john k... said:
Not sure about other AVRs, but I can dial in delay on my front channels if required.
I noticed the DCX/DEQ delay (I was using both in series) during my initial setup. The AVR indicated the primary subwoofer was slightly further from the mains than it is in reality, due to the delay (compared to direct path to sub amp). It made the appropriate adjustments to the mains and all was well.
john k... said:
John
I don't have that data memorized and I'm not sure what use it would be anyways. A subs free field performance is not a very useful concept. The sub needs to be able to produce output, sure, but what it does in a real room and what it does in a free field have almost nothing to do with each other. Hence, I don't pay much attention to the free field response.
I intend to get some nearfield data from them, but I don't have any at the moment, again, because its not all that useful.
markus76 said:
Your comment does not seem to agree with
"The JBL BassQ module will allow you to optimize the performance of 2, or more, JBL subwoofers.
This will allow you to equalize the output of each subwoofer, to match your listening preferences. The JBL BassQ has not been released, as of yet, and is scheduled for release later this year. As we get closer to the release date, more information will become available. "
From the JBL rep. And since its not even out yet how do you make such claims?
Did you really expect a sales person to answer anything else? The manual states the contrary:
http://manuals.harman.com/JBL/HOM/Owner's Manual/BassQ_OM_LR.pdf
Anyway, I'm not much interested in that box because nobody seems to know what it exactly does—even Todd.
Best, Markus
http://manuals.harman.com/JBL/HOM/Owner's Manual/BassQ_OM_LR.pdf
Anyway, I'm not much interested in that box because nobody seems to know what it exactly does—even Todd.
Best, Markus
Earl,
I've extracted the center channel from chapter 10 of the DVD "Hellboy II" and found lots of low frequency content—this is the spectrogram of the whole chapter (4 min):
This is a somewhat unexpected result. Hope someone else can verify this.
Best, Markus
I've extracted the center channel from chapter 10 of the DVD "Hellboy II" and found lots of low frequency content—this is the spectrogram of the whole chapter (4 min):
An externally hosted image should be here but it was not working when we last tested it.
This is a somewhat unexpected result. Hope someone else can verify this.
Best, Markus
why is it so surprising that there is a lot of lf content in the center output? In modern movies the main channels are used as true full range sources, and the bass management just removes that content.
I was told by one of the THX PR reps that this is the general current recommendation since, even if not THX speced, the general field does try and mimic the THX idea of 115db output below 80hz. To do this they put LF content in all of the channels to increase the likelyhood of achieving sufficient output in that range below 80hz. It's understood that most systems aren't capable of achieving the recommended levels (or even close to it) when taken on a "speaker by speaker" basis. In other words, if you went into the large majority of home theaters and looked to see if the subwoofer could achieve 10db's more output than the mains during peak action sequences, the answer would be no. Since many do have speakers capable of at least some output in the 50-80hz range, they just mix the content into all the channels.
Now my response was, but you guys recomend an 80hz highpass on all speakers, so why put all this content below 80hz if you know it's just going to be mixed into the one single subwoofer which you said yourself can't handle it? His response was that the highpass should be 2nd order, which isn't steep enough to get rid of everything that low, and as such, there should still be content at below 80hz helping out the sub, just not as much.
The guy also talked a bit to me about achieving reference levels, which talked about multiple subs. This, to me, doesn't really reflect the rationale behind mixing LF content into all channels, but he brought it in anyway. All current THX systems can only reach THX levels if using 2-4 of the THX subwoofers, and he suggested that this was somehow related.
I was told by one of the THX PR reps that this is the general current recommendation since, even if not THX speced, the general field does try and mimic the THX idea of 115db output below 80hz. To do this they put LF content in all of the channels to increase the likelyhood of achieving sufficient output in that range below 80hz. It's understood that most systems aren't capable of achieving the recommended levels (or even close to it) when taken on a "speaker by speaker" basis. In other words, if you went into the large majority of home theaters and looked to see if the subwoofer could achieve 10db's more output than the mains during peak action sequences, the answer would be no. Since many do have speakers capable of at least some output in the 50-80hz range, they just mix the content into all the channels.
Now my response was, but you guys recomend an 80hz highpass on all speakers, so why put all this content below 80hz if you know it's just going to be mixed into the one single subwoofer which you said yourself can't handle it? His response was that the highpass should be 2nd order, which isn't steep enough to get rid of everything that low, and as such, there should still be content at below 80hz helping out the sub, just not as much.
The guy also talked a bit to me about achieving reference levels, which talked about multiple subs. This, to me, doesn't really reflect the rationale behind mixing LF content into all channels, but he brought it in anyway. All current THX systems can only reach THX levels if using 2-4 of the THX subwoofers, and he suggested that this was somehow related.
Sorry guys, but I still don't get the gist of the problem being debated... 
If the purpose of the dcx optimization service is mainly to help optimize multiple subs, (in comparison to using a single sub) why is there so much argument about the requirements for preamp outputs? I still don't get it.
If someone was going to use one sub, wouldn't they be subject to the same limitations of the particular receiver they have?
If this is some argument concerned with the comparison to the jbl unit, from what I read in the manual I don't see the JBL option doing anything differently to solve this limitation. This uses a mono LF output from the receiver as well...
And if there is low frequency content in the center channel, in what way does this cause a problem with the subwoofer setup?
Thanks for helping me understand the issue...
-Tony
If the purpose of the dcx optimization service is mainly to help optimize multiple subs, (in comparison to using a single sub) why is there so much argument about the requirements for preamp outputs? I still don't get it.
If someone was going to use one sub, wouldn't they be subject to the same limitations of the particular receiver they have?
If this is some argument concerned with the comparison to the jbl unit, from what I read in the manual I don't see the JBL option doing anything differently to solve this limitation. This uses a mono LF output from the receiver as well...
And if there is low frequency content in the center channel, in what way does this cause a problem with the subwoofer setup?
Thanks for helping me understand the issue...
-Tony
pjpoes, TRADERXFAN, there's nothing wrong with low frequency content in the channels. The problem is how a multisub solution deals with that. It makes no sense to calibrate assuming that there's coherent bass from EVERY source at ALL times if bass management fails to create just that.
It gets even better—here's the left surround channel:
Best, Markus
It gets even better—here's the left surround channel:
An externally hosted image should be here but it was not working when we last tested it.
Best, Markus
Ah I now see what's being debated here. Well for this to work as intended requires that the internal bass management be capable of outputting the LF information in each channel to all speakers. There has been a lot of debate over this possibility, but Dr. Geddes claims his Pioneer can. I believe my processor can too (It has a mode called LF+SW). Where I am unclear with this feature is what frequencies are sent to the sub, my system fades out the frequency box, so I don't know if it does it at 50hz, 100hz, etc. The manual is very unclear as well.
The Behringer piece only has two inputs, you couldn't use this to do external bass management. There are systems with 6 inputs, or you could combine multiple units to serve this purpose, but one unit could not act as an external bass management device. You have no need to send the RCA output of every channel to the device, only the LFE channel, and all recievers have an RCA output for the LFE.
As I understand things, the main channels intended to be run full range with Dr. Geddes method, so external bass management of those speakers isn't necessary. What we want is to take the LF content of the main channels and the LFE, combine that, and use the processor to optimize the subs in room performance for that source. Since we are assuming that the receiver or processor can do this, the rest of this debate is a non-issue, no? As long as the receiver or processor can output an LFE+main LF, then there is no need for RCA outs from the mains. If it can't do that, and you do have rca outs for all channels, since you are using the built in amps of the receiver, there is no reason why you couldn't just use a bunch of rca Y splitters to combine all the channels together and feed the processor that way. I think it would not impact the crosstalk of the main channels as long as the outputs are buffered separately from the amplifier (the final dac output isn't sent to a buffer which is then internally split to both the amp and output, but rather a buffer exists between that split output and the rca, separate from the line feeding the amplifiers).
To directly answer the issue of differential bass output, it was my understanding all along that the system had to take the LF content of each channel and combine it into a single output at the sub. While turning off the HP filter on the main speakers would seem to undo that, as mentioned early, many processes seem to have the ability to do just this.
The Behringer piece only has two inputs, you couldn't use this to do external bass management. There are systems with 6 inputs, or you could combine multiple units to serve this purpose, but one unit could not act as an external bass management device. You have no need to send the RCA output of every channel to the device, only the LFE channel, and all recievers have an RCA output for the LFE.
As I understand things, the main channels intended to be run full range with Dr. Geddes method, so external bass management of those speakers isn't necessary. What we want is to take the LF content of the main channels and the LFE, combine that, and use the processor to optimize the subs in room performance for that source. Since we are assuming that the receiver or processor can do this, the rest of this debate is a non-issue, no? As long as the receiver or processor can output an LFE+main LF, then there is no need for RCA outs from the mains. If it can't do that, and you do have rca outs for all channels, since you are using the built in amps of the receiver, there is no reason why you couldn't just use a bunch of rca Y splitters to combine all the channels together and feed the processor that way. I think it would not impact the crosstalk of the main channels as long as the outputs are buffered separately from the amplifier (the final dac output isn't sent to a buffer which is then internally split to both the amp and output, but rather a buffer exists between that split output and the rca, separate from the line feeding the amplifiers).
To directly answer the issue of differential bass output, it was my understanding all along that the system had to take the LF content of each channel and combine it into a single output at the sub. While turning off the HP filter on the main speakers would seem to undo that, as mentioned early, many processes seem to have the ability to do just this.
the only way to send the LFE back to the mains is to turn off the subwoofer, this then would require a complete external "Bass management" system, as this is very non-typical. If this is in fact what Earl is suggesting, then yeah, you would need to have multiple processors (3 I believe) networked together along with RCA outs for all channels.
pjpoes, not sure that I understand what you're saying.
As soon as you run the mains full range and make them part of the multisub calibration then you have to make sure that they also reproduce coherent low frequency content with each and every source material. But this is something a DVD or Blu-ray doesn't deliver and there's no AVR (I know of) that has this kind of bass management. You can only mix the low frequency content of all channels to the LFE and output that from the sub out, but you can't mix that back to the other speakers. So every time the LFE carries a signal, the mains are no longer part of the low frequency array and therefore the multisub calibration won't work anymore.
The easiest solution would be to apply a HP to the mains and make only the subs part of the calibration.
Best, Markus
As soon as you run the mains full range and make them part of the multisub calibration then you have to make sure that they also reproduce coherent low frequency content with each and every source material. But this is something a DVD or Blu-ray doesn't deliver and there's no AVR (I know of) that has this kind of bass management. You can only mix the low frequency content of all channels to the LFE and output that from the sub out, but you can't mix that back to the other speakers. So every time the LFE carries a signal, the mains are no longer part of the low frequency array and therefore the multisub calibration won't work anymore.
The easiest solution would be to apply a HP to the mains and make only the subs part of the calibration.
Best, Markus
pjpoes said:
I don't think that is what Earl is suggesting at all.
It seems rather simple. Set the mains to run full range. That sends LF content to the front L&R preouts. Use the L&R preouts and sum them in the DCX. Send that summed signal to the various subs, using the processing within the DCX on each sub channel.
AVR->DCX->sub amps->subs
If people are that concerned with the center channel LF info they can put a mixer ahead of the DCX to combine the required signal prior to the DCX input, but that whole exercise seems like a solution in search of a non-existent problem.
Markus, I agree with what your saying. What I'm saying is that I don't think it's that important if the mains aren't a part of this optimization. I thought using the mains as LF sources is really somewhat incidental. If you make the mains full range, you can still mix their LF content into the sub channel and optimize that.
However, if you really felt it was important to mix all of the bass content into all speakers and subs, the only way I can know of to do this would be through external speaker management. It would be a lot more complicated, and I would somewhat question it's value.
However, if you really felt it was important to mix all of the bass content into all speakers and subs, the only way I can know of to do this would be through external speaker management. It would be a lot more complicated, and I would somewhat question it's value.
amiklos said:
Again, the only way to get the LFE signal would be to turn off the subwoofer in the processor, so to do as you say would require doing this. While that accomplishes the goal for all the LF content that would exist (LFE+LF of mains), Markus is right that different LF content is sent to different channels. While this was less true in the old days, modern media has the room and ability to have Discrete full range channels, and studios are using it. This would mean that you would need to output the L,C,R, SR, SL to an outboard set of DCX processors networked together.
Markus
You are wrong about the JBL box. It requires preamp outputs on the AVR just like the DCX does. Its no different in that regard. It ASSUMES a JBL AVR.
Matt
I don't follow why you say three processors are needed. Sum all three front channels (set surrounds to "small") with the "No Sub" setting in the receiver and you will have ALL LF (L, R, C and LFE) output as one signal. NOW, if you can only sum two (like in the DCX) THEN, IF there is DIFFERENT content on the channel that is omitted there could be a problem. BUT, this is rare to nonexistant. IF the LF signal is the same for the three front channels (as it usually is) then there is no problem. This is at least the third time that I have said this.
I would be leary of summing using Y-RCA as the output buffering is unlikely to be able to handle this. I would just take the signal off of the speaker out using a resistor bridge as this would be quite easy.
You are wrong about the JBL box. It requires preamp outputs on the AVR just like the DCX does. Its no different in that regard. It ASSUMES a JBL AVR.
Matt
I don't follow why you say three processors are needed. Sum all three front channels (set surrounds to "small") with the "No Sub" setting in the receiver and you will have ALL LF (L, R, C and LFE) output as one signal. NOW, if you can only sum two (like in the DCX) THEN, IF there is DIFFERENT content on the channel that is omitted there could be a problem. BUT, this is rare to nonexistant. IF the LF signal is the same for the three front channels (as it usually is) then there is no problem. This is at least the third time that I have said this.
I would be leary of summing using Y-RCA as the output buffering is unlikely to be able to handle this. I would just take the signal off of the speaker out using a resistor bridge as this would be quite easy.
Ah I guess I was over complicating this, we aren't trying to process the mains back again.
Ok so this makes more sense now, I was very fixated on having all 5 channels as full range and taking all this content and redistributing the differential LF content to all channels equally, including the LFE.
Differnt LF content is sent to different channels sometimes, but I think you are right Dr. Geddes, as I said earlier, I was told that they are often sending a lot LF content to all channels to accomplish the need for more output at those channels, it's not really like "stereo bass" or I guess really, surround bass. If they were doing surround bass and you needed to send this information back to all the speakers, then you would need to do as I said, use multiple networked processors.
As far as combining the RCA outputs in a fashion that doesn't cause cross talk issues, a very simple circuit can be built with 4 dual opamps and a small handful of capacitors and resistors. It would create a 3 into 1 signal, buffered (could be balanced too for going into the DCX), and would probably be the most ideal.
Ok so this makes more sense now, I was very fixated on having all 5 channels as full range and taking all this content and redistributing the differential LF content to all channels equally, including the LFE.
Differnt LF content is sent to different channels sometimes, but I think you are right Dr. Geddes, as I said earlier, I was told that they are often sending a lot LF content to all channels to accomplish the need for more output at those channels, it's not really like "stereo bass" or I guess really, surround bass. If they were doing surround bass and you needed to send this information back to all the speakers, then you would need to do as I said, use multiple networked processors.
As far as combining the RCA outputs in a fashion that doesn't cause cross talk issues, a very simple circuit can be built with 4 dual opamps and a small handful of capacitors and resistors. It would create a 3 into 1 signal, buffered (could be balanced too for going into the DCX), and would probably be the most ideal.
gedlee said:
Which box are you talking about? The BassQ? Didn't you read the manual?
"Although the
system has been designed to work
with the rest of the Performance Series
system, including AV1 and AVA7,
the unit can be used in almost any
system and can improve the in-room
response of almost any installation."
"There are two subwoofer inputs.
If using an AV1 processor or other
processor that has a single subwoofer
or LFE output, connect the subwoofer
output to the Left input and set the input
mode to Mono on the front panel of the
JBL BassQ unit. [...] If you are using
a preamp/processor such as the AV2,
or an AVR that has stereo subwoofer
outputs, connect the left and right
inputs and set the mode to Stereo on
the front panel of the JBL BassQ unit."
But you still don't have the LFE in the speakers.
What more proof do you need than real world data I posted??
Markus
pjpoes said:
I have a hard time believing that there is much unique LF content sent to those surround channels, at least not enough to justify the complexity of the system being suggested (yes I saw Markus's data). While in theory there may be something that gets missed, what is the practical impact in the course of 99% of listening? Studios aren't really expecting the average consumer to have 5hz-20khz reproduction on each channel are they?
Even if you did want to combine all the LF info from all the channels, what prevents you from using a mixer to sum sets of channels ahead of the DCX rather than needing several DCX units? The goal is still to send the same LF info to all subs (with requisite processing in place), correct?