that a single \"out of range\" low tone will? Is playing a 20hz tone any different than running Pink Noise? Just a thought.
At reasonable volumes of course.
White noise is = in all spectrums.
Pink noise is modified to how humans hear the spectrum. It has to do with the intensity in the upper ranges. Maybe Gadget will clarify.
DRA
You might want to also do the sweeps, they are all frequencies and that is an audible test that will quickly give you an idea if there's a problem in the frequency response...Give me your email address and I'll send you a freeware audio analyzer that is a LOT like SMAART.. I also have some RTA's with variable resolution.. some as high as 124 samples ... that's a lot better than 36 samples .. right
G
So really, we aren't shooting for \"flat\" frequency response. We want frequency response that matches the frequency response of human hearing. Which makes terriffic sense. Except that everyone hears differently, so we are just shooting for an average anyway. Which boils the whole thing down to \"what sounds good\" Which makes my wife correct, and we can't have that now can we.
Since the Pink Noise is more reflective of human hearing, then using my dB meter method won't be accurate, because it will be analyzing from a White Noise perspective. (expecting all frequencies to be the same dB) I would need to have a schematic of Pink Noise and then adjust the output accordingly. which I feel I couldn't do accurately enough to be a correct representation. So I will take you up on the RTA Gadget.
Quite often, as a music teacher, I have high school students in garage bands coming to me for advice on sound. Of course they want a wall of sound for $20 so they end up destroying what little gear they have. It is nice to have the tables turned and be the student for a change! Now I get why you need a high pass filter on the Bose, but the Controller does that anyway. If I end up using the controller between the DRPA and the amp, I need to use the DRPA HPF to set the Auto-EQ parameters. Will that interfere with the controllers HPF?
The more you know, the more you know you don't know!
Kevin
Pink Noise has equal sound pressure in every octave band. The higher you go on the spectrum, the more energy the sound has, so you don't need the dB as high to equal the sound pressure.
A good analog would be density in objects. A large piece of wood (low tones) weighs the same as a small piece of iron (high tones). The weight of course being the analog of sound pressure.
This still doesn't allow me to use my Decibel Meter method, If I ran tones at equal dB on the board, the higher tones would register more SPL due to their higher density.
G
I guess my whole question now is, what is flat. Is Pink Noise truely flat because in takes into account the increase in sound energy as frequency increases? Or is White Noise flat because it is flat across the dB. What do the speakers think flat is?
I will stop worrying about this now and get busy with my audio test. Thanks for all the help!
Kevin
They are discussing Pink noise and measurement here...
http://srforums.prosoundweb.com/index.php/t/38193/0/
Now, how are things going there with the stuff I sent?
G
Still trying to find time to do all this. Usually I can't get to it until evening and I don't want to wake up the whole neighborhood! Now I have all the tools I need, just need the time.
On another note, I found myself using a house system over the weekend. There were lots of problems with feedback and such but I managed to work them all out just by flattening out EQ here and there and backing down some compression. Even without any Feedback Reduction gear we got great GBF and the house said it rarely sounds that good. Just by turning a few knobs and nudging a few faders. Flat response really is the best starting place! Nice to know I have picked up something reading all this.
Full report to come on my test!
Hey, why not bring the Driverack along and have soem fun when you play out.. better yet get yourself a 260 and WOW the world becomes a whole different box of Pandora's...
G
Keep me informed on your progress with that software please... I know what you mean by time...
The whole goal for us is to get the SR \"out of the way\" so we can just play. Who would have thunk that not being noticed would take so much effort!
Here is theoretical question for you then.
If it is best practice to flatten out your speakers is it also a good practice to flatten out mic response? Understanding that you will never get a truely flat mic response and you probably don't really want one. Is it a good plan to RTA each mic (assuming the speakers are flat) and then adjust any extremes using the mixer EQ? I would do this of course with the voice or instrument playing. Making it more of a \"flatten out that mic with that instrument/voice\" than \"flatten the mic\"
Granted you don't have much eq control on the board. Especially ours, we have GEQ high and low with a parametric mid. But if you can smooth things out even a little, would it better serve the whole sound? Since we play acousitc music on traditional instruments we want it to sound as if there is no SR at all.
Or does that all fall into the heading \"sweeten to taste\"
Just thinkin about it to think about it!
Back when I used to mix a local, twice a year bluegrass festival (Alison Krauss & Union Station, 3rd Tyme Out, Bill Monroe, Tony Rice, and many others) we used SM81's for guitar, mandolin, banjo (you know the difference between a banjo and an onion? No one cries when you chop up a banjo.
Now I could be totally wrong. Maybe we had to EQ the mics to compensate for an un-flat system.
DRA
he still looked a bit shook-up!
He claimed his biggest problem wasn't hearing the banjos, it was the poor bass player in the back.
DRA
The idea behind a flat system response is a good one, the problem we have here is that with a finite number of actual sample points (in this case 28) there is an awful lot going on in between some of those \"arbitrarily\" chosen frequencies. To think that (even with the awesome arsenal of equipment available today) that we could actually achieve flat response is farcical...it AIN\"T possible, However, we do the best we can. There are those (Like Jack Alexander) that argue pink noise with a crest factor of 12db isn't accurate enough to even warrant trying to equalize the system using it... Couple this with the sonic destruction that GEQ utilization brings and the inaccuracy of the the whole idea of RTA measurement that takes into consideration ONLY volume based frequency criteria as a measurement instrument, and leaves time, coherence and any number of other factors out of the equation...
I have guest BE'd any number of systems and told the \"house\" that before I mixed on their system I was going to crawl up it with a microscope and it better be at least in a condition of all cones moving in the same direction at the same time...When visiting BE's come to my system they are allowed access to a GEQ and that's it...and it will be re-zeroed when he leaves. I have seen it over and over where they take a well tuned system that is properly set up for the room and butcher the response with a Fletcher Munson smile curve, and then struggle with the channel EQ's to try and replace that lost information...ridiculous...The point is, the visiting BE is offered the chance to set the system up as he see's fit, my input is not offered unless called for...I expect the same when I visit their house..and I WILL bring my favorite pieces..mics and tools...I will insert my 260, or 4800, and my favorite effects as well..I will set the system up to my liking, and when I'm done you can redo it to it's former sonics if you wish.
I mentioned that the GEQ caused a great deal of disturbance to the sonics for a reason. Each 'filter' sets up a sonic time shift that skews the accuracy , and sonic purity of the sound..I there fore postulate here that use of the GEQ is a bad idea in the tuning of a system, that the RTA is a poor or nearly useless tool for room compensation, and you will see my GEQ's are OFF.. I use only PEQ\"s and notch filters...
Try taking the same speaker and use the RTA to flatten it..(preferably outdoors away from all reflective surfaces, or in a pinch using the 'New indoor method'). Store that curve and then use the PEQ's to get as close as you can to what the GEQ did. Now A/B the sonic pallet... The GEQ'd speaker's sound will sound smeared...not focused, and generally duller. The better the speaker the greater the difference... In my system, if you close your eyes the speakers disappear...with GEQ doing the same kob the PEQ's are... the sound becomes grounded and the image blurs..and they are more a focal point than with the PEQ's...This I believe is what your looking for too right?
Try these things, take the Impulse lite and run it, you'll need to phantom power the measurement mic, and feed it into the audio input of the soundcard... select 'spectrum analyzer' and 'show peak'. Play first a swept tone and get a feel for the speakers response, do the same with the pink noise and then try and flatten out the response using only PEQ's.
Gadget
I assume you meant SWEEPABLE mid.. not parametric... because if it had those it would be as very expensive console...
Well, I actually got to set things up last night and started pushing buttons on the DRPA. Since it was 9 p.m. I couldn't do much other than just play around with things. (It was very hard NOT to turn things up) DRPA is very easy to use, once you figure out the navigation. Got everything setup and running pretty quickly. Just based on listening, I have to say that the DRPA can't do what the Bose Controller does. I ran one speaker through the controller and one through the DRPA. Doing an A/B comparison I tried to match them just by sound.
I ended up with big happy smiles on both the PEQ and the GEQ which got me close but after an hour of fiddling with it couldn't match it by sound.
So then I went from the DRPA into the controller and out. And WOW, It was really killing me not to turn it up. Next I went into the PEQ and gave it just a bit more on each end. I couldn't handle it anymore so I cranked it for about 30 seconds then ran inside to hide. (like someone else in the Neighborhood would crank Flogging Molly at 11:30 p.m.) I have never heard those speakers jump like that. I almost called in sick today just to play with things.
A few bits of interest -
1.I never really bought into comb filtering much, I always thought there were too many wavelengths under too many variables to really make it an issue. When I had the A/B setup, I slowly rolled the Delay up, making one speaker \"move\". It was amazing to hear the sound get weaker and stronger, DRAMATICALLY just by moving the speaker. Convincing me that even small adjustments in Delay can make great improvements to sound.
2. I couldn't (wouldn't) get it loud enough to run the Auto EQ, so all those tests are still pending.
3. My board doesn't have XLR outputs so I was stuck using my RAPCO DI boxes. I had a fairly low SNR which I attribute to my very low volumes and possibly to my lousy DI boxes so I am not concerned about it. Since I am going to have to DI the signal into the DRPA, what DI would work best? (I think I will post a new question if I can't find a thread on this, I can't be the only guy with a Mid-Level board that is without XLR outputs)
4. Spent about 20 minutes swapping cables to try and find a hiss, turns out that the barrells on my speaker line adapters were touching. Should something like that cause hiss and signal loss?
Having too much fun!
Kevin
you don't need to use direct boxes...find out if your mixer is +4, or -10, then look on the back for the output switch. It will toggle you between consumer-10 and pro +4 db...
Make sure you do a gain structure to get the best signal to noise... not sure what you mean about the 1/4 \" ers...
G
I have decided my best solution is to just get a different board. I wan't to get another DRPA and get it in the monitor chain. The EMX5016cf doesn't rout the Aux sends through the EQ/Feedback, so when you are using the onboard amp, you can't have any EQ on the monitors. In my opinion a glaring flaw in an otherwise great piece of gear. Not a major loss, since it is just a 9 band GEQ, and I am not convinced the FBE is worth anything anyway. I have solved most of the feedback issues by making adjustments with the channel EQ. Flattening the channels has worked 100% so far.
Had practice last night, so I got to hear things but I still haven't sat down to experiment. Had all of us with full system in my 20x26 shop. Deafening with no feeback, that is with the mains pointing directly at us, And monitors! We weren't up into 120dB or anything, but we were as loud as we get in any indoor venue.
And I haven't even really flattened out the speakers. I know I am getting ahead of myself!
I will actually sit down to do all of my experiments soon. Just too excited to play.
All the best!
Kevin
G
Kevin
G