What is the sound difference in the 170/340?

[MikeQ]

What is the difference in sound in two speakers.

Seem like the 340 would just be louder?

[bikeman]

This was posted by Dave F. in an earlier thread.


It is certainly OK to prefer the CBM-170 over the 340 main… both speakers were designed for specific purposes and what sounds best to you is purely subjective.

From a technical standpoint, the CMT-340 is superior… The CBM-170 uses a single high performance woofer while the 340 uses two. In any loudspeaker, distortion increases as output increases. Depending on how you look at it, the 340 has the capability to deliver either twice the output of the CBM-170 at the same distortion level, or close to half the distortion at the same output level.

The tweeter used in the CMT-340 is also technically superior, having lower distortion, a lower resonance frequency and extended high frequency response.

We actually post a very revealing graph on our website called the cumulative spectral decay. This is seldom understood, but still a highly important measurement. This is a measurement of a fast impulse consisting of thousands of frequencies ranging from 400Hz to 20Khz. What the graph reveals is what “noise” is left over once the initial impulse stops (in milliseconds). Notice on the 340 graph that there is very little (if any) artifacts left over after 1.92 ms past 2kHz (this is really amazing actually). On the CBM-170, there are artifacts between 2kHz and 5kHz almost reaching 3.5ms (about half that of the 340, which is still, quite good). Also you might notice more artifacts in the high frequency region as well..


CMT-340 cumulative spectral decay


CBM-170 cumulative spectral decay

From a purely objective perspective, the 340 is a more transparent, more revealing speaker and I believe this is what you might be hearing…

Hope this helps! __________________
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[MikeQ]

Ok, then...in my little comparison can I apply the above to mean that the 170's will rival the Paradigm Mini Monitors and the 340's will rival the Monitor 7?

I compare them because from a price point they are about the same. (Getting deal on the 7's and no need for stand makes them a dead heat on price)

Granted I have not heard the Ascend yet but my hope is that one of you can offer a comparison...

FYI, I have the 170's ordered for an in-home next week and plan on takeing them to the Paradigm shop to do a side by side...

[Mag_Neato]

The 170's have been compared to the Studio 20's. See Nicholas Mosher's posts regarding his 5.1 170 setup!

Except for lower bass and a slightly better tweeter(in Nick's opinion), overall he prefered the 170's for their more balanced, natural sound.

[millerwill]

I have had a pair of 170's for my L/R fronts (along with a 340C center) for about a month. I liked the sound very much, but did get the itch to see if the 340M's would be any better. I thus decided to swallow the shipping costs and give them a try; they arrived yesterday, and I set them up last night. Even with this very brief experience so far, I really do like the 340's better. I don't play them any louder (the 170's were plenty loud for my small/medium room of ~ 2200 cu ft), but they just produce a more eveloping sound, a fullness that the 170's don't have. I suppose it's the two drivers that does this (at 64, my higher frequency hearing has probably deteriated enough that the benefit of the better tweeter is lost on me!). And I don't detect any of the 'sibilance' that some people have commented on with the 340M's; again, maybe this is my insensitivity to higher frequencies. (My hearing is actually quite normal, I think, but when I do frequency sweeps with AVIA, etc., I can really hear it fall off above 8 to 10 kilohertz.) Anyway, this is my experience.

PS My AVR is the Pioneer 1014. Since it is usually characterized as 'warm', maybe that minimizes any 'sibilance'.

[bikeman]

The 170's have been compared to the Studio 20's. See Nicholas Mosher's posts regarding his 5.1 170 setup!

Except for lower bass and a slightly better tweeter(in Nick's opinion), overall he prefered the 170's for their more balanced, natural sound.

When I was speaker shopping, I compared the 340's to the Studio 40's. I prefered the 340's but the Studio 40's were no slouch. I would have been happy either way. My wallet was much happier with the 340's.

David

[Nicholas Mosher]

I have a question for Dave F (hopefully he'll answer here). I asked this question before, but I think he mis-understood my poor wording. I'll try again though.

Looking at those spectral decays, the "floor" is at two different levels. The floor for the 340s is at -42dB, while the floor for the 170s is at -48dB. This gives the graphic effect of 6dB higher peaks with the 170s. I'm curious if Dave has similar visuals with equal floors of say -42dB or -48dB.

I'm also curious about Dave's measured FR of the 170s vs 340s. Using 88dB as a reference, the 340's response has a a ~3dB hump @ 1.5kHz, and a ~3dB null @ 2kHz. The null then rises to roughly a 5dB peak at ~11kHz, which is that ear-piercing frequency. I'm wondering why this is a more accurate response than the 170s, which is nearly flat within +/-1dB it seems.

The tweeter seems to be further from the midrange driver, and the 340 is a larger speaker w/an MTM configuration and larger speaker face. I thought these things decreased off-axis frequency response? If you look at the off-axis frequency response of the 340 vs 170, the 340's looks much choppier to my eyes (could be reading it wrong though).

I understand the speaker is more sensitive, the tweeter has greater HF extension, and with two 6.5" drivers there is less distortion, but I'm not seeing (from the measurements atleast) how the 340 has a more accurate response than their little brothers. I'd like to see spectral decays with equal floors of course too. I should probably simply order a pair to compare with my 170s...

Anyhoo, just some things I'm thinking as I read this thread.

[curtis]

DaveF will have to answer all the other stuff......

But, I don't think anybody said the 340 is a more accurate speaker. FR is only one aspect of a much bigger picture.

[curtis]

BTW, last year, I got a chance to hear a pair of CBM-170's that had the crossover's modified by a well know DIY crossover guy. Although I did not see measurements, the claim was that the speaker had a flat FR just like the original.

That said, the speaker did not sound like the original....it was very easy to hear the difference. It didn't sound bad, but it was not the CBM-170 that most of us know.

[davef]

Hi Nicholas,

Happy to answer your questions....

I have a question for Dave F (hopefully he'll answer here). I asked this question before, but I think he mis-understood my poor wording. I'll try again though.

Looking at those spectral decays, the "floor" is at two different levels. The floor for the 340s is at -42dB, while the floor for the 170s is at -48dB. This gives the graphic effect of 6dB higher peaks with the 170s. I'm curious if Dave has similar visuals with equal floors of say -42dB or -48dB.

Actually, I did answer this in that original thread. Here was my original response

"You will notice on the graphs that the dB "scale" is the same... The amount of power fed to each speaker doesn't matter as this graph is time based and the results are normalized. No matter how much power I feed the speaker (up until compression begins) the results would be the same. The measurement equipment will automatically set the range of the dB axis so that the fundamental (the initial response) will fit inside the window. The fundamental is the first "slice" you see at 0 ms. Keep in mind that the CMT-340 is about 3dB more efficient than the CBM-170. "

In retrospect, and perhaps an easier way to explain it, each "slice" you see is in comparison to the fundamental slice (the first slice) which is the initial impulse. The dB level really means nothing at all. This is a visual display of sound vs. time... amplitude really has no meaning at all as each slice is measured at a specific time, and then calculated based on the fundamental. It is somewhat complicated, but shouldn't be too difficult to grasp (I've tried to explain it as best I can)

I'm also curious about Dave's measured FR of the 170s vs 340s. Using 88dB as a reference, the 340's response has a a ~3dB hump @ 1.5kHz, and a ~3dB null @ 2kHz. The null then rises to roughly a 5dB peak at ~11kHz, which is that ear-piercing frequency. I'm wondering why this is a more accurate response than the 170s, which is nearly flat within +/-1dB it seems.

Actually using 88dB as a reference, it is a 2.5dB peak at 1.5 kHz and a 2.5dB dip (or commonly called knee) at 3 kHz. Notice that the peak and the dip are exactly an octave apart? This peak and then subsequent dip is caused by the tweeters response reflecting off of the woofers. It is a simple cabinet reflection.

The null then rises to roughly a 5dB peak at ~11kHz, which is that ear-piercing frequency.

Not quite sure what you are looking at here... The response at 11 kHz is 90dB, which is only 2dB higher than reference level. The 4dB peak you see is at 18 kHz... quite inaudible actually.

Nicholas, how many frequency response measurements of loudspeakers have you actually seen? Trust me when I say that while not as ruler flat as the CBM-170 (it can't be, it uses more drivers) the response of the 340m is remarkably flat for a 3 driver loudspeaker. This is the danger of posting measurements and why all but a select few manufacturers care to do so.

The tweeter seems to be further from the midrange driver, and the 340 is a larger speaker w/an MTM configuration and larger speaker face. I thought these things decreased off-axis frequency response? If you look at the off-axis frequency response of the 340 vs 170, the 340's looks much choppier to my eyes (could be reading it wrong though).

Nicholas, I am not quite sure where you are getting your information from..

The 340 main was designed to take advantage of what an MTM design offers... The advantage of a properly configured MTM (not necessarily a D'Appolito) is controlled vertical dispersion. Careful contouring of vertical dispersion minimizes the effects of the first and (in most cases) 2nd reflections. First reflection being the response of the speaker bouncing off the floor (floor bounce), 2nd reflection (or 3rd, depending on the room) is reflections off the ceiling. Minimizing the effects of these reflections has been proven time and time again to enhance the clarity and detail of mids and highs.. No driver orientation does this better than a vertical MTM.

The 340 main was designed for exceptionally wide horizontal dispersion. The smaller baffle width of the CMT-340 (compared to the CBM-170), as well as a much wider dispersion tweeter contribute to this (as do several other features). Vertical spacing distance between drivers that are vertically aligned does not affect horizontal dispersion.

I understand the speaker is more sensitive, the tweeter has greater HF extension, and with two 6.5" drivers there is less distortion, but I'm not seeing (from the measurements atleast) how the 340 has a more accurate response than their little brothers.

The definition of an accurate response is the ability to reproduce the source material as accurately as possible. I have never said the 340 main's frequency response measures "flatter" then a CBM-170. There are many, many more factors involved in what an accurate response is (distortion, minimizing room boundary effects, phase alignment, transient response...)

I'd like to see spectral decays with equal floors of course too

As I explained earlier.. that is pointless. The graph is a cumulative spectral decay, cumulative meaning each slice is based on the previous slice, which is all referenced to the fundamental slice. The point of the graph is to show how quickly sound decays and reveal any resonances... dB level (amplitude) is quite meaningless when comparing one speaker's graph to another (provided they are different speakers).

Hope this explains things, I really tried my best here to make these concepts easy to understand.