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speaker excursion..."mo power"..and bass..Sean

I'd be interested in everyone's thoughts, but hopefully Sean will chime in...

Some reading I've been doing & the "is 22 watts enough" discussion has raised a question in my mind. I'll use the Linkwitz Orions as the example, but the real questions will (should?) apply to powering most any driver.

I've been reading Linkwitz's site on the Orions, some of the theory, what it takes to build them, suggested power..etc...and I remember some post that I read in the A-gon or AA archives stating that the 60 watts Siegfred suggests isn't enough to give significant bass. I read on the SL site that he likes the 60 watts as the amp will clip just before the speaker can reach full excursion & thereby the driver will not sustain damage. He continues to state that the higher power amp he suggests (a larger ATI) will result in the driver reaching full excursion prior to the amp bottoming out & thus driver damage may result.

>Proponents of "lower is plenty" might be, at least conceptually, in line with the needed power to reach a driver's maximum excursion (almost by defintion) being all the power necessary.

>Then comes the "more power, preferrably gobs more clean power" crowd that says more power is the best in most applications.

So my question(s):

>Is the difference between these two camps just "time"(instantaneous versus continuous power)? i.e Lots of mostly unused power sitting "idle" as a reserve for the couple millisecond demand of those dynamic peaks?

>From what I've read the SL Orions do very, to exceptionally, well on bass even with the 60 watts. How would 200 watts instead of his 60 improve the bass if the drivers bottom out at a little over 60 watts? Is it again just the millisecond peak demand for power that would be available or is there another reason?
fishboat
cinematic_systems
282 posts
 
Whoa!

This thread had a great technical edge and now its tumbling out of control.

Passive crossovers are "voltage dividers", this is where the power goes, to ground especially in 2nd order and filters with notch filter etc. There are small losses in the components but the passive filter itself is a loss as it is addressing the fully amplified signal.

Drew/Bombay & Sean your original long posts were about 75% correct but this second group is getting into the land of speculation. Again good posts but now you guys are down to about 50% correct.

Sorry,I don't have time to correct the errors point for point.
eldartford
4,262 posts
 
Cinematic_systems...In a passive crossover, power does indeed "go to ground", but it goes through the drivers, which is the whole point of the thing. The power "wasted" by notch filters is minimal, unless the drivers are truly aweful.

The 10 AWG air coil inductors in my MG1.6 have about the same resistance as the original iron core inductors. This is why most speakers use iron core inductors.

When estimating the broadband signal equivalent to two bandlimited signals, the usual approach is to do an RSS. For example...

100^2 + 60^2 = SIGNAL^2

SIGNAL = 117

If the two band limited signals are equal, the equivalent broadband signal is maximized at 1.41 times the band limited signal.

However this assumes that the two bandlimited signals are uncorrelated, and this is not typical of music, where loud low notes are often simultaneous with high frequency harmonics, not to mention cymbal clashes.

As to tweeters burning out...I guess that some may be huskier than others, but I just took out two SEAS Excel T25CF-002 Millenium tweeters with about a three second burst of noise due to an interconnect problem. And these tweeters were not driven directly from the amp, but rather through a passive crossover. However, replacement voice coils are available, and Madisound even installs them for free. This suggests to me that blown out voice coils must be quite common.
eldartford
4,262 posts
 
Cinematic_systems...Whoops! You are right that in a second order or higher passive crossover some power is "dumped to ground". For example, for the woofer, after the inductor rolls off the highs, a capacitor to ground rolls them off further. However, I don't believe that the "dumped" power amounts to much, as the "dumping" starts near zero at the X/O frequency and increases at 6 dB/oct, but working with an input that is already rolling off at 6 dB/octive. Perhaps there is an EE out there who still remembers how to calculate the "dumped" power in a second or third order crossover. Fourth order would involve a second "dump".

If Sean is right, and we all got rid of passive crossovers, perhaps the global warming problem would be solved.
kpinneo
10 posts
 
Great thread, and very interesting to me as I am in the process of building a highly-tweaked system around the Orions. I'm almost finished building them, and I added to Linkwitz' design by building in substantial dampening aids.
Here's my system as it will be in about one month:
McIntosh MC-275 driving tweeters
Tenor 75WP monoblocks driving midranges
Butler TDB 5150 driving woofers (150watts each)
Sony SCD-1
Supratek Sauvignon linestage
Linkwitz active x-over
Chimera labs litzbraid custom speaker cables
Chimera labs litzbraid interconnects
BPT 3.5 Signature Conditioner

I'm a bit concerned about the synergy between amps, and I intend to be extremely careful of volume levels,but it should sound fabulous. Any thoughts re: this setup from other members would be welcome. I know this doesn't directly answer the question, Fishboat, but maybe the system's performance characteristics when done would be interesting to you or others.
sean
6,231 posts
 
I've been busy for a few days, hence the lack of response.

As to my comments about "damping factor being a hoax", i'm not saying that low output impedances are a joke. What i'm saying is that how people interpret the impedance relationship between an amp and a speaker and what it means to "driver control" is mostly incorrect.

The closer your speaker impedance is to the output impedance of the amp, the more that the reactance / loading characteristics of the speaker will control or "highly influence" the output of the amp. The further apart they are ( a higher damping factor ), the less influence the loudspeaker load will have on the amp. This is NOT the same thing as the amp having greater control over the speaker. The only thing that allows an amplifier to "control" a loudspeaker is voltage and current output.

Cinematic: Your post saying that we are 50% wrong ( or is it 50% right? ) is 75% incorrect, but i don't have time to clarify point by point. Thanks for stopping by though... : ) Sean
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