Gain Structure for Home Theater Discussion Thread - Page 7 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #61 of 85 Old 07-17-15, 02:36 AM
Shackster
 
Join Date: Feb 2015
Location: Taipei
Posts: 10
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Thanks for the reply.

When I measure my AVP subwoofer channel maximum output voltage:

set Left and Right channel to small, set crossover at the highest possible frequency
set the AVP to Stereo mode
adjust the master level of AVP and the level for sub channel to max setting
Play 60 Hz Sine Wave 0 dBFS by Blu-Ray player(oppo 103d)->
send PCM to AVP(EMOTIVA UMC-200)->
measure the sub output voltage

But when I play a blu-ray movie with DTS-HD/Dolby TrueHD, the LFE channel is pre-set to play LFE data 10 dB higher than a main channel (or 10dB higher than the bass from a main channel). I believe this is the reason that channel 4 output of REW is 10dB higher than other channels.

So my question is that, for the maximum subwoofer output voltage when watching movie with DTS-HD/Dolby TrueHD encoded, do we need to add 10db with the subwoofer output measurement?If we need to do this, how to do it? The file is already 0 dBFS.

Last edited by guofong; 07-17-15 at 03:27 AM.
guofong is offline  
Sponsored Links
Advertisement
 
post #62 of 85 Old 07-17-15, 08:12 AM Thread Starter
HTS Senior Moderator
 
Wayne A. Pflughaupt's Avatar
 
Join Date: Apr 2006
Location: Corpus Christi, Texas
Posts: 9,166
Send a message via Yahoo to Wayne A. Pflughaupt
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Okay I get it now, sorry for being so dense.

You went through the process to measure the A/V processor’s subwoofer output, using a 0dBFS signal to get a voltage figure, right? So no, there is no need to add 10 dB to the subwoofer measurement. How do you add dB to a voltage figure anyway?

Here’s the deal: 0 dBFS is the maximum signal the AVP is going to output anyway, right? It can’t generate +10 dBFS - there is no such thing (as far as I know anyway). So, the only way the +10 dB LFE sub output can be achieved is to dial back the main channels by that much. Make sense?

Regards,
Wayne



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.
|
To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

Wayne A. Pflughaupt is offline  
post #63 of 85 Old 07-19-15, 09:34 PM
Shackster
 
Join Date: Feb 2015
Location: Taipei
Posts: 10
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Many thanks for the reply. This totally makes sense to me.

One more question regrading to the center output measurement:

https://drive.google.com/file/d/0B7-...EycDVtTnc/view
FL 3.45v
C/Pro Logic II music 3.3v
C/Pro Logic II cinema 5V
C/DTS Neo music 4v
C/DTS Neo cinema 5V

As my test results above, the max center output voltage is different when setting different playback mode. Using Pro Logic II music(3.3v) appears to be closed to FL channel output, but which test results is correct?
guofong is offline  
 
post #64 of 85 Old 07-20-15, 04:50 PM Thread Starter
HTS Senior Moderator
 
Wayne A. Pflughaupt's Avatar
 
Join Date: Apr 2006
Location: Corpus Christi, Texas
Posts: 9,166
Send a message via Yahoo to Wayne A. Pflughaupt
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Wow, that’s pretty peculiar. As to which figures are correct, if that’s what you measured with each mode (it never occurred to me to measure any way but with a total bypass!), then they both are correct, funny as that might sound.

The question is though, which figure would you use for gain structuring your system? Obviously, the lower figure. If you gain structure with the Cinema figure, practically-speaking you could end up clipping things when you switch to the Music modes. Assuming you play music as loud as you do movies, that is (I don’t think most people do).

Regards,
Wayne



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.
|
To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

Wayne A. Pflughaupt is offline  
post #65 of 85 Old 07-20-15, 08:09 PM
Shackster
 
Join Date: Feb 2015
Location: Taipei
Posts: 10
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

I totally forget to measure stereo(bypass) mode. Thank you!
guofong is offline  
post #66 of 85 Old 07-31-15, 01:55 AM
Shackster
 
Join Date: Feb 2015
Location: Taipei
Posts: 10
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Hi, Wayne:

I went through the process for Gain Structure.

The clipping indicator of my amplifier begins to blink when I increased the amplifier’s gain control to max. All the channel is the same situation, including my sub amp. Should I set my amplifier’s gain control to max? Is it a good idea to set gain to max? Could it be any danger? I usually set the gain control at around two-thirds of the maximum.

pre amp:EMOTIVA UMC-200
(L/C/R/LS/RS output maximum usable output:1.3v / sub maximum usable output:3.45V)
power amp for L/C/R/LS/RS:QSC DCA 1644/1222
power amp for sub QSC DCA 3022
guofong is offline  
post #67 of 85 Old 07-31-15, 09:52 AM Thread Starter
HTS Senior Moderator
 
Wayne A. Pflughaupt's Avatar
 
Join Date: Apr 2006
Location: Corpus Christi, Texas
Posts: 9,166
Send a message via Yahoo to Wayne A. Pflughaupt
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Certainly, the amplifier is going to clip if you turn up the gain controls. It’s perfectly normal. The volume got louder too, didn’t it? That means you’re pushing the amp harder. When amps are pushed too hard, they clip. Clipping shouldn’t be a danger – to the amp anyway (speakers, that’s another issue) – as most professional amps these days have detection systems to shut down if overstressed. However if you followed the gain structure process correctly, then the amplifier gain settings you ended up with are the ones you should use.

Regards,
Wayne



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.
|
To view links or images in signatures your post count must be 10 or greater. You currently have 0 signatures.

Wayne A. Pflughaupt is offline  
post #68 of 85 Old 12-26-15, 08:00 AM
Senior Shackster
 
Join Date: Jan 2014
Posts: 164
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Hi Wayne,

Great guide!!

If one has an AVR with its built in amp(s) driving their speakers and uses a pro-amp to drive their subs. Would this be the right procedure?

Assumptions:
1. Clean output to reference.
2. You have previously eq'ed your sub to where you like it .ie flat or with house curve etc.


1. Disconnect all speakers
2. Turn avr trim up on all speakers in avr
3. Play 0dbfs tone through all speakers, use "All Channel mode"
4. Crank avr to 0db (or cleanest level before distortion)
..now you have max voltage coming out of the avr's sub pre-out....
5. Turn your subs pro-amp input gain up until the indicator flickers red then goes solid red. (Note this setting, don't ever change it)
6. Rerun your room correction in the avr to set your speaker/sub trims in the avr OR use a spl meter to set your speakers and sub trims in your AVR, using your avr's built in tones so that each speaker and your sub are playing 75db at your listening position.
7.Enjoy

Last edited by corradizo; 01-03-16 at 06:53 PM. Reason: Need to play through all speakers not just L and R.
corradizo is online now  
post #69 of 85 Old 04-23-16, 05:28 PM
Pending
 
Join Date: Apr 2016
Posts: 1
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

That was awesone
epk10 is offline  
post #70 of 85 Old 03-16-19, 02:55 PM
Shackster
 
Join Date: Mar 2019
Posts: 9
I read your thread on gain structure. Thank you for the information. I have two questions. In both finding out your avr's clean output and setting your amps gains you say to turn your subwoofers trim up all the way. However, you say "Adjust the AVR’s subwoofer trim level to the maximum setting" in one paragraph and "There’s no need to adjust the AVR’s subwoofer trim, as it will be automatically reduced to “clean voltage” when the AVR’s master volume is turned down to the “clean voltage” setting" in the next. This confuses me. Also, after your done setting your gain you say "All that’s left to do at this point is adjust all the AVR's speaker and subwoofer levels using your usual method". I dont have a usual method. I dont have audicy or any room correcting software nor do i want it. I want to set my sub trim to 0. That brings me to my first question. Can i do everything you said exept keep my subwoofer trim at zero? Im not opposed to turning it up to +15 i just have to know what to set it on after i set my gains. 0? Leave it at +15? My second question is similar to my first. When determining your clean ouput voltage you say to turn your xover to its highest setting. Can i do it with it on 80? Again, im not opposed to setting it to its highest setting, however, i would like to at least put that back to 80 when the test is done to protect my speakers. Thanks wayne!!!
djcreative1 is offline  
Reply

Bookmarks

Tags
discussion , gain , home , structure , theater , thread

Quick Reply
Message:
Options

Register Now




PLEASE COMPLETE ALL REQUIRED FIELDS BELOW... THANKS!

REQUIRED FIELDS ON THIS PAGE
YOU MUST COMPLETE ALL OF THESE

Username
Password
Confirm Password
Email Address
Confirm Email Address
Random Question
Random Question #2




User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
PLEASE READ BELOW PRIOR TO ENTERING AN EMAIL ADDRESS!

ATTENTION!

YOU MUST ACTIVATE YOUR ACCOUNT!

Activation requires you reply to an email we will send you after you register... if you do not reply to this email, you will not be able to view certain areas of the forum or certain images... nor will you be able download software.

AN INVALID EMAIL ADDRESS WILL CAUSE YOUR ACCOUNT TO BE DELETED!

See our banned email list here: Banned Email List

We DO NOT respond to spamcop, boxtrapper and spamblocker emails... please add @hometheatershack DOT com to your whitelist prior to registering or you will get nowhere on your registration.


Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML is not allowed!
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


For the best viewing experience please update your browser to Google Chrome