benchmark and apogee

Shadorne: What do you mean by "metal or ceramic drivers"? What are the others? I suspect that every tweeter has many points of resonance to different extend.

I don't know how to make waterfall plots - have to read about it. Wouldn't spike at 9kHz show with frequency sweep?

Any rigid driver of very light weight material is prone to "ringing". Think how a cymbal is made...a rigid disc of metal...touch a cymbal even lightly and it will ring for a long time at low levels but audible. In the case of a cymbal it vibrates at many frequencies due to its mottled hammered surface - it "shimmers". In the case of a metal driver then its shape will also influence the kinds of sounds it makes - shape it like a cup or a bell then it will tend to ring at certain frequencies. Manufacturers normally compensate for this with a notch filter.

A woven fabric/silk/paper&pulp type driver will also be light but not as rigid and not as light...it will not resonate like a metal or ceramic driver. This is called "internally damped" it means that when it flexes it quickly stops and it also loses energy more quickly - less efficient and higher frequencies will roll off sooner.

Some hybrid designs use CLD - constrained layer damping - a viscous fluid between two rigid cones. Some use rubber dampers stuck to the cone. Many are coated with a damping fluid.

In any case, if you want to use an internallly damped cone then you forgo frequency bandwidth and efficiency...you may also need to carefully support the less rigid cone in the middle with a larger voice coil (expensive) or carefully shape it (dome) and drive it with a bigger motor and magnet (expensive). The bonus is that the limited bandwidth internally damped driver will have excellent transient response and waterfall plot - it plays a sound without adding coloration.

Shadorne: Morel Supreme 110 is a soft dome tweeter. It has huge magnet but for another reason (underhung coil).

Making notch filter seems to be easy but tuning it might be difficult. I have decent microphone (Blue condenser) but have to find computer program for plotting.

Revel Ultima2 uses Beryllium tweeter that, according to Stereophile review, reproduces deep brassy sound of cymbals - not the shimmering alone. I noticed deeper/fuller sound of cymbals at the concerts than played thru my (and others) system.

Kijanki,

Cymbals are of all kinds so be careful reading to much into the sound. Sabian are made in eastern Canada - each one hand made and tuned by ear. It also depends how they are hit - closer to the edge or towards the bell - how large is the bell. Large cymbals will resonate more and will shimmer less. Curved shapes towards the edge will get you into "gongs". Man there is just everything out there...that is why music is so wonderful. be careful interpreting what you hear at a concert versus at home - studio drum sets are very likely differently setup from those used at concert.

If a tweeter produces a deep brassy sound (more so than say a soft dome tweeter) then you might ask yourself is it the rexcording or is the tweeter behaving like a "bell" itself......are you hearing tweeter ringing? Remember brass instruments are resonant devices which ring (sizzle) too. I am always wary when a speaker produces something noticeably more pronounced than others... a reviewer may say this is impressive or a good thing...it is certainly a difference...but is it right??

Shadorne:

That is a very good question. People compare to sound at the concert as reference point. It doesn't work well for popular music or jazz (bad acoustics). Symphony orchestra might be the reference if you can afford good seats.

Getting back to Benchmark - It was compared to few other DACs in the studio by playing instrument (guitar) and comparing recorded sound played thru DAC to direct sound. Benchmark scored the highest.