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I'm confused about which amp to get. I'm building 4 Tuba 60s with an Lab 15. The GX7 is rated at 1000 watts per channel at 4 ohms (2 channel amp). The Lab 15 is rated at 600 watts (6ohm) . If I wired the tubas in series I should be able to put 2 speakers on each channel receiving about 500 watts each (speakers at 3 ohms). Is this correct?

Not quite correct darklango.

First up, add two ohms impedance for the acoustic impedance the actual cabs produces.
That's under "impedance" towards the end of your plans.

Then under "protecting your drivers" it says the lab 15 should be limited to 60V.

If you were to series wire two lab15 loaded cabs per channel, you would have an overall impedance of 16 ohms and a voltage limit of 120V.
The potential issue with series wiring is that if one driver fails for any reason, you lose all output on that channel, because the circuit is broken.

Since the nominal impedance of a single T60 cab in your case is 8 ohms, 2 wired in parallel per channel will run at the same 60V as one cab per channel. That = 900W into 4ohms per channel.

The GX7 will be fine for that, and you would expect to limit the 1000W capability by around 6dB
to bring it back to a 60V limit...

I'm a little out of my league right now. But I'm trying to get it.


If I run them parallel that would drop my load to 4 ohms? Which is what I need, right?


If that is correct, I'm guessing it would be better if I found a weaker amp and had two speakers on each amp. For safety reason (if an amp with out).


Also, the specs for the lab 15 are

600 watts
1200 watts music program

I'm guessing 600 watts is the RMS

Should I get a amp that peaks at the speaker RMS or get an amp that matches up with the total wattage of the speakers?

darklango wrote:I'm a little out of my league right now. But I'm trying to get it.


If I run them parallel that would drop my load to 4 ohms? Which is what I need, right?


If that is correct, I'm guessing it would be better if I found a weaker amp and had two speakers on each amp. For safety reason (if an amp with out).


Also, the specs for the lab 15 are

600 watts
1200 watts music program

I'm guessing 600 watts is the RMS

Should I get a amp that peaks at the speaker RMS or get an amp that matches up with the total wattage of the speakers?

That's ok, you will learn.

Yes, 2 x 8 ohm cabs in parallel is a 4 ohm load, ie what you need.
No, the amp you have chosen is fine. What you need to do is buy a brick wall limiter and limit that amplifier so it's output cannot exceed 60V, ever.
There is a number of ways this brick wall limiting can be achieved.

The way the drivers react in horn loaded cabs often means that you can't take them as high as you would in cabs of other designs.
So you need to forget watts limits as per the specs, because Bill has calculated (and allowed some safety factor) that the Lab15 in a T60 can be limited to 60V.

See if you understand that before we move further on...

And, to be prepared, buy another GX7, or similar power rated amp, as a spare. Scour Craigslist and Ebay for a good deal. This is just a precaution, and not mandatory. If you are DJing for pay, you need to be prepared. This is why I have a trailer. What I need to use gets off-loaded and set up, spares stay on the trailer. I have spares for all my audio equipment. If the light show craps out, it's not a party pooper. If the music stops(this has happened to me on 2 occasions, both power issues with the venue) the party stops, and your good reputation goes in the pooper.

Go with a Beta3 amp. 4 channels of goodness. Switching power supply, great for 4 and 8 ohm loads. Clean power and runs cool. I am using a XA4.14 Which is putting out 2600w @ 4ohm per channel. Sounds like you want a XA4.06 http://www.elderaudio.com/products/Ampl ... A4-06.html

Not sure what the XA4.06 will run though, mine was $1500. *for the XA4.14

For the record I have a GX5 and have ran a pair of T39s and a pair of T60s (all Lab 12 drivers) off each channel all night (7 hours+) at high volumes and it's been solid. A GX7 should be very comfortable pushing 4 cabs.

88h88 wrote:For the record I have a GX5 and have ran a pair of T39s and a pair of T60s (all Lab 12 drivers) off each channel all night (7 hours+) at high volumes and it's been solid. A GX7 should be very comfortable pushing 4 cabs.

And the 7 weighs about a third of the 5.