Technics Premium Class SB-C700 loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the Technics SB-C700's frequency response in the farfield; for nearfield frequency response, I used an Earthworks QTC-40, which has a ¼" capsule and thus doesn't present a significant obstacle to the sound.

The SB-C700's voltage sensitivity is specified as 85dB/2.83V/m. My estimate was usefully higher than this, at 87.5dB/2.83V/m. The speaker's nominal impedance is 4 ohms, but as fig.1 shows, the impedance magnitude drops below 4 ohms only in a narrow band in the lower midrange, reaching a minimum value of 3.5 ohms at 215Hz. I would classify the Technics as a 6 ohm load, though there is a combination of 4.9 ohms and a 41° electrical phase angle at 145Hz, suggesting that tube amplifiers would work best from their 4 ohm output transformer taps.

Fig.1 Technics SB-C700, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

Other than a very slight wrinkle at 600Hz, the impedance traces are free of the discontinuities that would suggest the presence of enclosure resonances. When I investigated the cabinet's vibrational behavior with a plastic-tape accelerometer, I did indeed find a low-level mode at 600Hz that was present on the top and sidewalls. However, the strongest mode on the top was at 492Hz (fig.2). Given the small radiating area, I doubt that this mode would lead to any sense of midrange congestion.

Fig.2 Technics SB-C700, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of top panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

The saddle between 45Hz and 55Hz in the impedance-magnitude trace suggests that the 2"-diameter port on the rear panel is tuned to this region. The blue trace in fig.3, which shows the nearfield output of the woofer, confirms this tuning, as it has a well-defined notch at 48Hz. (This notch is due to the backpressure from the port resonance holding the woofer diaphragm stationary.) The port output itself (fig.3, red trace) peaks in textbook fashion between 40 and 60Hz, and its upper-frequency rolloff is clean. The black trace below 300Hz in fig.3 shows the complex sum of the woofer and port nearfield responses. The broad peak between 70 and 300Hz is entirely an artifact of the nearfield measurement technique, the SB-C700's low frequencies extending at full level to below 80Hz, with the output down by 6dB at the port-tuning frequency and rolling off with the usual 24dB/octave slope below that frequency.

Fig.3 Technics SB-C700, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with nearfield responses of woofer (blue), port (red), and their complex sum (black), respectively plotted below 300Hz, 620Hz, and 300Hz.

Higher in frequency in fig.3, the black trace shows the Technics' quasi-anechoic response on its tweeter axis at 50", averaged across a 30° horizontal window. The response on this axis is impressively even, though a slight rising trend can be seen up to 10kHz. The SB-C700's lateral radiation pattern (fig.4) and vertical radiation pattern (fig.5), both referenced to the tweeter-axis response, indicate that the speaker's dispersion is wide and even up to 10kHz in both planes. Above that frequency there are the usual peaks and dips off axis, due to the tweeter being positioned in the center of the woofer diaphragm, but these will not affect the speaker's tonal quality.

Fig.4 Technics SB-C700, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

Fig.5 Technics SB-C700, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 45–5° above axis, reference response, differences in response 5–45° below axis.

Turning to the time domain, the Technics' step response on the tweeter axis (fig.6) reveals that both drive-units are connected in positive acoustic polarity and that the tweeter's output leads that of the woofer. However, the seamless blend between the decay of the tweeter's step and the start of the woofer's step implies optimal crossover design. The cumulative spectral-decay plot (fig.7) is impressively clean.

Fig.6 Technics SB-C700, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.7 Technics SB-C700, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

The Technics SB-C700's measured performance reveals some excellent audio engineering from an unexpected source. I am not surprised HR liked it.—John Atkinson

COMPANY INFO
Technics, Panasonic Corporation of North America
Two Riverfront Plaza
Newark, NJ 07102-5490
(800) 211-7262
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COMMENTS
AllanMarcus's picture

"effulgent hypersaturated musical hues"
why does that sound like something an Oenophile would say?

JoeinNC's picture

Pretension is apparently their hallmark.

K.Reid's picture

If the KEF LS50 is Class A sound, then it is only appropriate to classify the Technics as such. I had an extended listening session and they are every bit the bargain the KEFs are. Properly set up as Herb describes and, frankly, they leave the KEFs in the dust dynamically. Simply fantastic for the price. I really hope they can get the "street cred" they so deserve.

Steve C's picture

I had some Technics speakers back in the late 70's that were time aligned. Got them while I was stationed in the Azores, hooked up to a Kenwood integrated with a Thorens TT. Very nice overall sound. Wish I could remember the model #. Glad to see a comeback.

avanti1960's picture

At the end of the day it is difficult to eliminate distortion and maintain clarity / dispersion when a 6-1/2" woofer mates to a tweeter. Even the best 6-1/2" woofers typically begin breaking up at (and most certainly after) the lowest comfortable crossover point of a tweeter. Monitors with 5-1/2" woofers have the capability to be more transparent and with less distortion in the crossover region because of the smaller woofer.
I wish Stereophile would measure and publish harmonic distortion results with their speaker reviews.

Xyriut's picture

Totally agreed.

TJ's picture

... you could try Neumann KH-120 recording studio monitors with 100 watts of bi-amped class AB power, balanced inputs, plus an onboard DSP for ruler flat frequency response and rear panel EQ options. After ~200 hrs of break-in (electrolytic caps), the sound and imaging are exceptional. Any chance for a Stereophile review?

Russell Dawkins's picture

to see the extent to which the conclusions of this review differ from those in the What hi*fi review, brief though it is.
http://www.whathifi.com/technics/sb-c700/review

I guess, as usual, a personal audition is the answer.

crenca's picture

I auditioned these speakers at a well known dealer about a month ago. I can't recall the amp (though I remember it being a SS unit costing about $8k). I could only stand them for about 5 minutes. The treble had an overly forward/bright texture that sounded very "metallic" and "brassy" to me. It truly skewed the music. Within the first few seconds I was quizzing the dealer assuming he was applying an eccentric EQ (he was not). Now, I admit that I prefer an accurate treble presentation that is not overly bright (I had just been listening to GoldenEar's products through a Rougue Audio Spinx and that sounded like "real" music to me) but this was off the charts.

Is it sample differences? Are they really sensitive to what they are matched with concerning amplification? Can Mr. Herb Reichert hear anything above 5k? Like you say, always audition them for yourself...

K.Reid's picture

You speak nothing about the room you auditioned them in, positioning (feet from front wall and side wall) associated equipment, cabling, etc. Did you ask the salesman how long they were in house and break in time. Give some details. Just because you auditioned with an 8K amp is no guarantee of a good match. The salesman should have demo the speakers with Technics new integrated amp which sounds fabulous.

I had a very lengthy listening session with a well broken in pair. Room was about 12ft wide by 20ft length. Ceiling was 8ft. All Technics set up with their music server and integrated amp. Cabling was Shunyata. Speakers were about 4ft out from front wall pointing straight with no toe in. Holly Cole Temption, Christy Baron and classical pieces sounded great. I think definitely Class A (restricted low frequency). The treble was fine and detailed and most certainly not bright or strident. I too like an accurate treble presentation and this was spot on. They really do exceed the KEF LS50 in performance. If Herb could not hear anything above 5K he would not be a professional reviewer for Stereophile. Clearly, there was something wrong in your dealer's presentation.

crenca's picture

For example, could perfecting room placement (a few feet here or there) really have changed the fundamental character of the treble I heard? Sure, it could have changed it some, but what I heard was beyond (way beyond) room placement tweaks, cables, break in, etc. Besides the dealer I heard them at (name withheld on purpose) is well known, respected, and uses cables that are priced/respected well beyond what I pay for. The room/positioning was a high end (treated, etc) listening room - it might not have been set up specifically for these speakers but it is no concrete floored wharehouse either.

Now, the amplification might have been a complete mismatch, and I admit that - but even if this were true I tend to believe it probably does not account for everything I heard...probably not...

So, giving the dealer and myself the benefit of the doubt (that neither of us are not complete morons) what can account for the differences between our experiences (that it was more or less in line with what the "whathifi" review described as "harshness") and your's and Herb's?

Possibly it's amplification. If that is the case, these speakers are sensitive to that to strong degree I think. Sample differences? I tend to think this is probably the main culprit.

However, I have noticed that there are many in the "audiophile" world who like a forward/emphasized/"detailed" treble presentation that I simply don't like as I find it very unnatural to what acoustic instruments sound like live. Perhaps this in combination with sample differences (with a little amplification mismatch) leads to this very diverse evaluation???

I am open to other ideas...

K.Reid's picture

Don't be afraid to give the name of the dealer. I am curious to see who it was. There are many great dealers such as Overture AV, Innovative Audio Video, Lyric, Hanson and others. I will ask again, what brand name and model amplifier did you demo with? In terms of the speakers I still think it may have been a bad sample, amp mismatch or a pair that was not broken in. This speaker must be given plenty of break in time...and that matters a good degree with these monitors. Furthermore, it will easily point out bad recordings or less than great upstream equipment. It is not a forgiving speaker. I suggest you go to another dealer for a listen with Technics integrated amplifier and make certain they have had substantial use.

Also, JA can give them to another reviewer...say Art Dudley to get his second opinion. Properly set up and demonstrated, the speakers are fabulous.

K.Reid's picture

Steve Guttenburg has a contrary opinion on CNET.com. He loved the Technics. Perhaps What HiFi had bad sample. I had read that "so called" review and thought to myself what that they must have been a bad sample. Go listen yourself to the complete Technics system with well broken in pair placed out from the front wall. I think you will be impressed.

Ayre conditioned's picture

JA didn't listen to these speakers, as he sometimes does. Maybe he could have offered some more insight.

K.Reid's picture

JA may do a follow-up, who knows. I think it is a good idea. I have no doubt that if I were choosing between the KEF LS50 and the Technics SB-C700, my money would go to the latter - based on my time with them.

John Atkinson's picture
Ayre conditioned wrote:
I wonder why JA didn't listen to these speakers, as he sometimes does.

I didn't have time to listen to the Technics speakers in my room, I am afraid. However, Herb still has the review samples, so the opportunity might present itself.

Ayre conditioned wrote:
Maybe he could have offered some more insight.

One thing I didn't emphasize sufficiently is that the SB-C700's low-frequency alignment is maximally flat instead of featuring the upper-bass bump so often found in small speakers. They will therefore work better in small rooms. The larger the room, the leaner they might sound.

John Atkinson
Editor, Stereophile

K.Reid's picture

John, you may not recall that we spoke about this monitor at an event held at Innovative Audio in NYC recently where Peter McGrath of Wilson Audio was demonstrating the Alexandria XLF. Guttenburg and Chesky were there as well all discussing MQA and recording methods. I let you know that I had been impressed with the Technics and you informed me that one of your staff had reviewed the them and to look for it in the January issue.

Notwithstanding the above, I think that it would be a good idea for you to give these monitors an extended listen. I think Herb's review was spot on. Though the LS50 is no slouch, these just outperform them in many areas in a small to medium sized room provided they are properly set up with good associated equipment.

K.Reid's picture

If you want to read what other listeners have said about the speaker Google the speaker name/model and Audio Asylum forum and you will see mostly positive comments.

JGP's picture

Sure, we all have our opinions; however, I typically find those posted by users that have never owned that which they are quick to comment about (in respect to sound quality, value, and such) - is a bit jaded and unfounded. In other words, "hog-wash"...

Now, to my point - The SB-C700 are exceptional speakers in their price point. They do an exceptional job at bringing the best out of a good "front end" and amplifier. Very transparent, extremely convincing bottom end, and "boy do they image". With a late night session, particularly well recorded "new-age" music, you'll find yourself looking off to the left and the right trying to tell yourself "it's really coming from in front of me...from that little pair of speakers". These bookshelves play very nice indeed.

I've owned quite a few speakers in my day, like probably most of you...Anything from a good-ol' pair of Dynaco A25's to "art-like" Gallo Reference 3.1's. Some of my favorites, interestingly enough, were not the most expensive - in fact, some of these were the near opposite. These "bargain musical champions" would include the Rega RS3, PSB Imagine B, Acoustic Zen Adago (perhaps a bit more expensive), and these little Technics monitors. I'll call them monitors because they verge on the edge of just that due to their uncolored nature, easy drive, and holographic sounds.

The point is, some speakers just do a very good job at making you smile. Not just because your finding yourself rediscovering your favorite music, but - because you still have money in your pocket to continue doing just that.

These are the real deal.

K.Reid's picture

Just keep in mind that many are able to formulate an opinion on sound quality right away depending on their experience level listening to high end speakers and associated audio equipment. An initial impression can be formulated relatively quickly.

And I have owned the Technics SBC700 for a while now for a couple years now.

Brodie_McChoad's picture

I know that's not the standard bearer for "scientific" reviews, but it's pretty hard to get a ONE-STAR review and that's exactly what this Technics speaker did. So it's very polarizing at the least - even judging by comments here. I will make it a point to listen to them if I get a chance, but I find myself doubting that they truly outperform the LS50s that they appear to be at least in part trying to copy.

Brodie_McChoad's picture

Or "class" it seems like you might be compensating for something else.

jlwu's picture

Got a chance to audition the Technics R1 in Panasonic's Technics showroom in Osaka. Was mighty impressed but very reluctant to shell out that kind of money for a pair of speakers that likely wont hold their value like Wilsons or Focals.

The opportunity to own it's smaller sibling presented itself and I went for it. Initially I tried them with a Tenor OTL amp and positioned them way into the room thinking that they would image well based in the text-book rule of 1/3s. What I got was "overly forward/bright texture that sounded very "metallic" and "brassy"". Took them upstairs and placed them very close to the front wall and they started to sing at the expense of exaggerated bass.

Finally put them back in the main listening room again and push them back to about 24" from the front wall. Also switched amplifiers to a 45W class A solid state amp. That's when magic happened. Everything became smooth, coherent, musical and yes! That ghostly imaging.

I should have read the manual instead of using my jaded audiophile instincts. it reads " the distance between
the speakers and the front wall, which should be between 30 cm to 60 cm ....the distance between the
speakers and the side walls should be greater than 60 cm. "

RTFM...

OK1's picture

I enjoyed reading this review, and it was definitely a different kind of review from the UK's What-HiFi Magazine review. Clearly the What HiFi reviewers have bit of a different user base and market, who prefer a more colored presentation rather than this straight as a ruler translation of the Technics, which is what I prefer - give me without the frills, I can handle the truth.

It was interesting how you referred to this as very much like a studio monitor, and this works better for me. More and more of us use the same set of speakers for both playback of music, as well as playing music or creating music, and for this I would prefer a ruler flat frequency response, from the speaker, and especially since more of us play music back through computers and personal digital playback devices, there are options like Sonarworks, and other forms of eq, which we can use to artificially color the sound, to our taste. So we have the salt shaker, and no longer have to completely depend on the cooks(speaker manufacturers) to take an intelligent guess of our personal tastes in frequency preferences.

Or if we have an integrated amp, that's what the tone controls are for - to color to our taste and our room, as the last icing on the cake.

Thanks also for introducing me to a diverse set of reference tracks that I would typically never have come across. With the exception of the Bob Marley Exodus, the other tracks were all new to me.

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