is lab horn the best - Page 3 - diyAudio
Go Back   Home > Forums > Loudspeakers > Subwoofers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 3rd February 2010, 11:12 PM   #21
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"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.

Click the image to open in full size.

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%)
__________________
Candidates for the Darwin Award should not read this author.

Last edited by djk; 3rd February 2010 at 11:16 PM.
  Reply With Quote
Old 4th February 2010, 01:26 AM   #22
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
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?
Click the image to open in full size.
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
Click the image to open in full size.

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

Last edited by freddi; 4th February 2010 at 01:29 AM.
  Reply With Quote
Old 4th February 2010, 01:35 AM   #23
djk is offline djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
You need to sum all the power in the various harmonics and the reference that to the fundamental
__________________
Candidates for the Darwin Award should not read this author.
  Reply With Quote
Old 4th February 2010, 05:39 AM   #24
freddi is offline freddi  United States
diyAudio Member
 
freddi's Avatar
 
Join Date: Aug 2005
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
  Reply With Quote
Old 4th February 2010, 06:01 AM   #25
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Quote:
Originally Posted by soundhead View Post
Is there any bass horn out there better than the lab horn
Quote:
Originally Posted by soundhead View Post
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)
  Reply With Quote
Old 9th February 2010, 03:40 PM   #26
diyAudio Member
 
Join Date: Apr 2007
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
__________________
Don

Last edited by Don Snyder; 9th February 2010 at 04:03 PM.
  Reply With Quote
Old 9th February 2010, 04:44 PM   #27
diyAudio Member
 
davygrvy's Avatar
 
Join Date: Mar 2007
Location: Oakland, CA
Blog Entries: 1
Quote:
Originally Posted by Don Snyder View Post
Tapped Horns do have several advantages, but efficiency isn't one of them!
Not sure how you concluded that. Mutual coupling and tapped horns?
__________________
Think out of the box
  Reply With Quote
Old 9th February 2010, 05:38 PM   #28
MartinQ is offline MartinQ  Canada
diyAudio Member
 
Join Date: Jul 2004
Location: Ontario, Canada
Quote:
Originally Posted by djk View Post
Actual measurement of BFM cabinet:
Click the image to open in full size.

vs claims:
Click the image to open in full size.
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.
  Reply With Quote
Old 9th February 2010, 05:42 PM   #29
diyAudio Member
 
Join Date: Apr 2007
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?
__________________
Don
  Reply With Quote
Old 9th February 2010, 06:17 PM   #30
diyAudio Member
 
davygrvy's Avatar
 
Join Date: Mar 2007
Location: Oakland, CA
Blog Entries: 1
Quote:
Originally Posted by Don Snyder View Post
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.
__________________
Think out of the box
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Lab 12 Tapped Horn, Ron's Austin II, T-Horn, CNC Photo Background layertone Subwoofers 15 23rd January 2010 05:12 AM
Why Does The Lab Horn use Two Woofers? john van ommen Multi-Way 0 13th September 2006 05:27 PM
Searching for plans of Lab Horn sub Bull Multi-Way 4 15th November 2003 09:57 PM


New To Site? Need Help?

All times are GMT. The time now is 10:12 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2