Technics SB-C700 Review (Coaxial Bookshelf)

[Larry B. Larabee]

Its acting as a variable waveguide

The technics has a flat diaphram. The effects you show may not apply to this speaker.

 

[thewas]

The technics has a flat diaphram. The effects you show may not apply to this speaker.

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.

 

[Thomas_A]

Both Revel m105 and m106 seems to have a peak around 4,5 kHz . I have tested to set such a peak with my 8340 with the help of GLM , and listening to music with two loudspeakers in stereo, the sound gets a little better . However, there is no gain in sound quality with this peak using only one loudspeaker.
…so , in my opinion, the search for the holy grail regarding stereo system compensation is indeed at 1-2 kHz, but more important, also somewhere between 4,5 - 8 kHz. Do you agree on that ?

I have lately made measurements on the Linn akudorik exakt dsp loudspeaker, a 4-way high end loudspeaker, and with my line audio om1 mic measuring only one speaker from 1 metre, on axis and 20 degree off axis, they have a similar peak as the Revels at 4,5 kHz, otherwise very flat.

I believe that the troubled sound with coaxials in full range use, has the problem with the bass acting as a variable waveguide, modulating the tweeter and making directivity worse.

Technics SB-C700 Review (Coaxial Bookshelf)

I can understand from a visual point of view why coaxial designs are so popular. Using a coaxial driver fullrange is however not a very good idea for good sound. The sound gonna be worse than the measurements shows because of the bassdriver modulating the tweeter like a variable waveguide when...

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The dip 1-2 kHz (Shirley et al) can only be partly compensated for by reflections. The speaker in this review has rather low power at 1-2 kHz at wider angles. On-axis a dip 2-4 kHz and 7-8 kHz is then required to dampen the stereo errors. Which is not found with this Technics speaker.

 

[Geert]

Revel sounds much better mainly because its not a coaxial design- my five cents.

In the first place the Revel sounds better because of the extended low end and lack of a low-mid bump, as the measurements indicate. Potential modulation of directivity is far less important, and the effect depends on the situation. There are full range coaxials that sound very good.

 

[Tangband]

In the first place the Revel sounds better because of the extended low end and lack of a low-mid bump, as the measurements indicate. Potential modulation of directivity is far less important, and the effect depends on the situation. There are full range coaxials that sound very good.

I dont agree - havent heard one ( yet )

 

[Larry B. Larabee]

What is your definition of "Bias"? It seem what you are explaining is preference, or taste. If someone, after looking at the measurment would pretend to prefer the most neutral one because the measurment told them that's what should be preffered, that would be bias, If someone would choose to prefer the Technics because "If the measurments are interpreted correctly... the Technic is a better speaker in every conceivable way", that would be bias. Modulating what you prefer based on the measurments you see is the very definition of Bias.

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 much like the technics. Describing what's wrong with the amp other than the vague description I just mentioned there is nothing that can be pinpointed about the sound character because it doesn't have any. For that reason I would probably prefer the revel for listening and prefer the technics if I wanted accurate, sterile, boring reproduction.

 

[Tangband]

The dip 1-2 kHz (Shirley et al) can only be partly compensated for by reflections. The speaker in this review has rather low power at 1-2 kHz at wider angles. On-axis a dip 2-4 kHz and 7-8 kHz is then required to dampen the stereo errors. Which is not found with this Technics speaker.

With a loudspeaker with very good directivity , the frequency response measured on axis with only one loudspeaker thats made for stereo-use is gonna look like the opposite of this then ? :
Revel m105 for comparison.

 

[Larry B. Larabee]

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.

I can't tell if the tweeter is taking up any more surface area than a typical dust cap. Are you saying if the woofer were larger the increased membrane surface would solve the IMD problem? Larger than what?

 

[Thomas_A]

With a loudspeaker with very good directivity , the frequency response measured on axis with only one loudspeaker thats made for stereo-use is gonna look the opposite like this then ? :

View attachment 184606

Not exactly. The dip at 1.8 kHz can only be compensated for by more energy at larger angles. But then yes on-axis dip of 1-1,5 dB around 3-3,5 kHz and at 7-8 kHz should be fine. Not more.

 

[thewas]

I can't tell if the tweeter is taking up any more surface area than a typical dust cap.

On most current woofers the dust cap is not fixed (which is usually called phase plug) but part of the moving membrane, thus the larger surface.

 

[Tangband]

Not exactly. The dip at 1.8 kHz can only be compensated for by more energy at larger angles. But then yes on-axis dip of 1-1,5 dB around 3-3,5 kHz and at 7-8 kHz should be fine. Not more.

To go back to my own findings - I guess a dip of 1,5 dB around 3-3,5 kHz and a dip -1,5 dB at 7-8 kHz produce almost the same result as a single low Q peak from 4,5 kHz - 8 kHz + 1,5 dB ? This is the findings in GLM I have found sounding best with a loudspeaker used for stereo listening.

 

[PeteL]

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 much like the technics. Describing what's wrong with the amp other than the vague description I just mentioned there is nothing that can be pinpointed about the sound character because it doesn't have any. For that reason I would probably prefer the revel for listening and prefer the technics if I wanted accurate, sterile, boring reproduction.

OK but you said: "The technics is a better speaker than the revel in every conceivable way. That the review states otherwise is a problem unlikely to be resolved". How is it a problem exactly about the fact that Amir prefer the Revel?

 

[Thomas_A]

To go back to my own findings - I guess a dip of 1,5 dB around 3-3,5 kHz and a dip -1,5 dB at 7-8 kHz produce almost the same result as a single low Q peak from 4,5 kHs - 8 kHz + 1,5 dB ?

Approximate yes. I would say the Revel 4,5 kHz peak may not be as aggressive as it looks as it is more attenuated in the average listening window.

 

[TurtlePaul]

Interesting that Amir brought up the mids. I was thinking that I would bring down the 4k to 10k energy by 2-3 dB to achieve a steaper in room response. It seems that the problem is where the tweeter gets wider just above the crossover. I wounder if padding out the tweeter another few ohms would have fixed this.

 

[tomtoo]

So? Reading a lot of reviews, iam standing infront of Zero.


The tune tot much woerse measuring speakers sound better?
So the spinnorama tells us not so much? That makes things very complicated.

 

[Geert]

I dont agree - havent heard one ( yet )

This is not about agreeing, it's about understanding which attributes determine the sound of a speaker and to what extent. If you believe directivity modulation is more important than 3dB differences in frequency response, than tell me why Amirm concluded the speaker sound very nice after EQ-ing.

 

[Larry B. Larabee]

How is it a problem exactly about the fact that Amir prefer the Revel?

The problem is Amir is giving us his subjective opinion about the products tested. It's just that in this case I'm saying in terms of accuracy his opinion about the Revel being better is dead wrong.

 

[beagleman]

The problem is Amir is giving us his subjective opinion about the products tested. It's just that in this case I'm saying in terms of accuracy his opinion about the Revel being better is dead wrong.

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?

 

[Larry B. Larabee]

What I like and accuracy are two completely different things.
The point is the C700 deserves an unqualified recommendation. Anyone in his right mind can see that.

 

[beagleman]

What I like and accuracy are two completely different things.
The point is the C700 deserves an unqualified recommendation. Anyone in his right mind can see that.

Perhaps your amplifier example, was not the best way to express that?

I do somewhat agree,(the speaker) it has some great characteristics, but without hearing it, not "Sure" how much it would appeal to me in real life.

I would "hate" to see how my ideal speakers (to me anyways) measure up, if I could ever send them across country. I think what I think is neutral and flat, probably would not be....