is lab horn the best

[djk]

"Is the measurement in room, or does the ripple come from a too small mouth? Anyway... it looks like the official measurement is rather optimistic about its performance."

10M groundplane, ripple is too small of a mouth (will improve with 4x or more cabinets). With too small of a mouth the output frequently has less output in the dips than the same driver would have as a direct radiator.



Fig.5.10 shows imaginary impedance dropping below zero on a small mouth, those are the dips. 5.10E shows you can have too much mouth, and lose deep bass. 5.10 will allow you to determine how many cabinets (mouth area) are (is) optimum.

" i think you said on a different forum something about which fs is ideal for a tapped horn tuning and came up with a pretty exact number for it. Could i ask for a short explanation of it? (Dont want to steal the thread though). "

I look for Fs about a half octave above the Fc point desired, seems to work better that way.

"how's the distortion scale read on that LMS display and at what voltage was it taken?"

28.3V/10M groundplane, distortion is in dB below the main output (-30dB~3%, -40dB=1%)

[freddi]

does that mean I can cheat with coupler whose F10 half space is around 50Hz and its 50Hz/30vrms harmonics are 34dB down from the fundamental to call it "44dB" down?

fwiw it's a good deal cleaner than my Yorkville UCS1 for 1 sheet of plywood and
and old Eminence 18 - that horrid dip needs either a front board like K15 or a bit less baffle angle to look better
20vrms


re:BFM - seems like when Tuba24 it made its debut there was something about no distortion at 20Hz -?

[djk]

You need to sum all the power in the various harmonics and the reference that to the fundamental

[freddi]

ok - so eyeballing the first graph with the yellow spectrum trace might give:

sqrt((0.02^2) + (0.02^2) + (0.02^2) + (0.005^2)) = 0.035 for ~3.5% THD at 30vrms/50Hz - does that sound ballpark? - I'm obviously no good at math

[Brett]

Originally Posted by soundhead

Is there any bass horn out there better than the lab horn

Originally Posted by soundhead

plays louder and goes deeper

Yes, many of the TH designs from Danley would better it.
However, a pair corner loaded in my old house with my big FLH system was a hell of a lot of fun. This was the best I could find when I built them (when they came out)

[Don Snyder]

Six Labsubs are 50% efficient, and 6th order bandpass speakers (Tapped Horns) are no more than 2% efficient.

Tapped Horns do have several advantages, but efficiency isn't one of them!

Read Danley's white paper ... http://danleysoundlabs.com/pdf/danley_tapped.pdf

[davygrvy]

Originally Posted by Don Snyder

Tapped Horns do have several advantages, but efficiency isn't one of them!

Not sure how you concluded that. Mutual coupling and tapped horns?

[MartinQ]

Originally Posted by djk

Actual measurement of BFM cabinet:


vs claims:

djk, It looks like you're trying to say that BFM is being misleading and I don't think this is really the case. Does Bill mention how his measurements were acquired? Do we know how these two measurements were taken?

These two measurements look very close to each other to me.

[Don Snyder]

Hi Davy,

People were comparing one LabSub to one Tapped horn, which I think is bogus. If you look at Danley's whitepaper, it compares a tapped horn to a vented box. At the same power, they have the same output, which means the same efficiency. However, the Tapped horn driver has less excursion, and can be pushed to higher output. More power ... more output, but NOT more efficiency.

While a close stack of almost anything will gain in efficiency, I don't believe it's practical to stack Tapped Horns to get anywhere near 50% efficiency.

Am I wrong?

[davygrvy]

Originally Posted by Don Snyder

Am I wrong?

Yes, see Danley's graph I posted. He hits 50% with 4 TH-115 cabs. What multiple TH cabs don't do is to drop their cutoff point when in a pack.