Film-Tech Forum ARCHIVE: Checking DTS freq. responce

This is topic Checking DTS freq. responce in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Antonio Marcheselli (Member # 373) on 08-25-2004, 08:14 AM:

Hi everyone

I feel that our DTS unit (6D) has something wrong on the outputs. Seems that the SRD output is brighter than the DTS one.
Perhaps is the particular record, perhaps my ears.

How can I check? Can I use the pink noise used for level alignment and connect my RTA direclty to the DTS' outputs? Should the outputs be FLAT in this case?

Thanks for the replies

Bye
Tony bandito

Posted by Mike Olpin (Member # 1115) on 08-25-2004, 11:57 AM:

AFAIK, the 6D doesnt have any built in EQ, and should be outputing a flat response. Is the Dolby in the same house? Could it be a problem with the EQ in your analog procesor or perhaps an incorect setting on the crossovers?

Posted by Michael Schaffer (Member # 1204) on 08-25-2004, 01:13 PM:

quote: Antonio Marcheselli
Can I use the pink noise used for level alignment and connect my RTA direclty to the DTS' outputs?

Yes, you can!

Posted by Antonio Marcheselli (Member # 373) on 08-25-2004, 05:26 PM:

Mike

Since the DTS outputs pass through the same EQ and levels of SRD (CP650EX) I should notice no difference in sound tone on the booth monitor (DCM). I hear a big difference instead.

Perhaps someone made a mistake in the record (Street Dance Fighter had a completely different sub recorded in the two soundtrack) but I would like to check my equipment before!

Michael,

Thanks. Tomorrow I'll check all channels.

bye
A

Posted by Michael Schaffer (Member # 1204) on 08-26-2004, 03:39 AM:

Since the setup of the CP650 is software based, you can also flatten the eq, connect your RTA to the outputs of the DTS, then reconnect it to the CP650, check the output there, play pink noise from the unit, compare the frequency response at every step, then reload the original eq settings - if you saved them before!

Posted by Antonio Marcheselli (Member # 373) on 08-26-2004, 06:28 AM:

Thank you Michael.

But I feel that difference with two differents CP650. I have two possibilities:

1. My DTS is failing
2. Someone at the lab is messing with something!

I said that Street dance fighter had the same difference. I was not able to hear differences in HF in the auditorium (but I didn't had time to make accurate tests) but the SW channel was VEEERY different. Punch, loud and harsh in SRD (as should be for Hip-Hop music, IMHO) and lower in level and not definied with DTS. Very different, not just a detail.
But I had chance to hear LOTR 3 and Riddick, the SW channel was definively there, so I thought at a soundtrack problem for SDF. Perhaps this time is the same, but I cannot say until I've check the unit!

But should the DTS' PN be flat on an RTA? It sounds so different than dolby's one by ear!

Bye
A

Posted by Brad Miller (Member # 2) on 08-26-2004, 01:39 PM:

You are wasting your time on the subwoofer comparison. SRD and DTS will never behave the same way in regards to the subwoofer channel because of the way each system handles it. (I have heard comments from sound mixers that SRD is preferred to DTS because of the subwoofer issue.)

Posted by Antonio Marcheselli (Member # 373) on 08-26-2004, 02:40 PM:

Brad

I agree that SRD and DTS cannot play the SW track the same. But the difference was HUGE, there was a mistake in the record for sure. However the difference I hear is in the stage channels and not in the SW.

I checked the responce of my player and it is perfect, +/- 0.5dB.

Thanks to all for the help

Bye
A

Posted by Jack Ondracek (Member # 1466) on 08-26-2004, 02:58 PM:

In cases where we've moved prints from a DTS house to an SRD one, I find the SRD makes much less use of the SW channel. Sometimes, I wonder if it's even working... until it kicks in. It just seems the SRD "mix" has a higher threshold than DTS. Whether that's wrong or not, I don't know. They both seem to work when they should. If you weren't able to compare them, you probably wouldn't notice.

Posted by Ferdinando Innocenti (Member # 2477) on 08-26-2004, 04:58 PM:

Yes, Antonio,
the pink noise output must be flat.
If your RTA has a flat response...

Ciao
Nando

Posted by Michael Schaffer (Member # 1204) on 08-27-2004, 03:38 AM:

quote: Antonio Marcheselli
I checked the responce of my player and it is perfect, +/- 0.5dB.

We are all very happy for you, Antonio!

Posted by Brad Miller (Member # 2) on 08-27-2004, 04:31 AM:

quote: Antonio Marcheselli
However the difference I hear is in the stage channels and not in the SW.

That's interesting. So if you shut off all channels except for L, C, R and toggle between SRD and DTS you hear a drastic difference? You shouldn't. Sounds like dts goofed up again. Anyone remember the Dragonfly incident that I had to point out because it passed all of the QC check points and noone at dts noticed?

What movie(s) have you heard this on, Antonio?

Posted by Antonio Marcheselli (Member # 373) on 08-27-2004, 08:21 AM:

Brad,

No, sorry, I was not too clear. They're two different situation.

On "Street Dance Fighters" there was a HUGE difference in SW channel. Then, on the same movie, I noted just a little difference in stage channels. But I really didn't had time to made accurate tests in the auditorium, I heard the difference through the DCM.

I noted the same HF differences on Riddick and Starsky & Hutch. BUT, I was unable to hear the same differences with an old movie that we showed few days ago, LOTR 3. So I'm thinking that someone is making something wrong at labs!

But, I realize that I didn't had chance to made complete tests, hearing the sound coming out from a booth monitor cannot be the ultimate test.

I'll let you know if I'll discover something.