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Topic: Active setup help and recommendations (Read 17900 times) previous topic - next topic
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Re: Active setup help and recommendations

Reply #51 –
Quote from: silverprout on
Quote from: patate91 on
Where do you see the noise floor?
The distortion tab (red)
The NF (green)


Both sweep shows a different noise floor level : one with the highest peak at 3,87% and the other 6.79% at a different frequency.  

Sweep test are done at ~ 75dp spl in my basement at listening position. But there's no noise that I can hear (except the room noise), even If I place my ear in the horn. Also there's no audible distortion. I don't know what kind of noise floor is expected but looking at REW's help exemple and other users measurement there's no issue here. Maybe there's something I'm missing, can you point me out where the issue is, and what should I hear?

Re: Active setup help and recommendations

Reply #52 –
I browse the REW help file and it seems that a stepped sine measurement (from the RTA window), would give a better result for distortion measurements.

Re: Active setup help and recommendations

Reply #53 –
Quote from: patate91 on
Both sweep shows a different noise floor level : one with the highest peak at 3,87% and the other 6.79% at a different frequency.  
Sweep test are done at ~ 75dp spl in my basement at listening position. But there's no noise that I can hear (except the room noise), even If I place my ear in the horn. Also there's no audible distortion. I don't know what kind of noise floor is expected but looking at REW's help exemple and other users measurement there's no issue here. Maybe there's something I'm missing, can you point me out where the issue is, and what should I hear?

Have you calibrated your mic ?
Have you enter the calibration profile in REW ?
My test setup is 0.035% and the NF is around 45dB in the journey, it is not really a stellar performance.
Concerning the THD you have a serious issue around 70 Hz (over 6%... -23dB should be audible) and 1313Hz (over 4% -27dB should be audible because composed of H3 harmonics)

Re: Active setup help and recommendations

Reply #54 –
Quote from: silverprout on
Quote from: patate91 on
Both sweep shows a different noise floor level : one with the highest peak at 3,87% and the other 6.79% at a different frequency.  
Sweep test are done at ~ 75dp spl in my basement at listening position. But there's no noise that I can hear (except the room noise), even If I place my ear in the horn. Also there's no audible distortion. I don't know what kind of noise floor is expected but looking at REW's help exemple and other users measurement there's no issue here. Maybe there's something I'm missing, can you point me out where the issue is, and what should I hear?

Have you calibrated your mic ?
Have you enter the calibration profile in REW ?
My test setup is 0.035% and the NF is around 45dB in the journey, it is not really a stellar performance.
Concerning the THD you have a serious issue around 70 Hz (over 6%... -23dB should be audible) and 1313Hz (over 4% -27dB should be audible because composed of H3 harmonics)

Yep I use the umik-1 calibration file.

Around 70hz there's a room mode (height) as you can see on frequency graph, same thing goes for 1300hz region. (300hz too) So, no nothing can be really heard at those frequencies at listening position

Look at group delay graph with minimum phase you'll see that there's no hope to totally correct at those frequency.

I could check with a proper setup to measure distorsions, but again there's nothing I can hear.

Re: Active setup help and recommendations

Reply #55 –
By the way I'm using the last beta 5.19 I think.

Re: Active setup help and recommendations

Reply #56 –
Quote from: patate91 on
Yep I use the umik-1 calibration file.
Around 70hz there's a room mode (height) as you can see on frequency graph, same thing goes for 1300hz region. (300hz too) So, no nothing can be really heard at those frequencies at listening position
Look at group delay graph with minimum phase you'll see that there's no hope to totally correct at those frequency.
I could check with a proper setup to measure distorsions, but again there's nothing I can hear.

Do you calibrate the SPL of your mic... with an external device (calibrator) ?
I believe you, the numbers that you are pointing on are as you expect them.

Re: Active setup help and recommendations

Reply #57 –
Quote from: silverprout on
Do you calibrate the SPL of your mic... with an external device (calibrator) ?

No

I'll check again but in room noise floor was below 45db for sure.

Re: Active setup help and recommendations

Reply #59 –
Quote from: silverprout on
Your SPL measurement will be wrong with an uncalibrated microphone.

MiniDSP umik-1 only has a calibration file. Since it's usb there's not a lot things I can do to calibrate it.

Re: Active setup help and recommendations

Reply #60 –
Here'S an RTA window, with kids in the house.

Re: Active setup help and recommendations

Reply #61 –
Sorry took the measurment with wrong mic above I changed it

Re: Active setup help and recommendations

Reply #63 –
I did a couple of tests with the RTA and sine wave generator. The noise floor remained low, too low to have an effect.

Again using the tone generator, sine wave that I raise manually from 1200 to 2000 hz, 300hz and 68hz and nothing sound strange (no noise or distortion). There's a db drop but room related, moving in the room change the db level.

Re: Active setup help and recommendations

Reply #64 –
Quote from: patate91 on
Quote from: silverprout on
Your SPL measurement will be wrong with an uncalibrated microphone.
MiniDSP umik-1 only has a calibration file. Since it's usb there's not a lot things I can do to calibrate it.

IMHO Rew need to be exteraly calibrated with a mic calibrator in order to have an accurate SPL measurement.

Re: Active setup help and recommendations

Reply #65 –
... the whole point of getting a UMIK-1 (or similar) is that it's already calibrated at the factory and applying the calibration file will produce accurate SPL values in the application program.  Unless you feel you need to re-calibrate the mic because you don't trust their lab, in which case you're going to need ANOTHER calibrated mic, which if you don't trust...

Re: Active setup help and recommendations

Reply #66 –
Quote from: Nichttaub on
... the whole point of getting a UMIK-1 (or similar) is that it's already calibrated at the factory and applying the calibration file will produce accurate SPL values in the application program.  Unless you feel you need to re-calibrate the mic because you don't trust their lab, in which case you're going to need ANOTHER calibrated mic, which if you don't trust...

You are confusing two different types of calibrations... it is perhaps time for a good reading :
https://www.amazon.fr/gp/search/ref=a9_asi_1?rh=i%3Aaps%2Ck%3Asound+engineer+handbook&keywords=sound+engineer+handbook&ie=UTF8&qid=1532967654

Re: Active setup help and recommendations

Reply #67 –
Since you're not hearing noise it's a non-issue.   

And, you're not driving your amps into clipping (at least not under normal listening conditions) so amplifier-distortion is not an issue either.   

It's also highly-unlikely that you are driving your speakers in to "breakup".   There is always some speaker-distortion but it's generally unnoticeable (or at least tolerable) as long as the speakers are not over-driven, and there's not much you can do about it anyway without completely re-designing the speaker.

Re: Active setup help and recommendations

Reply #68 –
Quote
Amp : A-100 input 600mV ?ohm with 8 ohm load
                      50 w - 8 ohm
Amp - A-300 input 1.2 v 27k ohm with 8 ohm load
                      Gain 29 db
                     150w 8 ohm
Now that I've had a chance to get back to the spreadsheet...

Those two amplifiers are closely matched in gain.    (Possibly exactly-matched with some rounding in the published specs so they can publish "even numbers".)

50W @ 8 Ohms = 20V RMS
150W@ @ 8 Ohms = 34.64V RMS

Voltage gain = 20/0.6 = 33.3 = 30.5dB
Voltage gain = 1.2/34.64 =  28.9 = 29.2dB

...Feel free to double-check my numbers because I'm violating the rule, "Never do math in public."  ;)

Re: Active setup help and recommendations

Reply #69 –
Quote from: DVDdoug on
Since you're not hearing noise it's a non-issue.   

IMHO you should be more careful with this argument the noise get is sometimes higher with large amplitude modulations. 

Re: Active setup help and recommendations

Reply #70 –
Quote from: DVDdoug on
Now that I've had a chance to get back to the spreadsheet...

Those two amplifiers are closely matched in gain.    (Possibly exactly-matched with some rounding in the published specs so they can publish "even numbers".)

50W @ 8 Ohms = 20V RMS
150W@ @ 8 Ohms = 34.64V RMS

Voltage gain = 20/0.6 = 33.3 = 30.5dB
Voltage gain = 1.2/34.64 =  28.9 = 29.2dB

...Feel free to double-check my numbers because I'm violating the rule, "Never do math in public."  ;)

 :))  :))  Thanks for your help, except the typo for second amplifier's voltage gain it looks good.


For mic calibration I won't invest money to calibrate it. There's no audible noise or distortion so I'm not worry about that.

Re: Active setup help and recommendations

Reply #71 –
Quote from: DVDdoug on

I was doing the math for my current amplifiers and the Pioneer has 29,44 db of gain.

Now looking at the luxman R114 spec I found

50w @ 8ohm = 20Vrms
Main : 150mV @ 43khom (looks like the same thing as a line in).

20/0.15 = 133.33 db

That's huge, is it something possible? Do you think there's an error in the service manual? I understand that my amplifiers are not matching and that it'll cause issues.

Re: Active setup help and recommendations

Reply #72 –
Quote from: patate91 on
Quote from: DVDdoug on

I was doing the math for my current amplifiers and the Pioneer has 29,44 db of gain.

Now looking at the luxman R114 spec I found

50w @ 8ohm = 20Vrms
Main : 150mV @ 43khom (looks like the same thing as a line in).

20/0.15 = 133.33 db

That's huge, is it something possible? Do you think there's an error in the service manual? I understand that my amplifiers are not matching and that it'll cause issues.
You forgot something: 20*log(20/0.15)=42.5dB, not 133dB

Re: Active setup help and recommendations

Reply #73 –
Quote from: antz on
You forgot something: 20*log(20/0.15)=42.5dB, not 133dB

Yep thanks, it makes more sense.

There's still a big difference though.

Re: Active setup help and recommendations

Reply #74 –
At this point since de luxman main in, is just a line in, I should use my integrated amplifer, wich is 35w @ 8ohm. Input 150mV which gives me 40.95 db if gain, which is more closed. I'll gain a volume pot to match drivers sensitivity.