Coytee Posted August 22, 2007 Share Posted August 22, 2007 ? If someone has a room, speakers and not much more, what would you need to obtain/borrow/rent/steal to create a waterfall plot? PC, mic & software?? What are approximate costs on each? Quote Link to comment Share on other sites More sharing options...
capo72 Posted August 22, 2007 Share Posted August 22, 2007 I just spent about $200 on some measuring equipment recommended by Dr. Who. I bought a Behringer ECM 8000 mic for $50 and an M-Audio Moblie pre USB interface for $150. Both can be had cheaper on fleaBay, but I didn't want to wait for shipping or deal with other people, so I bought new at Guitar Center. The USB interface provides Phantom power to the mic, and from there it's plugged into my laptop. There is freeware available. Right now i'm playing around with Room Eq Wizard. It is available for free download at Hometheatershack.com. I'm still working the bugs out of my set-up, i'm having a feedback problem. That is all I have to offer right now. I'm sure some better advice will come along. Good luck! Jeremy Quote Link to comment Share on other sites More sharing options...
rcarlton Posted August 22, 2007 Share Posted August 22, 2007 I just spent about $200 on some measuring equipment recommended by Dr. Who. I bought a Behringer ECM 8000 mic for $50 and an M-Audio Moblie pre USB interface for $150. Both can be had cheaper on fleaBay, but I didn't want to wait for shipping or deal with other people, so I bought new at Guitar Center. The USB interface provides Phantom power to the mic, and from there it's plugged into my laptop. There is freeware available. Right now i'm playing around with Room Eq Wizard. It is available for free download at Hometheatershack.com. I'm still working the bugs out of my set-up, i'm having a feedback problem. That is all I have to offer right now. I'm sure some better advice will come along. Good luck! Jeremy Sounds like a good plan. To save money start with the Radio Shack sound meter, some RCA cables and use Room EQWizard (REW). Equipment Needed An SPL meter with a line level analogue output. The Radio Shack meter is perfectly adequate for low frequency room acoustics work, either the analogue or digital display version. Calibration files for the RS meter can be found in the Downloads section of the BFD/REW forum at www.hometheatershack.com/forums/ A microphone (with preamplifier to produce line level) may also be used to make measurements, but an SPL meter is still required to provide a reference SPL figure against which to calibrate REW's SPL display. A tripod to support the SPL meter (or microphone). Small movements of the meter can result in large variations in the measurements, for repeatable results a means of supporting the meter for a prolonged period is essential. For low frequency measurements (below a few hundred Hz) the SPL meter can be set pointing straight up. This avoids having to move the meter to measure different speakers and makes it easy to read the display. To make measurements at higher frequencies it is best to point the meter directly at the speaker being measured. In both cases the meter should be placed at ear height in your usual listening position. A soundcard (internal or external) which supports full duplex operation (simultaneous replay and recording) with line inputs and outputs. Inexpensive soundcards are typically adequate, a reference measurement is used to remove the soundcard's frequency response from the measurement. Examples of USB soundcards which have been found to work well are the Soundblaster MP3+, Soundblaster Live! 24-bit USB External and the M-Audio MobilePre-USB. Note that microphone inputs are NOT suitable and should not be used. Cables to connect from your SPL meter's output to your soundcard and from the soundcard's line output to an input on your AV processor or equaliser. The leads need to be long enough to reach from your computer to your listening position (where your SPL meter will be placed) and to your AV processor or equaliser. If your soundcard has phono (RCA) connectors phono-phono leads will be needed, if the soundcard has 3.5mm (1/8") sockets you will need a pair of jack plug to stereo phono plug leads (also called Y adaptor cables, Radio Shack part 42-2540) or stereo audio adaptors (Radio Shack part 274-883), see images below. If you use Y adaptor cables you will also need two phono socket-to-phono socket adaptors (also called RCA phono plug couplers, see image below) to connect to the leads that run to your SPL meter and AV processor (Radio Shack part 274-1553). Quote Link to comment Share on other sites More sharing options...
DrWho Posted August 22, 2007 Share Posted August 22, 2007 This is exactly why I'm putting this site together: http://measuresound.googlepages.com/gear If you'd like Richard, I can let you borrow my test rig. I bet there will be a way to make the shipping cheaper too - PM if interested. Are you still working on that feedback problem Jeremy? Maybe we can schedule a time here in the near future to see if I can't help ya over the phone. But really, I need an excuse to come home for the weekend so I can catch one of the last days of racing over at Sycamore Speedway...so if you wanted me to swing by that might be an option too. Things are less busy right now than I thought they'd be. I wouldn't recommend the ratshack meter because it's not a calibrated microphone. Sure you can impelement compensations, but it's not going to be as reliable. It should also be mentioned that you'll need to use different software (like praxis) if you wanted a full bandwidth waterfall. Quote Link to comment Share on other sites More sharing options...
rcarlton Posted August 22, 2007 Share Posted August 22, 2007 I wouldn't recommend the ratshack meter because it's not a calibrated microphone. Sure you can impelement compensations, but it's not going to be as reliable. I have no problem recommending the Radio Shack meter as a starting point. With the compensation curves it does a good job with the low frequency, plus you will need it to calibrate the ECM 8000. BTW I have all the other stuff Dr. Who has; it does a nice job. Got the fancy microphone because I was interested in the entire audible frequency response. Spend some time at the Home Theater Shack. JohnM is both a moderator and the author of REW. Quote Link to comment Share on other sites More sharing options...
mas Posted August 22, 2007 Share Posted August 22, 2007 Now I get to be the curmudgeon. Full range CSDs? This is a classic example of some discovering a pretty nifty measurement/display and so many rushing about without knowing exactly what they are looking for nor what the measurement says or for what it is useful... I doubt few here can tell me what the CSD tells them and what use it offers. Nor is this a true time domain measurement. Are resonances a major issue? In equipment or rooms? And while they can certainly be a concern in isolated mechanical instances and for standing waves below 300 Hz, I wonder if anyone can define their usefulness beyond this? They are useless in regards to indicating or analyzing diffusion. And I defy anyone to tell me why an SPL meter is necessary. Are absolute levels of any interest? (except for the curious anal types?) Or are we only concerned with relative levels? Hmmmmm. No wonder objective analysis gets such a lousy reputation - especially from the pure subjectivists who have even less of a clue and proceed to criticize that which they have even less understanding. [] I appreciate many desiring to move forward, but more would benefit from first learning about what they are looking for, and then determining what measurements are useful, and what a Valid measurement indicates. THEN one can proceed. THAT WOULD BE THE REALLY GOOD START! We ain't there yet, folks.[] There are a few options, but I suggest PMing me and that we speak of some of these off site if you are seriously interested. Quote Link to comment Share on other sites More sharing options...
gaspr Posted August 22, 2007 Share Posted August 22, 2007 But those waterfall plots are so purty[] As to the SPL meter...I think some of these measurement programs suggest that an SPL meter can be used as a microphone... Quote Link to comment Share on other sites More sharing options...
mas Posted August 22, 2007 Share Posted August 22, 2007 But those waterfall plots are so purty[] As to the SPL meter...I think some of these measurement programs suggest that an SPL meter can be used as a microphone... [] [*-)] ANY program that even suggests, let alone recommends it as being sufficient for general use, should be avoided like the plague!!! OK, to be fair, the use of the SPL meter that is not calibrated as a mic, despite the use of a 'corrective weighting' file is poor at best. And while ETF states that it is sufficient to 5K, anything over approximately 1500Hz is totally unreliable. If you want to use them, do not expect any kind of calibrated I/O. The best you will get will be an input for LF measurements. You will not be able to reliably use it for a general purpose full bandwidth mic. IMO, the money would be better put towards a more expensive mic such as the Behringer that Mike suggests or the mic & pre-amp sold by ETF Acoustic for $325. But if you want to try, just don't fool yourself into interpreting the results as anything other than one part of the display relative to another part. And realize the inherent limitations this imposes. You will not be able to use it for full range measurements. Still, not all is lost. Again, if folks ae serious about pursuing this, PM me with a phone number and we can discuss options... Quote Link to comment Share on other sites More sharing options...
jacksonbart Posted August 23, 2007 Share Posted August 23, 2007 . Quote Link to comment Share on other sites More sharing options...
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