Amp for Two T39s?

Is this amp OK?
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Nordo
Posts: 242
Joined: Thu Aug 25, 2011 4:25 pm
Location: Queensland, Australia

Amp for Two T39s?

#1 Post by Nordo »

Hi Guys.

I am building two T39s, each with a Lab 12 - 400w (800w music); 6.0 ohm Nom (8.0 ohm horn loaded).
Should be limited to 57 volts each.

I need advice on a suitable dual channel amp to power these T39s.
The signal will be going through a DCX which can attenuate down to -24dB.

This project is on a shoe-string budget, so a Behringer, Peavey, Crown or equivalent.
"D" class would be preferable, but would use old iron if the price is right.

I thought this would be a common question, but couldn't find anything relevant by searching.
Keep in mind that many amp specs use different type of "watt" specifications.

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dswpro
Posts: 314
Joined: Sun Oct 30, 2011 3:17 pm

Re: Amp for Two T39s?

#2 Post by dswpro »

I use a pair of Peavey IPR3000 amps, one for my Otop12's another for my T39's
Sometime I am out with 2 subs and 2 tops, other times 4 of each. The amps perform well under an 8 or 4 ohm load for me. Never had a problem in the past year.
I use a DCX2496 crossover / controller and a DEQ2496 system EQ.
Never going to buy heavy old amps again. My entire amp rack is under 25 lbs.
You can get the odd IPR3000 on Ebay from time to time, one of mine came from ebay for $250.00 US. The other was from a local Guitar Center, a sales floor unit I picked up for around the same price.
Some of the early IPR3000s suffer from an audible high frequency whine when the amp is quiescent with the volume wide open. I'm told this is an artifact of the switching power supply. One of mine does this. That's the one I use on my subs, where the speakers cannot reproduce the whine. I would not hesitate to try an Inuke, Crest, or other switching mode amp having had the good experience with these IPR units.

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BrentEvans
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Location: Salisbury, NC

Re: Amp for Two T39s?

#3 Post by BrentEvans »

+1 on the IPRs. The 3000 or the new IPR2-3000 would be the right choice. They've performed flawlessly for me for going on 3 years now. Just don't connect one to your buddy with a 1k test tone at full blast unless your buddy likes to be tasered....

Wish I had a pic of that, but since I don't, here's a pic of 7 of my 8 IPRs (the one that tasered my buddy was in the shop having a protection diode replaced....)

Image

Edit... Looking at that.... I need to take a new gear pron pic...
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

Grant Bunter
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Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
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Re: Amp for Two T39s?

#4 Post by Grant Bunter »

Hey Nordo,
Partly answered in your other thread as well.

Australia is Australia, and given our "usual" pricing, sometimes you can luck on a great deal, but not often.
We don't have GC or CL and, for our overseas friends, our local equivalent of CL, is called Gumtree, where everyone seems to have done their research and is looking for top dollar in the used market.

And, it seems, freight from overseas has caught up and combined with asking/BIN price on the bay means it is now more expensive to buy and ship than buy locally, more often than not, or with no saving. The other issue with some brands shipped from OS (especially the USA) is they are not wired for our local power supply requirements. Some are not as simple as flicking a switch. Of course, bringing in an amp throws warranty out the door, and may present servicing issues.

Output wise, you want over 50V (unless your plans say the Lab 12 is limited to 55V). In the light weight amps:
That takes it to Crown XLS 2000 (54V at 8 ohms).
Locally, the IPR's only seem to be available from OS on ebay (and I look fairly regularly and it seems to have been that way for a while), though if you can find a 3000 locally for a price you can accept, it puts out 59V at 8 ohms.

Mid weight.
Crown XLI (not XLS) 2500 15Kg and 63V/8ohms.

Old iron
Have a look around. They have a weight penalty though, probably a minimum of 25Kg/amp.
My Jands 920's are about 32Kg each and only put out 42V (which is ok for me as I'm limiting to 35V).
Look at the Australian Monitor series too.
There's an Australian Monitor AM1600 (rugged workhorse) @ 30kg with low 60 something volts at 8 ohms/channel pick up only on the Gold Coast:
http://www.ebay.com.au/itm/Australian-M ... 85b&_uhb=1

In case you find other amps, -6dB on the limiter will reduce by around 7V. The reduction isn't quite linear, but you don't want an amp you need to limit by -24db, or you're on the limiter all the time.
In another thread recently, -24dB on the limiter of an 800W/8 ohms (80V) amp yields high 40s in volts, but the limiter is always on...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

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