JBL 705i/708i (7 Series Master Reference Monitors) & 725G/728G (subwoofers): Jan 2015 - Page 90 - AVS Forum | Home Theater Discussions And Reviews
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post #2671 of 3042 Old 04-05-2019, 05:21 PM
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Regarding noise, when I auditioned the 708P's, I put my ear right up next to them and they were completely silent. This was in a quiet room but it was something that I just checked quickly. If there was noise present that I wasn't hearing, it must have been above 16 kHz or so. Sorry to hear that some of you have noise issues. I thought that noise was a non-issue with these.
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post #2672 of 3042 Old 04-05-2019, 06:30 PM
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Originally Posted by Zzzzz... View Post
Regarding noise, when I auditioned the 708P's, I put my ear right up next to them and they were completely silent. This was in a quiet room but it was something that I just checked quickly. If there was noise present that I wasn't hearing, it must have been above 16 kHz or so. Sorry to hear that some of you have noise issues. I thought that noise was a non-issue with these.
What was the source? What was the gain on the 708p set to?

Those are very important in how much noise you're going to get.
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post #2673 of 3042 Old 04-05-2019, 07:34 PM
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What was the source? What was the gain on the 708p set to?

Those are very important in how much noise you're going to get.
I had them connected to the pre-outs of my Denon X4000, which are RCA. I don't remember which of the two gain settings I used but I did check to make sure it was the correct one.
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post #2674 of 3042 Old 04-06-2019, 03:53 AM
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In addition to the high pitched whine/buzz, there is low pitched static, but the static noise is much lower, and I need to be very close to hear it. So, I guess perhaps the regular static is lower in volume than on 305 when I think about it.

The high pitched whine might be more like one of those teenager-repellent mosquito sound devices, except lower in volume. So, one problem replaced with another, I suppose.

But any of the noises from the speakers are the same regardless of volume or whether connected to anything. And it's the same for both speakers.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2675 of 3042 Old 04-06-2019, 04:02 AM
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Originally Posted by Palewing View Post
In addition to the high pitched whine/buzz, there is low pitched static, but the static noise is much lower, and I need to be very close to hear it. So, I guess perhaps the regular static is lower in volume than on 305 when I think about it.

The high pitched whine might be more like one of those teenager-repellent mosquito sound devices, except lower in volume. So, one problem replaced with another, I suppose.

But any of the noises from the speakers are the same regardless of volume or whether connected to anything. And it's the same for both speakers.
Does this "high pitched whine" comes from a twitter or is it a switching power supply whine they often have?

Last edited by aats; 04-06-2019 at 06:38 AM.
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post #2676 of 3042 Old 04-06-2019, 06:47 AM
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I checked just now, and it's surprisingly equal from tweeter and woofer, though I think somewhat more from the tweeter. It don't hear the noise on the side/back of the speakers.
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Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2677 of 3042 Old 04-06-2019, 12:58 PM
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I use 2 x LSR305 (MkI) + 1 x LSR310S as my desktop PC setup. I can only hear a faint hiss if I put my ear right next to either tweeter. At my normal listening distance of around 2-3 ft, they are pretty much dead silent. I have them hooked up to my Creative Sound Blaster X-Fi Titanium HD sound card via RCA to XLR cables to the subwoofer and then XLR to XLR cables from the subwoofer to each of the speakers. Love how they sound and they can get pretty damn loud.
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post #2678 of 3042 Old 04-06-2019, 01:38 PM
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Originally Posted by Palewing View Post
I checked just now, and it's surprisingly equal from tweeter and woofer, though I think somewhat more from the tweeter. It don't hear the noise on the side/back of the speakers.
Is there noise with nothing plugged into the speaker input? Both speakers same noise?

Check to make sure input sensitivity and gain trim are correct. Gain structure correct? Unplug the power cable from the speaker or wall, wait a minute, plug it back in. If all else fails, try a full factory reset (make note of any settings to dial back in). RTFM? Just kidding...

http://www.jblpro.com/ProductAttachm...ual-052417.pdf

Manual does not state full factory reset procedure. I'll check to find out what it is.
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post #2679 of 3042 Old 04-06-2019, 04:01 PM
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I'm looking at getting a pair of JBL subs to go with my 708i, any recommendations that pair nicely?

Thanks for any advice
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post #2680 of 3042 Old 04-06-2019, 04:58 PM
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Originally Posted by D0minic View Post
I'm looking at getting a pair of JBL subs to go with my 708i, any recommendations that pair nicely?

Thanks for any advice

The two obvious choices are the Sub 18 and the S2S-EX. Need more info on your room dimensions and layout, locations for them, full system details etc.
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post #2681 of 3042 Old 04-06-2019, 05:15 PM
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The two obvious choices are the Sub 18 and the S2S-EX. Need more info on your room dimensions and layout, locations for them, full system details etc.
Thanks for that, I'll make the room work, already have the room treated years ago with GIK acoustics when it was a studio. I didn't know what the main pairings people were using for subs with these, appreciated, I'll read up.
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post #2682 of 3042 Old 04-07-2019, 03:56 AM
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Originally Posted by Rex Anderson View Post
Is there noise with nothing plugged into the speaker input? Both speakers same noise?

Check to make sure input sensitivity and gain trim are correct. Gain structure correct? Unplug the power cable from the speaker or wall, wait a minute, plug it back in. If all else fails, try a full factory reset (make note of any settings to dial back in). RTFM? Just kidding...

http://www.jblpro.com/ProductAttachm...ual-052417.pdf

Manual does not state full factory reset procedure. I'll check to find out what it is.
The noise is the same for both speakers, the same whether they are connected to anything or not, regardless of having the volume at the speakers themselves at minimum or close to maximum, and regardless of being set to +4dBv or -10dBu.

It's been like this since I got them. My guess is that most people don't hear the noise because it is quite sharp/high in frequency.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.

Last edited by Palewing; 04-07-2019 at 04:07 AM.
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post #2683 of 3042 Old 04-08-2019, 08:19 PM
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How clean is your power? I don't hear noise from one unless my ear is literally an inch from them, and I am powering them through some pretty decent filtering.

Or, I am old enough that I am not hearing the 18Khz whine because I can't.
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post #2684 of 3042 Old 04-09-2019, 03:03 AM
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The voltage is stable, and the power is clean (no brownouts etc.), but it is an old house without grounding. Still, when the sound is present even without the speaker being connected to anything else, the grounding should not matter. And again, the "whine" is separate from the regular "buzz" that I can't hear either unless I am very close.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2685 of 3042 Old 04-09-2019, 03:47 AM
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The voltage is stable, and the power is clean (no brownouts etc.), but it is an old house without grounding. Still, when the sound is present even without the speaker being connected to anything else, the grounding should not matter. And again, the "whine" is separate from the regular "buzz" that I can't hear either unless I am very close.

Can you take one somewhere else (not your house) and plug it in to check it out?
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post #2686 of 3042 Old 04-09-2019, 05:51 AM
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Originally Posted by Rex Anderson View Post
Can you take one somewhere else (not your house) and plug it in to check it out?
I don't have that option right now.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2687 of 3042 Old 04-09-2019, 07:00 AM
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Originally Posted by Palewing View Post
I don't have that option right now.

Do you have access to a good power conditioner that has noise filtration (Furman PL-Plus)?
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post #2688 of 3042 Old 04-09-2019, 08:32 AM
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Do you have access to a good power conditioner that has noise filtration (Furman PL-Plus)?
No, nor do I have the budget for anything right now either.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2689 of 3042 Old 04-09-2019, 08:59 AM
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No, nor do I have the budget for anything right now either.

Sorry, I'm out of ideas to help you trouble shoot.
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post #2690 of 3042 Old 04-09-2019, 09:06 AM
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Sorry, I'm out of ideas to help you trouble shoot.
It is what it is. I've had them for a year and a half now. I like the general sound of the speakers, despite this issue. So I'll just have to live with it for now.

But I don't think I would invest in 708Ps later unless I got rid of this issue first, somehow.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2691 of 3042 Old 04-09-2019, 10:38 AM
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If you're getting noise through the power circuit, this indicates a poorly designed power supply in these. At $2000 a pop, you'd think they'd spend a couple dollars more to make a worthwhile supply.
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post #2692 of 3042 Old 04-10-2019, 03:17 PM
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Here is a recently posted, detailed, super positive review of the 708P: https://www.audiocircle.com/index.php?topic=162008.0
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post #2693 of 3042 Old 04-11-2019, 04:36 AM
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I just encountered something in regards to the 705P. This has happened a couple of times in the time I've had them.

I turned on both speakers, waited until they both showed a green light, and then started to play some music. But there was only sound from one of them. Turning a speaker off, then on again always fixes this. But before I did it this time, I listened to the speaker that gave no sound, and noticed that the low buzz was actually there, but there was no high pitched noise. When I "restarted" it, the whine (and music) came back.

I don't know if this sheds any light on anything at all, but I thought I'd mentioned it.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2694 of 3042 Old 04-11-2019, 05:23 AM
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Originally Posted by Palewing View Post
I just encountered something in regards to the 705P. This has happened a couple of times in the time I've had them.

I turned on both speakers, waited until they both showed a green light, and then started to play some music. But there was only sound from one of them. Turning a speaker off, then on again always fixes this. But before I did it this time, I listened to the speaker that gave no sound, and noticed that the low buzz was actually there, but there was no high pitched noise. When I "restarted" it, the whine (and music) came back.

I don't know if this sheds any light on anything at all, but I thought I'd mentioned it.
Have you tried using AES input on your speakers?
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post #2695 of 3042 Old 04-11-2019, 05:35 AM
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I don't have any devices which would allow me to send a digital signal to that connection, no. And as mentioned earlier, the whine is regardless of anything being connected or not.

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2696 of 3042 Old 04-11-2019, 09:27 AM
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Originally Posted by Palewing View Post
I don't have any devices which would allow me to send a digital signal to that connection, no. And as mentioned earlier, the whine is regardless of anything being connected or not.

Have you tried using Star Quad balanced line level cable to feed the inputs? Canare L-46ES http://www.canare.com/ProductItemDis...oductItemID=53


It solved problems I had when working as a live sound FOH mixing engineer. Some venues have bad power, lights etc that cause noise problems. Star Quad cable works in some situations.
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post #2697 of 3042 Old 04-11-2019, 09:46 AM
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Originally Posted by Rex Anderson View Post
Have you tried using Star Quad balanced line level cable to feed the inputs? Canare L-46ES http://www.canare.com/ProductItemDis...oductItemID=53


It solved problems I had when working as a live sound FOH mixing engineer. Some venues have bad power, lights etc that cause noise problems. Star Quad cable works in some situations.
Why should using those cables change anything when the whine is there without any connections?

Audio Gear: Sennheiser HD 800 & HD 650, SPL Phonitor, Abrahamsen V6.0 DAC, JBL 705Ps, Dual VNF Arendal 1723 Subwoofer 1.
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post #2698 of 3042 Old 04-12-2019, 02:43 AM
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Quote:
Originally Posted by Kain View Post
Here is a recently posted, detailed, super positive review of the 708P: https://www.audiocircle.com/index.php?topic=162008.0
Interesting that he finds it hard to switch from his current setup partially because of amplifier. I've looked up what amp he has and sure thing it would be hard to switch from that amp to cheaper amps active JBLs have.
That is why "i" version looks more attractive to me, even with passive (with some digital correction) crossover, I can ask someone to make me nicer amplifier and still use advanced waveguide tech, etc.
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post #2699 of 3042 Old 04-12-2019, 04:57 AM
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Originally Posted by Palewing View Post
Why should using those cables change anything when the whine is there without any connections?

Sorry, I forgot that detail.
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post #2700 of 3042 Old 04-12-2019, 08:21 AM
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Originally Posted by andyc56 View Post
Assuming this is the case, I made up a filter file for Equalizer APO covering the two-wire case of the 708i. The Equalizer APO documentation states that its filter coefficient convention is the same as the REW generic filter option, which according to John Mulcahy uses "proportional Q" (the RBJ convention) for its PEQ filters. The Matlab (or Octave) code for the conversion to proportional Q is as below.

Code:
function Qp = calcQp(gain_dB, Qf)
    %CALCQP Computes proportional Q from gain and fixed Q
    Qp = Qf / sqrt(10^(abs(gain_dB) / 20));
end
I've attached a file jbl708i.txt which puts the required filters into L and R channels. One just does an "include" of this file to bring the filters in. The contents are as below.

Code:
Channel: L R
Preamp: -2.8 dB
Filter 1: ON HPQ Fc 40.0 Hz Q 0.95
Filter 2: ON PK Fc 71 Hz Gain -1.2 dB Q 0.69061
Filter 3: ON PK Fc 197.5 Hz Gain 1.1 dB Q 2.9098
Filter 4: ON PK Fc 393 Hz Gain -0.8 dB Q 3.4380
Filter 5: ON PK Fc 580 Hz Gain 2.8 dB Q 7.6773
Filter 6: ON PK Fc 50 Hz Gain 2.0 dB Q 0.28520
Filter 7: ON PK Fc 700 Hz Gain -0.5 dB Q 0.85503
To avoid digital domain clipping, there's an attenuation of 2.8 dB in front because of the boost of Filter 5.
@andyc56
Have you managed to make it work with your JBLs?
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