TOPIC:

Hello,
I would like to know if I must to worry about the following differences between Dirac curves and Rew curves of my right front channel response.
For my untrained eye, the right speaker response in the lower frequencies around the roll-off (45hz) with Dirac



is very different than with Rew. (all variables other than software remain constant: mic position, speaker set-up etc)



For my untrained eye there is no such a difference with the left speaker






I might add that only the path between Rew and Dirac is different. I use NanoAvr-DL. With Rew, the signal goes from laptop to hdmi to video3 input in the receiver. Dirac signal goes from the sofware or the nano I do not know via hdmi and continue into the receiver via video1 input.
But the left signal is correct in those 2 cases. Not the right. The sub signal goes out the receiver via rca preout sub to left rca "LFE" in (SVS PC-2000). Again, I don't think that it is the problem : left is similar, not right.
I can add also that the center and the surronds are similar between Rew and Dirac.

Also I tried with only one round of sweep with Dirac as Rew does, and the curves were the same as those I downloaded here.

Also in all the cases, receiver was set to "no eq" speakers set to large, no sub or sub off (so no xover) because I wanted to get a set of filters for music only.
When I did Dirac measurements for my 5.1 set-up, left and right curves was similar to Rew with bass management active. It is logial because NanoAVR-DL asked for bass managed into the receiver.

So my difficulty is for stereo calibration.

I am afraid that the calibration of the right channel by Dirac will not be good because of this difference. Also, I ask to myself if I have a software problem and should uninstall and reinstal dirac ?

I should have added that I switched speakers (right to left position and vis-versa) to see if it was a speaker problem and I got the same readings.

Is it the signal into the right channel path that is different? Do I have a problem?

Is the subwoofer actually turned off when you are doing the measurements? What low frequency response would you expect from the speakers alone?

john.reekie wrote:

Is the subwoofer actually turned off when you are doing the measurements? What low frequency response would you expect from the speakers alone?

I setted (for Dirac) in the receiver (Rotel RSX1562) the speaker pattern like this: front right and left to large , center to NONE, surround left and surrond right to NONE subwoofer to NONE (I did not put the sub main switch to off). Doing that, I thought that I was sure that no xover can possibly be applied by the receiver which seems to be the case with the left channel.

I expect the low fr response for the speakers beeing approximatly what their spec are. Bower & Wilkins 705 are 45hz to 20k hz. It is what REW seems (to my untrained eye) to show correctly for left and right but not Dirac for the right.

Hi again, I'm not entirely following your testing method, but I would suggest:

1. Turn the subwoofer OFF to make sure that it's not somehow being used.
2. Connect your laptop for REEW measurement to the second input of the nanoAVR (not to a separate input of the receiver).
3. Check your signal-to-noise - on the Output and Levels screen, where is the meter sitting if you turn the output level all the way down?
4. If it's still doing the weird thing, swap the left and right channels at the speaker leads. Is the strange reading still on the right channel in DLCT, or did it follow the speaker?

john.reekie wrote:

Hi again, I'(...)
2. Connect your laptop for REEW measurement to the second input of the nanoAVR (not to a separate input of the receiver).
(...)
4. If it's still doing the weird thing, swap the left and right channels at the speaker leads. Is the strange reading still on the right channel in DLHi CT, or did it follow the speaker?

John,
great idea. My only concern is that the nano owner manual asks to have an active video signal to put the filters avtive.

If I connect rew laptop to nano I do not think that I will send an active video signal to nano ?

Anyway, I will try it asap.

Hi, the laptop will produce an active video signal (HDMI carries audio embedded in the video stream).

john.reekie wrote:

Hi, the laptop will produce an active video signal (HDMI carries audio embedded in the video stream).

Dear sir,
you had a great idea. Here are my results.
For all measurements the following are the same:
mic position
one sweep with Dirac
one sweep with REW
Receiver settings: front speakers to LARGE-Center to none-Surrounds to none- Subwoofer to NONE and just in case XOVER to OFF
levels left and right to 0db
Laptop to NanoAVR-DL via hdmi 2 input and from nano to receiver connected to Video 1 in the receiver (Rotel RSX-1562)

Now the procedure: One round with standard connections and one round with the front left output cables connected to the RIGHT speaker and the front right output cables to the LEFT speaker.

Now the results.
1- Standard connection
Left speaker Dirac


Right speaker Dirac



The same problem occured.

2- Reversed connection (left channel speaker to right speaker and vis-versa
LEFT speaker connected to the right outputs of the receiver


here is the fault

RIGHT speaker connected to the left outputs of the receiver


No fault.

Now REW via Nano
1- LEFT speaker standard connection and REVERSED


No fault

2- RIGHT speaker standard connection and REVERSED



Again NO FAULT

What is your conclusion ?

left Dirac

Hi again, there is a lot of low frequency noise esp in the second plot. Did you check this? How are you setting the input gain and output level?

"3. Check your signal-to-noise - on the Output and Levels screen, where is the meter sitting if you turn the output level all the way down?"

john.reekie wrote:

Hi again, there is a lot of low frequency noise esp in the second plot. Did you check this? How are you setting the input gain and output level?

"3. Check your signal-to-noise - on the Output and Levels screen, where is the meter sitting if you turn the output level all the way down?"

Sorry I did not notice. But you can be sure that the house was quiet, no children, not heat power, no vent no fridge etc. . Anyway, it is the same for Rew measuresthat are taken only minutes after Dirac and the roll-off of the right speaker at 45-50 db is there.

Still waiting for tech support.

Could you please answer the questions?

where is the meter sitting if you turn the output level all the way down?

How are you setting the input gain and output level?

john.reekie wrote:

Could you please answer the questions?

where is the meter sitting if you turn the output level all the way down?

How are you setting the input gain and output level?

Sorry I am not sure that I translate correctly your questions.
The "meter" is the little scale where the blue line must go in the green zone to -12db before to start the measure., isn't it? If I understand correctly, the blue line is not there (far from the left side of the bar) when I put the output way down. If I understand what you need to know, I raise firdt the output level of the left channel to around -40db to begin to see at the left side of the meter the blue line to begin to approche the green zone.
Is it what you ask for?

About the second question, I followed the user manual of Minidsp. First I raise the output level so the pink noise is loud enough to raise the voice to be understood by somebody near by me : -20 to -15 db it depends. After that I raise a little bit the input gain above 0 db till the blue line in the meter level cross the -12 db target. After that I check the next channel and it is always at the sme -12db target.
Is it what you needed to know?

Hi RenPa, thank you. The reason I asked is that your Dirac plots show an unusual level of signal at very low frequencies, but your gain setting procedure is correct so this is still a mystery....! I will try and run a two-channel measurement with my nanoAVR DL this weekend, I m not sure I have done that so far but perhaps it will help to compare...

john.reekie wrote:

Hi RenPa, thank you. The reason I asked is that your Dirac plots show an unusual level of signal at very low frequencies, but your gain setting procedure is correct so this is still a mystery....! I will try and run a two-channel measurement with my nanoAVR DL this weekend, I m not sure I have done that so far but perhaps it will help to compare...

Thank you very much John. Now I understand why you asked and it makes perfect sens. I only am an amateur-dinosaure-with-computer-guy-who-would-have-like-to-listen-the-best-of-his-system but even to me it was troubling: By what trickery a speaker with 45hz low end response can give sound from 0 or 5 hz...even my sub who has a 17hz lowendresponse can not do that.

You have to understand that I have NanoAvr-DL since more than 3 weeks and going from a problem to an other without having any result to hear and, worst, beeing scared that I might have broken a speaker (see my level too low problem now solved).

At least your help releaves my pain ! (all things beeing relative. It is not like having to fight a terminal cancer !!) Espacially taking into count the silence of tech support about this very problem until now; they are probably very busy.

Thanks again.

BTW you are the second one to tell that it seems a mystery...that console me a little...

@ Renpa,

Indeed a very odd one (compared to all units we have worldwide, a first.. ??)Based on your user account, you already opened a tech support ticket. Correct? If so let's just keep to the tech support ticket.

We're sorry to hear that you had some issues for the past 3 weeks but no such thing as "silence from us". Simply lots of people asking question, we're just trying to help everybody.. We can see that some were computer setup related but all solved at this point through many communications via your tech support ticket. Is that correct? The issue now is more to understand what's going on here for the stereo setup.. Something doesn't add up somehow in the configuration. We're wondering if it's a simple Bass management issue in the rotel . That's the most likely cause here I'd say but then again, just a wild guess.

Please use the tech support ticket as we can share file/dirac projects and screenshots. It's easier to track for our team. This forum is only for community and not a way to track easily tech support issue. Thanks for your patience!

DevTeam.

MiniDsp tech support is examplary, don't worry. I can understand that they are busy.