Gain Structure for Home Theater Discussion Thread - Page 4 - Home Theater Forum and Systems - HomeTheaterShack.com

Reply
 
Thread Tools
post #31 of 85 Old 03-11-13, 07:36 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


Hey Alain,

Typically the amp would only need to have its gains run wide open if it was getting a weak input signal. However, from what I’ve picked up on various forums, Onkyo receivers have unusually high voltage levels from their RCA outputs. So starting with the amp’s gains maxed out is a bad idea in your case. Your best bet would be to ignore what “everyone” is telling you and follow the simple steps laid out in Part 9 of the article.

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  
Sponsored Links
Advertisement
 
post #32 of 85 Old 03-11-13, 08:03 AM
Senior Shackster
 
apilon's Avatar
Alain Pilon
 
Join Date: May 2006
Location: Montreal, Québec Canad
Posts: 266
My System
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Quote:
Wayne A. Pflughaupt wrote: View Post

Hey Alain,

Typically the amp would only need to have its gains run wide open if it was getting a weak input signal. However, from what I’ve picked up on various forums, Onkyo receivers have unusually high voltage levels from their RCA outputs. So starting with the amp’s gains maxed out is a bad idea in your case. Your best bet would be to ignore what “everyone” is telling you and follow the simple steps laid out in Part 9 of the article.

Regards,
Wayne
Thanks Wayne

I believe i will need to perform step 7 before to get the sub maximum usable clean output ?? If so do i need to measure the mains also as stated or can i just measure the sub output?

Finally just to make sure i understand correctly, step 3 adjust the level of all channels utilizing outboard amplifiers to their max settings . Are you refering to the AVR trim level that i should max out to +15DB ??
apilon is offline  
post #33 of 85 Old 03-11-13, 10:05 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


Part 7 is mainly to help people determine if their receiver generates enough clean voltage to drive a pro amp. We already know that yours can, so you can skip that part. Just set your AVR’s sub output for 0 dB and adjusted the amp’s gains as needed, per Part 9.

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 #34 of 85 Old 03-11-13, 02:20 PM
Shackster
 
Join Date: Mar 2011
Location: California
Posts: 18
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Hi Wayne
I look forward to reading the rest of this article but I started on #5 (Myths) and am having a problem with a couple of your statements.

RE: "A 24-bit system in particular can shed several hundred thousand LSBs from its 16,777,216 quantization steps"
While it may be true that a 24-bit system could "shed several hundred thousand STEPs from its 16,777,216 quantization steps" it cannot shed more BITs than it has. Hence a 24 bit system will have One (1) MSB and 23 bits that are less significant and could possibly be called LSBs though once you get past halfway (12 bits) it starts to become semantics.

Any way you slice it you can not shed more bits than exist. ie 24


RE: The chart you show with the three bit system.
You have a left axis labelled "000 001 010 011 100 101 110 111" and you illustrate the loss of a BIT as being synonymous with the loss of the "000" state. This is incorrect
Loss of a bit isn't "really loss of the bit it is loss of the "usefulness" of the bit and the LSB is also NOT the lowest state representable by the system as you have shown.
A more correct chart would have had its left axis labelled "00x 00x 01x 01x 10x 10x 11x 11x". Note that ALL of the LSBs on the axis have been changed to 'x' representing the fact that while they still exist they cannot be relied on to provide [good] data.

In addition the sharp red line showing the steps should be changed to reflect this "uncertainty" by becoming a pinkish-grey area encompassing that part of the graph where the LSB could be either a '1' or a '0' .

Following the top edge of this grey area would show that now you actually have a TWO (2) bit system with another bit worth of grey area below it. The "uncertain area", where "valid data" does not exist is commonly referred to as noise.


An interesting extension of this chart would be to "lose" two (2) LSBs.
With the chart as you depict it only "two states" would be lost but with the axis label correctly it would depict a one (1) bit system with a considerable pink-grey area.

Of course the logical conclusion to this would be a 3-bit system with the loss of ... ... wait for it ... the three (3) LSBs the label would be an uninteresting list of 'xxx' and the entire chart would be pink-grey and it would be easy to see that the chart is nothing but noise.
dsime42 is offline  
post #35 of 85 Old 03-11-13, 06:21 PM
Senior Shackster
 
apilon's Avatar
Alain Pilon
 
Join Date: May 2006
Location: Montreal, Québec Canad
Posts: 266
My System
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Quote:
Wayne A. Pflughaupt wrote: View Post

Part 7 is mainly to help people determine if their receiver generates enough clean voltage to drive a pro amp. We already know that yours can, so you can skip that part. Just set your AVR’s sub output for 0 dB and adjusted the amp’s gains as needed, per Part 9.

Regards,
Wayne

Got it Thanks

2 more questions and i am on my way......

1. Do i leave the clip limiter on or off for that test on the ep4000?

2. as for the avr volume to i set it to max or 0db reference level?
apilon is offline  
post #36 of 85 Old 03-11-13, 07:37 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


Quote:
dsime42 wrote: View Post
Hi Wayne
I look forward to reading the rest of this article but I started on #5 (Myths) and am having a problem with a couple of your statements.
Thanks for clarifying, desime. The 3-bit graph came from Wikipedia (http://en.wikipedia.org/wiki/A/D_converter). Not being well versed in the finer points of A/D conversion, when they showed a quantization step as a LSB(it) I presumed that “bit” and “step” were the same thing.

The point of the discussion was to show that despite the fables that have circulated the home audio forums for nearly 15 years, 24-bit processors are essentially immune to poor input signal levels – you didn’t shoot that part down, so hopefully I’m okay there!

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 #37 of 85 Old 03-11-13, 07:40 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


Quote:
apilon wrote: View Post
2 more questions and i am on my way......

1. Do i leave the clip limiter on or off for that test on the ep4000?
I’d leave it off for the gain setting process. The whole purpose of the gain structure exercise is to make sure the amp clips at the same time as the pre-amp. So, once that’s done, the limiters merely add an extra layer of protection.

That said, I think most people would agree that 30 Hz is way too high a high pass filter for a home theater subwoofer. That essentially reduces the extension of a beefy DIY sub to par with the typical 10-inch manufactured sub.

Quote:
2. as for the avr volume to i set it to max or 0db reference level?
With your receiver, which has perhaps 2-3 times the output of most others, I don’t think you have to be overly concerned by all this. You can just adjust the amp’s gains for subwoofer level setting the same way that you would for a common powered sub.

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 #38 of 85 Old 03-13-13, 11:38 PM
Senior Shackster
 
apilon's Avatar
Alain Pilon
 
Join Date: May 2006
Location: Montreal, Québec Canad
Posts: 266
My System
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Good evening Wayne

I performed the steps in part 7 sub trim 0db played the sin wave but bottom line i had to max out the Onkyo volume to +18db in order to get the Behringer ep4000 to clip and got a steady clip light at +25db on the ep

Thanks for your help

Alain
apilon is offline  
post #39 of 85 Old 03-20-14, 08:00 AM
New Member
hdtv4me
 
Join Date: Mar 2014
Posts: 2
Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Wayne, thanks for this great thread on gain setting. I guess I'm a little late to the party.

I have a Denon 4520 that I'm trying to match up with a Crown XLS2500. Running through your steps I am a bit stuck determining the 4520 preout harmonic distortion threshold. I downloaded your test tones to a USB stick and are running the tones off the USB stick and 4520's MP3 decoder. Using the 1kHz sine signal I can easily detect harmonic distortion once I hit 78 on the Denon volume control (whereby the range is set for 0-98). The problem I have is that I hear this distortion at 78 no matter how high or low the speaker levels are set for - on the 4520, that would be -12 to +12dB. Is this typical? Wouldn't I expect to at least "move" the harmonic distortion point along the volume continuum as I change the speaker levels? Any reason why I can only hear it at volume level 78?
tomstrade is offline  
post #40 of 85 Old 03-30-14, 04:32 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


Hey Tom,

So you’re saying that you run the Denon’s master volume up to 78, and at that point you can hear the distortion begin. And from there if you adjust the per-channel level from the menu for the speaker you’re hearing, that there is no change? IOW, you can reduce the volume of the speaker that way and still hear distortion?

If that’s the case, yes I would think that’s unusual, but then again there are just too many receivers on the market for me to know if this is typical or not, and digital processing can be tricky.

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  
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