REW Beta Release Message stating high distortion

J

JIm586music

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• Sep 23, 2024

• #1

Hello, Very new user here.
I'm using a MacBook Pro 2015 Monterey 12.7.6 and the latest REW beta.
I believe I'm all set up ok with the UMIk 1 however, after I take a measurement I get a box either saying I have high distortion or sometimes the signal to noise ratio is low.
I check the levels before each measurement (80db) and it says level ok.
what am I doing wrong?

Thanks in advance.
Jim

 

John Mulcahy

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• Sep 24, 2024

• #2

Speakers and subs may have high distortion at low frequencies, or the low end may be mostly noise. Easiest is to attach an mdat file from an example measurement.

 

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• Sep 24, 2024

• #3

I will try and get my head around doing that tonight as the Mrs is out for Tai chi.
Cheers

 

John Mulcahy

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• Sep 24, 2024

• #4

Saving a measurement produces an mdat file.

 

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• Sep 24, 2024

• #5

Hi John.
I'll attach the file. Hopefully its a minor issue.
Kind regards

 

Attachments

• LFE L1 Sep 24.mdat

  600.6 KB · Views: 5

J

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• Sep 25, 2024

• #6

As a an update.
I made a few subwoofer measurements at 85db last night and the error messages didn’t appear. They were obviously louder but I encountered an issue whereby I couldn’t align sbl( to calculate the average) without increasing the measurement on the graph to over 100db! Not sure if it was fatigue on my part but I was managing this with previous measurements.
Cheers

 

John Mulcahy

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• Sep 25, 2024

• #7

The sub has a lot of 2nd harmonic distortion at around 25 Hz, but the measurement is otherwise OK.

 

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• Sep 25, 2024

• #8

John Mulcahy said:

The sub has a lot of 2nd harmonic distortion at around 25 Hz, but the measurement is otherwise OK.

Click to expand...

Hiya, thanks for the reply.
Ok, I’ll carry on then.
Ive tried again tonight and I don't get any error messages when I sweep with the subs at 85db?
I've moved the subs around. I have a Monoprice monolith 10' thx. this is the measurement I'm getting.
why is it rolling off from 40hz so much? is it normal or is my room?
cheers

 

Attachments

• 
  Left sub.jpg

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John Mulcahy

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• Sep 26, 2024

• #9

The shape of the response will depend on the sub, your room, where the sub is in the room and where the mic is placed.

 

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Preamp, Processor or Receiver

Nad 578

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Tom Evans The Vibe

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Nad 298

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Dennafrips Pontus 11

Universal / Blu-ray / CD Player

Panasonic 820

Streaming Equipment

Node 2i modded ps and rechecked

Front Speakers

Quadra Galan

Screen

P

Video Display Device

Projector Epson Ls12000b

• Sep 26, 2024

• #10

John Mulcahy said:

The sub has a lot of 2nd harmonic distortion at around 25 Hz, but the measurement is otherwise OK.

Click to expand...

Hiya, thanks for the reply.
Ok, I’ll carry on then.
I do wonder there’s a mic gain issue as it didn’t happen when I raised the level to 85db.
Cheers

John Mulcahy said:

The shape of the response will depend on the sub, your room, where the sub is in the room and where the mic is placed.

Click to expand...

Thank you.