Trdat
Junior Member
Posts: 78 
|
Post by Trdat on Aug 15, 2017 13:02:17 GMT
Dear Crew,
I am scouring the internet to understand why my measurments have noise. According to Bernt from Audiolense DSP software, my impulse response and frequency response have noise in them. He is out of ideas and thought a forum might help, and I think this forum in particular can point me in the right direction. I personally have been going of the measurments from Audiolense but the REW measurments are the same.
I personally still don't know/understand if it is just High frequency noise entering in from somewhere or electrical noise cause by whatever interference.
I have a simple set-up with a laptop connected to the DAC of my NAD amp and a crossover in between the power and pre amp of my integrated NAD amp. With my sub connected to the crossover. The crossover is a Marchand XM66, Phil the owner guaranteed that it should not cause interference with the measuring. My microphone is new plus my soundcard is also new a Presonus Audiobox 2.
All this is connected to a power conditioner/Surge protector Furman M-10LxE I know Ethans thoughts on this but I am in a X-Soviet Union nation with electricity shutting down often enough to warrant a conditioner.
I would of thought the power conditioner would of done the job to cut out noise but it seems there is something else causing interference in the rig or the conditioner is just not doing its job. I wonder if the electricuty meters outside my apartment could be it? But I doubt it... Out of my 30 measurments I have one good measurment so its possible just have no idea how one was okay.
I know it is a process of elimination but if anyone has any ideas it would be great.
Regards
|
|
|
|
Post by Ethan Winer on Aug 15, 2017 14:02:09 GMT
What happens if you record audio through the same microphone? The best way for us to help you is if you record yourself speaking from 2-4 feet away from the microphone using an audio recorder program. Then post that somewhere where we can hear it. We only need five seconds, and you can convert it to MP3 if you'd like. Then if that's clean, post one REW graph and point out the part you think indicates noise in the measurement. If you really do have a problem with electrical noise, this may help: Hum and Buzz, Clicks and Pops |
|
|
|
Post by arnyk on Aug 15, 2017 14:55:38 GMT
Dear Crew, I am scouring the internet to understand why my measurments have noise. According to Bernt from Audiolense DSP software, my impulse response and frequency response have noise in them. He is out of ideas and thought a forum might help, and I think this forum in particular can point me in the right direction. I personally have been going of the measurments from Audiolense but the REW measurments are the same. I personally still don't know/understand if it is just High frequency noise entering in from somewhere or electrical noise cause by whatever interference. I have a simple set-up with a laptop connected to the DAC of my NAD amp and a crossover in between the power and pre amp of my integrated NAD amp. With my sub connected to the crossover. The crossover is a Marchand XM66, Phil the owner guaranteed that it should not cause interference with the measuring. My microphone is new plus my soundcard is also new a Presonus Audiobox 2. All this is connected to a power conditioner/Surge protector Furman M-10LxE I know Ethans thoughts on this but I am in a X-Soviet Union nation with electricity shutting down often enough to warrant a conditioner. I would of thought the power conditioner would of done the job to cut out noise but it seems there is something else causing interference in the rig or the conditioner is just not doing its job. I wonder if the electricuty meters outside my apartment could be it? But I doubt it... Out of my 30 measurments I have one good measurment so its possible just have no idea how one was okay. I know it is a process of elimination but if anyone has any ideas it would be great. Regards Most likely cause of excess noise is the gain setting on the mic preamp. Turn it up to clipping, and then back it off a little for clean operation. An acoustic noise source in the room such as a room air conditioner could be relevant. I think you will find out that power conditioning is snake oil - unnecessary and/or ineffective. |
|
Trdat
Junior Member
Posts: 78
|
Post by Trdat on Aug 15, 2017 18:16:37 GMT
Thanks for immediate reply.
Arnyk I get this feeling its not acoustic noise, I even tried a measurement at night with no sound outside or around and it was similar to previous measurments but I will play around with the gain and volume control on the soundcard.
Ethan thanks record with the mic and upload it somewhere for you to listen and I will send through a REW measurment soon.
I will also read your article. Thanks again.
|
|
Trdat
Junior Member
Posts: 78
|
Post by Trdat on Sept 4, 2017 16:25:21 GMT
Firstly I apologize for not yet figuring out how to record on my Studio one software but I will get to recording some voice so at least I can eliminate the microphone. I tried turning the frigde off while measuring, I separated all my equipment moving them around, I switched the power plug upside down, I moved the laptop out of the path of the microphone and speakers. And still to no avail. The other thing i might need to take in consideration is ambient noise, I was convinced that it is not possible but I dont understand the causes well enough so i need to try again late at night to see if ambient noise is interfering with the measurement. My question is after reading your article i have 2 options first being to add an RFI filter you recommended, Im curious if the Corcom filter can add to my power conditioner which already "apparently" has a RFI filter which will only get rid of Greater than 20DB, 1.5MHz to 200MHz on my Furman 10LXE. So in essence I will have 2 RFI filters.... Secondly you are correct about isolator tranformers being expensive, do i need to add it in between all unbalanced lines? Or is there a few culprates that are I should be looking at? I have attached a REW measurment and i am not sure where and how the noise is effecting the measurment but all my measurments except one which is in my Audiolense looks very different.  |
|
|
|
Post by Ethan Winer on Sept 8, 2017 14:58:15 GMT
The graph you posted looks more or less normal.
|
|
Trdat
Junior Member
Posts: 78
|
Post by Trdat on Sept 13, 2017 7:26:08 GMT
The impulse response on my DSP measurement is indicative of noise. And my DSP works with a previous measurement that has a smooth impulse response(without crossover in my rig) while with the measurement I posted the DSP doesnt work.
After a process of elimination, I have discovered that it is my crossover that is causing the interference, I also hear a hiss from my speakers as soon as I turn the crossover on.
The crossover is an important part of my set-up and i would like to keep it in my rig.
I have read your article and understand it so and so.... What would be the best option to get rid of this interference?
Add an RFI filter to the crossover or better add an isolator transformer between the Crossover and Amp? or perhaps both...?
My set up is a crossover in between the pre amp and power amp of my integrated amp with the low input of the crossover going to a sub.
Kindest Regards
|
|
|
|
Post by arnyk on Sept 13, 2017 18:28:08 GMT
The impulse response on my DSP measurement is indicative of noise. And my DSP works with a previous measurement that has a smooth impulse response(without crossover in my rig) while with the measurement I posted the DSP doesnt work. After a process of elimination, I have discovered that it is my crossover that is causing the interference, I also hear a hiss from my speakers as soon as I turn the crossover on. The crossover is an important part of my set-up and i would like to keep it in my rig. I have read your article and understand it so and so.... What would be the best option to get rid of this interference? Add an RFI filter to the crossover or better add an isolator transformer between the Crossover and Amp? or perhaps both...? My set up is a crossover in between the pre amp and power amp of my integrated amp with the low input of the crossover going to a sub. I don't what kind of crossover you have, but often problems like this are due to what is known as "Gain Staging" If your system has two or more volume controls in series, such as one on the input to the crossover and one on the input to the amp, there are actually an infinite combinations of settings of the two that will have the same over-all results. If the input gain on the crossover is set low and the amp input gain is set high, then this may drop the signal through the crossover and make any noise it generates more audible. If the input gain on the crossover is set high and the amp input gain is set low, then this may raise the signal through the crossover and make any noise it generates less audible. There are other gain settings in the system that actually have a simular role as the input gain on the crossover in that their settings can control the level of the signal passing through the crossover, and cause the input gain on the amp to end up set high, thus emphasizing any noise that the crossover generates. |
|
Trdat
Junior Member
Posts: 78
|
Post by Trdat on Sept 25, 2017 18:04:38 GMT
Arnyk,
My crossover is the Marchand XM66 its a variable crossover.
The only gain settings are the high and low pass out puts for left and right. That is if I understood you correctly regarding Gain staging....
I played around with the knobs the noise/hum is constant....
|
|
|
|
Post by arnyk on Sept 29, 2017 20:43:05 GMT
Arnyk, My crossover is the Marchand XM66 its a variable crossover. The only gain settings are the high and low pass out puts for left and right. That is if I understood you correctly regarding Gain staging.... I played around with the knobs the noise/hum is constant.... I can't find any service manual or schematic for any of the Marchand products, so I can't even hazard a guess which controls are in what order inside the box. Does turning the eq off change anything? Are there gain controls on the power amps that you can back off? |
|
