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I read a lot of people saying hey, this DP has twice the power of that one, that's why it sounds so much better! Even got a salesman pull that one on me at the store. So I would like to post this to clarify to everyone the common misconception of what power rating means and why DP with more power sounds better (do they really?)

There is NOT a big difference in power rating between the higher end and the lower end. Let's take a look at a doubling of power in the case of the Yamaha CLP-340 v CLP-330 or Roland HP207 v HP203. The way amplication power is rated, every doubling of amplication power provides a 3 dB increase in volume. How much is 3 dB? Not very much. Human hearing could barely perceive a 1 dB change, so 3 dB is just a little. (If you have a stereo receiver with dB readout for volume, try this test of changing the volume by 3 dB. Yup, that's the difference in doubling the power. Shockingly little.)

Normal listen volume requires about 1W at -30 dB. (Yeah, only 1W.) 2W provides -27 dB.

4W -24 dB
8W -21 dB
16W -18 dB
32W -15 dB
64W -12 dB

The difference between -18 dB and -15 dB is pretty loud to a tad louder. That's all. Dealers like to point at things like amp power rate (40W v. 20W) and say look double! Well, double means a 3 dB difference.

The reason why a high end DP sound better than the low end is wholly dependent on type of speakers used not because of power. If you have the speakers of the CLP-340/HP207, it will sound just as good at 10W, which is pretty loud. The reason is, these higher end models have 2-way speakers. In today's world, you would think a pair of decent 2-way speakers could be had for $200 (cost of $20 to make), so why do DP costing $2,000 or more only have 1-way speakers? DP makers also routinely claim their DP have 4 speakers instead of a pair of 2-way speakers to boost their marketing value. A pair of 2-way speakers? My cheapo home theater-in-a-box comes with 5 pairs of 2-way speakers. I guess I could say it has 10 speaker!

I digress. The point is, 2-way speakers will always sound much better than 1-way speakers, and it has nothing to do with power. Put the 2-way speakers of the HP207 in the HP203, and the HP203 will sound the same as the HP207 without changing the power amp. The same goes with the CLP-370/340. Put those speakers in the CLP-330/320 and the the CLP330/320 will sound the same as the CLP-370/340 regardless of the fact that the CLP330 only has a 20W amp. It's irrelevant. Don't get sucked into the numbers game.

One way around this game is to buy the model with the very nice GH3 / PHA-II w/escapemt and provide your own speakers. I have this http://www.cambridgesoundworks.com/store/category.cgi?category=mul_spk_csw&item=1100001246 left over from an old PC and they sound great, way better than the speakers in the HP203. It even has a sub and it's loud! Just hook it up to the second headphone jack. Now your HP203 or CLP-330 will sound as good or better as the next model up with a simple $99 upgrade.

(I can just see all the, "but the xxx has 4-layer sampling..." Well, I compared the CLP-370 and CLP-S308 side by side and honestly, the 370 with its 4-layers doesn't sound better. Actually, the CLP-S308 sounded better with its 3-layers sampling since it's got better speaker design.)

Thanks for that post. Many folks do have a tendency to get caught up in numbers (which is precisely why the manufacturers do that ).

That said, I would also caution about simply automatically assuming that a 2 way speaker will outperform a single driver speaker (or that a 3 way will outperform a 2 way). As you allude to, there are other factors that are in play.

Really what a prospective buyer needs to do is to simply do the ultimate test, listen with your ears. Like 4evrbgner mentions strengths in one area can make up for "weaknesses" in others (and vice versa). His final statement about the difference between the 370 and S308 should be tempered though in that the 4 layers can make a difference with headphones and recording through line out.

I've always thought of the wattage ratings on digital pianos as being like the MPG rating on a new car. Take it with a grain of salt.

I absolutely agree on the speaker comments. Building a great instrument like the HP-203 and then not spending another $5 for a pair of tweeters is almost a crime. It really would make a difference.

On the amp side, one reason why the higher wattage is nice is to avoid clipping (i.e. distortion) on sudden volume peaks. Piano is very percussive and peaky, so the extra wattage headroom can improve the sound, even if the total increase in volume isn't so much. Ans some cheaper DPs have very small amps, which really are marginally loud (and/or distortion-prone).

On a similar topic, I should perhaps point out that not all digital piano manufacturers adhere to the same THD (Total Harmonic Distortion) level when listing the Output Power specification of their instruments.

Kind regards,
James
x

Yeah, THD issues when rating is obviously an issue as most amps would deliver more watts at 1 KHz than across the board. My comments must be used to compare same make/brand, but it is not reliable to compare Yamaha's 40W with Roland's 30W or Kawai's ratings. This is complicated by makers not releasing spec on speaker resistance (ohms), which drastically alter measured amp power. I didn't want to complicate things with a lot of caveats.

IMO all the DP makers purposefully make the mid and lower end products sound worse in order to steer the consumer to the top end. Otherwise, having heard what a HP203 / CLP330 would sound like with 2-way speakers and 40W amps (both are dirt cheap to add these days) few would pay for the other features in the HP207 / CLP340.

It's a typical business strategy the same way Microsoft turns off featues from Windows Premium and force people to pay more to get it even though it actually cost a lot more just to maintain a separate Windows Basic SKU on a product that's identical with manufacturing cost that is practically the same. It is just a way to increase revenue stream.

4evrBeginR,
Let me add my "second" to your reference to the Cambridge Soundworks 3-piece speaker systems. I have 2 of those systems--the $99 one (which I picked up at Goodwill for $10 long ago) and the 80 Watt total system now on sale for about $150. I still have the little old system hooked to the DP, as apparently you do, and it is more than satisfactory for my small practice room. I think the gain control on the bass unit is essential--it seems like the DP's output to its small speakers is biased to the bottom end. I cut mine back to the minimum.

I will agree that comparing specifications is not the way to select a digital piano. They don't always tell the tale needed to be told.

4evr,
Where did you come up with your formula 2 x X watts = +3dB? I have never heard/read this before.

That said, anyone that cannot hear and appreciate the difference between the Yamaha CLP340 and CLP330 doen't have much of an ear.

Higher end digital pianos can feature 500 watt sound systems while the lower end start with 10-20 watts. Quite a spread to negate out of hand the benifits of more powerful sound systems.

The benifit of higher power sound systems is not greater volume (although it is there) is about the greater texture and detail you hear in the music. It is true about sterio systems and even more evident in digital piano sound.

Some manufacturers of digital pianos are blessed with the opportunity to used their own purpose designed amplifiers, cross over circuitry, and speakers in their instruments. They often achieve great effeciencies and greater performance over those companies who buy off the shelf components from vendors and lash them up.

In the newest Larry Fine opus there is an interesting presentation of how many watts of power it takes to recreate certain traditional dynamic levels on a grand piano. I had never seen/heard this discussion, but tried out examples and found it most interesting. Following 4evr's logic and formula LF is all wet, which is dangerous around electronics.

That's standard engineering mathematics.

It's been around since the invention of the vacuum tube. Read any literature on the amplication of sound published in the last 75 years.



Yes, because the CLP340 has a two-way speaker (5cm+16cm) and the CLP330 has a one-way speaker (16cm). All the frequencies cannot be well handled by a single 16cm driver. Power has nothing to do with why the 330 sound worse.



There is no such thing as a 500 watt sound system. Adding all channels together is cheating and does not count. Yes, I could negate it out of hand because a 20 or 30 watt system would be enough for piano if the makers would only include better speakers in the low end. They don't because they don't want their low end to sound good.



Incorrect. Higher power is preciously equal to higher volume. Texture and detail is the result of higher volume. More power do not provide better sound. Better speakers provide better sound. This is the most common misconception and the whole reason I wrote the original post to begin with.



I have two Yamaha pianos, so I like them a lot, but you have been drinking too much Yamaha-coolaid, my friend.



I've never read Fine's book, so can't comment. Please providing proper citing of Fine's work including power to dB requirements, otherwise, what's the point of mentioning it?

4evr - the discussion of audio systems Marty is referring to is on page 113 of Piano Buyer in the Digital Piano Basics article. The intent is to give the average buyer (not EEs) an overview the the subject.

That said, I'm genuinely interested in your take on the subject.

You can access the online edition at http://pianobuyer.com/

Cheers,
Alden

Folks make misguided assumptions based on numbers, not only with wattage, but even things like speaker qty and size. Two amps of the same wattage can sound completely different from a quality perspective. Two speakers of the same size can sound completely different from a quality perspective. When it comes to a DP, the numbers are neigh on irrelevant. Unlike a home audio system, where one will be mixing and matching components, thereby making knowledge of the various numbers more meaningful, the only thing that really counts on a DP in the end is how the whole system sounds, irrespective of any numbers. We won't even go into how the size/shape/material/placement of the speaker enclosures themselves have a huge impact on the quality of the sound.

BTW, did you really mean to say that higher volume equals more texture and detail? While a higher volume may allow our ears to pick up the texture and details easier, I would think that this link is again secondary to the parts (amp, speakers) being able to properly reproduce them.

All important points. On page 111 I put in *A cautionary note* against the temptation to rank instruments by their numbers. The two introductory articles on DPs should provide buyers with an understanding of what the numbers may or may not mean and help them determine the relative importance of different characteristics for their needs.

I believe there is merit in Marty's comment about higher power contributing to greater clarity in that the additional power can allow for some *headroom* for sonic details that may have been clipped by a lower-powered amp. Perhaps a scope trace of a waveform driven into clipping would be useful.

I welcome suggestions on clarifications and topics for subsequent issues.

Cheers,
Alden

Don't we need to be careful when we say "details"? It's usually the bass that needs all that power, so even a rather modest wattage amp can produce great mid to high details (how well it does it has more to do with factors that wattage alone can't quantify). The biggest concern is that while having a higher wattage can provide for more headroom, there is no way to really quantify the quality of that "power" based on simple wattage. You might get that deep bass feel in your gut, but if it sounds like someone playing a 20' piano in a 1000sqft foam lined room, then who cares?

Reminds me a bit of my youth when I had a nice car stereo (pickup in this case). My system didn't have the raw thump or ear bleeding volumes as others. Instead I chose higher quality amps and smaller but "faster" woofers (hey, I was a classical and opera head even back then). So from a numbers perspective I was way behind the "other guys", but I would easily say that my system sounded far superior than the majority of those systems, unless of course your idea of superior is measured in SPL

If I were recommending what to look for in a DP, I would omit any mention of wattage and speakers, from a numbers perspective, completely. Instead, I think it's far more useful to suggest methods to test the "extremes" to listen for the audible cues to what a good system should sound like. Play a fortissimo bass chord and with the sustain pedal play a treble chord. Can you hear the high notes, does it sound like mush? Set the volume so you can barely hear your most pianissimo, then play as loud as you can, is it loud enough? Play as loud as you can and find the point where you get audible distortion, is the volume at 90%, 60%, 40%? Those are things off the top of my head and I'm sure others can pipe in with more.

I've purchased four DP's in my lifetime, from low end Casio's to higher end Yammies. The first one I purchased and I knew literally 0 about pianos (acoustic or digitals). The last one was about a year ago and I knew a lot more. In all instances though, not once did I care about the wattage, how many, or what kind of speakers a system had, in the end it was all about the end product, the sound.

Now if you want to talk home stereos, that is another issue entirely

Thanks for this post. But I guess every consumer should really know how to assess a good salesman from a good sales talk. I do not know if one can even manage to draw the line. Sometimes a good salesman is bound to do a good sales talk even if it means selling words and not the product itself. Again, consumers need to be wise these days.

I always take wattage with a massive pinch of salt. It is the sensitivity of the speakers that also matters. The higher the sensitivity of the speakers, the lower the wattage needed to get a higher volume. something I have never seen quoted when comparing dps.

I agree with bitWrangler, try it and see if it is loud enough for you and ignore the spiel.



Andy T

Yes, very true....

You are spot on with this. Freqencies from a single piano do not consume power the way full on orchestra would. There is little chance of driving anything to clippng because all DP makers severely limit the volume control. Headroom is there. There are no tweeters to blow here (DP's do not employ tweeters - smallest 5cm speakers are not tweeters). That's why it's OK to crank the volume on a DP to max and not lose all your speakers within minutes.

In the Yamaha line:
The CLP380, CLP280, CLP270, CLP240 have 1.0" tweeters.
The CLP265GP have 1.1" tweeters.
The CLP295GP, DGX630, CVP409GP, CVP409, CVP407 have 1.2" tweeters.
The YPG635, YPG625 have 1.3" tweeters.

bitW - I have to agree on being careful with the use of "details" as many people seem to feel that detail implies only upper freqs. Maybe definition is a better term? As for leaving out power figures, I lean towards including them but hope people will read the tutorial and gain some understanding of what effect they may or may not have.

4evr - my definition of DPs includes "ensemble" models which go *way* beyond piano voices. As for clipping, I've personally driven DPs into clipping. I'll be limiting mine to 80%.

I think of a driver as a tweeter based on the frequencies it produces rather than its size. Anything specializing in spectrum much north of 3kHz is a tweeter in my mind.