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#1
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Freq Response Graph Paper
I can't believe how difficult it is to find some audio frequency response
graph paper. I am doing some measuring and would like to plot it from time to time, getting a new 31 band equalizer, just want to go to the internet and download some FR graph paper. No dice. I have been to several sites that offer free this, free that, Wikipedia, have run out of key words to try. Anyone know where I can beg, buy, or steal some FR graph paper? The measurement equipment companies? I was actually hoping to be able to have it plot the readings for me and then print it out, but I will take anything. Gary Eickmeier |
#2
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Freq Response Graph Paper
Gary Eickmeier wrote:
I can't believe how difficult it is to find some audio frequency response graph paper. I am doing some measuring and would like to plot it from time to time, getting a new 31 band equalizer, just want to go to the internet and download some FR graph paper. No dice. I have been to several sites that offer free this, free that, Wikipedia, have run out of key words to try. log-log paper semilog paper three-cycle paper A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#3
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ...
A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. Whether or not, that's what they're made for! Five bands don't provide the "subtlety" to make genuinely useful adjustments. In cars, people commonly push all the controls all the way up, simply to make the system louder. |
#4
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Freq Response Graph Paper
William Sommerwerck wrote:
"Scott Dorsey" wrote in message ... A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. Whether or not, that's what they're made for! Five bands don't provide the "subtlety" to make genuinely useful adjustments. The problem is that 31 bands make for worse ripple problems than even five. I understand the argument for PA applications because if a system is starting to ring you can quickly pull down the slider for the frequency that it's ringing at. But it's not exactly a precision device. In cars, people commonly push all the controls all the way up, simply to make the system louder. Yes, well, we don't talk about those people. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#5
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Freq Response Graph Paper
Thanks all for the info - will try those searches and see what pops up. My
earlier search resulted in one of those nightmares of links within links full of sites that want to download all kinds of crap to you beside what you are after. On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. Gary Eickmeier |
#6
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Freq Response Graph Paper
On 08/05/2014 04:46, Gary Eickmeier wrote:
Thanks all for the info - will try those searches and see what pops up. My earlier search resulted in one of those nightmares of links within links full of sites that want to download all kinds of crap to you beside what you are after. On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. There are systems that go one stage further. You play a sweep with a microphone at the listening position, and it automatically sets the frequency response to give you a flat(ish) response there. They're not cheap... -- Tciao for Now! John. |
#7
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ... A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. Which is why only a moron would try to use one that way (yes I know there are plenty of morons) However graphics and parametrics are still indispensable for reinforced live sound at least. The days of everyone having one in their HiFi seems have gone fortunately. Trevor. |
#8
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Freq Response Graph Paper
Gary Eickmeier wrote:
Anyone know where I can beg, buy, or steal some FR graph paper? The measurement equipment companies? I was actually hoping to be able to have it plot the readings for me and then print it out, but I will take anything. Try: http://www.poppyrecords.co.uk/other/...hPaper0-80.gif http://www.poppyrecords.co.uk/other/...Paper20-20.gif They took about 5 minutes to knock up with ClarisWorks4 spreadsheet; and it would also have plotted the graphs for me if I had put in some data. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#9
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Freq Response Graph Paper
Scott Dorsey wrote:
Gary Eickmeier wrote: I can't believe how difficult it is to find some audio frequency response graph paper. I am doing some measuring and would like to plot it from time to time, getting a new 31 band equalizer, just want to go to the internet and download some FR graph paper. No dice. I have been to several sites that offer free this, free that, Wikipedia, have run out of key words to try. log-log paper semilog paper three-cycle paper A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. Why do people persist in calling it an "equaliser"? It is an effects unit and does not equalise anything -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#10
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Freq Response Graph Paper
In article id.invalid,
Adrian Tuddenham wrote: A quick sweep of the graphic equalizer with all bands set at +5 will show just how bumpy it is! It's horrifying that people try and use those things for audio. Why do people persist in calling it an "equaliser"? It is an effects unit and does not equalise anything I'd say it dates from when landlines had their frequency response adjusted to match another - so equalised. I've seen that term used dating from the 1930s. The term stuck for any frequency response adjustment. -- *The best cure for sea sickness, is to sit under a tree. Dave Plowman London SW To e-mail, change noise into sound. |
#11
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Freq Response Graph Paper
"John Williamson" wrote in message ... On 08/05/2014 04:46, Gary Eickmeier wrote: Thanks all for the info - will try those searches and see what pops up. My earlier search resulted in one of those nightmares of links within links full of sites that want to download all kinds of crap to you beside what you are after. On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. There are systems that go one stage further. You play a sweep with a microphone at the listening position, and it automatically sets the frequency response to give you a flat(ish) response there. They're not cheap... Well, what I mean is you don't necessarily want flat, but a "room curve" at the listening position. McIntosh used to publish such a curve that their technicians used in the field to set up their speaker systems when requested. It has a slight hump below 1k and a gradually falling hi freq beyond that. Gary Eickmeier |
#12
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Freq Response Graph Paper
"Adrian Tuddenham" wrote in message valid.invalid... Gary Eickmeier wrote: Anyone know where I can beg, buy, or steal some FR graph paper? The measurement equipment companies? I was actually hoping to be able to have it plot the readings for me and then print it out, but I will take anything. Try: http://www.poppyrecords.co.uk/other/...hPaper0-80.gif http://www.poppyrecords.co.uk/other/...Paper20-20.gif They took about 5 minutes to knock up with ClarisWorks4 spreadsheet; and it would also have plotted the graphs for me if I had put in some data. Beautiful - thanks Adrian. Gary |
#13
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Freq Response Graph Paper
"Adrian Tuddenham" wrote in message
nvalid.invalid... Why do people persist in calling it an "equaliser"? It is an effects unit and does not equalise anything. Its original purpose was to remove known errors in frequency response. But, of course, as with many inventions, its use has been perverted. Current consumer systems can automatically flatten the response at the listening position. These have been around for several years. |
#14
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Freq Response Graph Paper
On 5/7/2014 3:25 PM, Gary Eickmeier wrote:
I can't believe how difficult it is to find some audio frequency response graph paper. You want semi-log graph paper, four cycles if you want the full audio range (10 Hz to 100 kHz). Here's a "make your own" web site that's pretty flexible: http://customgraph.com/piart.php?art=579 What I'm surprised that I can't find, given how common computers with sound cards are, is a modern computerized version of the clunky General Radio chain-driven synchronized oscillator and plotter that we had in our college lab in 1960. Connect the device you want to test between the audio output and input of a computer, use a program to generate a slow sine wave sweep, and generate a plot of what comes back into the computer's audio input. There are a number of FFT programs but it's just not the same thing. I've tried Room EQ Wizard and RightMark but haven't had much success with either one. This seems so simple. Why hasn't anyone done it? -- For a good time, visit http://mikeriversaudio.wordpress.com |
#15
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Freq Response Graph Paper
On 5/8/2014 4:36 AM, Adrian Tuddenham wrote:
They took about 5 minutes to knock up with ClarisWorks4 spreadsheet; and it would also have plotted the graphs for me if I had put in some data. I've spent years fighting with Excel's plotting routines and still haven't been able to figure out how to make a normal looking frequency response graph. Is ClarisWorks a Mac-only program? It's an old name but I haven't heard much about it in at least 10 years. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#16
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Freq Response Graph Paper
Gary Eickmeier wrote:
On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. These days, a lot of them _are_ digital. But in the studio world, people use parametrics instead of graphics so they don't have any of those problems to begin with. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#17
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Freq Response Graph Paper
John Williamson wrote:
There are systems that go one stage further. You play a sweep with a microphone at the listening position, and it automatically sets the frequency response to give you a flat(ish) response there. They're not cheap... But the end result sure sounds that way.... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#18
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Freq Response Graph Paper
Mike Rivers wrote:
On 5/8/2014 4:36 AM, Adrian Tuddenham wrote: They took about 5 minutes to knock up with ClarisWorks4 spreadsheet; and it would also have plotted the graphs for me if I had put in some data. I've spent years fighting with Excel's plotting routines and still haven't been able to figure out how to make a normal looking frequency response graph. Is ClarisWorks a Mac-only program? It's an old name but I haven't heard much about it in at least 10 years. It was developed in the early 1990s; the spreadsheet was based on Lotus123 (Excel also came from the same origins), the drawing section started as MacDraw and it also integrated a database, a word processor, painting and communications packages (it could emulate a Teletype and program a modem). Version 4, which I still use, was from 1995 and was the last one that worked as an industrial heavyweight before they added all the eye-candy. In conjunction with "Pub & Sub" (now also discontinued in OSX) it could provide all the software to run a medium-sized business. Although the full version is only meant for Macs (because the comms module doesn't work on P.C. hardware) there is a version for Windows (CW5) and documents are interchangeable between the two platforms as long as Mac users remember to put the ".cwk" file extension on the file name. It exports drawing files in PICT format, which any photographic program can convert to GIF or JPEG. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#19
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Freq Response Graph Paper
Adrian Tuddenham wrote:
Why do people persist in calling it an "equaliser"? It is an effects unit and does not equalise anything It is a historical holdover from the days of telephone practice when filter banks _were_ used to equalize line response. Now we are stuck with it, just as we are stuck with "condenser microphones" that do not condense any fluid and "passive preamplifiers" that are actually attenuators. Please notify the Oxford University Press. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#20
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Freq Response Graph Paper
Gary Eickmeier wrote:
"John Williamson" wrote in message They're not cheap... Well, what I mean is you don't necessarily want flat, but a "room curve" at the listening position. McIntosh used to publish such a curve that their technicians used in the field to set up their speaker systems when requested. It has a slight hump below 1k and a gradually falling hi freq beyond that. Yes, and the end result was terrible sound... because making everything so that all third-octave sections have the same level is NOT the same as making the system "flat," even ignoring the non-minimum-phase effects. Thank God that the Seventies are over and people have pretty much abandoned all that stuff. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#21
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Freq Response Graph Paper
On Thu, 08 May 2014 09:43:50 -0400, Mike Rivers wrote:
What I'm surprised that I can't find, given how common computers with sound cards are, is a modern computerized version of the clunky General Radio chain-driven synchronized oscillator and plotter that we had in our college lab in 1960. Connect the device you want to test between the audio output and input of a computer, use a program to generate a slow sine wave sweep, and generate a plot of what comes back into the computer's audio input. ... This seems so simple. Why hasn't anyone done it? Possibly something like this? http://kokkinizita.linuxaudio.org/li...jaaa-pict.html Admittedly I'm not sure whether it'll do a frequency sweep. I don't use this software very frequently, and I've not tried to make it do that, but it seems to be pretty good at giving the user a sense of frequency response of connected equipment (photos in the link above are of noise floor not frequency response, I know ...) -- ---------------------------------------------------------------------- Sylvain Robitaille Systems analyst / AITS Concordia University Faculty of Engineering and Computer Science Montreal, Quebec, Canada ---------------------------------------------------------------------- |
#22
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Freq Response Graph Paper
Gary Eickmeier wrote:
I can't believe how difficult it is to find some audio frequency response graph paper. I am doing some measuring and would like to plot it from time to time, getting a new 31 band equalizer, just want to go to the internet and download some FR graph paper. No dice. I have been to several sites that offer free this, free that, Wikipedia, have run out of key words to try. Solving what problem? - measure at iso frequencies and plot on standard "squares" and be happy. Gary Eickmeier Kind regards Peter Larsen |
#23
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Freq Response Graph Paper
Gary Eickmeier wrote:
"John Williamson" wrote in message ... There are systems that go one stage further. You play a sweep with a microphone at the listening position, and it automatically sets the frequency response to give you a flat(ish) response there. They're not cheap... Some actually are, considering that they are built into AV amplifiers. Well, what I mean is you don't necessarily want flat, but a "room curve" at the listening position. McIntosh used to publish such a curve that their technicians used in the field to set up their speaker systems when requested. It has a slight hump below 1k and a gradually falling hi freq beyond that. 20 Hz - 6 dB, 200 Hz 0 dB and 20 kHz -6 dB is a good starting point for a 20 to 40 square meter room, larger room make it 20 kHz -10 dB, beyond "larger" - whatever that is - the theather curve 40 to 1000 linear and -3 dB / octave above gets to be the target curve. With a sanely designed loudspeaker system those curves will be what the system tries to provide. Note that it is often claimed that it malpractice to move sliders on a graphic eq that are next to each other to opposites, ie. boost one and attenuate the next. That is misunderstood because just that is how to move the adjustment center sideways as is "easily seen" in 10 minutes when equalizing with an analyzer running. Two important points: the treble may not appear to be detached and a subwoofer, if available, may not be detectable on male vox. Gary Eickmeier Kind regards Peter Larsen |
#24
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Freq Response Graph Paper
Mike Rivers wrote:
On 5/7/2014 3:25 PM, Gary Eickmeier wrote: I can't believe how difficult it is to find some audio frequency response graph paper. You want semi-log graph paper, four cycles if you want the full audio range (10 Hz to 100 kHz). Here's a "make your own" web site that's pretty flexible: http://customgraph.com/piart.php?art=579 What I'm surprised that I can't find, given how common computers with sound cards are, is a modern computerized version of the clunky General Radio chain-driven synchronized oscillator and plotter that we had in our college lab in 1960. Connect the device you want to test between the audio output and input of a computer, use a program to generate a slow sine wave sweep, and generate a plot of what comes back into the computer's audio input. There are a number of FFT programs but it's just not the same thing. You want Speaker Workshop by Audua. I've tried Room EQ Wizard and RightMark but haven't had much success with either one. This seems so simple. Why hasn't anyone done it? His marketing flunked, but it is should be out there somewhere, I may still have the download archive if an old computer powers up as expected. Kind regards Peter Larsen |
#25
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Freq Response Graph Paper
On Thu, 08 May 2014 09:43:50 -0400, Mike Rivers
wrote: On 5/7/2014 3:25 PM, Gary Eickmeier wrote: I can't believe how difficult it is to find some audio frequency response graph paper. You want semi-log graph paper, four cycles if you want the full audio range (10 Hz to 100 kHz). Here's a "make your own" web site that's pretty flexible: http://customgraph.com/piart.php?art=579 What I'm surprised that I can't find, given how common computers with sound cards are, is a modern computerized version of the clunky General Radio chain-driven synchronized oscillator and plotter that we had in our college lab in 1960. Connect the device you want to test between the audio output and input of a computer, use a program to generate a slow sine wave sweep, and generate a plot of what comes back into the computer's audio input. There are a number of FFT programs but it's just not the same thing. I've tried Room EQ Wizard and RightMark but haven't had much success with either one. This seems so simple. Why hasn't anyone done it? Not surprising. You can't equalise a room. You can equalise the path from one speaker to one ear provided you don't move, and that is it. You know as well as I do that if you move more than a few inches the modal patterns surrounding you have changed utterly. "Equalizing" at one position makes things ten times as bad at another. The best you can ever do is make the source as good as possible. d |
#26
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Freq Response Graph Paper
"Peter Larsen" wrote in message k... Gary Eickmeier wrote: I can't believe how difficult it is to find some audio frequency response graph paper. I am doing some measuring and would like to plot it from time to time, getting a new 31 band equalizer, just want to go to the internet and download some FR graph paper. No dice. I have been to several sites that offer free this, free that, Wikipedia, have run out of key words to try. Solving what problem? - measure at iso frequencies and plot on standard "squares" and be happy. Hi Peter - I sort of ended up doing that, before I got all the responses above. In the Bruel & Kjaer test CD the booklet has a teensy tiny FR graph that goes along perfectly with the recorded pink noise narrow band signals. So I scanned it into my photo edit program, enlarged it to sheet of paper size, and then I can plot the FR directly above the test band freqs listed along the horizontal axis. It is also great because it has the vertical axis in dB from 50 to 100 dB, so I can plot the readings directly without having to interpolate or translate. Hey Peter - you are the one with the "orange" freq response plot theory for recordings, right? That thing has fascinated me ever since. This is the fact that there is a rising response up to 100 Hz, then a gradually falling response the rest of the way. For the readers who haven't seen it, it is based on the frequency analysis graph that probably most audio edit programs have. You can highlight any section of your track, and that curve will almoat always hold true. If you have an unwelcome resonance or deviation, this window will tell you what to cut and how broadly. Why does this work so well???? Gary Eickmeier |
#27
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Freq Response Graph Paper
On 5/8/2014 1:03 PM, Don Pearce wrote:
I've tried Room EQ Wizard and RightMark but haven't had much success with either one. This seems so simple. Why hasn't anyone done it? Not surprising. You can't equalise a room. I know that, and I was never trying to equalize a room. I was using it like I described it, pretending that the device I was testing was the room. Room EQ Wizard wasn't simple enough to remember how to work, and RightMark was never happy with the input level. Either it clipped or it said that it was too low. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#28
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Freq Response Graph Paper
On 5/8/2014 12:51 PM, Peter Larsen wrote:
Speaker Workshop by Audua. That looks like it's an FFT sort of program. I want a simple sine sweep that measures the amplitude at one frequency, them moves on to the next frequency. I can do this with my NTI Minirator and Minilizer, but it generates only at 1/3 octave steps. That's not good enough resolution to see what the response of an equalizer really looks like. I'm not looking to measure rooms or speakers here, I want to measure hardware with analog inputs and outputs. I can do it by hand of course, it's just that this seems like the sort of thing that a computer can do well, if only someone bothered to write the program. Actually, Chris Juried of Tube Equipment Corporation has just what I'm looking for, and he's offered to send me a copy a few times now, but hasn't, so I guess it may not be ready to get out of the shop yet. He uses it to characterize transformers and tubes. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#29
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Freq Response Graph Paper
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#30
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ...
...the end result was terrible sound... because making everything so that all third-octave sections have the same level is NOT the same as making the system "flat," even ignoring the non-minimum- phase effects. I did a fair number of consumer equalizations, all intended to produced "flat" response at the listening position. If the room wasn't overly reverberant, the result was invariably an improvement -- lower coloration, better imaging, etc. Thank God that the Seventies are over and people have pretty much abandoned all that stuff. Current EQ systems don't necessarily aim for flat steady-state response. But I haven't studied them, and I'm not sure how they work. |
#31
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ...
It is a historical holdover from the days of telephone practice when filter banks _were_ used to equalize line response. Now we are stuck with it, just as we are stuck with "condenser microphones" that do not condense any fluid... You are mistaken, sir... They condense the electrical fluid! |
#32
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Freq Response Graph Paper
"Frank Stearns" wrote in message ... Chuckle, no kidding. Freq response is only one thing - uneven or inappropriate reverb times and phase (time) irregularities being the others, often more significant. All you can do with graphic EQ is typically make it worse, even though it "measures" flat. Woo hoo. Parametric is "better" but is still only a partial solution for many underlying problems. But hey, whatever floats your boat or bumps your already peaky/dippy bass. (For that, traps are highly recommended.) Maybe I missed it. Tell me again, Gary, why you're looking for category of solution, particularly this one? I thought you were happy with your room. Frank Mobile Audio Hi Frank - Whew - I am getting some odd reactions about the whole subject of EQing a room or a speaker system. Basically, my system has no tone controls on the receiver. I have no big complaints, but some of my audio buddies are always wanting me to measure the FR in my system, so I did. Just a Radio Shack SLM, digital, and a B&K test CD with 30 bands of narrow pink noise, but it works and reveals some anomolies that I cannot correct with my system as is. I am using a Velodyne subwoofer and just setting it by ear. So in measuring at the listening position, I am getting a hump at 63 Hz that is about 5 dB higher than I would like, then fairly smooth thru the midrange from 100 Hz to 5k, then another hump at 8k of 5 or 6 dB too high, then falling off smoothly to 20k with the zero crossing at 12.5 and 8 dB down at 16k. When we did the Linkwitz Challenge with my cheap hacked together prototype emulating my radiation pattern ideas, the test designer Dave Clark was able to EQ both challenger speakers, mine and a pair of Behringer box speakers, to sound just like the Linkwitz Orions in freq response. This was necessary to eliminate that one variable from the one under test, the radiation pattern and its effect on imaging. It was impressive to me that he was able to do this with mine and make it sound so good that it won the challenge. I am now building, or having built by someone that knows how to build speakers, a final prototype that my engineer is doing with computer models and by ear on the voicing and a variable radiation pattrn etc etc for which I predict it will be very useful to have the ability to shape the response of the things with a 31 band. I will be using the Velodyne with those new speakers too, and this Behringer FBQ6200 equalizer has a subwoofer output and adjustable crossover freq that is almost designed for my situation. I will be able to shape the sub bass curve as well as the upper range so that the FR is not a factor in the audibility of my design for rad pat and room positioning of speakers for soundstaging. The engineer has already listened in mono to the first one, and he remarks that it has the ability to "shape" the soundstage anywhere from too far forward and too small, to too far rearward and too flat a presentation (imaging wise, not FR wise). This is exactly what I wanted, and should prove educational as well as spectacular in stereo. To screw this up by not being able to voice it to my room would be a true tragedy! Gary |
#33
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ... Gary Eickmeier wrote: On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. These days, a lot of them _are_ digital. But in the studio world, people use parametrics instead of graphics so they don't have any of those problems to begin with. --scott Is that because a parametric has a broader Q than a 31 band graphic? Gary |
#34
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Freq Response Graph Paper
On 09/05/2014 03:52, Gary Eickmeier wrote:
"Scott Dorsey" wrote in message These days, a lot of them _are_ digital. But in the studio world, people use parametrics instead of graphics so they don't have any of those problems to begin with. --scott Is that because a parametric has a broader Q than a 31 band graphic? A parametric can be set up to have almost any Q that you wish at any centre frequency that you wish. You could, if that's what's wanted, set it to almost completely take out a band a tenth of an octave wide, leaving the rest of the spectrum undisturbed. Or pass only that tenth of an octave band while almost removing the rest of the spectrum. Or you can set it to give a 0.5 dB or less lift or cut spread over a five octave bandwidth. -- Tciao for Now! John. |
#35
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Freq Response Graph Paper
Gary Eickmeier wrote:
"Scott Dorsey" wrote in message ... Gary Eickmeier wrote: On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. These days, a lot of them _are_ digital. But in the studio world, people use parametrics instead of graphics so they don't have any of those problems to begin with. --scott Is that because a parametric has a broader Q than a 31 band graphic? Many of the frequency/phase distortions that need equalising are caused by resonant systems and their effect on the response can be represented by three parameters: Q, centre frequency and amplitude. The parametric equaliser allows all three to be adjusted so as to accurately counteract the distortion. The graphic effects unit has fixed frequencies and fixed Q factors, which means that only the amplitude can be adjusted, therefore it incapable of being used as an equaliser (unless the distortions happen to lie exactly at the correct frequencies with the correct Q factors). A similar relationship exists between proper equaliser networks and "tone controls". -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#36
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Freq Response Graph Paper
Peter Larsen wrote:
Note that it is often claimed that it malpractice to move sliders on a graphic eq that are next to each other to opposites, ie. boost one and attenuate the next. That is misunderstood because just that is how to move the adjustment center sideways as is "easily seen" in 10 minutes when equalizing with an analyzer running. Well, it's almost always a bad thing to do that becauyse invariably if you see two adjacent bands that are considerably different in level, you're apt to be seeing narrowband problems that you can't fix with a graphic equalizer and attempting to fix them that way is apt to cause more harm than good. If you're trying to equalize something with an analyzer whose filters are no more narrow than the equalizer you're using, you're going to be doing more harm than good. The good news is that we now live with inexpensive FFT systems that can show you what the narrowband response really is, so you know what you can fix annd what you can't. Two important points: the treble may not appear to be detached and a subwoofer, if available, may not be detectable on male vox. Detached? --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#37
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Freq Response Graph Paper
Gary Eickmeier wrote:
Whew - I am getting some odd reactions about the whole subject of EQing a room or a speaker system. Basically, my system has no tone controls on the receiver. I have no big complaints, but some of my audio buddies are always wanting me to measure the FR in my system, so I did. Just a Radio Shack SLM, digital, and a B&K test CD with 30 bands of narrow pink noise, but it works and reveals some anomolies that I cannot correct with my system as is. I am using a Velodyne subwoofer and just setting it by ear. So in measuring at the listening position, I am getting a hump at 63 Hz that is about 5 dB higher than I would like, then fairly smooth thru the midrange from 100 Hz to 5k, then another hump at 8k of 5 or 6 dB too high, then falling off smoothly to 20k with the zero crossing at 12.5 and 8 dB down at 16k. And that 63 Hz hump moves around, depending on where you do the measurement. It sounds like you have some serious room problems. Equalization does not fix room problems, because the frequency response aberration is only the _symptom_ of a time-domain problem. Fix the room. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#38
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Freq Response Graph Paper
Gary Eickmeier wrote:
"Scott Dorsey" wrote in message Gary Eickmeier wrote: On equalizers, I wonder why they aren't all digital yet, with infinitely fine number of sliders that are set automatically by the RTA. I know that some receivers have these "room correction" modes, right? I would love to see one that measures the output of your system, then allows you to draw the curve that you want, and have it do it perfectly with no lumpies. Ah well, we'll see now it goes. These days, a lot of them _are_ digital. But in the studio world, people use parametrics instead of graphics so they don't have any of those problems to begin with. Is that because a parametric has a broader Q than a 31 band graphic? It's because a parametric has whatever Q you want it to have, so you can match whatever it is that you're trying to deal with whether it is a narrowband problem or a wideband one. I can notch out PA feedback in a recording without touching the notes a semitone above or below the feedback tone, with the Q very narrow. I can make a very minor reduction in the top end with the Q very wide. I just set the knob for where it needs to go. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#39
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Freq Response Graph Paper
Scott Dorsey wrote:
Peter Larsen wrote: Two important points: the treble may not appear to be detached and a subwoofer, if available, may not be detectable on male vox. Detached? Yes, apparently elevated after a dip, something like: [perception] xxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxx xxxxxx x xxxxx --scott Kind regards Peter Larsen |
#40
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Freq Response Graph Paper
"Scott Dorsey" wrote in message ... It's because a parametric has whatever Q you want it to have, so you can match whatever it is that you're trying to deal with whether it is a narrowband problem or a wideband one. I can notch out PA feedback in a recording without touching the notes a semitone above or below the feedback tone, with the Q very narrow. I can make a very minor reduction in the top end with the Q very wide. I just set the knob for where it needs to go. --scott I suppose I should look up a few of the parametric kind and see just what they can do, and for how much. It does seem quite ideal to be able to adjust those factors, if you know just what they are with a really good RTA. But how many center freqs do most of them have? In my case I have three, maybe four freqs at which I would like to make a counter-adjustment. On your room comment, one thing that happened is that when I moved the Velodyne from two or three ft out from the corner along one side wall to right into the corner, the bass response jumped up so much that I had to completely reset the level control. I do believe in corner placement, but I didn't realize it would make that kind of difference. Anyway, my response is quite smooth and flat other than those two anomolies, one at 63 and one at 8k. I think the 8k one is the main reason I wanted to do something about my system, my big band recordings sounding a little to bright, horns not as "creamy smooth" as in real life but everything else wonderful. Gary Eickmeier |
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