Diamond Tweeter?

[mikesiskav]

Only if they had the same impedance, which they don't. The Crystal Cable speaker's impedance is significantly higher (roughly double, or a little more). It needs more voltage to play loud, but less current.

If one speaker has a 3dB higher voltage sensitivity but twice the impedance of another speaker, isn't the power needed to play at a given level the same for both speakers?

Well the standard definition of speaker sensitivity is output vs wattage, not output vs voltage

Assuming input voltage = 2.83
Voltage ^ 2 / impedance = power

For an 8 ohm speaker:
2.83 ^ 2 / 8 = 1 watt

For a 4 ohm speaker
2.83 ^2 / 4 = 2 watts

If both speakers output 84dB with 2.83v, then the 8 ohm speaker is 84dB per watt. The 4 ohm speaker is 84dB per 2 watts (or 81dB per watt).

[Beave]

Well the standard definition of speaker sensitivity is output vs wattage, not output vs voltage

Assuming input voltage = 2.83
Voltage ^ 2 / impedance = power

For an 8 ohm speaker:
2.83 ^ 2 / 8 = 1 watt

For a 4 ohm speaker
2.83 ^2 / 4 = 2 watts

If both speakers output 84dB with 2.83v, then the 8 ohm speaker is 84dB per watt. The 4 ohm speaker is 84dB per 2 watts (or 81dB per watt).

No, it's not the standard definition of speaker sensitivity to give it as dB per watt. It's a definition sometimes used by manufacturers, but it is a confusing method of giving a spec. John Atkinson explains why in Stereophile:

http://www.stereophile.com/content/m...muo7w5s52VM.97

There's a reason that both NRC measurements and Stereophile measurements give sensitivity for 2.83V input levels. They then go on to give plots for impedance.

If you were to play a constant wattage sweep on a speaker, the output level would vary considerably because the current AND the voltage would be going up and down as the speaker impedance varies. The result wouldn't look like a frequency response measurement you're used to seeing. Speaker impedance varies considerably with frequency and is reactive in addition to being resistive.

The rest of your post is correct, but it's not consistent with your previous post, in which we had speaker A with sensitivity of 81dB with 2.83V input, and an impedance of (simplified for this discussion) 8 Ohms. Speaker B has a sensitivity of 84dB with 2.83V input, and an impedance of 4 Ohms.

[Beave]

It's also worth pointing out that giving sensitivity in terms of 2.83V makes sense because amplifiers, in their comfortable operating range, act as voltage sources. Models of amplifier-speaker systems use voltage sources for the amplifier. You turn up the volume, you are increasing the voltage output (of course the current and power output increase as well, but since the load impedance isn't a simple 4 Ohms or 8 Ohms, the resulting current and power aren't so simple to calculate in the real world).

[mikesiskav]

Very interesting. I see it is a more complex issue than I thought. Very confusing if some companies rate 1w/1m and others use 2.83v/1m. I guess it's just another marketing tactic to make theirs speakers look better. Apparently, there can also be differences in frequencies measured. Are they measuring full bandwidth, limited bandwidth, single frequency? Here's another article which discusses the issues:

http://www.audioholics.com/loudspeak...g-vs-marketing

[Beave]

Right, it gets complicated. Good link.

Yes, some manufacturers like to list it 1w/1m, probably to make their numbers look a little better.

But some manufacturers stretch their numbers even more than that. I've seen sensitivity given in room, not anechoic (room gain will make that number higher than anechoic). I've seen sensitivity given in room, with both speakers playing (definitely no longer an apples-to-apples comparison).

And a real kicker: Sensitivity is generally agreed to be an average of the output level across a frequency range comprising the midrange, ie, an average of the frequency response from something like 300Hz to 3kHz. But I've seen manufacturers cherry-pick a single point where their speaker has a peak and say that that is their sensitivity. Speaker manufacturers play games with sensitivity just like amp/receiver manufacturers play games with their power ratings, maybe worse sometimes.

Dave does it right. He gives sensitivity for 2.83V, and he gives us impedance plots. He also gives an estimated in-room sensitivity. No cheating, no cherry-picking, no exaggerating.

[sludgeogre]

All I know is I wish I could afford a couple sets of Sierra Lunas (hopefully that's the name) with that incredible diamond tweeter as an upgrade. I haven't been using headphones as much and these would be the absolute ultimate desktop speaker if paired with a little sub at a desk.

Anyway, these things really are incredible, and yes they're very different beasts compared to the PSB tweeters or many others. It's easy to throw tons of power at a $25 tweeter, but I think everyone here would cringe if one felt even the slightest bit wary of putting dangerous amounts of power on a $5,000 tweeter. This is speaker design only for the pros. You need to know exactly what you're doing as you can't risk making a mistake during testing.

It reminds me of blowing a bunch of speakers I got at goodwill in college trying to make corn starch monsters videos for a physics project. I made mp3's of different frequencies with a tone generator and used my roommates crappy receiver to power the speakers. I blew 4 pairs or so before I got a decent video. I think I was throwing all kinds of crap at those speakers that I shouldn't have been, wondering what was going wrong. I'm not to be trusted with such matters!

[Beave]

The Stereophile review of the Diamond version of the Crystal Cable speaker is now up on their website:

http://www.stereophile.com/content/c...swXDGdRSrSI.97

[mikesiskav]

Doesn't look like they did any THD measurements.

[davef]

The Stereophile review of the Diamond version of the Crystal Cable speaker is now up on their website:

http://www.stereophile.com/content/c...swXDGdRSrSI.97

Measurements look odd to me - a bit colored.

Doesn't look like they did any THD measurements.

Taking distortion measurements with MLSSA (Stereophile uses MLSSA, as do we) is quite time consuming. Sometimes it is more useful to use less sophisticated measurement gear (LMS or CLIO for example) for distortion sweeps. The advantages of MLSSA are very sophisticated time domain measurements, which is key to the performance of all of our products.

[FirstReflect]

So one of the things I've suggested in the past is for Ascend Acoustics to pursue what appear to be the two fastest growing market segments in speakers: compact wall-mountable speakers, and extremely high output speakers. They're basically the two opposite ends of the spectrum, but that seems to be the way things are trending, and it's also the two ends that Ascend doesn't already fully cover.

Now, the compact wall-mountable segment is being taken care of! The HTM-200SE already handles that task for the SE Series. And the new Sierra Luna will handle it for the Sierra Series; especially since all three tweeter options should be available with the Sierra Luna, making it a perfect match no matter which Sierra Series speakers one might already own.

But that leaves the super high output category. In the very first post of this thread, Dave mentioned that this diamond tweeter has nearly limitless power handling and dynamics capabilities. To me, that says it all right there.

Don't get me wrong, I super appreciate Dave's efforts to make new components available for existing cabinets and customers. The Sierra-2 could have easily been a completely new model. But instead, Dave found a way to allow Sierra-1 and Sierra-1 NrT owners to upgrade to the new Sierra-2 components. And it sounds as though Dave has a similar idea in mind with this new diamond tweeter.

And maybe that's ok. Maybe there's nothing wrong with offering the new diamond tweeter with a new crossover as yet another Sierra Series variant for customers to consider. But I have to say that my initial reaction and thought on this is that the "Ascend Diamond Series" really should be a completely new Series of speakers.

My instant thought is that an "Ascend Diamond Series" should have Ascend's highest output capabilities ever. A new Tower that can compete with the JTRs and JBL Everests of the world. Maybe not the super high efficiency of those designs. But so long as a customer has the amplifier power on hand, maybe similar sorts of sheer output capabilities.

A new bookshelf that can play just as loud or louder than the Sierra Tower RAAL. A new mega-Center that can fill a genuine cinema-sized room.

If this diamond tweeter has the capability (and it sounds as though it does), then my thought is to match it with new woofers and new cabinets that will allow it to play to its maximum capabilities. While offering it as yet another upgrade option to the Sierra Series might also be very cool, it seems as though the diamond tweeter would essentially need to be tamped down and held back.

So I'd like to see an entirely new Series from Ascend with this diamond tweeter fully unleashed! Ascend's $2700/pair speakers already compete with $15,000/pair models from other brands. Perhaps a new "Ascend Diamond Series" could be something like $8,000/pair speakers that compete with the $60,000+ options that are out there