[Ed.] – This review about fine tuning has been anticipated by an article on the listening impressions about the Klipsch Belle: a typology of loudspeakers whose high efficiency is a characteristic that divides the audiophile world in detractors and supporters.
A loudspeaker with an effective sensitivity of 104/105 db watt/m, does not require many watts to be driven. It is just a metropolitan legend thinking to make it play with 100, 200 or more watts with a transistor amplifier. On the basis of several repeated tests, the amplifiers this system appreciates most, are settled on 10 watts RMS, maybe 20. More watts have no meaning. With such wattages, we can obtain, if we want to speak about quantity, impressive sound volumes. These volumes are impossible to be reproduced by other cone speakers with 87-90 db watt/m of efficiency. The problem here is not how much they play, but how they play: that is how to exploit their very high efficiency.
I suggest matching these speakers with tube amplifiers, possibly single-ended triode (SET). I mean, amps with the 300B, like Sun Audio or Audion, IT2 Audio Tekne, the integrated (with the 300B) Meishu Audio Note. Amazing performances with the Legend 300B by Hiraga. By the way, all these electronics have been tested with the Klipsch Belle.
In effect, of the 8-10 watts delivered by these amplifiers, the speaker uses more or less 1 or 2 watts in the moments of top dynamics, when the orchestra performs at very high volume. But what counts in the end, is the very realistic tonal and musical outcome. Having said that, if you think to drive this loudspeaker with 100-200 watts, you are wasting your time because it cannot operate under its best working conditions.
Bear in mind that with a speaker with this superior efficiency you can catch “the flying flies”. I mean, every single fault or mistake in your audio system chain, mostly noises, residual hums, etc.: they will emerge implacably from the bottom of your room. The problem here is how to get a sound that emerges from a real silence.
So, the first two data to acquire from the match with a hyper-efficient loudspeaker are:
a) a painstaking care in connecting your system to the earth;
b) an effective tonal synergy in the pieces of your audio chain, from the pick-up to the power amp, via the intermediate links, where it is determinant the contribution of the connecting cables. Some micro differences between interconnections, that in another speakers system with a more standardized efficiency are not evident, here become unbridled and sharp.
c) a further prejudice to eliminate is the ratio between the size of the loudspeakers and the room. It is not true that the Klipsch Belle need a wide space to perform. Obviously, the bigger is the room, the more they will respond and prompter than every other speaker of medium and low efficiency. What I propose to you is, instead, to let them play in smaller rooms, let’s say 5 x 4 x 2,70 meters: enough space for these speakers, since they can stay rather close to the back wall without causing any problems. For rather close I mean 30-50 cm. from the back wall and at least 50 cm from the sidewalls.
In this position, the speaker, if amplified by SET power amps mounting a 300B tube of high quality and low power, gives its best. In these driving conditions, it is possible to get a mass of micro information and micro details at reasonable or rather low volumes, which are unthinkable for the other audio systems. This is due to the very high efficiency of the horn and of the driver that does not need to move with excessive excursion of the cone. It rather tends to vibrate without moving. At a quality level, this is the best functioning condition for this typology of loudspeaker and this is our target too.
If you consider that a directly-heated SET amp, at a power of one tenth, one fourth or half watt, has an unimportant distortion, but can express at best its tone and its musical potentialities, you can understand how this can be considered as the best working point.
The best listening tests can be made during the night at a very low volume as for the quantity, but very high as for the intensity of the nuances perceived.
If you make a comparison between the distortion graphics of a driver, a 38 horn back-loaded woofer, driven by ½ watt – we are talking of 101 dB per watt/m in the peaks – and the distortion graphics of a 25 traditional woofer, with a 87 dB driver that has to reach 101dB, we can notice that we need 32 watts to get the same result. The real problem, however, is elsewhere: the cone moves a lot and during this mechanical operation, there are aberrations, distortions and space-time lags.
Let us give us a practical rule, in order to understand the units of measurement that we are talking about. For every added 3 dB of power, the amp needs a doubling power. With peaks of 8 watts, the Klipsch Belle can reproduce, in a realistic and undistorted way, 113 dB watt/m. In most of the 87-90 dB drivers, the cone is already broken or has reached the break-up, hitting on the magnet and with audible distortions
With the above-mentioned 87 dB, we need 450 watts per channel to reach 113 dB. It is easy to understand that a similar wattage cannot be tolerated by this kind of drivers: the system has already collapsed before getting to this level.
In summary:
- It is false that the Belle needs wide rooms.
- It is false that it needs lots of power to play or that it performs better with very powerful amplifiers. Here the cone does not nearly move, but vibrates. Hence, the matching modalities are different from the current standard of the medium and low efficiency drivers.
- It is true that the Belles can perform very well at low and very low volumes. Actually, at very low volumes it plays better than any other dynamic loudspeaker, because there are no steps. I mean, there is not a threshold above which it starts to play well and below which it does not play causing the entrapment of the information in the cone of the driver. The frequency excursion is very wide and linear down to the lowest volumes where the intensity, the soundstage depth and the air among the instruments are still wonderful.
- It is false that the Belle is picky like other loudspeakers and for this reason it requires particular settings in the room. It is, instead, rather tolerant with the environment.
- It is true that a pair of Belles, put smartly in an adequate context of hi-fi system and room, allows for an astounding level of realism in the reproduction. For realism, I mean the illusion of having right in front of you the performers with their instruments. The Klipsch Belle can come off from the mechanical reproduction of the sound, clearing some intricacies that are typical of several dynamic loudspeakers. When an adequately enhanced Belle plays, everything seems easy. It does not require nor any effort to be accepted by the listener, neither an excessive laboriousness.
I think that our systems should always reproduced the music like that, shouldn't they?
