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best way to run 4 T60s

Posted: Sat Feb 22, 2014 11:15 am
by snowphish
So we've almost completed the 3 extra T60s, so we'll have 4 in total, each loaded with a LAB 15.

Now we have the following amps:

2x Crown MT1200
http://www.crownaudio.com/media/pdf/legacy/102990.pdf

QSC MX1500a
http://www.usc.edu/student-affairs/bova ... df/mxa.pdf

Yorkville AP4040
http://yorkville.com/amplifiers_process ... ct/ap4040/

I'm thinking I should run one on each channel of the ap4040, and one on each MT1200 ?

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 11:21 am
by Bruce Weldy
snowphish wrote:So we've almost completed the 3 extra T60s, so we'll have 4 in total, each loaded with a LAB 15.

Now we have the following amps:

2x Crown MT1200
http://www.crownaudio.com/media/pdf/legacy/102990.pdf

QSC MX1500a
http://www.usc.edu/student-affairs/bova ... df/mxa.pdf

Yorkville AP4040
http://yorkville.com/amplifiers_process ... ct/ap4040/

I'm thinking I should run one on each channel of the ap4040, and one on each MT1200 ?

Huge discrepancy of power between the yorkville and the Crown. Yorkie at 750watts/8ohm and the Crown at 310/8ohm. The crown will only deliver half the power. Same with the QSC.

Either put all 4 on the Yorkville or get matching amps.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 1:17 pm
by snowphish
I was thinking of bridging the Crowns, I have seen the warning about voltage swing, but I don't really have much choice or budget at this point. I was also thinking of getting 2 more MT1200s eventually as to have one for each tuba, perhaps not such a good idea? even with proper limiting/tweaking?

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 1:22 pm
by Bill Fitzmaurice
snowphish wrote:I was thinking of bridging the Crowns
:cop:
http://billfitzmaurice.info/forum/viewt ... =6&t=19292
I was also thinking of getting 2 more MT1200s eventually as to have one for each tuba, perhaps not such a good idea? :?
The Yorkville will run two per channel. It's all you need.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 1:36 pm
by snowphish
Alrighty, thank you! This does make sense, although it won't leave much headroom, if its safer for our drivers than bridging then it's the way to go. We finally have a hard limiter (driverack PA2) so we'll set it right.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 2:13 pm
by BrentEvans
snowphish wrote:Alrighty, thank you! This does make sense, although it won't leave much headroom, if its safer for our drivers than bridging then it's the way to go. We finally have a hard limiter (driverack PA2) so we'll set it right.
Headroom doesn't come from power, it comes from output capacity. The two are related, but not synonymous. The T60 has a defined output capacity set by its voltage limit. If you need more headroom (which means more output) then you need more T60s, not more power to each T60.

It is not safer for your drivers to have far more voltage available than is required. When you use a hard limiter, the limiter cuts off signal that is unsafe. As Bill said, the Yorkville has enough voltage swing for your cabs, so you don't need to get more by bridging, nor will you get more headroom by bridging, because you'll still have a hard voltage limit.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 2:13 pm
by Bill Fitzmaurice
snowphish wrote:Alrighty, thank you! This does make sense, although it won't leave much headroom
With the sensitivity of T60s you don't need it.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 2:35 pm
by snowphish
BrentEvans wrote:
snowphish wrote:Alrighty, thank you! This does make sense, although it won't leave much headroom, if its safer for our drivers than bridging then it's the way to go. We finally have a hard limiter (driverack PA2) so we'll set it right.
Headroom doesn't come from power, it comes from output capacity. The two are related, but not synonymous. The T60 has a defined output capacity set by its voltage limit. If you need more headroom (which means more output) then you need more T60s, not more power to each T60.

It is not safer for your drivers to have far more voltage available than is required. When you use a hard limiter, the limiter cuts off signal that is unsafe. As Bill said, the Yorkville has enough voltage swing for your cabs, so you don't need to get more by bridging, nor will you get more headroom by bridging, because you'll still have a hard voltage limit.
I understand this, but I did not realize that the ap4040 would be sufficient for 4 tubas; I mean supplying the LAB15s near their limit ~60v, without clipping. I will measure and set the limiter accordingly! THANK you very much for your help, this will be our first event with 4 T60s, outdoors in Montreal, cold and snowy but we'll have good shelter for everything; any issues for running power amps at -10/-20 Celsius? This is the 3rd year we're doing this event and the only problem we've had in the past was a Crown xls that blew a capacitor.

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 2:40 pm
by BrentEvans
snowphish wrote:have good shelter for everything; any issues for running power amps at -10/-20 Celsius? This is the 3rd year we're doing this event and the only problem we've had in the past was a Crown xls that blew a capacitor.
The only thing to watch out for is condensation. Generally, keeping electronics cool is good for them (unless you'r talking about LCD panels). The problem with being in sub-freezing temperatures is that when the amp heats up, moisture can condense out of the atmosphere and short things out. Is the shelter you're talking about a tent, or something like a trailer, which an be closed up and kept at least slightly above freezing?

Re: best way to run 4 T60s

Posted: Sat Feb 22, 2014 3:07 pm
by doncolga
snowphish wrote:Alrighty, thank you! This does make sense, although it won't leave much headroom, if its safer for our drivers than bridging then it's the way to go. We finally have a hard limiter (driverack PA2) so we'll set it right.
I run two T30's per side on one amp when I run all four and it does just fine. I have the voltage swing that I need with no trouble. Great to get all that from one little amp.

Re: best way to run 4 T60s

Posted: Mon Feb 24, 2014 4:42 am
by escapemcp
From the Yorkville specs:
Hum and Noise (un / Aweighted -dB): 0.971698113207547
:loler:
WTF? That's some hardcore accuracy! I would have guessed that at least 2/3 of those digits are the result of the noise floor of the measuring equipment, rather than the amp itself. Maybe it's because they are using A weighted measurements at the SAME TIME as unweighted :confused: :confused: :lol: