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Discussion Starter · #1 ·
I recently read on this forum that the FR tones in should be created in mono. I have been doing sweeps using stereo tones.


Just for S&Gs I tried mono tones and SPL meter went off the chart as now the center channel was playing sound as well (system currently calibrated to 75dB).


Should I use a stereo mode on the AVR with the mono tones, or just the stereo tones by themselves? It's my understanding its best not use any signal processing (like a stereo mode).


Suggestions?


Thanks,


Jeff
 

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For in-room sweeps where you will be assessing the FR above the XO for the mains (like up to 150 Hz for example), I like to simply use a mono signal and then use a y-splitter at the analog input of the pre-pro.


That way your bass management circuit will be in the loop, and both mains will be playing the signal so you can assess for comb filtering and other negative interactions between the mains, as well as evaluate the transition to the subwoofer.
 

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What is the recommended method for in-room FR below XO?
 

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Discussion Starter · #4 ·
So, connect a Y cable to the left channel of stereo OUT on the DVD and into an AUX or VCR IN on the AVR?


Gosh, I hate pulling the AVR to access the panel. But being already "certifiable" by the wafe, I'LL DO IT!!! :eek:
 

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Quote:
Originally Posted by drhack
What is the recommended method for in-room FR below XO?
The same.


If you just want to FR the sub, then run a mono signal directly to it. But it's better to run a dual mono signal to the pre/pro and keep the mains and the bass management in the mix. Then you can run say 20-150 Hz and see how the system interacts as a whole.
 

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Quote:
Originally Posted by JeffD2.
So, connect a Y cable to the left channel of stereo OUT on the DVD and into an AUX or VCR IN on the AVR?


Gosh, I hate pulling the AVR to access the panel. But being already "certifiable" by the wafe, I'LL DO IT!!! :eek:
No, just go directly into the AVR or pre/pro analog inputs (provided it does bass management at those inputs and most do). I leave a y-splitter and short cable permanently attached back there specifically for this purpose.
 

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Ed,


How do you get a mono from a CD/DVD player?


I am running 5.1 cables & Optical SPDIF from my Denon 2200 into the Onkyo701 (supports 5.1 analog In). I play an MP3 with Snpabug test tones to get the FR, but it wont generate a mono signal. So will this give wrong FR readings?


Thanks.
 

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Easy:


ipod stereo mini-jack->L&R RCA

L RCA->RCA Y-cable (both sides of the Y-cable will now have only the left channel)

Y-cable L&R RCA to Receiver L&R Input (Now receiver outputs same signal to all channels)


Or, as long as the MP-3 tones are encoded as mono MP3 files, the ipod should be outputing the same signal to both channels - so it probably doesn't matter if you just come directly off the ipod into the receiver. You can use any decent MP3 editor/encoder to create a mono MP3 file. I think even iTunes can do it if you change the settings on the MP3 encoder in the advanced options.
 

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Can't you just make sure the MP3 is encoded in mono? Any decent MP3 editor/encoder can convert an MP3 file from stereo to mono.
 

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I didn't know you were burning a CD......that's probably making it more difficult than needed. I just go straight from the PC sound card into the pre/pro with my test rig. Most sound cards are 1/8" (mono or stereo), so some adapters from Radio Shack are all you need to size up to RCA.


The NCH test tones can be saved to your hard drive as .wav files so you can create a bunch of discrete tones or a slow sweep or w/e and play them anytime.
 

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Laptops are a great tool for audio testing & measuring - they let you take the PC to the problem. :)
 

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Ed & Billybob - thanks for the inputs. I will probably go the laptop to the pre/pro route. Now I have to repeat the 60-70 RF plots all over again to calibrate my SVS PB12+2 & PB10 :(


One more question - would the FR be different if we had the pre/pro running in Direct/Stereo mode vs DTS:Neo or Dolby PLII? I got dramatically different FRs for the same signal with the pre/pro in Stereo vs DTS:Neo. Why would this be so?
 

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I think that in Neo all the speakers (including the center & all surrounds) are being fed the signal, but in direct stereo it is only the mains & sub.
 

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Discussion Starter · #14 ·
Quote:
Originally Posted by Ed Mullen
No, just go directly into the AVR or pre/pro analog inputs (provided it does bass management at those inputs and most do). I leave a y-splitter and short cable permanently attached back there specifically for this purpose.
Okay, I'm lost...


First, I'm not using a computer but a CD in the DVD player. I'm completely not getting why I need a y splitter and a short cable. Maybe I need it spelled out for me. I swear I'm not a crackhead. I swear!!
 

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Quote:
One more question - would the FR be different if we had the pre/pro running in Direct/Stereo mode vs DTS:Neo or Dolby PLII? I got dramatically different FRs for the same signal with the pre/pro in Stereo vs DTS:Neo. Why would this be so?
Some of these DSP modes EQ the signal. You want direct stereo with no EQ so you can get a correct baseline. Then anything DTS Neo adds will be evident as DSP EQ. I can't stand that particular DSP mode BTW.
 

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Quote:
Originally Posted by JeffD2.
Okay, I'm lost...


First, I'm not using a computer but a CD in the DVD player. I'm completely not getting why I need a y splitter and a short cable. Maybe I need it spelled out for me. I swear I'm not a crackhead. I swear!!
If you have been using stereo tones successfully, then stick with it. Both speakers playing are better than one.


All I was saying originally, is that my test tones are mono from the PC sound card, so I use a y splitter to get both speakers to play.
 
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