It is currently Sun Nov 19, 2017 9:12 am

All times are UTC-05:00




Post new topic  Reply to topic  [ 11 posts ] 
Author Message
PostPosted: Sun Aug 28, 2016 3:58 pm 
Offline
User avatar

Joined: Sat Aug 06, 2011 3:25 pm
Posts: 1020
Location: Manchester, UK
I need a sanity check on a few numbers please.

If one has a 4x12 cab which is a 16ohm load then that can only have 16ohm drivers in it configured as 2 pairs in series and then those pairs in parallel...?

Now, if one used two of those 16ohm drivers to make an 8ohm 2x12 cab, for the same voltage (knob position) on the amp, the 2 driver cab would be the same loudness as the 4 driver cab...? I've run this on sengelpie audio calculator and the wattage definitely doubles for the same voltage when you half the impedance, ...fairly obvious, so unless someone is running at insane SPL they will be able to achieve the same loudness without needing more of something; by swapping from 4 drivers to 2, if the impedance drops by half anyway.

_________________
2xJ12L (3012HO) switchable/melded (viewtopic.php?f=30&t=18773)
2xT30 : viewtopic.php?f=30&t=20386

No sound is better than bad sound.


Top
   
PostPosted: Sun Aug 28, 2016 4:40 pm 
Offline
User avatar

Joined: Tue Jul 29, 2008 12:56 pm
Posts: 1866
Location: Tucson, AZ
For starters.....what's the real question here?

Charles Jenkinson wrote:
If one has a 4x12 cab which is a 16ohm load then that can only have 16ohm drivers in it configured as 2 pairs in series and then those pairs in parallel...?
or four [4 ohm speakers] in series
Charles Jenkinson wrote:
Now, if one used two of those 16ohm drivers to make an 8ohm 2x12 cab, for the same voltage (knob position) on the amp, the 2 driver cab would be the same loudness as the 4 driver cab...?
All fine until you introduced "loudness" into the fold. Loudness can have a relationship to power, but it is not discrete. There's much more to it than that.

Especially where instrument sound is concerned, and particularly guitar cabs.

_________________
Good food, good people, good times.


Top
   
PostPosted: Sun Aug 28, 2016 7:51 pm 
Offline

Joined: Fri Nov 27, 2009 11:37 am
Posts: 6092
Location: New Braunfels, TX
Radian wrote:

Especially where instrument sound is concerned, and particularly guitar cabs.


It's a scientific fact that if the cab looks bigger and has more speakers it will be louder....regardless of any other factors.

From "The Guitarist's Guide to Physics"

_________________

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."


Top
   
PostPosted: Sun Aug 28, 2016 8:45 pm 
Offline
User avatar

Joined: Sat Aug 06, 2011 3:25 pm
Posts: 1020
Location: Manchester, UK
Radian wrote:
For starters.....what's the real question here?

Charles Jenkinson wrote:
If one has a 4x12 cab which is a 16ohm load then that can only have 16ohm drivers in it configured as 2 pairs in series and then those pairs in parallel...?
or four [4 ohm speakers] in series
Charles Jenkinson wrote:
Now, if one used two of those 16ohm drivers to make an 8ohm 2x12 cab, for the same voltage (knob position) on the amp, the 2 driver cab would be the same loudness as the 4 driver cab...?
All fine until you introduced "loudness" into the fold. Loudness can have a relationship to power, but it is not discrete. There's much more to it than that.

Especially where instrument sound is concerned, and particularly guitar cabs.


I forgot about 4ohm speakers. :fruit:

Ok, I should have not used the term loudness. What I mean is 'is the approximate 6dB loss from halving the numbers of speakers accommodated by halving the impedance?'

Radian, I know you're one of the best there is at this sort of thing. :ugeek:

_________________
2xJ12L (3012HO) switchable/melded (viewtopic.php?f=30&t=18773)
2xT30 : viewtopic.php?f=30&t=20386

No sound is better than bad sound.


Top
   
PostPosted: Sun Aug 28, 2016 8:47 pm 
Offline
User avatar

Joined: Sat Aug 06, 2011 3:25 pm
Posts: 1020
Location: Manchester, UK
Bruce Weldy wrote:
Radian wrote:

Especially where instrument sound is concerned, and particularly guitar cabs.


It's a scientific fact that if the cab looks bigger and has more speakers it will be louder....regardless of any other factors.

From "The Guitarist's Guide to Physics"


I'd better get a copy of that. Could be handy.

_________________
2xJ12L (3012HO) switchable/melded (viewtopic.php?f=30&t=18773)
2xT30 : viewtopic.php?f=30&t=20386

No sound is better than bad sound.


Top
   
PostPosted: Sun Aug 28, 2016 9:48 pm 
Offline
Site Admin
User avatar

Joined: Tue May 02, 2006 5:59 pm
Posts: 25667
The 16 ohm cab will have the same sensitivity as the 8 ohm cab. It's able to go 6dB louder than the 2x12 because it has twice the cone displacement, but it will take four times the power to realize that 6dB.


Top
   
PostPosted: Sun Aug 28, 2016 11:05 pm 
Offline
User avatar

Joined: Tue Jul 29, 2008 12:56 pm
Posts: 1866
Location: Tucson, AZ
Charles Jenkinson wrote:
Radian, I know you're one of the best there is at this sort of thing. :ugeek:
You won't find me designing my own speakers anytime soon. :wink:

_________________
Good food, good people, good times.


Top
   
PostPosted: Mon Aug 29, 2016 6:52 am 
Offline

Joined: Mon Jun 30, 2014 8:07 pm
Posts: 271
Location: Berea, Kentucky
Bruce Weldy wrote:
Radian wrote:

Especially where instrument sound is concerned, and particularly guitar cabs.


It's a scientific fact that if the cab looks bigger and has more speakers it will be louder....regardless of any other factors.

From "The Guitarist's Guide to Physics"



Wow. I didn't know that. Is it like hot rodding cars where you can add horsepower with the addition of chrome engine components and speed parts stickers? I wonder how many chrome air cleaners you'd need to add to a guitar cabinet to add 6dB?

_________________
4 Jack 112L- 3012HO, melded array
2 Jack 112 (bought), straight array
17.5 wide AutoTuba with Infinity 860w
6 Wedgehorn W6 w/ Panel Mount Piezos
2 T48 Slims (15" wide) with 3012LF


Top
   
PostPosted: Mon Aug 29, 2016 7:23 am 
Offline
User avatar

Joined: Sat Aug 06, 2011 3:25 pm
Posts: 1020
Location: Manchester, UK
Bill Fitzmaurice wrote:
The 16 ohm cab will have the same sensitivity as the 8 ohm cab. It's able to go 6dB louder than the 2x12 because it has twice the cone displacement, but it will take four times the power to realize that 6dB.


Thanks Bill

_________________
2xJ12L (3012HO) switchable/melded (viewtopic.php?f=30&t=18773)
2xT30 : viewtopic.php?f=30&t=20386

No sound is better than bad sound.


Top
   
PostPosted: Mon Aug 29, 2016 11:11 am 
Offline

Joined: Fri Nov 27, 2009 11:37 am
Posts: 6092
Location: New Braunfels, TX
Charles Jenkinson wrote:
Bill Fitzmaurice wrote:
The 16 ohm cab will have the same sensitivity as the 8 ohm cab. It's able to go 6dB louder than the 2x12 because it has twice the cone displacement, but it will take four times the power to realize that 6dB.


Thanks Bill



Of course, the reality is that using a 4x12 or even a 2x12 is really overkill 90% of the time.

I ran sound for 4 bands last weekend ...... the loudest guitar player was running through a Fender Blues Junior w/18 watts and a single 12.....and he was still too loud. This wasn't a small place and we were thumping it pretty danged good.

The old days of high powered heads and big guitar cabs is gone - especially with PA support.

_________________

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."


Top
   
PostPosted: Mon Aug 29, 2016 11:24 am 
Offline
Site Admin
User avatar

Joined: Tue May 02, 2006 5:59 pm
Posts: 25667
Bruce Weldy wrote:
The old days of high powered heads and big guitar cabs is gone - especially with PA support.
+1. I saw Brian Wilson last night, 8000 seat amphitheater, there wasn't anything on stage larger than a 2x12.


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 11 posts ] 

All times are UTC-05:00


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
banner
Powered by phpBB® Forum Software © phpBB Limited