T60 Limit

Get the lowdown on the down low.
Locked
Message
Author
SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

T60 Limit

#1 Post by SethRocksYou » Sun Aug 19, 2018 8:10 pm

I'm not currently building any T60's, so it's purely out of curiosity and a desire to understand that I ask...

In the T60 plans it says "The Lab 15 power and displacement ratings are both 600 watts, so 60 volts is the maximum allowable."

Yet, 60 volts is only 450 watts for that driver in that cab. Why is the limit not 69.28 volts? Confused, I'm sure I'm just missing something.

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26427
Joined: Tue May 02, 2006 5:59 pm

Re: T60 Limit

#2 Post by Bill Fitzmaurice » Sun Aug 19, 2018 8:21 pm

60 volts into 6 ohms is 600 watts. I never use the added impedance from the horn loading as an excuse to push the voltage envelope, because what really defines the voice coil capacity is DCR, which is unaffected by impedance.

SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: T60 Limit

#3 Post by SethRocksYou » Sun Aug 19, 2018 8:45 pm

So, at 60 volts, is it 450 or 600 watts?

Bruce Weldy
Posts: 6433
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: T60 Limit

#4 Post by Bruce Weldy » Sun Aug 19, 2018 9:34 pm

SethRocksYou wrote:
Sun Aug 19, 2018 8:45 pm
So, at 60 volts, is it 450 or 600 watts?
It's 600 with a 6ohm Lab.

Use this ....

http://www.sengpielaudio.com/calculator-ohm.htm

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."

SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: T60 Limit

#5 Post by SethRocksYou » Sun Aug 19, 2018 9:49 pm

Hi Bruce, thanks...

So, the acoustic impedance of the horn doesn't effect that at all? Or, we ignore it in favor of a margin for driver safety? Or, what?

Grant Bunter
Posts: 5944
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: T60 Limit

#6 Post by Grant Bunter » Mon Aug 20, 2018 1:38 am

SethRocksYou wrote:
Sun Aug 19, 2018 9:49 pm
Hi Bruce, thanks...

So, the acoustic impedance of the horn doesn't effect that at all? Or, we ignore it in favor of a margin for driver safety? Or, what?
Yep, ignore it for driver safety...
Built:
DR 250: x 2 (melded array) with March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26427
Joined: Tue May 02, 2006 5:59 pm

Re: T60 Limit

#7 Post by Bill Fitzmaurice » Mon Aug 20, 2018 6:34 am

SethRocksYou wrote:
Sun Aug 19, 2018 9:49 pm
Hi Bruce, thanks...

So, the acoustic impedance of the horn doesn't effect that at all? Or, we ignore it in favor of a margin for driver safety? Or, what?
what really defines the voice coil capacity is DCR, which is unaffected by impedance.

Bruce Weldy
Posts: 6433
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: T60 Limit

#8 Post by Bruce Weldy » Mon Aug 20, 2018 9:45 am

Bill Fitzmaurice wrote:
Mon Aug 20, 2018 6:34 am
SethRocksYou wrote:
Sun Aug 19, 2018 9:49 pm
Hi Bruce, thanks...

So, the acoustic impedance of the horn doesn't effect that at all? Or, we ignore it in favor of a margin for driver safety? Or, what?
what really defines the voice coil capacity is DCR, which is unaffected by impedance.
Or, in layman's terms.....the cone will only move so far, then silence. The wattage is really irrelevant. The voltage determines how far the cone moves. The only reason to calculate the wattage is so that you know how powerful of an amp to buy.....since the manufacturers won't list voltage output, only wattage.

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."

SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: T60 Limit

#9 Post by SethRocksYou » Mon Aug 20, 2018 1:20 pm

Bill Fitzmaurice wrote:
Mon Aug 20, 2018 6:34 am
what really defines the voice coil capacity is DCR, which is unaffected by impedance.
I read that the first time and it raised more questions than it answered for me. Trying to ask follow up questions that are easy to answer, that would also cure my confusion.

Will 60 volts drive the LAB15 in a Tuba 60 to Xmax?

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26427
Joined: Tue May 02, 2006 5:59 pm

Re: T60 Limit

#10 Post by Bill Fitzmaurice » Mon Aug 20, 2018 1:27 pm

It will.
The voice coil is a piece of wire. Given enough voltage it will burn out. That voltage limit is unaffected by capacitive and inductive reactance, which are the other components of impedance.

SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: T60 Limit

#11 Post by SethRocksYou » Tue Aug 21, 2018 1:24 am

Thanks Bill. I'll let that roll around upstairs for a bit.

User avatar
heavybdrums
Posts: 360
Joined: Fri May 22, 2015 3:46 pm
Contact:

Re: T60 Limit

#12 Post by heavybdrums » Wed Aug 22, 2018 9:52 am

Also let this "roll around upstars"..lol. I have 3 t60's and I use them rarely.
The only situation where I use t60's is when a DJ asks for frequency extension to 25 hz instead of the Titan 39's which cut off @ 45 hz for less than four cabs (40 hz for four or more), so I bring them (two of them in most places).
I find that most DJs think their material has significant 25 hz content when it does not.They look at the spectral analyzer and see 25 hz in their content and think they need the Tubas, but In order for their content to have enough 25 hz to warrant the incredible size of the T60, their material needs to have a lot of 25 hz because 25 hz is not audible and needs to have 110 DB of 25 hz in order to really feel it shake the room.
In conclusion, I find VERY few DJ compositions require Tuba 60s, but admittedly when one does really "tickle" the Tubas it's really cool.
Also know that cab for cab, Titans are louder than Tubas, but don't go as low.
Also make sure you REALLY need Tuba 60s, and hope that your pack space can handle them and that the venue doesn't have ANY stairs. l have one venue where they go and the ONLY way they get in there is for two people to carry them over the stairs( the venue is in the basement)
A hand truck will not move Tuba 60s up or down stairs due to their length. So I require the organizers to carry them in if they request them, and usually find they don't really need them as their content really doesn't have much 25 hz.
They of course pay just the same for sound reinforcement regardless, and I feel I need to bring what they ask for.
The real fun for me is when a DJ actually does need Tubas and they shake the room nicely
4x WH8 delta pro
2x WH10 Deltalite 2510
4x Dr250 Deltalite II 2510
4X Titan 39 3012lf, 28"
4X Tuba 60 W/ lab 15
FB: https://www.facebook.com/sunsoundservices/ likes appreciated

SethRocksYou
Posts: 206
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: T60 Limit

#13 Post by SethRocksYou » Wed Aug 22, 2018 1:33 pm

Pretty much my exact line of thinking. The current plan is 8 DR200 and 8 T39, which is for an annual show my family puts on. The T60 became a consideration when I started to think about what to do with the system for the other 364 days of the year. Renting it out in parts or whole is the obvious solution. Seems like it would be smart marketing to offer the best sound system, with bass no other rental is likely to touch.

In any case, a T60 build is a long ways out for me and really, the T60 reference in this thread is somewhat rhetorical... the same power, limit, impedance, acoustic impedance confusion I have is universal to all the horn subs. Just happens I was reading the T60 plans when the confusion struck. LOL

Personally, I can hear 25hz just fine and actively seek out music content with sub 30hz content. I use earbuds though. Keeps the neighbors friendly.

Grant Bunter
Posts: 5944
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: T60 Limit

#14 Post by Grant Bunter » Wed Aug 22, 2018 3:11 pm

Seth,
Think it in reverse perhaps.
Just know that the voltage displacement limit is set by Bill without adding the horns impedance, but then having that horn impedance there actually increases driver safety.
The Labs are a bit pesky in that they don't have those lovely round figures like 8 or 4, what we get used to looking at when checking out amplifier specs.

The driver itself in a horn cab doesn't "know" about the extra horn impedance. It simply responds to voltage in line with it's design, and final, parameters, so it makes more sense to set limits based on that.

Remember also that any given driver has nominal impedance. Nominal impedance is determined at the design stage of the driver. Example: X driver will have an impedance of 8 ohms, be made with a pressed steel basket, have a paper cone blah blah blah.
When they finally built it, it turned out that the impedance wasn't the nominated 8 ohms, but it was meant to be.
Also remember impedance is frequency dependant, so varies.

As far as other business from the cabs, think long and hard about the conditions or circumstances under which you might hire.
Personaly, my rig doesn't go out unless I'm running it...
Built:
DR 250: x 2 (melded array) with March 2012 plans.
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26427
Joined: Tue May 02, 2006 5:59 pm

Re: T60 Limit

#15 Post by Bill Fitzmaurice » Wed Aug 22, 2018 3:37 pm

SethRocksYou wrote:
Wed Aug 22, 2018 1:33 pm
I can hear 25hz just fine
If I had a dollar....
What you're hearing is harmonics of 25Hz. To know what you're capable of hearing you need a sine wave generator, a speaker with essentially no harmonic distortion, a Z weighted sound meter and an RTA to see what's present. It just so happens that I have all of those. I can play a 25Hz tone at 100Hz outdoors, with no audible harmonics, and not hear a thing. The meter tells me it's there, stuff within 50 feet vibrating like mad tells me it's there, my skin tingling and chest being pounded tell me it's there, but if not for that you wouldn't know there was any sound. Having below 30Hz capability is nice indoors for HT, where you literally feel the room pressurization, but where music is concerned it's a capability you don't need and can't use.

Locked