J

jmhc

Audioholic Intern
Hello there:

My receiver (Onkyo TX-SR805) has an option in which you can specify if the subwoofer is THX certified or not.

My question is, besides the certification what are the differences between a high quality THX subwoofer/speakers and a non certified high quality subwoofer/speakers?

Thank you.
 
J

jmhc

Audioholic Intern
and non certified gear doesnt make it inferior. The majority of audio products are not certified.[/QUOTE] That's exactly what I think, but don't know why some receivers has some option to specify if the subwoofer or speakers ar THX or not, does it has something todo with SW crossovers settings or something else?
 
zhimbo

zhimbo

Audioholic General
That's exactly what I think, but don't know why some receivers has some option to specify if the subwoofer or speakers ar THX or not, does it has something todo with SW crossovers settings or something else?
I would guess that it defaults to some default THX bass management settings instead of computing them during auto-calibration...?
 
S

sptrout

Audioholic
Straight from THX (translation to English not provided):

"THX Certified Subwoofer Performance
THX Select2 and Ultra2 Certified subwoofers extend to 20Hz (-6dB), providing a rich bass response for multi-channel soundtracks. And, when combined with a THX Certified receiver or pre-amp using THX Boundary Gain Control technology, bass response is accurate with or without room boundaries - allowing consumers flexibility on subwoofer placement."

Here is a link to a much better discussion about THX subwoofers, and THX in general: http://www.hometheaterhifi.com/technical-articles/165-what-it-means-and-how-to-use-it.html?start=3
 
Last edited:
BoredSysAdmin

BoredSysAdmin

Audioholic Slumlord
From 805 Manual
If you’re using a THX-certified subwoofer, set the THX
Subwoofer setting to Yes. You can then apply THX’s
Boundary Gain Compensation (BGC) to compensate the
perceived exaggeration of low frequencies for listeners
sitting very close to a room boundary (i.e., wall).
 
krzywica

krzywica

Audioholic Samurai
Make sure you put a flux capacitor between your THX gear and your receiver if you get some. That way you aren't limited by placement and can put your speakers wherever you want with no audio penalties.
 
BoredSysAdmin

BoredSysAdmin

Audioholic Slumlord
you can get flux-capacitor here, just make sure to provide 1.21 Jigawatts to power it.
 
J

jmhc

Audioholic Intern
Straight from THX (translation to English not provided):

"THX Certified Subwoofer Performance
THX Select2 and Ultra2 Certified subwoofers extend to 20Hz (-6dB),
Forgive me if I sound ignorant. I assume the 20hz (-6dB) extend reffers to the SW frequency response, but take a look at this:

http://atlantictechnology.com/default.asp?NodeId=51
http://www.teufel.eu/THX/Theater-8-THX-Ultra-2.cfm?show=technik#tab
http://www.teufel.eu/THX/Theater-10-THX-Ultra-2.cfm?show=technik#tab

All of them are 25hz (-3dB)
 
P

popotoys

Audioholic
Hello there:

My receiver (Onkyo TX-SR805) has an option in which you can specify if the subwoofer is THX certified or not.

My question is, besides the certification what are the differences between a high quality THX subwoofer/speakers and a non certified high quality subwoofer/speakers?

Thank you.
I think as well, if you choose this, all speakers are set to small and the crossover in your AVR is set to 80hz.
 
BoredSysAdmin

BoredSysAdmin

Audioholic Slumlord
Forgive me if I sound ignorant. I assume the 20hz (-6dB) extend reffers to the SW frequency response, but take a look at this:

http://atlantictechnology.com/default.asp?NodeId=51
http://www.teufel.eu/THX/Theater-8-THX-Ultra-2.cfm?show=technik#tab
http://www.teufel.eu/THX/Theater-10-THX-Ultra-2.cfm?show=technik#tab

All of them are 25hz (-3dB)
Atlantic sub is not Ultra2/Select2, just regular THX Select certified,
Teufel M 11000 -
Frequency response 25-200 Hz (-3 dB / ±0,5 dB; -6 dB at 20 Hz)
Teufel M 12000
Frequency response 25-200 Hz (-3 dB / ±0,5 dB; -6 dB at 20 Hz)
 
S

sptrout

Audioholic
Forgive me if I sound ignorant. I assume the 20hz (-6dB) extend reffers to the SW frequency response, but take a look at this:

http://atlantictechnology.com/default.asp?NodeId=51
http://www.teufel.eu/THX/Theater-8-THX-Ultra-2.cfm?show=technik#tab
http://www.teufel.eu/THX/Theater-10-THX-Ultra-2.cfm?show=technik#tab

All of them are 25hz (-3dB)
The THX spec is -6dB at 20Hz and most of the speakers you referenced show -3dB at 25Hz as you said (although I think the last one does mention -6 at 20Hz). The only reason that I can think of for the difference between THX and the listed speakers are that speakers are almost always rated down (or up) to their -3dB point. Why THX choose -6dB at 25Hz is something that they only know. My guess that all the speakers that you listed could do 20Hz at -6dB, but they choose to stay with the standard speaker specs. That is ALL a guess on my part.
 
J

jmhc

Audioholic Intern
Atlantic sub is not Ultra2/Select2, just regular THX Select certified,
Teufel M 11000 -
Teufel M 12000
I thought THX select and Ultra has the same certification standards and the only difference between them was the size of the room where the're gonna be used.
 
J

jmhc

Audioholic Intern
No Ultra2 Specs are different per the article at: http://www.hometheaterhifi.com/technical-articles/165-what-it-means-and-how-to-use-it.html?start=4

I highly recommend that anyone that is interested in THX Certificiation Processes read the complete article.
I started reading the article you mentioned, about reference level it says:

"Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel). "

Does this mean that in order to play movies at reference level I have to set my receiver volume to the 0.0dB mark??

Does this means that if I set my receiver at -20.0 dB the loudest sound would be 85 dB and 95 dB for LFE??
 
JerryLove

JerryLove

Audioholic Samurai
Does this means that if I set my receiver at -20.0 dB the loudest sound would be 85 dB and 95 dB for LFE??
If your receiver is THX, that's how I read it, and it fits my experience with my THX gear (though I've never pulled out an SPL meter, I routinely run movies at -10

My THX Marantz does not top out at 0 however.
 
J

jmhc

Audioholic Intern
This is a quote from the article that SPTROUT mentioned above
http://www.hometheaterhifi.com/technical-articles/165-what-it-means-and-how-to-use-it.html


Any single channel of the system is calibrated to play 0 dB FSD (the loudest sound the sound track can contain) at 105 dB (115 dB for the LFE channel).
.

My receiver's manual says that if I'm using a sound level meter to adjust the level of each speaker the device must read 75dB for each speaker at the listening position.

What about subwoofer?? does the device must read 75dB for it or 85dB???.

Thank you guys for all your help and commentaries.
 
S

sptrout

Audioholic
This is a quote from the article that SPTROUT mentioned above
http://www.hometheaterhifi.com/technical-articles/165-what-it-means-and-how-to-use-it.html


.

My receiver's manual says that if I'm using a sound level meter to adjust the level of each speaker the device must read 75dB for each speaker at the listening position.

What about subwoofer?? does the device must read 75dB for it or 85dB???.

Thank you guys for all your help and commentaries.
Yes, when using an SPL meter all speakers should be set at 75dB SPL assuming that you are using a bass management system (BMS) either in your AVR or in a Blu-ray or DVD player that has its own BMS and you are using analog connections between them. It starts to get real confusing when no device is providing bass management (which is common when using analog interconnection between older devices), then you have to boost the LFE channel either 10dB (if using "large speakers") or 15dB (if you are using "small" speakers).

Setting the LFE channel to exactly 75dB SPL with an SPL meter can be a real pain since the level meter typically jumps all over the place. Therefore, you have to kind of guess what the proper setting should be (try a setting and see if you like the results).

Even though it is the recommendation that all speakers be set equally, some folks will add a couple dB to the LFE channel because they like the extra bass.
 
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