Gain Structure for Home Theater Discussion Thread - Page 3 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #21 of 85 Old 11-09-11, 12:38 PM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Quote:
Wayne A. Pflughaupt wrote: View Post

That would be contrary to standard gain structure protocol. According to most professional references, post-pre amp signal boosting is not recommended because it will increase the noise floor from the source component and pre amp. This is supported by the Rane article referred to in Part 2 (among other sources), which notes that the only gain changes that should be effected in downstream processors is to counter what might come from the processor itself – like an overall change in signal strength from an equalizer, for instance. The signal is not – and indeed should not – be “amplified” from one component to the next. I think you’d be hard pressed to come up with any professional references that say otherwise.

...

Quiet (read quality) equipment is what determines system noise, not signal levels. Every gain structure-related thread I’ve ever seen that dealt with a noise issue, the problem was ultimately isolated to a certain piece of equipment (a classic example can be seen in the link to an AVS thread found in Part 4). I’ve yet to see a thread where a noise issue was determined to be caused by inappropriate signal levels.

Hi
I'm just a little confused here.
The "post-pre amp signal boosting is not recommended" statement seems diametrically opposed to your Figure 2 where 3dB is added between the Notch Filter and again before the Limiter, but I don't see anything on that graphic labeled "preamp" hence my confusion.

Also
When I look at Figure 1 I see a System Dynamic Range (SDR) of 72dB and the Figure 2, after alignment, shows an SDR of 90 dB. Then in the rest of the article you make the case that the original 72dB was enough and in fact loss of an additional 6 or 12 dB would not be an issue. Sorry I think I missed something.
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post #22 of 85 Old 11-09-11, 06:29 PM Thread Starter
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System


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soho54 wrote: View Post
What I posted is fact, and can be easily demonstrated. The input and output levels at every stop along the chain will effect the total/final/in room system noise floor.
This problem could easily be avoided by making sure the input and output levels are the same for each processor in the signal chain – as they should be. Standard pro-audio gain structure protocol, that in this case works for home theater too.


Quote:
soho54 wrote: View Post
I have a mixed pro/home setup that is dead silent with my main set of speakers, but I demo a lot of gear, and know that it is not dead silent with other speakers hooked up. It takes different amps, processors, and a completely different gain setup to get close to dead silent with say the DSL SH60s in my room.
If your system is dead silent and you get noise after changing out a piece of equipment, it should be obvious that it is an inferior piece of gear.


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soho54 wrote: View Post
I going to give up now.
We are still waiting for your recommendation for a better method for “regular Joes” who don't have any professional calibration equipment.


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dsime42 wrote: View Post
I'm just a little confused here.
The "post-pre amp signal boosting is not recommended" statement seems diametrically opposed to your Figure 2 where 3dB is added between the Notch Filter and again before the Limiter...
Yes, they do seem contradictory. The graph came from a different reference source than the Rane article. As I noted in Part 1 a few paragraphs above the graphs, it’s not uncommon for different gain structure references to have a certain amount of inconsistencies from one to the next. For a mixed home/pro system, the Rane information is what's relevant, because we don’t use outboard components like notch filters and limiters that have their own gain-boosting capabilities (the exception being sophisticated systems that use electronic crossovers or digital speaker processors).


Quote:
...but I don't see anything on that graphic labeled "preamp" hence my confusion.
Keep in mind that the graphs depict a professional PA system. In a PA system, the mixing console has essentially the same function as a home audio pre amp – i.e. it’s the piece that all the input sources plug into.


Quote:
When I look at Figure 1 I see a System Dynamic Range (SDR) of 72dB and the Figure 2, after alignment, shows an SDR of 90 dB. Then in the rest of the article you make the case that the original 72dB was enough and in fact loss of an additional 6 or 12 dB would not be an issue. Sorry I think I missed something.
Sorry but I have no idea how you arrived at the conclusion that I said the original 72 dB SDR was adequate. The primary purpose for those two graphs was to show that a proper gain structure would improve system dynamic range. The equipment depicted in the graphs is pro gear from top to bottom, and as such isn’t specifically relevant to a mixed home/pro system. The only reference I made to a “loss” of signal not mattering was specifically referring to any 24-bit digital processors used in a home system downstream from the pre amp.

Regards,
Wayne



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post #23 of 85 Old 11-10-11, 03:03 AM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Hi, Wayne:
just some junior questions:
i am using pure Pre amp(7.1) + poweramp(5 channel) + powered Sub.
and i'd like to know what you are refering to for "Gain control", " volume control" and "speaker level setting" in pure preamp? i only know that Volume control shall be the volume Knob in Preamp's front panel.
what about other two, shall be in the menu right??

and for Preamp setting as analog input with Bypass(is that what you mentioned as setting to "bypass" , "Stereo","direct"? ), which means there is no Dsp working for bass management at all. so Subout will be no signal, and Xover point setting will be bypassed also, in this case how to measure sub?
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post #24 of 85 Old 11-10-11, 02:40 PM Thread Starter
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System


Quote:
i am using pure Pre amp(7.1) + poweramp(5 channel) + powered Sub.
and i'd like to know what you are refering to for "Gain control", " volume control" and "speaker level setting" in pure preamp? i only know that Volume control shall be the volume Knob in Preamp's front panel.

what about other two, shall be in the menu right??
Yes, with an AV pre-amp, speaker-level settings are typically in the menu. Gain controls for the various input sources are kind of rare, but they would be in the menu, too.

Quote:
and for Preamp setting as analog input with Bypass(is that what you mentioned as setting to "bypass" , "Stereo","direct"? ), which means there is no Dsp working for bass management at all. so Subout will be no signal, and Xover point setting will be bypassed also, in this case how to measure sub?
Many AV receivers (or pre amps) keep the subwoofer output active when you set it for “Bypass” or “Stereo Direct.” If yours isn’t like that, just go ahead and use whatever setting is needed to activate the subwoofer output, so you can take your voltage measurements.

Regards,
Wayne



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post #25 of 85 Old 03-30-12, 10:32 PM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

i just cant figure it out, so this is what i am running for gear first of all:

marantz sr7000 avr
2 - dual 15" jbl bins with jbl horns for the fronts
1 - center channel speaker
1 - 15" peavy sub
2 - b & w speakers for the surrounds
1 - behringer mx882 line level matching/splitter/mixer
1 - behringer epq1200 for the surrounds
1 - behringer epq1200 for the center and for the sub
1 - behringer epq2000 for the fronts

total power is 4400 watt

this is how i have it hooked up, i hope this is right.

from the avr preouts, fronts, center, sub and surrounds connect to the inputs on individual channels ( 1 through 6 )on the mx882 with rca to xlr, then from the mx882 outputs for each channel (using xlr cables )go to the dedicated amps, and the speakers are connected from the amps, it just seems to me that since i am running 4400 watts that it should be much louder, the amps are maxed out and the volume control on the avr has a range from -60 to +15, so when i am watching tv the volume is set at around -24, so i dont know if this is correct or someone can help me out here, and help would be appreciated

Last edited by rob92266; 03-30-12 at 10:41 PM.
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post #26 of 85 Old 03-31-12, 10:23 AM Thread Starter
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System


See this cross-posted thread.

Regards,
Wayne



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post #27 of 85 Old 05-11-12, 03:37 PM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Wayne,

I am thinking of using a Pro Crossover for example a DBX 223( or similar unit from Behringer, ART etc) as a crossover for bass management between a tube preamp and SS power amp. to integrate a SVS subwoofer Now that I read your articles above I am wondering whether this is a suitable application of the DBX 223 as a bass management unit in a home Stereo environment. BTW I am already using a BFD for Sub EQ

I have questions re the gain settings of this unit. Does 0db in the gain dials mean unity gain ?

Maybe its better to find a used XO unit designed specifically for home audio like the Paradigm X-30 , Energy EAC etc. ? Bryston XO unit is too costly for me.

Advice?

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Speakers: Salk Song Towers , Surrounds Polk Ceiling Spkrs, Subwoofer SVS PC12-NSD
Receiver: Onkyo NR3007 ; PreAmp: Jolida Fusion ;Amp : Odyssey Khartago SE+++
Sources: DirecTV HR24 and H25 ; Oppo 980H ; Toshiba HD -A2 ; WDTV Live; Panasonic BDT110; SB Touch
Display : Panasonic 58PH10UKA, Panasonic 50ST30
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post #28 of 85 Old 05-12-12, 09:22 AM Thread Starter
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System


Yes, a 0 dB setting on the input and output knobs is unity gain.

There’s no reason a pro crossover won’t work, from a functional standpoint. However, with any budget pro audio gear there is a concern that it might not be as quiet or as clean as good home equipment. I’d suggest subjecting it to the battery of tests I outlined in Part 8 to make that determination.

Naturally, this is only a concern if you intend to use both the high and low pass outputs from the crossover. If you’re only using the low pass (for the subs), then noise is not an issue.

Regards,
Wayne



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post #29 of 85 Old 05-12-12, 10:16 AM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

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Wayne A. Pflughaupt wrote: View Post

Yes, a 0 dB setting on the input and output knobs is unity gain.

There’s no reason a pro crossover won’t work, from a functional standpoint. However, with any budget pro audio gear there is a concern that it might not be as quiet or as clean as good home equipment. I’d suggest subjecting it to the battery of tests I outlined in Part 8 to make that determination.

Naturally, this is only a concern if you intend to use both the high and low pass outputs from the crossover. If you’re only using the low pass (for the subs), then noise is not an issue.

Regards,
Wayne

I was planning to use it for LP and HP. So I think I might be better off buying a used XO specifically designed for home stereo. Used equip from Paradigm, Mirage, Energy and Outlaw are about the same price as new Pro XO from Behringer, DBXpro , Rane etc . This way I dont have to worry about noise floor and dynamic range . Looks like I will be patiently scouring the ads

Tks

HT/2 Ch Audio
Speakers: Salk Song Towers , Surrounds Polk Ceiling Spkrs, Subwoofer SVS PC12-NSD
Receiver: Onkyo NR3007 ; PreAmp: Jolida Fusion ;Amp : Odyssey Khartago SE+++
Sources: DirecTV HR24 and H25 ; Oppo 980H ; Toshiba HD -A2 ; WDTV Live; Panasonic BDT110; SB Touch
Display : Panasonic 58PH10UKA, Panasonic 50ST30
Remote: Harmony 720
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post #30 of 85 Old 03-10-13, 04:10 PM
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Re: Gain Structure for Home Theater: Getting the Most from Pro Audio Equipment in Your System

Wayne

very informative articles. My question is i drive a DIY sub with a Behringer EP-4000 which is connected to an Onkyo TX-NR818

Everyone is telling me to set the ep4000 gain to max and use the sub trim to bring it down to 75 DB but even with the trim max out at -15 db the spl is registering over 80 db

How can i use your article to properly do a gain structure on my sub??

Alain
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