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JBL 705P / 708P

Bjorn

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Perhaps you can provide some clarification here....? Did you happen to notice the phase response is as good as the frequency response in the measurements provided in the article? Look's like ideal minimum phase response at the LP to me... I have had several excellent loudspeakers come through my room, (e.g. Kii THREE, D&D 8c), some use FIR filtering to correct for frequency and phase and some don't. I am comparing a pair of KEF LS50's to my JBL speakers that are eq''d with Audiolense, both in frequency and phase. Article forthcoming with binaural recordings of both speakers so folks can compare and can clearly hear there is no "weird or unnatural sound" from the eq'd speaker as compared to the LS50's with no eq.
There's nothing in your article that disproves what I said. It's simply not possible to correct myriads of specular reflections arriving from multiple places at different time. About the best you can do is to treat one reflection at one single point with a FIR filter. Move the head a bit and it will change, especially in the higher frequencies where wavelengths are short. The time behavior of the room will not be fixed when you correct the frequencies. You need minimum phase behavior for that to happen and most of the room response isn't unless the room is heavily treated.

IMO the result of such correction is anything but good sound but I can't argue with what you think. I have heard numerous setups with Audiolense and have owned the software myself.
 

Music1969

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Hi all

Apologies for the silly question, but since the 705/708P both have digital inputs, I assume these use digital crossover which cannot be by-passed?

So best to feed these via digital AES3 and NOT analogue (to avoid double D to A conversion)?
 

andreasmaaan

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Hi all

Apologies for the silly question, but since the 705/708P both have digital inputs, I assume these use digital crossover which cannot be by-passed?

So best to feed these via digital AES3 and NOT analogue (to avoid double D to A conversion)?
That's correct, yes.

OTOH, if the ADC is well-implemented (which I suspect it is), there may not be an audible difference when fed from a decent DAC.
 

dreite

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The ADC is transparent, in my listening.
One potential negative aspect of using the AES input is (depending upon how your head end operates) you can get some disconcerting snaps/pops/etc during lock/unlock/lock transitions in the data stream. These could be associated with start/stop, track switches, SR or bit depth changes, etc, etc.

Dave.
 

xyvyx

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Yes. It’s compatible with AVB and Dante.
So do AVB devices from different vendors tend to play nicely together?

I just purchased a pair of the 708Ps..... they'll be delivered Thursday and my original intention was to connect them to the balanced outputs from my DAC. But upstream of my dac is a Motu LP32 which is fed from a couple PCs and & Chromecast audio (RIP) via toslink. But if I could send the signal to the JBLs via AVB/ethernet, that'd be kinda cool.... Looks like maybe I could purchase a small AVB / AVNU compliant switch to connect the speakers with the Motu, then that switch would talk to the rest of my network via standard ethernet.

The signal wouldn't likely be any better than what I could send via the AES digital ports, but if I could also control their filters via. Audio Architect over the same interface, that just sounds way cleaner. From what I've been reading, the whole network audio landscape looks like a mess... HiQnet, CobraNet, Dante, AVB, BLU-link, AES67. Lots of standards, questionable compatibility.

FWIW, I've been reading this to get a better understanding of what AVB is:
https://adn.harmanpro.com/software_...ystems_Guide_To_Audio_Networking_original.pdf
 

12B4A

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I've not seen anything to indicate that the 7Pseries HiQNet port can be used to receive audio data.
 

12B4A

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If they did, they don't mention it anywhere in the manual nor in their promotional material. This is what describes the RJ45 port:
  1. HiQnet PORT – This port allows feature updates as they become available
 

SIY

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Sal1950

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I have a pair of LP-6 in for review in AudioXpress. I can't say too much in advance beyond "if you get a set of these, you will not be unhappy." Input is analog, so if you need AES/EBU or SPDIF or USB, you'll want something else.
A sneak preview? LOL
 

Jaimo

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My 708P's arrived yesterday. It took me a couple of minutes to remove the LSR308's and hook up the new puppies. Wife was confused "they look almost the same as your old speakers" until I played Santana's "Maria Maria" and cranked up the volume...

This is likely going to be my party trick for the coming weeks.

I ran a set of REW Curves on the 308's and will do the same for the 708's as soon as I can stop listening to music.
 

Krunok

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About the best you can do is to treat one reflection at one single point with a FIR filter. Move the head a bit and it will change, especially in the higher frequencies where wavelengths are short.
I don't agree with this. After I did correction of my speakers response at LP wherever I make measurements the response above Schroeder frequency (in my case it's app at 300Hz) stays consistenty flat throughout the entire room. Only the response below 300Hz changes but it is also better in practically all positions than it was before correction. Step and phase response also measures much better than before correction, so my listening impressions and measurements after the correction confirm what @mitchco said.

When doing room EQ higher frequencies are usually corrected only slightly with low Q or are not corrected at all. Basis for correction are usually measurements taken in multiple points so it's not that response is optimised for the point where your head is and not for the point where your head would be if you move it a little, and that is what I experience - I don't hear any change in higher frequencies when I move my head a bit, neither in LF as well. :)

No sudden changes will happen when you move your had a bit, either with correction or without it, assuming you did correction the right way. Even when walking around the room I don't hear any sudden unnatural changes.
 
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Bjorn

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@Krunok
If you only care about frequency response, that's true. But the the reflections will not really be dealt with and you actually end up introducing time distortion. Personally I don't think that sounds good or natural. But I can't argue with what you prefer.
 

Krunok

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@Krunok
If you only care about frequency response, that's true. But the the reflections will not really be dealt with and you actually end up introducing time distortion. Personally I don't think that sounds good or natural. But I can't argue with what you prefer.
Well, personal preferences surely exist but I believe here we are discussing technical aspects based on measurements and not personal preferences. What exactly do you mean when you say "time distortion"? As I did correction not only in frequency domain but in time domain as well I measured great improvement in step response, phase response and GD. So what "time distortion" do you think I introduced with correction and why it is not showing in measurements?

Certainly the things would be even better if I had a chance to do room treatment to reduce reflections, but that is not applicable as in my case it is my living room where I listen music the most.
 

Sal1950

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@Krunok
If you only care about frequency response, that's true. But the the reflections will not really be dealt with and you actually end up introducing time distortion. Personally I don't think that sounds good or natural. But I can't argue with what you prefer.
Since the severity of the reflection situation will vary drastically from room to room and speaker setup, isn't the truth of the time distortion issue a large variable? In some rigs it can be huge while in others only a minor influence?
 

Krunok

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Would step response be a good measure of "time distortion" as room reflections and drivers time (mis)alignement would show there?
 

mitchco

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Timing response of my JBL/Rythmik sub 3-ways before any timing (i.e. excess phase) correction:

before.JPG


Step response over 200ms with mic at LP in my room. Shows a maximum phase room reflection 30ms after the direct sound. Side note, subs are negative going polarity.

After correction:

after.JPG


Aside from the drivers time aligned, the woofers/subs follow the target response, while inverting the polarity of the subs and removing the maximum phase room reflection. Note this is an ideal "minimum phase" loudspeaker response at the LP.

Folks forget that for a given impulse response can be split into its minimumphase and excessphase parts. The minphase part describes the given frequency response whereas the excessphase part describes the timing. Both can be corrected independently using a FIR filter. And it is not just at one point in time either. In my book I show both frequency and timing response stays consistent across a 6ft x 2ft listening area with 14 validation measurements.

Details with verification measurements in this article. This article shows how timing correction can reduce low frequency group delay at the LP.

Finally, this article includes binarual recordings of the above speaker system, comparing to KEF LS50 with sub. People can hear for themselves that so called digital loudspeaker and room correction does not sound "weird or unnatural".
 

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