Powered Speaker solution for Digital Pianos

Hello Mate and welcome to this forum,

I am glad you are happy with your speakers.  May you enjoy a long, healthy listening relationship with them.

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With your being a relatively new person to this forum (5 posts at the time of this writing), I do not intend to sound rude to you, nor to slam any given manufacturer [EDIT: without due cause].

With this stated as a prelude, I believe the facts should be made known about this product, based on information collected from the website offered in the initial thread:

Caveat Emptor!

Upon going to their website, I checked out the frequency response of the Model ST50P powered monitors to see what they meant by a frequency response of 45-20kHz -- it is unusual for a company to publicize frequency response without also specifying a +/- tolerance for the sound pressure level.

Most manufacturers of top-quality speakers/monitors specify the frequency response within a +/-3dB range.  Sometimes, in order to extend the apparent frequency response, a less-than-forthright company will report frequency response within a +/-6dB range.  At the same time, some companies use time- or 1/3 octave averaging to make their products' frequency responses look "smoother" than they actually are.

In light of the above, here is what I gleaned from the publicized frequency response (without their stating whether this was white noise, pink noise, a swept sine wave response, etc.):

The company did employ some sort of "smoothing" to present its data, as represented by curved lines between specific data points.  The did not state whether the data were collected in an anechoic chamber (to minimize room reflection effects and possibly improve the apparent frequency response).  They also presented their data in 10db vertical increments so as to partially conceal the apparently wide responses in sound pressure level (SPL).

Now, if we were to believe the smoothed curve, the frequency response within +/- 3dB  (a 6dB spread, which btw is equivalent to a change in 4 times the amplifier output) would be on the order of between only 200 and 5kHz!  If we were to open up the tolerance to +/- 6dB (a 12dB spread), the frequency response would be "extended" to include about 90 to 5kHz!

No wonder the manufacturer stated frequency response as 45-20kHz without mentioning the spread in loudness -- otherwise they would have to publish AT LEAST +/- 12dB!! (at least a 24dB spread!)

Now, if they would have published the range from 20-20kHz, the tolerance is a whopping +/-18dB, or approximately a spread of 36+dB (*).  Please recall this wide spread in frequency response is on a "smoothed" curve, of which the manufacturer did not state how the data were accumulated.  I am assuming this curve represents the best of their product.

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Now, if you are happy with the way Pianoteq performs on these speakers, you are certainly entitled to say so.  At the same time, if you are somehow affiliated with the manufacturer -- and you chose not to represent that fact, then I would caution everyone to beware of any product they are prospectively purchasing, whether it is this product or from some other manufacturer.

Cheers,

Joe

(*) On Amplifier Power output:
A difference in 3dB in sound pressure level requires a doubling (or halving) of amplifier output.  A difference of 6dB SPL represents a quadrupling of amplifier power; a difference in 12dB represents of multiplying the amplifier output by 4 x 4 or 16 times.  If we continue upward to a 36dB change in SPL, requires multiplying the amplifier output by some 4096 times!!! (4 raised to the power 6 = 4x4x4x4x4x4 = 4096, required for six increments of 6db to equal a change in 36dB)  Now consider that the amplifier is rated as 50Watts (without stating RMS, or peak power, etc).  Even if the average output is only 1 watt, then it would take over 4000 watts to effect a rise in 36dB.  The numbers do not compute.

If you are a manufacturer's representative, please feel free to contradict any or all of my statements.  Just beware that I possess Bachelors and Masters of Science degrees in Engineering from the Illinois Institute of Technology in Chicago, Illinois USA.

Damn, i will keep quiet ! it sounds like a weapon of some kind or am i wrong ?

Hi Craig,

I read with interest your post about the Australian Monitor ST50P speakers.  I have (among other dp's) a Kawai MP4 for gigs but have been struggling to get a good sound  out of them.  I actually purchased a Bose L1 Compact but have not been entirely happy with the sound with a digital piano.

I tried to get hold of ST50P's in response to your post, but AM don't make them anymore, but make the AMPAV30 and AMPAV40.  Their catalogue refers to an AMPAV50, but I have confirmed that this is a typo and the 40 watt is the highest.  I obtained a demo pair and tried them out.  I liked the sound very much but am concerned that 40watt won't be enough for a small, noisy venue.

I would very much like to know what your experience has been using the ST50P's for gigs and whether they have enough power, and whether you think the AMPAV40 might have sufficient power.

I was also interested to see that you previously tried the Yamaha Stagepas system.  I actually have a Yamaha Stagepas 300.  The digital piano doesn't sound bad through them in my opinion, but I would like to know your view as to how the Stagepas compares to the ST50P's in terms ofdigital piano sound. 

I would also like to use Pianoteq through the sound system.

Thank you in anticipation.

Tony

My guess would be the headphones are so they can hear conductor cues, metronome, etc. that they don't want to record.

I completely agree with your assessment, Luc.  If you note the excessive number of microphones in this photo, this particular session is not for a performance of classical music repertoire.  This is either movie score material (with click track), background music of an advertisement, or making a track for Yanni or music of that ilk -- that requires no conductor.  The supposed additions of "expression" and reverb will be post processed at a later time in Pro Tools.

Aside:  Look at the general lack of musical expression on the faces of these performers as they "saw" away on their instruments.  Look at the brick wall within 10 or 20 feet of the performers -- further evidence of reverb and soundstage panning to be subsequently convolved into the music.  Look at the discomfort of the cellist, at the far right of the photograph, in terms of the way he positioned the uncomfortable 'phones on his head.  Ahh, music making at its finest!

Cheers,

Joe