Genelec 8341A SAM™ Studio Monitor Review

[andreasmaaan]

@QMuse do you have links to any interesting papers on the audibility of pre-ringing? You seem to be more confident than I would be as to what is and isn't audible

I have one or two papers I can post when I get home later if you're interested, but based on research I'm familiar with, the issue is still pretty far from settled.

 

[QMuse]

@QMuse do you have links to any interesting papers on the audibility of pre-ringing? You seem to be more confident than I would be as to what is and isn't audible

I have one or two papers I can post when I get home later if you're interested, but based on research I'm familiar with, the issue is still pretty far from settled.

Unfortunately I don't have any, but I would gladly read yours so pls do post them.

I am confident only because I did blind test with 2 sets of filters for my speakers and it turned out that with these pre-ringing was audible:

.. but with these it was not:

 

[spacevector]

drink some more whiskey

Man all this talk of whiskey has made me thirsty and its not even 9am =(

 

[QMuse]

Man all this talk of whiskey has made me thirsty and its not even 9am =(

LOL

 

[Soniclife]

Has it been discussed yet how these coaxial speakers don't seem to have the on-axis dip problem, that fills on off axis? They just seem perfect in this respect.

 

[ctrl]

Devilant Reactor 900 max. SPL

That said... 80dB @1m - say 83 dB for stereo - seems much too low given my in-room measurements. That's ~73.5dB at my listening position with stereo speakers. So how am I getting ~96dB at 30Hz my listening position and 30Hz? Even factoring in room gain doesn't give me 23dB worth of extra bass... What am I missing?

the Reactor has a basically flat frequency response from 25Hz to 10+ kHz (based on the reasoning I just explained)

We can take this as a starting point for a theoretical calculation.

The two bass chassis of the Reactor 900 should be smaller then the size of a CD (12cm diameter) - maybe 0.1cm diameter. This results in a membrane area of 160 cm² (both chassis combined).
Don't really know the dimensions of the drivers, these are only assumptions.
If the drivers have a linear coil travel (p-p) of 10 mm, the "Volume of Displacement" (Vd in cm³) is 80 cm³.

The sound pressure for chassis in a closed cabinet with frequency f is:
SPL=20log(0.37 * f² * Vd)

This results in a maximum sound pressure level:
25 Hz => 85dB
30 Hz => 88.5dB
40 Hz => 93.5dB

Audio.de's measurements of the Reactor 900 thus seem to indicate a somewhat too low maximum sound pressure level - provided that my assumptions correspond to reality.

 

[JAP]

Is this a home setup? One issue I have with W371 is that it would place listening position higher than optimal with normal couch seating position. The unit itself is already 43 inches.

Yes it is. Tilting coax unit may be one option. Also listening height can be adjusted by chair. I will definitely consult Gelenec professionals how to set it up when the time comes.

 

[Pio2001]

The issue is that Devialet doesn't claim no audible pre-echo, they claim:

""The process is strictly causal and generates no pre-echo."

Hi, the discussion is going way too fast for me.
What "process" are they talking about ?

 

[QMuse]

Hi, the discussion is going way too fast for me.
What "process" are they talking about ?

Read more about it here.

 

[Pio2001]

They write

Similar to transfer function, this physical model is inverted in real time using digital signal processing technology before digital-analog conversion occurs. [...] A temporal process, SAM® runs on an open loop and without sensors. No changes to set-up are required. The process is strictly causal and generates no pre-echo.

They say that it is a DSP (Digital [signal] Processing).
"Open loop" loosely reminds of an IIR filter.
"Strictly causal" and "no pre-echo" confirms that they are talking about an IIR equalizer.

"Transfer function", "inverted in real-time", "temporal process" are just used here to impress the reader.
The DSP doesn't care if it "inverts" something. A process is always the inverse of another.
Any device, DSP or not, with an input and an output has a transfer function.
And the DSP doesn't care if the user decides to plot its transfer function in the time domain or in the frequency domain. It just produces its output according to its input.

However, if they want to correct the phase response of a bass reflex in addition to the amplitude response, they'll have to use FIR filters in addition to the minimal phase IIR filters (I guess that minimal phase filters are causal).
It can be done without introducing pre-echo as long as the phase response is properly corrected, so that the original signal is restored.

 

[andreasmaaan]

However, if they want to correct the phase response of a bass reflex in addition to the amplitude response, they'll have to use FIR filters in addition to the minimal phase IIR filters (I guess that minimal phase filters are causal).
It can be done without introducing pre-echo as long as the phase response is properly corrected, so that the original signal is restored.

Could you elaborate on how this can be done without introducing pre-echo, please?

Also interested to hear why you focus on BR boxes here, given sealed boxes also create an acoustical high-pass filter (2nd order as opposed to 4th order for BR).

 

[QMuse]

However, if they want to correct the phase response of a bass reflex in addition to the amplitude response, they'll have to use FIR filters in addition to the minimal phase IIR filters (I guess that minimal phase filters are causal).
It can be done without introducing pre-echo as long as the phase response is properly corrected, so that the original signal is restored.

Sure, minimal phase IIR filters are causal, so without any pre-ringing. But as soon as you touch the phase..

So, the million-dollar question seems to be how do you correct phase without introducing any pre-ringing visible in step response?

 

[andreasmaaan]

I have one or two papers I can post when I get home later if you're interested, but based on research I'm familiar with, the issue is still pretty far from settled.

Unfortunately I don't have any, but I would gladly read yours so pls do post them.

Looked again, there's really very little research that I can find. Try here and here. (I have many reservations about the methodology in these papers.)

 

[QMuse]

Looked again, there's really very little research that I can find. Try here and here. (I have many reservations about the methodology in these papers.)

Thank you!

 

[infinitesymphony]

Has it been discussed yet how these coaxial speakers don't seem to have the on-axis dip problem, that fills on off axis? They just seem perfect in this respect.

IIRC this is the reason behind the front baffle's waveguide design and the point source design in general:

"Dispersion is controlled over an unusually wide frequency range thanks to the large integrated waveguide and the hidden dual woofer design."

(taken from The Ones brochure)

 

[andreasmaaan]

Sure, minimal phase IIR filters are causal, so without any pre-ringing. But as soon as you touch phase..

So, the millin dollar question seem to be how you correct phase without introducing any pre-ringing visible in step response?

Ok, I simply misunderstood what "it" referred to in this sentence: "It can be done without introducing pre-echo as long as the phase response is properly corrected, so that the original signal is restored." I thought "it" referred to phase correction, but it referred to IIR filtering.

We are on the same page, asking the same million-dollar question

 

[bobbooo]

I have exactly that (cage bare and cage with absorber). I shared one of these samples as a quick check and it is posted here and got compared with no cage and with different settings. So I provided the context for that.

I'm a bit confused, does this mean you've done three measurements of the Genelec in total?

1. Test using exactly the same method as per the previous speakers (with mic cage, symmetrical option unchecked)
2. Test without the mic cage, symmetrical option unchecked (the measurements of which you've shown in the review)
3. Test without the mic cage, but with padding around the speaker, and symmetrical option checked

Is this correct? And is it the test results from method 1 above that you provided to @MZKM which he showed in this post, for which he calculated a preference score 0.5 points lower than the one for your review results (test 2 above)?

I don't think that is the case. The slight ripple here only matters when the speaker has very flat response. Otherwise it gets lost in the noise of high level of variations. This is why Klippel has not focused on fixing this problem even though they are well aware of it.

I'm not sure I follow the bit in bold. Is this what Klippel told you, or is this conjecture? (Or both?) I would have thought the original sound field from the speaker and the sound field from the reflections off the mic cage would superpose, with the resultant sound field measured by the mic being the sum of the two, meaning it could have at some frequencies an amplitude higher than the original sound from the speaker, ultimately resulting in the frequency response becoming more uneven. I don't really see how this would be any different for a speaker with non-flat frequency response - I would think it would just make an uneven response more uneven, and also erroneously affect the calculated preference rating, like we've seen it did with the Genelec.

If Klippel's not willing to test this, the only way to know for sure is for you to test a speaker with non-flat response twice - once as per your original Genelec measurements with the mic cage on, and again without the mic cage, and compare the difference/correction curve for these two measurements with the correction curve for the two Genelec measurements with and without the mic cage.

 

[briskly]

This results in a maximum sound pressure level

Seems to underestimate pressure by roughly half a decibel. This is the axial pressure characteristic of the piston on the plane, ignoring diffraction gain.

 

[infinitesymphony]

Speaking of questionable resonance:

 

[ctrl]

Devilant Reactor 900 max. SPL

Seems to underestimate pressure by roughly half a decibel. This is the axial pressure characteristic of the piston on the plane, ignoring diffraction gain.

Due to the translation/my bad English I cannot understand the train of thought. Can you describe this in more detail.


But thanks to your remark I have thought about the calculation again and think that it refers to chassis in half space.
For free field conditions you have to subtract 6dB from the results. The influence of the baffle can be ignored because of the Reactor 900's enclosure dimensions and the wavelengths under consideration:

SPL=20log(0.37 * f² * Vd)

So if this formula gives the half-space sound pressure, the results from Post#433 have to be corrected down by 6 dB:

This results in a corrected maximum sound pressure level under free-field conditions:
25 Hz => 79dB
30 Hz => 82.5dB
40 Hz => 87.5dB

Maybe someone can check if I am right this time.

Thus the measurements from Post#371 made by Audio.de correspond very well with the calculated maximum sound pressure.

The German "Audio magazine" (06-2019, audio.de) has measured the Reaktor 900. According to their statement, the low bass remains up to about 80dB@1m. A limiter prevents higher sound pressure for the low bass (everything below 40Hz).
At 85dB the limiter starts at about 50Hz, at 90dB a bit higher again about 60Hz.