Simplified REW Setup and Use (USB Mic & HDMI Connection) Including Measurement Techniques and How To Interpret Graphs - Page 708 - AVS Forum | Home Theater Discussions And Reviews
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post #21211 of 28111 Old 01-22-2017, 01:17 PM
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Originally Posted by AustinJerry View Post
Thank you for testing this out. Next question, have you conducted the test from Windows audio to make sure the laptop is actually outputting a signal to all of the channels? See the attachment below. Open Playback Devices, click Configure, make sure 5.1 is the selected configuration, and then click Test. Do you get a test tone from all channels/
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One more question. With REW running, and while outputting a test tone to the left or right speaker, what does the audio status on you AVR show? On my AVR (see pic below), the status is "Multi Ch In 7.1".
Hallo Jerry,
Today, I did further testing. I tested two situations: one with connecting the laptop directly to the AVR, and one connected to the Oppo which outputs to the AVR.

Connection to the AVR:
Same problem as before: I could only output channel 1.1 and 1.2.
On the windows output, I could not output a signal to any channel. However, REW could output channel 1.1 and 1.2.
When REW outputs a signal, on the AVR the message appears: Unlock, PCM, Multi PCM (3/4).1. Strangely, this also appears when the channels were output where I could not hear anything.

Connection to the Oppo:
Here I could output a signal from Windows audio. Outputting from REW was same as before and same as outputting directly to AVR: could only hear channel 1.1 and 1.2, however the AVR displays the message "Unlock, PCM, Multi PCM (3/4).1" on all channels.

Afterwards, I left the HDMI connection to the Oppo, and played around with settings a lot. At one stage, a miracle happened and I could output all channels and perform measurements on all channels. However, after switching the home theatre and laptop off and on again, the same problem came back where I could only output channel 1.1 and 1.2. Messing around with settings did not solve the problem.
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post #21212 of 28111 Old 01-22-2017, 01:24 PM
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@turboman123 , what AVR do you have?

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post #21213 of 28111 Old 01-22-2017, 01:45 PM
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@turboman123 , what AVR do you have?
hallo Markus,
My AVR is a Cambridge Audio Azur 351R.
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post #21214 of 28111 Old 01-22-2017, 02:29 PM
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Originally Posted by turboman123 View Post
Hallo Jerry,
Today, I did further testing. I tested two situations: one with connecting the laptop directly to the AVR, and one connected to the Oppo which outputs to the AVR.

Connection to the AVR:
Same problem as before: I could only output channel 1.1 and 1.2.
On the windows output, I could not output a signal to any channel. However, REW could output channel 1.1 and 1.2.
When REW outputs a signal, on the AVR the message appears: Unlock, PCM, Multi PCM (3/4).1. Strangely, this also appears when the channels were output where I could not hear anything.

Connection to the Oppo:
Here I could output a signal from Windows audio. Outputting from REW was same as before and same as outputting directly to AVR: could only hear channel 1.1 and 1.2, however the AVR displays the message "Unlock, PCM, Multi PCM (3/4).1" on all channels.

Afterwards, I left the HDMI connection to the Oppo, and played around with settings a lot. At one stage, a miracle happened and I could output all channels and perform measurements on all channels. However, after switching the home theatre and laptop off and on again, the same problem came back where I could only output channel 1.1 and 1.2. Messing around with settings did not solve the problem.
Very peculiar results. You should be able to get a test signal to play from Windows audio. The fact that you can't leads me to believe the underlying issue is not REW, but with how your PC and AVR interact. I have no additional advice at this time.
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post #21215 of 28111 Old 01-22-2017, 10:59 PM
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Originally Posted by turboman123 View Post
hallo Markus,
My AVR is a Cambridge Audio Azur 351R.
Seems to be a issue with the AVR needing to re-lock onto the incoming audio stream.
Try to output 5.1 (not 7.1) from your PC/REW. Set surround mode to "Multi PCM (3/2).1" on your AVR.
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post #21216 of 28111 Old 01-23-2017, 02:52 AM
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Originally Posted by AustinJerry View Post
Very peculiar results. You should be able to get a test signal to play from Windows audio. The fact that you can't leads me to believe the underlying issue is not REW, but with how your PC and AVR interact. I have no additional advice at this time.
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Originally Posted by markus767 View Post
Seems to be a issue with the AVR needing to re-lock onto the incoming audio stream.
Try to output 5.1 (not 7.1) from your PC/REW. Set surround mode to "Multi PCM (3/2).1" on your AVR.
hallo Markus, Jerry,
Finally I got things to work. My configuration is now laptop to Oppo. I have not retested the direct connection to the AVR.
Here is the procedure I have to follow after each laptop startup. First, in the Windows audio configuration, I select stereo configuration. Then I ping the speakers but I do not hear anything.
Then I change the configuration to 5.1, I ping the speakers and hear sound on each speaker, then next, next OK to finish.
After starting up REW, I get a test signal on all channels and I can make measurements on all channels.
I can stop REW and restart without problems. However, if I restart the laptop I have to repeat the procedure.
The laptop is completely updated, including graphics and Intel Display Audio HDMI drivers.

Any idea what I can do to improve this? I can live however with the present state.
Thanks for all the help.
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post #21217 of 28111 Old 01-23-2017, 03:08 AM
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Thanks for all the help - I'll report back in a couple of days.


I couldn't finish during the weekend since other projects prevailed, so I am aiming towards next weekend.


Thanks again and talk soon,


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post #21218 of 28111 Old 01-24-2017, 07:25 AM
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MiniDSP Voltage Question

Hello,

I have a miniDSP 2x4 rev A. I have starting using AustinJerry’s tutorial on how time align two subs on one channel before room correction (thank you for this great tutorial, AustinJerry). I have a question about step 7 (Determining Gain Structure). I do not have a voltmeter and would prefer not to have to purchase one if it’s not absolutely necessary. I’m using a fairly standard AVR (Marantz SR5005), similar to what I assume most users on here with a miniDSP might use. I’ve looked in the manual and looked online, but haven’t been able to find out what the output voltage is for its SW pre-out. I contacted Marantz and they said it is about 5V. Will this cause a problem given the miniDSP I have has an input voltage of only 0.9V RMS? Does this mean it will be necessary for me to pick up a voltmeter and go through this step?

Sorry, I am a miniDSP noob for sure.
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post #21219 of 28111 Old 01-24-2017, 08:34 AM
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Voltmeters are cheap (around $10-$15) and can be used for other things around the house. Worth the small investment IMO.
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post #21220 of 28111 Old 01-24-2017, 09:06 AM
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Originally Posted by buckchester View Post
Hello,

I have a miniDSP 2x4 rev A. I have starting using AustinJerry’s tutorial on how time align two subs on one channel before room correction (thank you for this great tutorial, AustinJerry). I have a question about step 7 (Determining Gain Structure). I do not have a voltmeter and would prefer not to have to purchase one if it’s not absolutely necessary. I’m using a fairly standard AVR (Marantz SR5005), similar to what I assume most users on here with a miniDSP might use. I’ve looked in the manual and looked online, but haven’t been able to find out what the output voltage is for its SW pre-out. I contacted Marantz and they said it is about 5V. Will this cause a problem given the miniDSP I have has an input voltage of only 0.9V RMS? Does this mean it will be necessary for me to pick up a voltmeter and go through this step?

Sorry, I am a miniDSP noob for sure.
First of all, a voltmeter is not an absolute requirement, and there are fairly easy ways to validate your current configuration without using one.

Follow the instructions to output the REW 60Hz test signal to the sub channel with the AVR volume set to zero and the sub channel trims set to zero as well. The input and output level sliders on the 2x4 should be set to zero as well. While the test tone is playing, observe the output meters on the 2x4. If the level is extending into the Red area, then clipping is occurring. Using the AVR sub channel trim adjustment, gradually lower the trim until the 2x4 output meter no longer reaches the red zone. Make a note of the trim setting. If you lower the trim setting all the way to -12 and are still getting output into the red zone, then you have a more serious gain issue.

Next step is to run the Audyssey calibration. For the purposes of this exercise, you can run a single Audyssey measurement (the first measurement sets the speaker trims and delays) and complete the calibration so that the sub trim is set. Open the AVR menu and observe the trim level set by Audyssey. If the trim level is equal to or lower than the value you determined in the first step, then you have no gain issue. You can play your system at reference levels (which is very loud) without risk of clipping.

If, however, the Audyssey sub channel trim is higher than what you determined in step 1, then you must make adjustments using the master volume control--specifically you will not be able to set the master volume control to zero (reference) without risking clipping on the sub channel. Compensate as follows: if the trim level determined in the first step is -6, and the Audyssey trim is -3, then you should restrict playback master volume to -3.

Finally, you can leave your laptop connected and the 2x4 plug-in output meters displayed on the screen while you are playing content (a movie or music). Observe the output meters to verify that while playing content at normal levels, you are not seeing the output go into the red area. This should give you reasonable assurance that the gain setting for the 2x4 is appropriate. Of course, if what I have outlined doesn't work for you, report back here and we'll se what the next steps are. And Alan makes a good point--a voltmeter, if you end up needing one, is not a very costly investment.
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post #21221 of 28111 Old 01-24-2017, 09:46 AM
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I have two subwoofers, but my AVR only has one sub out (so I use a Y splitter). My AVR does not have a setting for subwoofer distance/delay. But my subs are about equidistant from the MLP.

The subwoofers both have knobs on them for LEVEL and for LF EQ. And even though I tried to make certain that both are set the same, the position of knobs on two different subs, does not mean that they are identical in output. At the very least, they are located apart from each other, so the room itself would affect their sound.

Do I use REW measure the two subs separately, and adjust those LEVEL and LF EQ knobs, until the measured SPL and frequencies are nearly identical for both subs? And then I would start the regular REW measurements (treating both subs as one)?

Help me out here, I'm sure I'm not asking the questions correctly.

'ppreciate it.

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post #21222 of 28111 Old 01-24-2017, 10:07 AM
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Originally Posted by XBR11 View Post
I have two subwoofers, but my AVR only has one sub out (so I use a Y splitter). My AVR does not have a setting for subwoofer distance/delay. But my subs are about equidistant from the MLP.

The subwoofers both have knobs on them for LEVEL and for LF EQ. And even though I tried to make certain that both are set the same, the position of knobs on two different subs, does not mean that they are identical in output. At the very least, they are located apart from each other, so the room itself would affect their sound.

Do I use REW measure the two subs separately, and adjust those LEVEL and LF EQ knobs, until the measured SPL and frequencies are nearly identical for both subs? And then I would start the regular REW measurements (treating both subs as one)?

Help me out here, I'm sure I'm not asking the questions correctly.

'ppreciate it.
What AVR and what subs do you have? This will help us be more specific with our answers.

Generally, if you want to level match the subs, you would place your REW mic at the MLP and adjust gain on each sub individually so that the output at the MLP is the same dB level. If you want to gain match the subs, that is a whole 'nother can 'o' worms.
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post #21223 of 28111 Old 01-24-2017, 10:58 AM
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Quote:
Originally Posted by AustinJerry View Post
First of all, a voltmeter is not an absolute requirement, and there are fairly easy ways to validate your current configuration without using one.

Follow the instructions to output the REW 60Hz test signal to the sub channel with the AVR volume set to zero and the sub channel trims set to zero as well. The input and output level sliders on the 2x4 should be set to zero as well. While the test tone is playing, observe the output meters on the 2x4. If the level is extending into the Red area, then clipping is occurring. Using the AVR sub channel trim adjustment, gradually lower the trim until the 2x4 output meter no longer reaches the red zone. Make a note of the trim setting. If you lower the trim setting all the way to -12 and are still getting output into the red zone, then you have a more serious gain issue.

Next step is to run the Audyssey calibration. For the purposes of this exercise, you can run a single Audyssey measurement (the first measurement sets the speaker trims and delays) and complete the calibration so that the sub trim is set. Open the AVR menu and observe the trim level set by Audyssey. If the trim level is equal to or lower than the value you determined in the first step, then you have no gain issue. You can play your system at reference levels (which is very loud) without risk of clipping.

If, however, the Audyssey sub channel trim is higher than what you determined in step 1, then you must make adjustments using the master volume control--specifically you will not be able to set the master volume control to zero (reference) without risking clipping on the sub channel. Compensate as follows: if the trim level determined in the first step is -6, and the Audyssey trim is -3, then you should restrict playback master volume to -3.

Finally, you can leave your laptop connected and the 2x4 plug-in output meters displayed on the screen while you are playing content (a movie or music). Observe the output meters to verify that while playing content at normal levels, you are not seeing the output go into the red area. This should give you reasonable assurance that the gain setting for the 2x4 is appropriate. Of course, if what I have outlined doesn't work for you, report back here and we'll se what the next steps are. And Alan makes a good point--a voltmeter, if you end up needing one, is not a very costly investment.
Thank you, AustinJerry. MiniDSP should be paying you, if they aren't already.
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post #21224 of 28111 Old 01-25-2017, 11:12 AM
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When running a sweep is the frequency played the max possible output for each given frequency at that MV/Trim/Gain/Audyssey combo?

Example: 80Hz in the sweep is the loudest that it would hit my system and a movie wouldn't pushout something louder at 80Hz assuming all other variables (MV/trim/gain/audyssey) are the same?

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post #21225 of 28111 Old 01-25-2017, 11:21 AM
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Originally Posted by tjcinnamon View Post
When running a sweep is the frequency played the max possible output for each given frequency at that MV/Trim/Gain/Audyssey combo?

Example: 80Hz in the sweep is the loudest that it would hit my system and a movie wouldn't pushout something louder at 80Hz assuming all other variables (MV/trim/gain/audyssey) are the same?
Well, the REW sweep level is controlled by the "Level (dBFS)" setting on the Measurement screen. So if I am understanding your question, the sweep level is dependent on the REW level setting and has little to do with the level of that frequency when playing a movie.

Now, if you set REW to output -3dBFS with the AVR MV=0 and all trims set to zero, then the output will be at "Reference", i.e. it will produce a level of 105dB at the MLP. That should guarantee that the sweep level is the highest you would typically see when playing at reference. Warning: running a measurement sweep at -3dBFS with MV=0 will be very loud, and will most likely clip the mic input.

What exactly are you trying to accomplish?
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post #21226 of 28111 Old 01-25-2017, 11:27 AM
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Well, the REW sweep level is controlled by the "Level (dBFS)" setting on the Measurement screen. So if I am understanding your question, the sweep level is dependent on the REW level setting and has little to do with the level of that frequency when playing a movie.

Now, if you set REW to output -3dBFS with the AVR MV=0 and all trims set to zero, then the output will be at "Reference", i.e. it will produce a level of 105dB at the MLP. That should guarantee that the sweep level is the highest you would typically see when playing at reference. Warning: running a measurement sweep at -3dBFS with MV=0 will be very loud, and will most likely clip the mic input.

What exactly are you trying to accomplish?
making sure that the audyssey SubEQ and the MiniDSP are not amplifying signals too much. With the MiniDSP I do a max of 3dB gain on anything so it's mostly cut only. I have no clue what the Audyssey SubEQ is doing so I was running compression sweeps with the mic in front of my sub. The room response is flat but that doesn't mean the sub is.

I'm considering taking the sub completely out of the equation and plugging the RCA into an audio interface and see the signal being sent.

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post #21227 of 28111 Old 01-25-2017, 11:58 AM
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Originally Posted by tjcinnamon View Post
making sure that the audyssey SubEQ and the MiniDSP are not amplifying signals too much. With the MiniDSP I do a max of 3dB gain on anything so it's mostly cut only. I have no clue what the Audyssey SubEQ is doing so I was running compression sweeps with the mic in front of my sub. The room response is flat but that doesn't mean the sub is.

I'm considering taking the sub completely out of the equation and plugging the RCA into an audio interface and see the signal being sent.
Why not simply observe the output level meter on the MiniDSP to see if there is any clipping?
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post #21228 of 28111 Old 01-25-2017, 12:12 PM
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Why not simply observe the output level meter on the MiniDSP to see if there is any clipping?
that would work. But couldn't the sub gain introduce a clip?

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post #21229 of 28111 Old 01-25-2017, 12:27 PM
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that would work. But couldn't the sub gain introduce a clip?
Measure the sub output at a level just below clipping on the MiniDSP using REW. Then look at the distortion level of the measurement.
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post #21230 of 28111 Old 01-25-2017, 02:01 PM
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Measure the sub output at a level just below clipping on the MiniDSP using REW. Then look at the distortion level of the measurement.
So the distortion graph doesn't change off of room or multisub implementations? Should I put the mic in the middle of the room or right in front of the sub?

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post #21231 of 28111 Old 01-25-2017, 02:46 PM
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So the distortion graph doesn't change off of room or multisub implementations? Should I put the mic in the middle of the room or right in front of the sub?
You should be concerned with each sub's distortion level, not the distortion of the combined sub signal.
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post #21232 of 28111 Old 01-25-2017, 02:51 PM
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You should be concerned with each sub's distortion level, not the distortion of the combined sub signal.
Cool. When checking distortion should the mic be at MLP or in front of the sub?

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post #21233 of 28111 Old 01-25-2017, 03:12 PM
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Cool. When checking distortion should the mic be at MLP or in front of the sub?
MLP of course.

Keep in mind that there is some debate on whether or not the distortion that is represented in REW is actually coming from the speaker or whether it is actually as high as represented, esp. in the ULF range. It could very likely be things in the room resonating or vibrations induced in whatever you are using to hold the mic.
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post #21234 of 28111 Old 01-25-2017, 04:27 PM
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Originally Posted by Alan P View Post
MLP of course.

Keep in mind that there is some debate on whether or not the distortion that is represented in REW is actually coming from the speaker or whether it is actually as high as represented, esp. in the ULF range. It could very likely be things in the room resonating or vibrations induced in whatever you are using to hold the mic.
Why the MLP, Alan? A near-field measurement would minimize the resonating and vibrations you are talking about. If the sub is clipping, causing distortion, this would be easily measured near-field.
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post #21235 of 28111 Old 01-25-2017, 06:03 PM
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Originally Posted by AustinJerry View Post
First of all, a voltmeter is not an absolute requirement, and there are fairly easy ways to validate your current configuration without using one.

Follow the instructions to output the REW 60Hz test signal to the sub channel with the AVR volume set to zero and the sub channel trims set to zero as well. The input and output level sliders on the 2x4 should be set to zero as well. While the test tone is playing, observe the output meters on the 2x4. If the level is extending into the Red area, then clipping is occurring. Using the AVR sub channel trim adjustment, gradually lower the trim until the 2x4 output meter no longer reaches the red zone. Make a note of the trim setting. If you lower the trim setting all the way to -12 and are still getting output into the red zone, then you have a more serious gain issue.

Next step is to run the Audyssey calibration. For the purposes of this exercise, you can run a single Audyssey measurement (the first measurement sets the speaker trims and delays) and complete the calibration so that the sub trim is set. Open the AVR menu and observe the trim level set by Audyssey. If the trim level is equal to or lower than the value you determined in the first step, then you have no gain issue. You can play your system at reference levels (which is very loud) without risk of clipping.

If, however, the Audyssey sub channel trim is higher than what you determined in step 1, then you must make adjustments using the master volume control--specifically you will not be able to set the master volume control to zero (reference) without risking clipping on the sub channel. Compensate as follows: if the trim level determined in the first step is -6, and the Audyssey trim is -3, then you should restrict playback master volume to -3.

Finally, you can leave your laptop connected and the 2x4 plug-in output meters displayed on the screen while you are playing content (a movie or music). Observe the output meters to verify that while playing content at normal levels, you are not seeing the output go into the red area. This should give you reasonable assurance that the gain setting for the 2x4 is appropriate. Of course, if what I have outlined doesn't work for you, report back here and we'll se what the next steps are. And Alan makes a good point--a voltmeter, if you end up needing one, is not a very costly investment.
When I run a test signal in REW, or when I play music, the output meters on the 2x4 don't move.

Edit: I unplugged it, plugged it back in. Now we're in business.
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post #21236 of 28111 Old 01-25-2017, 06:40 PM
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Originally Posted by AustinJerry View Post
If the sub is clipping, causing distortion, this would be easily measured near-field.
I don't think I've ever seen a good answer to the question: "What is an acceptable level of distortion?"
Michael

Did you really need to quote that entire post in your reply?
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post #21237 of 28111 Old 01-25-2017, 07:03 PM
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I don't think I've ever seen a good answer to the question: "What is an acceptable level of distortion?"
Michael
I think it would be easier to come up with what is an unacceptable level of distortion. For example, if you had 50% distortion for your sub at 70 Hz, wouldn't you consider this unacceptable?

First comes the measurement. Then comes the discussion whether the result is acceptable or not. And I agree, there don't seem to be any standards.

Last edited by AustinJerry; 01-25-2017 at 07:18 PM.
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post #21238 of 28111 Old 01-25-2017, 07:35 PM
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I don't think I've ever seen a good answer to the question: "What is an acceptable level of distortion?"
Michael
For subs a place to start is 10%, as that is the line that makes a sub fail during a review on Sound and Vision and sites like that.

Personally, I really liked the sound when I got my distortion levels below 5%. So that's what I go for. Only time I ignore that rule of thumb is when dealing with the distortion caused by room modes.
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post #21239 of 28111 Old 01-25-2017, 08:11 PM
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Hey guys. I have a question.... I have adjusted the input setting on my minidsp so it doesn't clip... It's about -14db now. I played the hulk at reference and it doesn't go in the red. How about the output settings on the minidsp? Do I leave it at 0 or should I reduce that as well? Or is it only the input settings that matter to adjust the gain structure.

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post #21240 of 28111 Old 01-25-2017, 08:16 PM
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Originally Posted by buddhamus View Post
Hey guys. I have a question.... I have adjusted the input setting on my minidsp so it doesn't clip... It's about -14db now. I played the hulk at reference and it doesn't go in the red. How about the output settings on the minidsp? Do I leave it at 0 or should I reduce that as well? Or is it only the input settings that matter to adjust the gain structure.

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Are we talking about a 2x4? Both the input and output of my balanced 2x4 are set to zero. I would certainly leave the output settings at zero.
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