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Technics SB-C700 Review (Coaxial Bookshelf)

Rate this speaker:

  • 1. Poor (headless panther)

    Votes: 6 2.5%
  • 2. Not terrible (postman panther)

    Votes: 27 11.3%
  • 3. Fine (happy panther)

    Votes: 144 60.5%
  • 4. Great (golfing panther)

    Votes: 61 25.6%

  • Total voters
    238

don'ttrustauthority

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The biggest problem of 2-way coaxials is anyway not the changing of the directivity for the tweeter but rather the higher IMD due to their reduced membrane surface of the midwoofer compared to a conventional one of the same outer diameter.
Why would it have reduced membrane surface?
 

staticV3

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Why would it have reduced membrane surface?
Because there's a tweeter in the middle of the woofer.
Technics SB-C700 Review coaxial bookshelf speaker.jpg
 

don'ttrustauthority

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But, at the same time, a few posts up, you just told us:

"I have an amp that measures as close to perfect as is possible. It has so little coloration that the sound is unbearably sterile. It just won't reproduce music with any involvement"

That comes off sounding, how do I say it without sounding rude......A bit non-sensical?
How is that non-sensical? Makes perfect sense. Absent the musicians in the room, you kind of have to involve yourself.
 

fineMen

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Well as said, that is your experience and preference, mine is different, ... my SPL needs they are all enough and for the other listening system all need sub for my needs.
It is a 3 way.

Yep, the R3 is three-way. It uses another variant of the coax, with way better midrange performance.

I just want to reiterate my personal, subjective impression, that the frequency range around 150Hz +/- one octave or so makes a big difference regarding clarity of sound. The C700 performs sub-par, even in comparison to equivalent sized conventional speakers.

I don't know why people accept up to 30% of intermodulation distorsion, 10% being the rule for moderate levels (76dB) when using 5"..7" drivers. I confirmed Erin's findings with my own measurements: 10% in the midrange is common for bookshelf speakers.

The C700, at least without sub, addresses a market segment, which doen't comprise the serious stereo lover. My 2cc
 

thewas

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I don't know why people accept up to 30% of intermodulation distorsion, 10% being the rule for moderate levels (76dB) when using 5"..7" drivers
Could you please upload or link to the corresponding measurements?
Now about your above question, for me because they do better in other aspects which are more important/audible to me for my usage cases, as said other people's mileages may vary.
 

Larry B. Larabee

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Take a look at the specs for this review of the JBL 4309 2-way speaker. $2000/pair!
This speaker was recommended? I fail to see how that is possible based on the horrible measurements, which begs the question what is to be objectively learned from any of these reviews when something like this can happen with no reasonable explanation provided for it?
 

Jmudrick

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Yep, the R3 is three-way. It uses another variant of the coax, with way better midrange performance.

I just want to reiterate my personal, subjective impression, that the frequency range around 150Hz +/- one octave or so makes a big difference regarding clarity of sound. The C700 performs sub-par, even in comparison to equivalent sized conventional speakers.

I don't know why people accept up to 30% of intermodulation distorsion, 10% being the rule for moderate levels (76dB) when using 5"..7" drivers. I confirmed Erin's findings with my own measurements: 10% in the midrange is common for bookshelf speakers.

The C700, at least without sub, addresses a market segment, which doen't comprise the serious stereo lover. My 2cc

Not all serious listening requires 96db levels . Serious stereo listeners would be using this with subs unless their listening was limited to music not requiring full range playback I would think. In my use I'll see 92db orchestral peaks, two subs, high passed 80hz.
 
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fineMen

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Could you please upload or link to the corresponding measurements?

You may want to lookup Erin's driver tests. While SB Acoustics or Purify perform so and so--see down below the IM graphs, the well renown Dynaudio generates the desired IM at moderate levels, despite being an 8" mid/woof. Especially the lower mids are enriched by IM at way lower levels of bass content.

In another table Doppler is considered, theshold at 20% or so, reached at 22mm of excursion, hence way beyond mechanical destruction. But, as far as I know, the Doppler is linear. To keep IM of Doppler type below 1%, which I would consider close to not bearable anymore, the excursion should not exceed 1mm. That's not that much.

Why is it, that people accept so much IM? Because the concept is a bit more complicated than HD, maybe.

Not all serious listening requires 96db levels . Serious stereo listeners ...

Sure! I not only recently got to listen to quite unusual musical content, though. Standard music, as often used for tests and then after to entertain guests isn't as sensitive to a flattening out of short spikes in amplitude with howling noises. Overprocessed as it is anyway. I don't speak the word of highend-ish blahblahblah. It is the feel of a vanishing loudspeaker not only in stereo-imagery, but in very aspect from white sheet tonality to rock solid dynamics, again all in every frequency range without any exception. Just no flaw to be unconciously excused. Of course it adjusts the focus on inherent draw-backs in the priciples of stereo recording/mixing itself ;-)

In a nutshell: remember non-linear distortion as a relevant workfield

Add.: an ethusiast should have a measuring microphone; measure the IM of a 80Hz tone with a simultanously played 1kHz tone; repeat with a 2kHz tone; comments are appreciated

The IM of specifically a coax, namely woofer cone moving, tweet radiating through it, as was mentioned here several times, isn't the thing, it's the IM itself everywhere ;-)
 
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thewas

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You may want to lookup Erin's driver tests.
I don't see a IMD test? https://www.erinsaudiocorner.com/driveunits/kef-ls50-drive-unit/
Also be careful measuring pure drivers as the reflex port of a complete loudspeaker significantly reduces distortion and IMD level due to the minimisation of the oscillation amplitude of the woofer at its operation range.

In another table Doppler is considered, theshold at 20% or so, reached at 22mm of excursion, hence way beyond mechanical destruction. But, as far as I know, the Doppler is linear. To keep IM of Doppler type below 1%, which I would consider close to not bearable anymore, the excursion should not exceed 1mm. That's not that much.

Why is it, that people accept so much IM? Because the concept is a bit more complicated than HD, maybe.
The reasons I wrote, also theory is nice but let's look at some real measurements, 2 modern such loudspeakers, a 5" coax and a 5" conventional one at similar total SPL (one is 3dB less) levels, I drew a reference line at 1% of the total level of each:

1644447965830.png



1644448038536.png


I don't see any clear advantage of the non-coaxial, rather the opposite.

I not only recently got to listen to quite unusual musical content, though. Standard music, as often used for tests and then after to entertain guests isn't as sensitive to a flattening out of short spikes in amplitude with howling noises.
I agree, but interestingly mainly listen to EDM and Jazz which belong to the most demanding genres regarding dynamics and bass level.

Add.: an ethusiast should have a measuring microphone; measure the IM of a 80Hz tone with a simultanously played 1kHz tone; repeat with a 2kHz tone; comments are appreciated
I also agree there and personally use even my own made noise signal which is shaped like in the EIA-426B standard, here for example of my ex large 3-way JBL 4312SE, would you like to share your own ones too?

1644448494988.png
 
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heflys20

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I recall when people asked Amir to measure IMD.

 

Xyrium

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Panasonic is one of those companies that resists adoption of western technology like Hypex unless they have no choice. Way too much pride in what their own engineers can do than to go and license something like that.
I can appreciate that, for certain. I have insane respect for companies who stay focused, especially on quality. I can't recall, but wasn't it Panasonic who created the BASH amps, kind of a mix of Class D and A/B?

They certainly made this beast:
 

fineMen

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I recall when people asked Amir to measure IMD.

Problem is, there is no useful standard (see below). If the objective is to represent a cross section of the market, how to integrate such data? Inventing an own standard, which wouldn't get ridiculed by other advisors is a hard thing to do.


As said, for the recent SB Acoustics, Purify and Dynaudio the data is there.

Problem with multitone is the unrealistically low volume per frequency! So the IM barely raises beyond the noise floor. Same with HD--in the multitone plot, which proves the point, I think.

The same with Your marking, as You said, "@1%". This doesn't look right. If You take the 90dB (first chart) as a reference, then You have to integrate over the full spectrum of IM/HD/noise ;-)

If You would refer to roughly 75dB level of the individual tones, the blue line for 1% would sit at (75-40)dB = 35dB. For the LS50 meta it would be below the range of the chart then: (70-40)dB = 30dB. Tons of IM product well above 1%, right? Spot on in the precious midrange, still at only 70dB, if there were only a few tones, like with a solo instrument or a duett ... and still the LS50, not equalized for flat refuses to represent bass with full volume as it is tilted hard at 80Hz or so?

As said, a tad more complicated this is ...

Not to forget: Your JBL 4312SE--good one! Three way! Big bass! Reasonably sized midrange! JBL! (just kidding)
 
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thewas

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As said, for the recent SB Acoustics, Purify and Dynaudio the data is there.
That doesn't help when we want to compare with coaxial and also as said doesn't take into consideration the IMD reduction due to a port loading.

If You would refer to roughly 75dB level of the individual tones, the blue line for 1% would sit at (75-40)dB = 35dB. For the LS50 meta it would be below the range of the chart then: (70-40)dB = 30dB. Tons of IM product well above 1%, right?
We can dispute which level is which and what is audible, but what really matters is that the plots show that the IMD of the LS50 isn't really worse then the comparable non-coaxial B&W (it actually seems even better) which is opposite to your initial statement.

Not to forget: Your JBL 4312SE--good one! Three way! Big bass! Reasonably sized midrange! JBL! (just kidding)
And I still preferred my LS50s and sold those after some time, so like you say:
a tad more complicated this is ...
 

fineMen

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That doesn't help when we want to compare with coaxial and also as said doesn't take into consideration the IMD reduction due to a port loading.
...
We can dispute which level is which and what is audible, but what really matters is that the plots show that the IMD of the LS50 isn't really worse ...

My objective isn't to discriminate coax versus conventional. To the contrary; I suggest to not focus on the objectively measurable IM from woofer cone movement versus tweeter radiation. I suggest to focus on IM as a common phenomenon instead for all such tiny speakers. My 'panther' was "just fine",. The speaker is suitable for occasional background music as a life-style product for people of lower interest in music as an artform. Well better than the next alternative, namely Bose, I assume.

As we don't agree on how to read the graphs, we won't finally conclude. I'm actually more interested in quantitatively backed-up discussion, than in in parts speculative qualitatve discussions. My contribution so far is as was already said twice, sorry.
 

thewas

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I suggest to not focus on the objectively measurable IM from woofer cone movement versus tweeter radiation. I suggest to focus on IM as a common phenomenon instead for all such tiny speakers.
Well you brought the IM measurements into the discussion "I don't know why people accept up to 30% of intermodulation distorsion, 10% being the rule for moderate levels (76dB) when using 5"..7" drivers. I confirmed Erin's findings with my own measurements: 10% in the midrange is common for bookshelf speakers." but when asked to show some of those measurements you drew back.
The speaker is suitable for occasional background music as a life-style product for people of lower interest in music as an artform. Well better than the next alternative, namely Bose, I assume.
Nah, those Technics and Kefs are worse than a kitchen radio and all owners and reviewers (both are the only below $3000 loudspeakers in the Stereophile A rankings) are just deaf dilettantes which just have "lower interest in music as an artform"...
 

Jmudrick

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Well you brought the IM measurements into the discussion "I don't know why people accept up to 30% of intermodulation distorsion, 10% being the rule for moderate levels (76dB) when using 5"..7" drivers. I confirmed Erin's findings with my own measurements: 10% in the midrange is common for bookshelf speakers." but when asked to show some of those measurements you drew back.

Nah, those Technics and Kefs are worse than a kitchen radio and all owners and reviewers (both are the only below $3000 loudspeakers in the Stereophile A rankings) are just deaf dilettantes which just have "lower interest in music as an artform"...
Thank you
 

heflys20

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The speaker is suitable for occasional background music as a life-style product for people of lower interest in music as an artform. Well better than the next alternative, namely Bose, I assume.
Well, that was a bit condescending. Lol.
 

fineMen

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Well, that was a bit condescending. Lol.

I don't feel so. Depends, maybe. Look, I was miserable enough to start my musical education with Arnold Schoenberg. That guy on school was an indisposed composer by education, the teacher of us. Don't automatically think of 'music as an artform' as something good.

Regarding snobbism, there are alternatives: Genelec, Neuman etc active, ..., etc. for the same price, guys!

Just one other word regarding the plots of IM using multitone excitation, see post #191.

The blue line is wrong, as I already stated in post #194.

The actual distortion (IM + HD) of the first two samples is about 3% 5%++ with just 65 to 75dB high spectral lines (k.e.f worse, slightly). Consider the case of a bass plus female voice. Even single spectral lines would generate the same percentage of IM, but wouldn't be as loud as the stated 90dB--sorry, can't explain any further; shall be clear to educated people anyway, sorry.

The JBL below generates only a thenth of that (level unknown, sigh ...), maybe even less due to random noise in the measurement.

If You don't accept that difference as relevant, there You go.

Case closed me thinks.
 
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