Steve Guttenberg on active speakers

[andreasmaaan]

Yes of course - perhaps my language was too flowery and I realize the comparison wasn't totally valid. Still, my point was simply to highlight one example where an active design gave a company that traditionally designs passive speakers more flexibility in balancing the trade-offs you mentioned. You don't see many passive towers comfortably reaching <25hz in-room, let alone passive bookshelf speakers (certainly none of B&Ws). I recognize SPL and distortion are compromised for lower bass with a small driver, but this isn't of much consequence if the compromised SPL limits and distortion aren't particularly noticeable in typical listening. That appears to be the case with the Formation Duo.

I don't know of any measurements of that particular speaker, but I imagine that the claimed 25Hz, if it actually is the -3dB point, is achieved only at quite low SPLs (perhaps 75dB anechoic for a woofer that size). Moreover, whether it's the -3dB point or some other point is not specified by B&W in this case; this suggests it's the -10dB point that is being referred to.

 

[napilopez]

I don't know of any measurements of that particular speaker, but I imagine that the claimed 25Hz, if it actually is the -3dB point, is achieved only at quite low SPLs (perhaps 75dB anechoic for a woofer that size). Moreover, whether it's the -3dB point or some other point is not specified by B&W in this case; this suggests it's the -10dB point that is being referred to.

My apartment is no anechoic chamber, but I have made some measurements at home that should provide a picture. Here's the quasi-anechoic horizontal response, measured at 1m with nearfield bass spliced at 300hz and roughly compensated for baffle step.

Here are three in-room measurements I just made at different SPLs, measured from the listening position at 8 feet/2.4m away from each tweeter. Speakers are about 2ft away from the nearest boundaries. The top/red curve is with the Duo set to their maximum volume setting, where you can clearly see some compression. B&W seems to start limiting the bass a bit above 90dB. So not super loud if you listen from a distance, but I think plenty of bass for most households. The white curve is the KEF R3, which I've included for comparison purposes; KEF rates it as 38hz (-6dB) and 30hz for "typical in-room response." Seems about right to me.

(Yeah, I've got some nodes)

Edit: I should say I'm rather new to taking measurements, so take all this with some grains of salt. Still, I've repeated them several times and think they should be fairly representative.

 

[SIY]

That midrange dip in the quasi-anechoic is alarming. That has to be coloring the in-room sound.

 

[napilopez]

That midrange dip in the quasi-anechoic is alarming. That has to be coloring the in-room sound.

They are definitely colored speakers, like most of B&W's stuff. That said, at least in my room, it all seems to balance out better than I'd have expected once I got the positioning right. Curiously, B&W specifically recommends your ear height being between the tweeter and midrange driver in the manual, so that's what I used for the quasi-anechoic. But in my room the sound is definitely more linear at tweeter height or slightly higher. They are very finicky about positioning.

 

[SIY]

They are very finicky about positioning.

That is almost universally true for speakers with less-than-excellent polar patterns. Of course, that's a positive- "Unusually revealing of room acoustics defects."

 

[napilopez]

That is almost universally true for speakers with less-than-excellent polar patterns. Of course, that's a positive- "Unusually revealing of room acoustics defects."

Yeah, it's just always insteresting to see that play out in person. Here's the vertical.

 

[SIY]

By contrast, here's a similar plot from a pair of inexpensive two ways that are well-engineered, quite neutrally balanced, and not terribly critical regarding placement.

 

[napilopez]

Nice; what speaker is that?

And yes, B&W seems very attached to its whole 'floating tweeter design,' which I assume isn't doing it any favors in terms of directivity. But at least there does seem to be some care in balancing the overall room response and I do quite like the sound when everything is set up right. Not really a speaker for me because I prefer smooth off-axis performance (an open floor plan apartment means a lot of listening locations), but the on-axis isn't terrible and tbh most buyers will probably just notice the bass coming out of a small cabinet with decent clarity and be happy about that.

 

[SIY]

Nice; what speaker is that?

Ask me again next month after the review appears. I will say that it's a two way active, and the horizontal dispersion is equally excellent.

 

[Sal1950]

Ask me again next month after the review appears. I will say that it's a two way active, and the horizontal dispersion is equally excellent.

a pair of inexpensive two ways

Appox what's your definition of inexpensive?

 

[SIY]

Appox what's your definition of inexpensive?

Under $350 the pair. Including amplification, of course.

 

[napilopez]

Neat. I have a couple of those coming up too. Long live well-engineered inexpensive speakers!

 

[Biblob]

I won't spoil them!

 

[LTig]

[..] Curiously, B&W specifically recommends your ear height being between the tweeter and midrange driver in the manual, [..]

This is standard. Neumann specifies for each speaker the location of the acoustical axis, e.g. for the KH120:
The acoustical axis of the KH 120 is located at the midpoint of the bass and tweeter drivers. (Source: manual page 10)

 

[LTig]

Ask me again next month after the review appears. I will say that it's a two way active, and the horizontal dispersion is equally excellent.

Must be coax speaker ...

Under $350 the pair. Including amplification, of course.

.. or maybe not (not for this price).

 

[SIY]

Must be coax speaker ...

Nope, just skilled engineering.

 

[Sal1950]

Under $350 the pair. Including amplification, of course.

Nice. Amazing when we start looking closely (measuring) how much great equipment there is today at really affordable prices.
To read certain magazines and websites today, you'd think it takes at least $10k to put together a decent system.

 

[napilopez]

This is standard. Neumann specifies for each speaker the location of the acoustical axis, e.g. for the KH120:
The acoustical axis of the KH 120 is located at the midpoint of the bass and tweeter drivers. (Source: manual page 10)

Yeah, I'm aware - I use a pair of Neumann KH80 in my office =] I just meant to say that listening slightly above the tweeter axis sounded and measured better from the listening position, but that might've just been something about my room, perhaps the couch.

 

[SIY]

Nice. Amazing when we start looking closely (measuring) how much great equipment there is today at really affordable prices.
To read certain magazines and websites today, you'd think it takes at least $10k to put together a decent system.

Absolutely. This is a golden age.

I have several sets of excellent small speakers on hand; my wife looks at them, looks at my main speakers, looks at me, and keeps asking, "Ummmm... why?"

 

[andreasmaaan]

Here are three in-room measurements I just made at different SPLs, measured from the listening position at 8 feet/2.4m away from each tweeter. Speakers are about 2ft away from the nearest boundaries. The top/red curve is with the Duo set to their maximum volume setting, where you can clearly see some compression. B&W seems to start limiting the bass a bit above 90dB. So not super loud if you listen from a distance, but I think plenty of bass for most households. The white curve is the KEF R3, which I've included for comparison purposes; KEF rates it as 38hz (-6dB) and 30hz for "typical in-room response." Seems about right to me.

The fact that the R3 and the Duo seem to have similar bass response in-room suggests to me that the anechoic -3dB point of the Duo is in fact similar to that of the R3, which in turn is similar to the passive B&W you mentioned.

But of course, it would be completely inexplicable if it weren’t so. A 6.5” woofer just can’t do even moderate SPLs at 25Hz, especially not in a small-ish sealed box. Add some room gain and then of course you have some audible (and measurable) sound down there

OTOH, it’s hard to deduce too much about bass extension from in-room responses, as the room is so dominant at these frequencies.