benchmark and apogee

Shadorne:

Thanks. It shows as one hot high sibilant - audible at first but much better now (but still there). I will think of notch filter at 9kHz. In spite of that it is still a lot cleaner than $25 Vifa it replaced.

I would not do this again - it is way to complicated and requires equipment (and experience) I don't have (not to mention room acoustics). I updated crossover components and was planning to continue further (Dueland resistors and capacitors) but it's another $400. I want to listen to new Revel Studios 2 and possibly get used one within few years.

I will think of notch filter at 9kHz.

Most speakers with metal or ceramic drivers have notch filters built into the crossovers - the frequency, depth and width (Q) of the filter need to be chosen carefully though. You would probably need to be able to perform waterfall plots to make appropriate adjustments.

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.