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Monty
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Re: New Graph using REW with and without calibration

Getting an accurate reading on the high frequencies (above 10K) has been a real problem with inexpensive measuring devices like the Radio Shack meter. I've done a bit of experimentation using RS's analog meter and it's really not any use for the high frequencies. I guess the mics just aren't up to the task. It did great from about 40hz to 10K and was a lot of fun to mess around with.
I used JA's test disc.

It's a great way to get your wife to leave the house for a bit. On the downside, she'll probably go shopping and spend money.

Lamont Sanford
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Re: New Graph using REW with and without calibration

I agree with Monty that the 13khz and 16khz tones are harder to get an accurate measurement. But, on the other hand, the pink noise testaudio.com results kind of dispute this to a certain extent since the overall average was the same as the full spectrum pink noise track. The reason for the flat pink noise response is that these are filtered pink noise tracks. Of course, the average of each test tone measurement combined should equal the dB of full spectrum pink noise track was set at. In my test the full spectrum pink noise was set at 80dB. The average for all the measured audio test tracks was 81dB.

There is so much conflicting information on the Internet concerning these RS meters that what I'm going to do is eventually post graphs showing the result of several different test CDs and test tones sent directly to the receiver from the audio software and also get an average result. The average result will be my typical room response as a "response" to all the different controversy concerning the RS meter. I may even invest in the so-called recommended meter and do whole thing all over again and compare the results. After that, and at the very least, I could calculate a percentage of error for the RS meter. And make determinations like whether or not RS percentage of error is material.

Buddha: My ears tell me the treble is response is very good and not fatiguing. Actually, the treble response is very interesting. I love listening to recordings I have listened to for years only to hear what was recorded and never heard before myself. Little things like more detail to guitar solos and the occasional brief percussion instrument that wasn't there before. As with all of us, I strive to get to the point that I'm hearing what was recorded. I also listen to a lot of these recordings in the car. It as an average sound system. The difference is quite striking and useful.

Jim Tavegia
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Re: New Graph using REW with and without calibration

Lamont,

You might want to pick up a inexpensive Behringer 8000 omni measurement mic for $49 and record the pink or white noise in your room. It is the same mic that many home theater receiver companies are including with the higher end receivers for room correction. You could even mate it with an inexpensive M-Audio Audiobuddy dual mic pre for $79 and with a pair of 800's, have some fun.

It has a fairly high noise floor, but not enough to make a difference in what you are doing. As a matter of fact, I have made some decent recordings with just a pair of them.

One of my recording programs, NCH "Wavepad" has a FFT analyzer so you can record your response and view it as you replay the file. I doubt that it is totally accurate, but for our purposes it work well IMHO. Wavepad is downloadable for about $69 and is a very nice program and takes VST and DirectX plug ins if the recording bug hit you.

Enjoy these posts.

Jim

Lamont Sanford
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Re: New Graph using REW with and without calibration

Thanks Jim. I looked at the Behringer as well as the Galaxy CM-130. Both were about the equivalent of the RS meter. I opted for the the recommended Galaxy CM-140 by Home Theater Shack, which seems to be the one place on the Internet that has studied both meters quite a bit. As mentioned earlier I hope to come up with some sort of error rate between the two meters for entry level purposes.

RGibran
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Re: New Graph using REW with and without calibration

Here's a graph I borrowed from Ethans' site showing the amazing difference in response by moving the mic 1 inch times 7 from the listening position. Hard to believe it's the same room at the upper frequencies.

Thanks Ethan.

RG

Lamont Sanford
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Re: New Graph using REW with and without calibration

That's cool. I wish it had one last plot showing the average of the 7 measurements. I'm into statistical averages. The mic/meter measures the SPL but our ears are not as perfect. Somewhere in there is about what one would hear or rather what our fictional listener would hear. I would hate to use the words "typical listener".

Jim Tavegia
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Re: New Graph using REW with and without calibration

The Behringer mic is flat to past 16k. The Radio Shack meter, which I own, is not even close to being accurate, but you know that already.

I use the Radio Shack meter when someone tells me, generally, how loud they "think" they listen to music and they are quite surprised.

I'm glad I own it, but I do not delude my self into thinking that is a true audiophile tool.

Jim

Lamont Sanford
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Re: New Graph using REW with and without calibration

I apologize for the confusion, Jim. The ECM8000 is a mic and not a meter. That is one of the reasons I excluded it. Like the RS meter(s), there are calibration files for the ECM8000 as well as the CM-140. The Behringer ECM8000 is also recommended by Home Theater Shack with the proper preamp, which goes beyond entry level. I'm defining entry level as using an SPL meter and test CD tracks. I'm only using the REW software and other software for my own use, like making test tones and so forth. To avoid confusion I will eventually post something on a dedicated web page separate from the forums here.

I'm not so sure the RS meter is not an audiophile tool that can be useful based on my own goofing around with it. It seems to be holding it's own weight thus far. But I have more testing to accomplish. I want to reiterate that I'm using the digital version of the RS meters available for use.

Jim Tavegia
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Re: New Graph using REW with and without calibration

Thanks for the clarification. I look forward to your future info on this.

We all probably need to look at our system(s) closer for speaker placement. In my living room where we only causally listen I just put them where the fit. It is mostly for holidays and my wife's interest in having music going most of the time. With a vaulted ceiling and an open area on just one side and brick fireplace on the other it is probably a measuring nighmare.

Jim

Jim Tavegia
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Re: New Graph using REW with and without calibration

It appears that they at REW have issues with any Bell or ATT internet providers at this time. Too bad.

Jim

Lamont Sanford
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Rives Test CD: Radio Shack vs Checkmate Meters

Radio Shack 2055 meter versus CheckMate CM-140 meter using Rives Test CD. 1kHz set at 80dB.

RGibran
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Re: Rives Test CD: Radio Shack vs Checkmate Meters

I have heard a few claim the RS is unreliable from as low as 500K and up. That graph would seem to support their claims, assuming the Galaxy is accurate as claimed. Love to see the REW sweep comparison between the two.

Lamont Sanford
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Re: Rives Test CD: Radio Shack vs Checkmate Meters


Quote:
I have heard a few claim the RS is unreliable from as low as 500K and up. That graph would seem to support their claims, assuming the Galaxy is accurate as claimed. Love to see the REW sweep comparison between the two.

I plan on doing a sweep between the two as well as comparison with my other test cds as time allows.

ncdrawl
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Re: Rives Test CD: Radio Shack vs Checkmate Meters

Jim,

two other DAWs are nice and have FFT Capability too...

http://audacity.sourceforge.net/

http://www.cockos.com/reaper/

free and peanuts

also..free VST FFT

http://www.rndigitallabs.com/Plug-ins/Inspector/inspector.html

ncdrawl
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Re: New Graph using REW with and without calibration


Quote:
Thanks for the clarification. I look forward to your future info on this.

We all probably need to look at our system(s) closer for speaker placement. In my living room where we only causally listen I just put them where the fit. It is mostly for holidays and my wife's interest in having music going most of the time. With a vaulted ceiling and an open area on just one side and brick fireplace on the other it is probably a measuring nighmare.

Jim

best tool for placement==Chesky LEDR test.

Monty
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Re: Rives Test CD: Radio Shack vs Checkmate Meters

Try measuring only one speaker up close to minimize the room and then both speakers from the listening position. If you maintain a starting point of 1k @ 80db in both microphone locations you should be able to get a feel for the room reflections and boundary interaction.

If you really want to go out in the deep, take one speaker outside and measure it in free air and then meausre in your room.

BTW, I can't help raising an eyebrow at that much difference in the RS meter and the other meter at 1.2K. I think something other than the meter is not being accounted for. Still, they are pretty close absent that particular frequency.

Lamont Sanford
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Re: Rives Test CD: Radio Shack vs Checkmate Meters

I noticed that weird opposite end stuff on 1.3khz. One reason I want to use the Binks and testaudit test cds as well.

I've taken note of your other suggestions. Maybe part II?

Lamont Sanford
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REW Sweeps RS2055 and CM140 Meters

Radio Shack Model 2055 REW Sweep 08/21/09

Check Mate CM140 REW Sweep 08/21/09

Summary REW Sweep for RS2055 and CM140 meters 08/21/09

Lamont Sanford
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Re: Bink Test CD: Radio Shack vs Checkmate Meters

As you can see there are material differences between the Rives Audio Test CD and the Bink Test CD. Next up, testaudio.com test CD.

Lamont Sanford
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Re: testaudio.com Test CD: Radio Shack vs Checkmate Meters

This goes back to the original post of this thread. This is the type of overall response I'm hearing when I listen to music on this system. There are material differences between test CDs. The REW software sweep test is the best economical method for home use with no material difference between the Radio Shack digital meter and the CheckMate digital meter using REW. Incidentally, as with the same using the testaudio.com Test CD indicating less than 3dB difference between each 1/3 octave test tone using the two different meters as seen below. Thus, no average data used between the two test meter data shown in the graph. This concludes my fiddling around with test tones, Test CDs, software, equipment, cables, and driving my ears crazy for at least the time being. I will let the readers draw their own conclusions about these somewhat layman tests on my part. Nevertheless, it was fun as well as interesting. Thanks for the suggestions leading up to this.

KBK
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Re: testaudio.com Test CD: Radio Shack vs Checkmate Meters

Lamont, please do yourself a solid and get that crap out of your signature. We don't need that running all over the forum. It's very bad news. I don't give a darn about BOC, obviously..but the offensive bits are now attached to every post you've ever made (in all forum areas) and this is not good for the forum overall.

Lamont Sanford
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Re: testaudio.com Test CD: Radio Shack vs Checkmate Meters

Crap I forgot to change that before I left on vacation. Okay, I changed it for you KBK.

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