# "The soundcard measurement varies by 11db"



## jake5 (Apr 28, 2013)

"The soundcard measurement varies by 11 dB between 20Hz and 20kHz, that is much higher than it should be, the measurement may not be valid and should not be used to make a calibration file"

I just tried calibrating my external USB soundcard and I got this result. I matched the out/in levels very closely and completed the process correctly. 

What does this mean and what should I do now?

Thanks


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## jake5 (Apr 28, 2013)

Reviewing the guide, it seems I made a mistake by using a dual-ended 3.5mm cable. In the tutorial it is stated that two 3.5mm to RCA splitters (in combination with a single inline RCA connecter for the right channels only) should be used. Maybe that explains my results?

I need to get an inline RCA connecter before I can try it out again. Any advice is appreciated, thanks.


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## EarlK (Jan 1, 2010)

It's not a mistake to connect together the stereo mini to stereo mini ( 3.5mm ) jacks found on your soundcard.
- Doing so simply means you are feeding 2 output channels to 2 input channels .

I suspect your issue lies within the soundcards own unique software ( control panel ) .

It looks like a HighPass filter ( bass-roll off ) is engaged within its' input section ( of said software ) .

REWs directions assume users will have a basic working knowledge of the soundcards that they have chosen to buy ( ie; the directions aren't "cradle to grave" ) .


:sn:


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## jake5 (Apr 28, 2013)

The ext soundcard is a $13 ebay special, and it doesn't appear to have xover functions. I'm afraid it's the overall poor quality that's created this messed up response.

However, it seems REW's message is more of a warning that something may have been set up incorrectly. If that is not the case, can't I just use the soundcard cal file that was created and be good to go?


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## JohnM (Apr 11, 2006)

You could just use it as is, might want to try applying a tiny amount of smoothing to it before generating the cal file to clean up the glitches at 1 kHz multiples (USB noise breakthrough).


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## jake5 (Apr 28, 2013)

JohnM said:


> You could just use it as is, might want to try applying a tiny amount of smoothing to it before generating the cal file to clean up the glitches at 1 kHz multiples (USB noise breakthrough).


Please forgive the noob question, but wouldn't I want the calibration curve to be unsmoothed/unaltered, considering my goal is to create a completely flat frequency response?

Thanks


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## EarlK (Jan 1, 2010)

> The ext soundcard is a $13 ebay special, and it doesn't appear to have xover functions. I'm afraid it's the overall poor quality that's created this messed up response.


If you have a built-in sound-card ( on the computer being used with REW ), measure it's performance ( via a loop-back cable ). Maybe it's better than this eBay special . 

:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> If you have a built-in sound-card ( on the computer being used with REW ), measure it's performance ( via a loop-back cable ). Maybe it's better than this eBay special .
> 
> :sn:


The computer is a netbook w/ a built in card, but I went external because the onboard card only has a single trrs jack which is mic in/ headphone out. In the guide it is stated that a line in port is needed, so I went for the cheap ext card that has line in.


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## Phillips (Aug 12, 2011)

Matter of interest what mic are you using?


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## jake5 (Apr 28, 2013)

Phillips said:


> Matter of interest what mic are you using?


A Dayton iMM-6

http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-810


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## Phillips (Aug 12, 2011)

jake5 said:


> A Dayton iMM-6
> 
> http://www.parts-express.com/pe/showdetl.cfm?partnumber=390-810


I can't say i have heard of this mic been used for REW.

I see it has calibration file, have you downloaded this?


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## jake5 (Apr 28, 2013)

Phillips said:


> I can't say i have heard of this mic been used for REW.
> 
> I see it has calibration file, have you downloaded this?


Yes, I've downloaded it and applied it in REW.


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## jake5 (Apr 28, 2013)

Here is my first pink noise measurement. It is of my near-field desktop setup which uses a small pair of Mirage speakers (~3" woofer, 1" tweeter) and a Mirage 6" sub.


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## EarlK (Jan 1, 2010)

PartsExpress said:


> *Highlights*
> 
> 
> Precision condenser microphone for critical measurement
> ...


- It's a serious "no-no" to send ( ie; "feedback" ) the input signal, back to the output ( when using REW ). 

- The ( above ) written specs on the iMM-6 "strongly suggest", that is in fact the way the line-out ( on the iMM-6 ) is wired ( again, a real "NO-NO" if true ) .

- Any potential user should seek clarification ( at the Dayton Forum I suppose ) before using this unit's line out to drive REW's test signals into a speaker .


:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> - It's a serious "no-no" to send ( ie; "feedback" ) the input signal, back to the output ( when using REW ).
> 
> - The ( above ) written specs on the iMM-6 "strongly suggest", that is in fact the way the line-out ( on the iMM-6 ) is wired ( again, a real "NO-NO" if true ) .
> 
> ...


I am not using the imm-6's line-out. The ext soundcard has it's own output, which I would use for a loopback setup. The measurement I posted was made by playing a pink noise track on a system outside of REW.


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## EarlK (Jan 1, 2010)

- My previous post is meant as general information ( & a cautionary yellow flag ) to those who might wrongly conclude that this Dayton mic/line adapter is a workable solution ( for "all-in-one" hardware ) .

- I don't believe that it is a usable all-in-one unit ( for the reason previously mentioned ) .

- How you have chosen to handle this drawback is reasonable ( & workable ) from what I've seen so-far . 

:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> - My previous post is meant as general information ( & a cautionary yellow flag ) to those who might wrongly conclude that this Dayton mic/line adapter is a workable solution ( for "all-in-one" hardware ) .
> 
> - I don't believe that it is a usable all-in-one unit ( for the reason previously mentioned ) .
> 
> ...


cool. 

it seems the previous measurement I posted was actually made using the netbook's onboard mic (explains a lot). I had to re-select the ext soundcard as the input device, and when I tried to make a recording it was clear the Dayton mic (plugged into the line-in) was not registering (no change in measured dB with significant volume increase).


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## jake5 (Apr 28, 2013)

delete


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## jake5 (Apr 28, 2013)

jake5 said:


> cool.
> 
> it seems the previous measurement I posted was actually made using the netbook's onboard mic (explains a lot). I had to re-select the ext soundcard as the input device, and when I tried to make a recording it was clear the Dayton mic (plugged into the line-in) was not registering (no change in measured dB with significant volume increase).


Can anyone please suggest what I might do to get my mic working?


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## EarlK (Jan 1, 2010)

jake5 said:


> Can anyone please suggest what I might do to get my mic working?


- Since that Dayton mic is now plugged into your computers on-board soundcard ( whatever it's called ) , you'll need to select it ( the onboard soundcard ) as your input ( from within REW's preferences window ).

- Whether or not the iMM-6 ( when it's plugged into a computers mic input ) auto-disables that computers on-board builtin mic , is any-ones guess . 
- That info will need to come from your computer's operators manual ( or maybe even the online Dayton forum ) .

- If your computers mic can't be disabled in this particular scenario, then you'll simply need to get a different mic ( such as the UMIK-1 from Cross-Spectrum Labs ) .

:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> - Since that Dayton mic is now plugged into your computers on-board soundcard ( whatever it's called ) , you'll need to select it ( the onboard soundcard ) as your input ( from within REW's preferences window ).
> 
> - Whether or not the iMM-6 ( when it's plugged into a computers mic input ) auto-disables that computers on-board builtin mic , is any-ones guess .
> - That info will need to come from your computer's operators manual ( or maybe even the online Dayton forum ) .
> ...


With the Dayton mic plugged into the nbooks mic input, the rta is identical to the one taken with the nbooks internal card/onboard mic. So no, it appears when a mic is plugged into the onboard sound card's jack, the onboard mic is not disabled (at least not by default). However, I am confident it is being disabled by de-selecting the onboard card as the input device in preferences.

What I'm trying to do is use the external sound card and bypass the internal card (the ext also has line-in rather than mic-in). I've selected the ext card as the input device in REW, but the mic is not registering when plugged into the ext card's line-in (I also tried the ext card's mic-in to no avail). The ext card's driver is loaded and the card seems to be functioning based on my ext card calibration results. Is there anything else I can try? I don't suppose this would have to do with the Dayton mic using a TRRS connecter and the ext card not having a TRRS-specific input.


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## Phillips (Aug 12, 2011)

Did you purchase this mic *specifically *for REW and how along ago?


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## jake5 (Apr 28, 2013)

Phillips said:


> Did you purchase this mic *specifically *for REW and how along ago?


I originally intended to use it with a cell phone RTA app. However, after purchasing I decided to try to hook it up to my netbook with REW for better visibility and more options. I also don't want to spend $80-$100 for a mic.


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## Phillips (Aug 12, 2011)

jake5 said:


> I originally intended to use it with a cell phone RTA app. However, after purchasing I decided to try to hook it up to my netbook with REW for better visibility and more options. I also don't want to spend $80-$100 for a mic.



Contact Dayton to see if it can be used with REW, worth a try. You could be going around in circles.

In the sound properties of your computer what does it show?


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## EarlK (Jan 1, 2010)

jake5 said:


> Can anyone please suggest what I might do to get my mic working?



Compare ( research ) the pin-out arrangements ( 3.5mm TRRS ) for your Dayton mic, to that of your computers combo input/output jack .

There are 2 arrangements in use ( meaning by definition, there is not actually a standard ) .

- The differences in these two approaches have the ground & the microphone signal line reversed ( ie; the signals on the sleeve & the last ring or "R2", are flipped ) .

Your microphone may simply be shorting out to ground ( due to compatibility issues ) .

Here's one adapter cable ( to fix this sort of wiring problem ) ;



:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> Compare ( research ) the pin-out arrangements ( 3.5mm TRRS ) for your Dayton mic, to that of your computers output jack .
> 
> There are 2 arrangements in use ( meaning by definition, there is not actually a standard ) .
> 
> ...


Thanks. The input jacks on my ext soundcard are trs, so it looks like I'll need a trs male to trrs female adapter (not easy to find). So far I've only found one of these online for something like $25, which is more than the mic cost me :unbelievable:


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## Wayne A. Pflughaupt (Apr 13, 2006)

Looks like you’re going to have to stick with the cell phone RTA app... 

Regards, 
Wayne


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## EarlK (Jan 1, 2010)

jake5 said:


> Thanks. The input jacks on my ext soundcard are trs, so it looks like I'll need a trs male to trrs female adapter (not easy to find). So far I've only found one of these online for something like $25, which is more than the mic cost me :unbelievable:



- I'm not sure what adapter you located for $25.00 ( since you didn't provide a link ) , but one would usually want ( something like the following ) to give the  *iMM-6*  a fighting chance of working with the standard 2 jack ( 3.5mm ) systems ( as typically found on computers ). 

- I wouldn't use the headphone jack with the iMM-6 for the reasons previously mentioned above . 

- These types of "VOiP-Phone" adapters will properly separate ( ie; via redirected pin-outs ) the microphone signal from the line out signals .

- Whether or not your mic will receive the necessary  *Phantom Power*  which is necessary to power your iMM-6 condenser mic is another question ( again, you'll need to research the specs for the 2 soundcards that you currently own ) .





NOTE : This adapter type may still not completely solve your wiring problem ( because , as previously mentioned, the 2 wiring implementations for TRRS jacks, flip the mic signal with the ground signal // ie; "sleeve" & the "last ring" or "R2" ) . Therefore, one might still need to use the R2 to Sleeve ( "cross-over" ) cable that I previously provided a link for .

:sn:

PS: "All-In-ALL" , going the UMIK-1" budget" approach, looks better all the time ( at least, it's known to work right-out-of-the-box ).


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## jake5 (Apr 28, 2013)

EarlK said:


> PS: "All-In-ALL" , going the UMIK-1" budget" approach, looks better all the time ( at least, it's known to work right-out-of-the-box ).


Thanks, I think I'll contact Dayton for more info and perhaps try a $6 adapter similar to the one you suggested. btw, this is the adapter I found originally:

http://head-direct.com/Products/?act=detail&id=119


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## Phillips (Aug 12, 2011)

> PS: "All-In-ALL" , going the UMIK-1" budget" approach, looks better all the time ( at least, it's known to work right-out-of-the-box ).


+ 1, purchase from Cross - Spectrum.


Personally i would have doubt with the accuracy of the Dayton mic calibration file.

The thing is if you get it up and running, then there is the accuracy factor.


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## jake5 (Apr 28, 2013)

*a bit of progress*

I received my trrs splitter and I was able to get a measurement with the Dayton mic, but only with it plugged into MIC IN on the ext soundcard (and with MIC IN selected as the input method in my ext soundcard's software). When plugged into LINE IN on the ext soundcard (and with LINE IN selected as the input method in my ext soundcard's software) I could not get a measurement in REW. The USB ext soundcard is selected as the input device in REW.

[edit: I tested the line-in functionality of my ext soundcard by hooking it up directly to an output signal (not using the mic) and this did register in REW]


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## EarlK (Jan 1, 2010)

It would be useful to others ( in this same situation ) if you would provide links to both the USB soundcard ( you bought ) and the TRRS splitter adapter that you ended up using .

Thanks <> :sn:


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## jake5 (Apr 28, 2013)

http://www.ebay.com/itm/170348061325?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
http://www.ebay.com/itm/140902438667?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649


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## EarlK (Jan 1, 2010)

Thanks !

:T


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## jake5 (Apr 28, 2013)

Anyone? In the REW guide it's stated that the MIC IN shouldn't be used, and I still haven't gotten my LINE IN to register with the Dayton mic.


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## EarlK (Jan 1, 2010)

jake5 said:


> Anyone? In the REW guide it's stated that the MIC IN shouldn't be used, and I still haven't gotten my LINE IN to register with the Dayton mic.


With your Dayton mic ( or any condensor type mic ) you must use the MIC IN for that mic to work ( LINE IN will never work with your mic ) .

Don't fret over what the REW guide says ( you're simply mis-interpreting & mis-applying directions that were meant for SLM-type devices which output line-level ) .

:sn:


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## jake5 (Apr 28, 2013)

EarlK said:


> With your Dayton mic ( or any condensor type mic ) you must use the MIC IN for that mic to work ( LINE IN will never work with your mic ) .
> 
> Don't fret over what the REW guide says ( you're simply mis-interpreting & mis-applying directions that were meant for SLM-type devices which output line-level ) .
> 
> :sn:


Good news. Many thanks to the members of this board for helping me get my budget setup going. 

After recalibrating my ext soundcard using MIC IN rather than LINE IN, here's the FR I measured for my Mirage near-field computer setup (6" sub, 3.5" mids, 1" tweets).


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## Phillips (Aug 12, 2011)

jake5 said:


> Good news. Many thanks to the members of this board for helping me get my budget setup going.
> 
> After recalibrating my ext soundcard using MIC IN rather than LINE IN, here's the FR I measured for my Mirage near-field computer setup (6" sub, 3.5" mids, 1" tweets).



That doesn't look right?
It should be showing in the +70 db range.
Take the sound card file out and see if that changes anything.


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## jake5 (Apr 28, 2013)

Phillips said:


> That doesn't look right?
> It should be showing in the +70 db range.
> Take the sound card file out and see if that changes anything.


I think this is because i didn't properly check my levels first and I played the pink noise at too low a volume. Below is a second measurement made with levels that registered ~-16db in REW's level meter. I should also note that I've not calibrated REW's db meter, which I assume is necessary to get an accurate db measurement.

edit: I am getting nearly identical readings with the soundcard file applied and not applied.


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## jake5 (Apr 28, 2013)

The second chart I posted was made with the test signal playing quite loudly (I wore ear protection). 

The mic sensitivity is maxed in my ext soundcard's controls. Is there anything elso I can look into as to why my reading is registering so low?


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## JohnM (Apr 11, 2006)

jake5 said:


> I should also note that I've not calibrated REW's db meter, which I assume is necessary to get an accurate db measurement.


Correct, to get the graph drawn at the correct level go through the REW SPL meter calibration.


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## Barleywater (Dec 11, 2011)

Please try using simple recording application, and recording your voice and listening to playback. Posted graphs look like total garbage.


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## jake5 (Apr 28, 2013)

Barleywater said:


> Please try using simple recording application, and recording your voice and listening to playback. Posted graphs look like total garbage.


I've done what you've suggested and playback sounds fine to me.:dontknow:


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## Barleywater (Dec 11, 2011)

Thanks for reality check. Nice to have microphone that works.

In previous posted plots, are these produced with noise or with sweeps?


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## jake5 (Apr 28, 2013)

Barleywater said:


> Thanks for reality check. Nice to have microphone that works.
> 
> In previous posted plots, are these produced with noise or with sweeps?


Thanks for caring. The plots were done with pink noise. It's possible (but not certain) that there is some distortion in the second plot because I played the track at a high volume (with earplugs in).


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## Barleywater (Dec 11, 2011)

How do sweep measurements compare?


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## jake5 (Apr 28, 2013)

Barleywater said:


> How do sweep measurements compare?


The first chart is simply a measurement of a fairly quiet room with no ac, fan, or other overt noise sources. My desktop, which to me is inaudible, is in the room as well as a single-bulb overhead light. Mic cal and soundcard cal files were both loaded for these tests.

The second two charts are of a 20-20k sweep done using REW's measure feature.


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## JohnM (Apr 11, 2006)

Pretty substantial mains hum in the 'quiet room' plot (the spikes at 60/180/300/420 etc). Might want to check your cables or try different cables while watching the RTA plot to see if you can cure that.


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## Barleywater (Dec 11, 2011)

Yep, that is substantial interference.

What does loop back of signal to speakers measure?

It may be helpful to save measurements and post resulting .mdat file.


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## jake5 (Apr 28, 2013)

JohnM said:


> Pretty substantial mains hum in the 'quiet room' plot (the spikes at 60/180/300/420 etc). Might want to check your cables or try different cables while watching the RTA plot to see if you can cure that.


Doing a bit of experimenting today, I seem to be getting roughly the same FR with the mains on or off. 



Barleywater said:


> Yep, that is substantial interference.
> 
> What does loop back of signal to speakers measure?
> 
> It may be helpful to save measurements and post resulting .mdat file.


This is looping speaker out to mic in with no signal generated:


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## Barleywater (Dec 11, 2011)

Not sure what this is. No signal?

Loopback measurement using sweep, such as used for making soundcard calibration or measuring speaker would provide information.

Regards,

Andrew


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## jake5 (Apr 28, 2013)

Barleywater said:


> Not sure what this is. No signal?


That was a measurement taken rta'ing a loopback and not playing any type of test tone whatsoever (I naively thought that's what I was being asked to do to measure noise in the hardware).

Here is a loopback of the sine sweep measure:


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## Barleywater (Dec 11, 2011)

Plot reveals calibration curves for soundcard, and microphone, but power mains noise is absent. Microphone may turn cable into antenna; noise may actually be in room, or connection of soundcard to speaker system is introducing ground loop.

Soundcard has quite the high pass filter below 200Hz. Hope this mostly the mic input.

Thanks for sweep data.


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## JohnM (Apr 11, 2006)

You would be better off not using the Dayton cal file, mics simply do not have responses as random and erratic as Dayton's cal files suggest.


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## Barleywater (Dec 11, 2011)

Dayton's description is blatantly overstatement of performance relative to any standard measurement microphone. "Y" appendage is horrific obstacle. Plugged directly into i thingy is huge variable, let alone if on end of own cable, or if another cable is plugged into "Y".

Dayton is not doing their image any good in marketing such product.

Similar straight tube, or more at nub, devices exist at similar, even lower price point that avoid acoustical interference.


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## jake5 (Apr 28, 2013)

All I can think of at this point is to try shielded cables.

Also, when I RTAd a loop of silence the noise showed up and I was wondering if I could somehow subtract that noise result from any measurement I take - the result being a significantly more noise-free final measurement.


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