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Qsc 4050hd


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I've been doing my research for the subs I am trying to get and have compared the specs on this amp to various others. I have determined that, even though my tops are running on a QSC amp, I am going to get the Yorkville AP4040 to run the subs under an 8 ohm load. Equivalent or better specs and $300 cheaper. The Yorkie also takes up two spaces instead of three and weighs less. The QSC is rated at 800 wpc at 8 ohms and the Yorkville is rated at 750 wpc at 8 ohms.

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I am driving the JBL SR4715X Dual 15's. Cabinet rated at 1200 watts RMS. The cabinet is a 4 ohm load. I really don't want to bridge a MT2400 because it will take 4 of them ( 4 cabinets) and that is more money than I want to spend. So I looking at least this kind of power. I hope I will never use all of it, but what power is there should be clean.

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Originally posted by agedhorse

That's an awful lot of power to any single 8 ohm driver. I would look at an amp that delivers between 500 & 600 watts personally.


What sub are you trying to drive?

 

 

The Yorkville LS1208. It is rated at 1200 watts and I figured that 1.25 the estimated RMS rating (750 watts) would be OK for me. I know that Flanc is running 1500 watts into his off two bridged RMX2450s. Am I trying to put too much power through it?

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Originally posted by J the D



The Yorkville LS1208. It is rated at 1200 watts and I figured that 1.25 the estimated RMS rating (750 watts) would be OK for me. I know that Flanc is running 1500 watts into his off two bridged RMX2450s. Am I trying to put too much power through it?

 

 

I was seeing concern over the 8 ohm rating and assumed it was for a single 8 ohm driver.

 

For the dual 15" JBL, the RMS is about 800 watts (assuming you high pass at about 40Hz!!!) so I would recommend between 800 and 1200 watts into 4 ohms. I would not exceed this amount as failure rates increase dramatically on those drivers. I think the 4050 would be plenty of power.

 

If you were to bridge an amp (not my recommendation), an RMX-1850 would be an good choice as well.

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Uh, Gentlemen, the LS1208 sub IS a single 18".... 8 ohms, rated at 1200 watts program. That's roughly 600 watts RMS. It's a B&C, 4" voice coil, designed for this cab which is a expanding horn, and yes, this type of sub horn gets great reviews. From what I've heard, good sound (no one-note response), and max SPL per cu. ft./ $$.

I believe that a Yorkville tech told Flanc to go ahead with 1500 watts per driver, properly controlled I'm sure. Yes, it seems like a bit much, but then again, he hasn't blown one (yet), has he?......Flanc???? Any problems bridging that 2450 into an 8 ohm load? ?? No?.... me neither.

"Let's live for today.";)

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Haven't blown one yet ;) ...and I did call the guys at Yorkville to get their thumbs-up!

 

It's mostly headroom for me since I don't push those amps into clipping and I still have plenty-o-thump. Since I'm bridging into an 8ohm load, the RMX2450's don't get very hot at all. I also have my DRPA limiting my sub's incase something awful happens (God Forbid)...but what the hell...they are still under warrenty!!

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If you are hard-limiting the DRPA before clipping the amp (or limiting at the amp) then that's power that is not being used, can't be used, but you did pay for!

 

It's like buying 100 mph tires for a race car... then putting a govener on the car to limit yourself to 100 mph.

 

As a manufacturer, I can't possibly understand how Yorkville can expect the speakers to hold up under 1400 watt amp... any oops and it's toast. I am familiar with the driver... it's a good driver but not that good!

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As usual Agedhorse, you are right, but I happened to have those amps, so I put 'em to use (with Yorkvilles blessing). The limiters give me peace of mind and protection from those accidents you are so quick to bring to our attention. Sometimes killing a fly with a hammer sitting next to you is better than going out a and buying a new fly swatter.....awful analogy, but you get the point.

 

In the perfect world, I'd have one of these driving both subs in stereo. A perfect 1100watts/channel and saving me:

1) about 50lbs in my amp rack

2) considerable power draw

3) a couple rack spaces

4) Peace of mind

 

The problem is spending $2800 to fix something that ain't broke. Even if I sold the two RMX2450's...it's about 2K out of pocket; not feasible right now but on the ole wish list!

 

Lab Gruppen FP3400

http://www.mia.dk/usr/mia/mia.nsf/0/658DCBCCA3B50F75C1256BA000403856?OpenDocument

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Originally posted by flanc

As usual Agedhorse, you are right, but I happened to have those amps, so I put 'em to use (with Yorkvilles blessing). The limiters give me peace of mind and protection from those accidents you are so quick to bring to our attention. Sometimes killing a fly with a hammer sitting next to you is better than going out a and buying a new fly swatter.....awful analogy, but you get the point.


In the perfect world, I'd have one of these driving both subs in stereo. A perfect 1100watts/channel and saving me:

1) about 50lbs in my amp rack

2) considerable power draw

3) a couple rack spaces

4) Peace of mind


The problem is spending $2800 to fix something that ain't broke. Even if I sold the two RMX2450's...it's about 2K out of pocket; not feasible right now but on the ole wish list!


Lab Gruppen FP3400

 

Yes, as long as you don't break something valuable with the hammer!

 

This is a good example of where compromises are necessary. Not everybody understands that more is not always better though.

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I haven't seen the schematic for the 4050, but generally, QSC tends to stay with familiar topologies, like the Series 1 ---> USA ---> RMX progression, that we are familiar with. It's a smary way to proceed from a manufacturer's perspective.

 

As power levels increase, it becomes impractical to use a conventional class AB topology and must go to class H to achieve better efficiency ana power draw. This is where the lines begin to blur.

 

I would expect that the RMX 4050 is based on either the MX-EX technology, or some revision of it via their PLX/PL line... but I don't know for sure which.

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When I picked up my first 4000, I was pretty confused,

when the manual spoke about Dip Switches, and, mine

didn't offer any.

 

Then after talking to Bob Lee (QSC) I found out, that

the EX 4000 had two versions, and, I had the newer

version with the old versions guide.

 

Old Version, 20 - 20Khz 0.1% THD

 

720 watts per channel @ 8 ohms

 

1100 watts per channel @ 4 ohms

 

 

New Version, 20 - 20Khz 0.1% THD

 

800 watts per channel @ 8 ohms

 

1200 watts per channel @ 4 ohms

 

 

Both offered 3 step High Efficency Circuitry

 

MX 3000a, 20 - 20Khz 0.1%THD

 

800 watts per channel @ 8 ohms

 

1200 watts per channel @ 4 ohms

 

This one also offered 3 step High Efficency Circuitry.

 

 

This is why I feel the RMX 4050 is nothing

more than the predecessor of the EX 4000

with a beefier power supply.

 

Of course there is the same power consumption,

weight, and overall appearance. (With the exception

of the face plate)

 

And, all these models are class H.

 

Sounds Possible?

 

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I stand corrected, the change from 2 step to 3 step rails occurs between the MX-2000 and MX-3000. I was thinking specifically of the MX-1500 actually.

 

There are other differences, such as octal socket compatability (none w/ MX line), DIP switch programing, speed/bandwidth of semiconductors, packaging etc that cam make up the differences also.

 

Bob Lee is a very well educated resource... I think he just received an IEEE appointment (or award?). I respect him and his work very highly.

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