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JBL Synthesis Calibration video

19K views 109 replies 15 participants last post by  andyc56 
#1 ·
Hello,


I have read much about the different types of equalization systems, and always end up reading that the Synthesis EQ is as good as it gets. I found this video showing a complete calibration: http://www.youtube.com/watch?v=PHaWWAKAGEM


I'm a little surprised though... It looks like, it is "just" a set of PEQ's for each channel? Trinnov and Audyssey always write about how they calculate the room in the time domain etc, but is the Synthesis EQ just some simple PEQ's to match a given target curve (with some really good processing equipment)?


If anyone has details about the Synthesis EQ-setup (Called Harman ARCOS i believe), then I'm very interested in hearing what exactly is being done
 
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#52 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20842702


Of course it remains to see how good the new Lexicon MP-20 really is, and then there's also the upcoming Datasat RS20i. I wonder how the Dirac Live® room correction compares to ARCOS?

I wonder if the RS20i will still have the noisy fans of the AP-20 inside. If so, it must be remotely located. That was not an option in my humble theater.


And since it will not have QLS, nor L7, nor PLIIx, but only Neo:X, that would be a showstopper for me. Neo:X is not in the league of high fidelity, nor is it spatially interesting as a 2-to-7.1 surround upmixer.


Having heard a direct comparison of Dirac with a simple 5-band PEQ (modeled after the Dirac filters), I can say that Dirac offered nothing special in my room/system wrt "impulse response" or whatever else it claims to fix. So I would see no reason that ARCOS would not do as good of a job, being PEQ-based.
 
#53 ·
Quote:
Originally Posted by Roger Dressler
I wonder if the RS20i will still have the noisy fans of the AP-20 inside. If so, it must be remotely located. That was not an option in my humble theater.
Very good point! I need to keep that in mind.

Quote:
Originally Posted by Roger Dressler
And since it will not have QLS, nor L7, nor PLIIx, but only Neo:X, that would be a showstopper for me. Neo:X is not in the league of high fidelity, nor is it spatially interesting as a 2-to-7.1 surround upmixer.
Personally I don't care for any of those as long as the HD sound tracks can be reproduced. When using a player like the OPPO 93 or 95 this should not be a problem since these players can send the signal as 8-channel LPCM over HDMI.

Quote:
Originally Posted by Roger Dressler
Having heard a direct comparison of Dirac with a simple 5-band PEQ (modeled after the Dirac filters), I can say that Dirac offered nothing special in my room/system wrt "impulse response" or whatever else it claims to fix. So I would see no reason that ARCOS would not do as good of a job, being PEQ-based.
Yes, I'm afraid you're right. The best result can be achieved if the anechoic properties of the speakers are known. In Synthesis this is preprogrammed and with DEQX you can measure it.


Amir: Do you think that JBL will keep the SDP-40HD processor around for now (it is a rebadged Lexicon MC-12HDB right?), or do you expect it to be effectively replaced by the Lexicon MP-20 when released? My gut react is that production of the old Lex probably will cease with the release of the new model...
 
#54 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20845642


Yes, I'm afraid you're right. The best result can be achieved if the anechoic properties of the speakers are known.

I do not see that as an essential factor. It has not prevented SDEC from achieving great results with various speakers, has it?
 
#55 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20846632


I do not see that as an essential factor. It has not prevented SDEC from achieving great results with various speakers, has it?

I don't know about anybody trying SDEC and HATS/ARCOS with third party (non-Syntheis) speakers. I think Amir said they're going to give it a try, but so far I have not heard any success stories...


AFAIK the anechoic measurements are fundamental to DEQX, so I assume ARCOS also makes good use of this info....
 
#56 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20846712


AFAIK the anechoic measurements are fundamental to DEQX, so I assume ARCOS also makes good use of this info....

Actually, not. ARCOS does not pull such data into the system. It lets you select "other" for the speaker brand/model.


If ARCOS really needed "anechoic" data, it would presumably do as DEQX does, and ask for a near field measurement (1 meter). It does not. Nor does Dirac which also works well from in-room measurements.
 
#57 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20846916


Actually, not. ARCOS does not pull such data into the system. It lets you select "other" for the speaker brand/model.

Well, what are the advantages of using Synthesis speakers then? Are you sure that selecting "other" will perform the same quality of tuning compared to when a "known" speaker is selected?

Quote:
Originally Posted by Roger Dressler /forum/post/20846916


If ARCOS really needed "anechoic" data, it would presumably do as DEQX does, and ask for a near field measurement (1 meter). It does not.

That does not rule out that anechoic data is used for known speakers. Maybe the "other" speaker option does not produce the same quality of result and the result is more like what is achieved with systems like Dirac Live or TacT. It would be great if someone had factual info on this...
 
#58 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20846935


Well, what are the advantages of using Synthesis speakers then?

Other than they are are well designed speakers, none in particular.

Quote:
Are you sure that selecting "other" will perform the same quality of tuning compared to when a "known" speaker is selected?

Yes. It tunes to hit the target curve. But if someone has any evidence to the contrary, I'm happy to be corrected.

Quote:
That does not rule out that anechoic data is used for known speakers.

No, but if such data were to be of any value, they would have to ask for the serial number and unit update history in case there are ongoing engineering changes to crossovers or drivers over the life of the model.

Quote:
Maybe the "other" speaker option does not produce the same quality of result and the result is more like what is achieved with systems like Dirac Live or TacT. It would be great if someone had factual info on this...

Is there something wrong with Dirac results?
 
#59 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20847093


No, but if such data were to be of any value, they would have to ask for the serial number and unit update history in case there are ongoing engineering changes to crossovers or drivers over the life of the model.

AFAIK, with Syntheis such changes result in a new model number. Also, the Synthesis One does not have built in crossovers with the exception of the mid/high crossover in the SAM1HF. The drivers used are also clearly specified by JBL (at least in the higher end models). Changing a driver most definitely requires a new model number in order not to scam the customer!

Quote:
Originally Posted by Roger Dressler /forum/post/20847093


Is there something wrong with Dirac results?

I'm questioning what warrants the $20,000+ investement in the SDEC-4500 if Dirac Live can do the same for less than half that cost. My understanding has always been that ARCOS can do a better job because it knows all details about the actual speakers. Maybe all that is FUD. That's what I'm trying to find out. Also, DEQX can supposedly achieve a better result than the competition (Dirac, TacT, Audessey, etc.) thanks to the anechoic measurements. Not sure if that is true or only FUD...
 
#60 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20847406


I'm questioning what warrants the $20,000+ investement in the SDEC-4500 if Dirac Live can do the same for less than half that cost.

Good question. I don't know which BSS boxes the SDEC-4500 is based on, but it looks like any two of them would be well under $10k, like the BLU-800 and BLU-320. What cost, ARCOS??

Quote:
My understanding has always been that ARCOS can do a better job because it knows all details about the actual speakers. Maybe all that is FUD.

According to the SDEC-4500 manual it has:


Built-in crossover for bi-amp outputs

Delay adjustment for each output

Delay adjustment for driver compensation

Screen compensation

Driver compensation


Not sure why they list "driver compensation" a second time. There is no further explanation on that doc. In an older SDEC doc they explain:

Quote:
When you initialize DACS4, you input information about the Synthesis model being calibrated. With this, DACS4 loads configuration information into the SDEC, which customizes it for use with the particular model, whether Cinema only or Cinema + Music, and even compensates when the speakers are placed behind a perforated screen. At the same time, appropriate target curves are loaded into memory.

So if it knows the Synthesis speaker model, it can preselect the right crossover for bi-amping. It can also know the right delay offsets to apply to each driver. All of that is important to get right, and a lot more tedious to do manually as is necessary with other outboard EQs.


It also loads the different target curves for movies and music, again very convenient, especially if they are well proven targets that sound good!


There is no question in my mind that the whole Synthesis kit is highly evolved and solid. I'm not as sure the AP-20 is as comprehensive, mature or solid. Just my gut feeling.

Quote:
Also, DEQX can supposedly achieve a better result than the competition (Dirac, TacT, Audessey, etc.) thanks to the anechoic measurements. Not sure if that is true or only FUD...

Everyone claims to be best--it's only natural. I would like to see some comparisons of DEQX vs other EQs to learn more about it.
 
#61 ·
We tried to get our hands on DEQX to compare but after some contact with the company, they went cold on us.


On speaker selection and ARCOS, it does use the anechoic performance of the speaker as to not force it to do unnatural things. That said, as Roger mentioned, you can set it to an unknown speaker and it still tries to do its own thing. We are about to do precisely that, optimizing our Wisdom speakers with it. Will report our experience soon.
 
#62 ·
BTW, ARCOS asks about screen material and somehow takes this into account too. None of the other products do that...


In any case it's good to know that ARCOS does allow selecting "other" as a speaker choice. I need this since I use Magnepan 20.1s for stereo listening (placed on the side of the screen), wheras my Synthesis One fronts are all behind my Stewart Cinewide AT screen.
 
#64 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20847769


Hear hear! I'm happy to hear I was not wrong

My apologies for FUDing.

Quote:
Originally Posted by amirm /forum/post/20847631


On speaker selection and ARCOS, it does use the anechoic performance of the speaker as to not force it to do unnatural things.

That's pretty vague. You'd think Harman could do a better job of explaining about this in their lit, especially as it might imply added value to the end user. OTOH, they did a pretty good job of hiding BassQ from the planet, too.
 
#65 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20847799


That's pretty vague. You'd think Harman could do a better job of explaining about this in their lit, especially as it might imply added value to the end user. OTOH, they did a pretty good job of hiding BassQ from the planet, too.

They do in dealer training. I gave the shorthand version
. It is part of the Flyod/Alan presentation. They show examples of what should not be corrected with specific measurements of example speakers.


I agree on BassQ. It is a hidden gem.
 
#66 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20847799


My apologies for FUDing.


That's pretty vague. You'd think Harman could do a better job of explaining about this in their lit, especially as it might imply added value to the end user. OTOH, they did a pretty good job of hiding BassQ from the planet, too.

They've got some of the best minds in research, development, engineering, and design...


...and some of the worst in marketing, sales, distribution, and the executive office.
 
#67 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20847799


That's pretty vague. You'd think Harman could do a better job of explaining about this in their lit, especially as it might imply added value to the end user. OTOH, they did a pretty good job of hiding BassQ from the planet, too.

I agree - there's a ton of hidden secrets. Not even Harman Tech support knows it until you're persistent and ask them do dig out the info. Apparently a lot is secret too, like the SAM2LF-SAM1HF crossover frequency, which is one thing tech support would not reveal to me saying it is a trade secret (apparently they want me to use the Synthesis passive crossover or an SDEC solution and want me to stay away from 3rd party crossover solutions). Funny thing is that three months later the crossover frequency was publicized in newly released marketing material. (Possibly accidentally? I doubt it was in any way related to my request).
 
#68 ·

Quote:
Originally Posted by amirm /forum/post/20848009


They do in dealer training. I gave the shorthand version
. It is part of the Flyod/Alan presentation. They show examples of what should not be corrected with specific measurements of example speakers.

I am sure there are many things that should not attempt to be corrected in a room EQ system. Like a room mode or an SBIR cancellation notch, or a response error that appears in only one mic position. One would think the room EQ would be smart enough to determine those things as part of its evaluation, and I'm sure that is true for ARCOS. That being the case, what specific sorts of insight does ARCOS gain from having access to the anechoic responses of the subject speakers?
 
#69 ·

Quote:
Originally Posted by Peter Nielsen /forum/post/20850311


Apparently a lot is secret too, like the SAM2LF-SAM1HF crossover frequency, which is one thing tech support would not reveal to me saying it is a trade secret.

It's not much of a trade secret if you can walk up to it and measure it with a voltmeter and a sine wave generator.
 
#70 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20850314


That being the case, what specific sorts of insight does ARCOS gain from having access to the anechoic responses of the subject speakers?

From what I recall, one example that was given was the natural frequency response roll off a speaker due to the way it is designed. That pushing it to do more will result in lots of distortion.
 
#71 ·

Quote:
Originally Posted by Roger Dressler /forum/post/20850321


It's not much of a trade secret if you can walk up to it and measure it with a voltmeter and a sine wave generator.

That requires that I have the passive crossover or SDEC at hand, which I don't. I have the speakers, but not the crossovers or SDEC (yet). But, yes, you're right. It's not a showstopper. I could have purchased one of the $500 passive crossovers and used it for reference. If Harman thinks it's a secret, that's their prerogative.
 
#72 ·

Quote:
Originally Posted by amirm /forum/post/20847631


We tried to get our hands on DEQX to compare but after some contact with the company, they went cold on us.

I had a bit of the same experience. The support was "cold". Granted, this was way back in late 2005 when the product still was in its baby steps... (I did actually purchase a unit, but came to the conclusion that it's better in the hands of a speaker designer than system calibrator/end user).
 
#73 ·

Quote:
Originally Posted by amirm /forum/post/20850343


From what I recall, one example that was given was the natural frequency response roll off a speaker due to the way it is designed. That pushing it to do more will result in lots of distortion.

Thanks to super sleuth Sanjay
, what appears to be a good answer to my question comes from a 1999 Harman paper :

Quote:
The JBL Synthesis home theater systems incorporate all of the required characteristics for successful equalization. The dedicated digital controller has 95 individually-configurable parametric filters distributed among the 5.1 channels. In the laboratory, based on high-resolution spatially-averaged anechoic measurements, some filters are preset to address small residual problems in the speakers themselves. The equalizer has helped to create better speakers. Once the system is installed in the customer's home, a trained installer arrives with a custom measurement system to adapt the system to match the room at low frequencies. The system employs five microphones connected to a multiplexer, coupled to a laptop computer which, in turn, is coupled to the digital processor. In a carefully controlled sequence, the appropriate test signals are sent through each of the channels, the measurements are compared to predetermined target functions, and a set of filters is automatically designed that will allow the system performance to approach the target with minimum error. Built into the system are safeguards that attempt to prevent it from trying to equalize the unequalizable. Manual override is always an option, so human intervention can modify a bad decision by the computer, or accommodate customer preferences in spectral balance.

Assuming that is what is going on in ARCOS when the user inputs the Synthesis models, it is clearly a cut above the "uninformed" room EQ modes we normally see. BTW, the rest of that paper is quite good. Harman updated the paper to remove some of that info and talk more about bass EQ and SFM. Both papers are worth reading. Which is what I should have been doing instead of spouting off here.
 
#107 ·
Thanks to super sleuth Sanjay
, what appears to be a good answer to my question comes from a 1999 Harman paper :




Assuming that is what is going on in ARCOS when the user inputs the Synthesis models, it is clearly a cut above the "uninformed" room EQ modes we normally see. BTW, the rest of that paper is quite good. Harman updated the paper to remove some of that info and talk more about bass EQ and SFM. Both papers are worth reading. Which is what I should have been doing instead of spouting off here.
Hi Roger. An oldy but a goody of a discussion. The links above to the Harman paper you mention are no longer active. Do you know where to find them now?

Thanks
 
#75 ·
This has become an interesting thread! I am against auto eq as well, because it can dó more harm than good if it is just eq'ing blind.


But apart from knowing the response of each speaker, what does ARCOS do besides eq'ing for a predefined target curve? Knowing amps and processor should not matter, as these must be expected to be flat.


And do you know if the target curve depends on the speaker, or has JBL designed all synthesis speakers to match the same response?
 
#76 ·

Quote:
Originally Posted by JonasHansen /forum/post/20857809



But apart from knowing the response of each speaker, what does ARCOS do besides eq'ing for a predefined target curve? Knowing amps and processor should not matter, as these must be expected to be flat.

Here "expected" is the operative word. It's not so much that it needs to tell one Synthesis® amp from another, but it at least needs to know it's a Synthesis® amp with predictable parameters. One could drop in a bevy of tube amps, which wouldn't be "expected" or predictable in the same sense.


Even among the Synthesis® amps, however, knowing if a channel is driven by a single amp module from an S5160 or by a bridged S800 would make a difference. If nothing else, trying to run an S1S-EX sub with less that 160W or trying to run a SAM1HF with 800W might get a warning from the software.
 
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