JBL 708P Review (Professional Monitor)

[Robbo99999]

I think this review took me about a minute to read - there's that little wrong with the speaker, and hence very little to say about it!

 

[thewas]

Filter 5: ON PK Fc 2295 Hz Gain +2.51 dB Q 12.00

Mind you that positive PEQ cause ringing in time domain which can be audible especially at higher Qs and such higher frequencies which is something that the Harman score doesn't take into account:
https://support.genelec.com/hc/en-u...-does-GLM-not-fix-dips-on-frequency-response-
Which is also obvious when taking into account that those are DSP loudspeakers, so if all problems could be fully corrected by DSP the experienced engineers who tuned them would have already done so.

 

[Robbo99999]

Yeah, looking back at the JBL LSR308P MkII review, it's clear that JBL might be eating its own lunch with that model at an 85% discount versus the 708P. The 308P MkII has smoother in-room response and better directivity, and the only sacrifice appears to be a bit more distortion.

Good point, and measured distortion (THD) of my JBL 308p at my max listening levels is below 1% across the whole frequency range, although I got a bit torn apart by posting this in another thread, so take my results as you will, I think some people find them questionable:

That's 2 speakers measured at 2m distance at about 83dB, which happens to be my absolute max listening level.

 

[LeftCoastTim]

I own the 708 as the 308p (gen1) and the KH80.

They are all excellent speakers. Maybe I'm not sensitive to the small ripples in FR as other people maybe. I have played with Harman's "How to Listen" software and have managed to distinguish 7 frequency bands reliably.

What makes a big difference for me is the wide dispersion. The 708 and 308 both are much easier to live with, as the sound does not change as you move away from the center. The KH80 is perfect for a desktop setup (no hiss), but at twice the cost of the 308s (and much less space

The bang-for-buck factor of the 308p is simply obscene. They were my first foray into Floyd Toole design speakers, and I haven't looked back since. One could get serious hi-fi quality speakers without exotic price or materials. The 708s play much louder and cleaner, which is why I upgraded.

I love all of them.

 

[3125b]

Now with this and the Neumann KH 310 A (wich objectively did better than the JBL) reviewed, I'd really like to see how the Genelec 8350 APM does.

 

[sweetchaos]

Nicely done @pierre
Thank you for publicly publishing your calculated PEQ profile for others to try.
Keep it up!

 

[daftcombo]

Thanks Amir!
Does the 705p hiss? Is it worse than 305p mk2 ?

 

[Matias]

They do react very well to EQ. If you push a bit the number of PEQs, you get a score of 6.7 which is as good as Genelec 8341.

Eq is:

EQ for JBL 708P computed from ASR data
Preference Score 5.0 with EQ 6.7
Generated from http://github.com/pierreaubert/spinorama/generate_peqs.py v0.4
Dated: 2021-02-02-07:53:25

Preamp: -1.1 dB

Filter  1: ON PK Fc  1126 Hz Gain -3.77 dB Q 0.10
Filter  2: ON LS Fc  1961 Hz Gain +2.87 dB
Filter  3: ON PK Fc   905 Hz Gain -3.77 dB Q 4.41
Filter  4: ON PK Fc 14315 Hz Gain -4.04 dB Q 1.43
Filter  5: ON PK Fc  2295 Hz Gain +2.51 dB Q 12.00
Filter  6: ON LS Fc   509 Hz Gain -1.70 dB
Filter  7: ON PK Fc  7169 Hz Gain -1.59 dB Q 4.17
Filter  8: ON PK Fc 10339 Hz Gain +1.01 dB Q 4.57
Filter  9: ON PK Fc  4385 Hz Gain +0.92 dB Q 11.35
Filter 10: ON PK Fc   667 Hz Gain -1.31 dB Q 12.00
Filter 11: ON PK Fc   607 Hz Gain +2.47 dB Q 12.00
Filter 12: ON PK Fc   752 Hz Gain +1.48 dB Q 12.00
Filter 13: ON PK Fc  1562 Hz Gain +1.58 dB Q 12.00
Filter 14: ON PK Fc  5357 Hz Gain -0.54 dB Q 6.56
Filter 15: ON PK Fc  2494 Hz Gain -0.62 dB Q 12.00
Filter 16: ON PK Fc  1134 Hz Gain +0.80 dB Q 12.00
Filter 17: ON PK Fc   644 Hz Gain -1.77 dB Q 12.00
Filter 18: ON PK Fc  2742 Hz Gain +1.12 dB Q 12.00
Filter 19: ON PK Fc  1937 Hz Gain +0.91 dB Q 12.00
Filter 20: ON PK Fc  1759 Hz Gain -0.93 dB Q 12.00

The PEQs are not sorted by frequency on purpose. You can cut the filter where you want, the most effective PEQ being at the beginning.
Here is how the score evolved per iteration. For example, with 7 PEQs you get a score of 6.04.
After peq 5 you start to see a lot of high Q PEQs which are smoothing the frequency (and then boosting the score) but they may not be that audible.

(pid=98842) ITER  LOSS SCORE -----------------------------------------------------
(pid=98842)    0 +722.43 +4.97
(pid=98842)    1 +13.52 +4.34
(pid=98842)    2 +8.23 +5.23
(pid=98842)    3 +13.93 +5.34
(pid=98842)    4 +8.69 +5.80
(pid=98842)    5 +9.03 +5.91
(pid=98842)    6 +7.84 +5.93
(pid=98842)    7 +6.56 +6.04
(pid=98842)    8 +6.65 +6.03
(pid=98842)    9 +6.27 +6.09
(pid=98842)   10 +6.07 +6.15
(pid=98842)   11 +5.32 +6.23
(pid=98842)   12 +5.34 +6.36
(pid=98842)   13 +5.04 +6.52
(pid=98842)   14 +4.94 +6.54
(pid=98842)   15 +4.98 +6.56
(pid=98842)   16 +4.88 +6.58
(pid=98842)   17 +4.48 +6.58
(pid=98842)   18 +4.05 +6.65
(pid=98842)   19 +3.92 +6.71
(pid=98842)   20 +3.70 +6.72
(pid=98842)   21 +3.70 +6.72

View attachment 110058

and then the EQ version:

View attachment 110059

What is the target tilt for estimated room responses? 13 dB from 20 to 20 kHz?

 

[restorer-john]

JBL claim to have 2 channel amplification for these speakers with a 250W amplifier for the LF and a 250W amplifier for the HF. Clearly they understand the importance of having equal capability power delivery across the audible spectrum, unlike many other companies who economise on the HF amps. Not that a single tweeter compression driver voicecoil could absorb 1/4kW for long...

@amirm most interesting review! The menu/selector wheel reminds me of my Canon EOS cameras. Do they have captive nuts/mounts on the bottom for standmounting BTW?

 

[daftcombo]

JBL claim to have 2 channel amplification for these speakers with a 250W amplifier for the LF and a 250W amplifier for the HF. Clearly they understand the importance of having equal capability power delivery across the audible spectrum, unlike many other companies who economise on the HF amps. Not that a single tweeter compression driver voicecoil could absorb 1/4kW for long...

Can you explain why it is important? I don't understand why a tweeter should ever need 250W.

 

[Doodski]

JBL claim to have 2 channel amplification for these speakers with a 250W amplifier for the LF and a 250W amplifier for the HF. Clearly they understand the importance of having equal capability power delivery across the audible spectrum, unlike many other companies who economise on the HF amps. Not that a single tweeter compression driver voicecoil could absorb 1/4kW for long...

@amirm most interesting review! The menu/selector wheel reminds me of my Canon EOS cameras. Do they have captive nuts/mounts on the bottom for standmounting BTW?

 

[MZKM]

Yet the preference rating of the 308 is so much higher to nearly clear the range where you'd expect one to prefer it rather conclusively.

I think better max SPL (less bass distortion) is a main factor. Also, the 308P has the PIR starting to slope down at around 200Hz, whereas this 708P is around 100Hz, so bass could be heard as louder. This 708P also has wider directivity (which Amir probably prefers, but reduces it‘s score).

And again, the preference rating is for far-field listening. The near/mid field listening that these monitors are typically used for will cause some inaccuracy with the score.

 

[LearningToSmile]

Thanks Amir!
Does the 705p hiss? Is it worse than 305p mk2 ?

I'm also interested, though I'm assuming it doesn't at this price range. Do compression drivers even have hiss issues? I have no experience with them.

Now with this and the Neumann KH 310 A (wich objectively did better than the JBL) reviewed, I'd really like to see how the Genelec 8350 APM does.

Yeah, same - those are the prime candidates for me if I ever want to get an endgame upgrade from my 308p's. Interesting that with a quick look at sweetwater(not sure if they sell at MSRP), the JBL is by far the cheapest at $1799, followed by KH310A at $2200 and the 8350A at $2399 - but here in Europe if I take a look at local pro audio retailer I've used before it's ~$2050 for the Neumann's, followed by ~$2280 for the Genelecs and with the JBL selling for a whopping ~$2340. I guess it makes sense with Genelec and Neumann being European brands, but I didn't expect this much of a difference on the JBLs.

 

[BDWoody]

Do they have captive nuts/mounts on the bottom for standmounting BTW?

Top and bottom.

Great review!

I've been nothing but happy with mine.

There isn't a sub out, but it does let you pass AES/EBU through it, and you can set lowpass crossover, so a sub could just get in the line somewhere.

It also offers a bit of internal EQ available through that menu on the back.

I haven't seen these on B-Stock sale for a while... Maybe some early failures led to an oversupply? No idea, I just know for the $1k B-Stock price, I don't know where I'll find better value.

Yes 250wx250w per speaker means I almost never see that little red clip light.

Oh...I did put tape over the spotlight on the front. Very worthwhile mod.

 

[pma]

Can you explain why it is important? I don't understand why a tweeter should ever need 250W.

Because the short peaks are not impossible. And where is the crossover frequency? At 1.7kHz!! You will have full energy up to 5kHz. It seems to me many of you guys just do not understand what you speak about.

 

[daftcombo]

Because the short peaks are not impossible. And where is the crossover frequency? At 1.7kHz!! You will have full energy up to 5kHz. It seems to me many of you guys just do not understand what you speak about.

That was the reason of my question: learning.

 

[Pearljam5000]

Impressive, I wonder how they compare to 8050B

 

[pma]

Just for info, it is a popular belief that energy in music generally follows 1/f distribution. However, it is not true in general. I am posting 2 spectra of
1) Beethoven No.2 symphony, first 11 minutes
2) Dukes of Dixieland vinyl, mid sixties, track No. 1
The spectra are cumulative in a peak hold mode. We can see that Beethoven has full energy up to some 1.5kHz. And the Dixieland has plenty of energy up to 4kHz, because of brass instruments.
It was/is an usual mistake in speaker design to have power rating of midrange driver lower than the bass driver. In fact, the midrange driver is the most loaded one.

More in a scientific paper
[1] Overley, J.P.: Energy Distribution in Music, IRE Transactions on Audio, 09-10, 1956

 

[YSC]

Looked nice, but for a dsp speaker I am a bit disappointed by the FR flatness don’t match those of kh80 dsp

 

[respice finem]

Anyone got a reason as to why companies bother making drivers do anything beyond 20kHz in this sector? I get perhaps if you're using singal generators to output some odd sounds in some scientific field. But 36kHz? I don't get it.

There are many more Hi-Fi enthusiasts than pros buying upper class studio monitors, I guess. There is a German saying that goes: "why will a dog lick his balls? - because he can" The marketing dept. has a nice point od sales etc. Similar to having 100M pixels in a phone camera (or was it 200?). Or amps with frequency response touching the long wave radio spectrum (with funny side effects sometimes). Ken Ishiwata once in the good old days of Marantz had called this "popular technology" - spot on IMHO.