Hey guys,

Which Mackie speaker are we talking about here?

Must not be the SRM450's since they are bi-amplified using a 300 Watt RMS amp for the bass and a 100 Watt RMS amp for the mid/hi.

http://www.mackie.com/products/srm450/index.html

Just trying to get on the same page as you guys here.

mike

[This message has been edited by msutliff (edited 08-20-2003).]

Mike is certainly right about the specs on the SRM450's. Mackie doesn't claim these are 450 watt speakers, although some may think that based on the model number. And they are indeed bi-amped, which allows them to use an active cross-over network.

In designing an integrated amp/speaker package such as the 450's, you'd better believe that the amps and speakers are matched for best overall performance. They've got a limited volume, a limited ability to dissipate heat and they've got to strive for the best overall performance given all the variables they have to work with and the design compromises that have to be made. And based on what I've heard and what others have said about the Mackies, I think they've done a darn good job.
Paul C.

The inside scoop on the SRM450's from a Mackie tech is that the power amp can indeed, produce 300 watts for the lows, but NOT at the current ohm load. I love the sound of the 450's, but they were far from perfect. The overheating was a constant threat in high output situations or when used on their sides.
Anyway - that's thw way it was told to me from a Mackie insider.
I doubt that they are optimized for the full 300 watts,..... just like the EV sxa100's - rated at $350 watts? Naw. These are made up peak numbers I think.

If UD's "inside scoop" is true, then I'd agree that it's bordering on false advertising to claim you have a 300 watt RMS power amp when the speaker impedance will never allow the amp to deliver that level of power. Most non-integrated amps have their electrical output ratings tied to the load (speaker) impedance, which is the correct way to spec. an amp. If Mackie has done otherwise, then shame on them.

While I have personally not owned the Mackie 450's I have heard about the overheating problem and that it does indeed create a limitation under certain operating situaitons. Engineering always involves compromises and trade-offs and good engineering can minimize the "bad" and maximize the "good."

Re the heat dissipation problem, some of the manufacturers of powered speakers are using fans to help with cooling and others are using the air movement created by the low frequency speaker to aid in cooling.

Cooling is certainly an issue at high power levels, especially given the compact nature of the newer powered speaker ssemblies. But so is sound quality and maybe, as is the case with keyboards, (there is no perfect keyboard, as echoed many times on this Forum) so too there may be no perfect powered speaker.
Paul C.

Frank,
I concur with your formula. As per some of my technical training: P=EI. Power (in watts) = Voltage X Current.
Starkeeper

You know Dave, truth is for the most part, shaded, and sometimes hard to believe if not. In real life shaded truth sells better than pure white truth in merchandizing, including all areas, from products to religion. With merchandise, sometimes truth aggravates people and they try to defend what they want to believe. In religion when truth is brought forth they will try to do in the purveyor of it as evidenced over the past millenniums, from the prophets to Mr. King. Even the guy who said the world was not flat but round, got it in the neck. True religion? Which is worse? Truth is always truth but will not always be very popular. Round and round she goes and where she stops nobody knows.

Just thinking, Grandpa Doug

It looks like some writers in this thread think the output of speaker-cabinets depends on the impedance (Z) of the speakers ?!

The lower the Z, the higher the audio-power.... but be careful please !!

The optimum match between an amp and speaker is when they both have the same impedance. Current amps are able to auto-adjust within limits, but there ARE limits. (max.speaker Z and min.speaker Z)
When users keep lowering the speaker impedance often amps get damaged because the power-supplies and other components get overheated.

There are 400W speakers with 4 Ohm Z, but also 400W speakers with 8 Ohms. The amp used for the 2nd one has the double output voltage.

Roel

I'd like to ask Brickboo a question.

Yo Brickboo,

Are you gettin' anything out of all this?

mike

PS. I did get a kick out of the swimming pool analogy, Grandpa Doug.

Nice discussion.

Here is another very important issue to think about: in order to get more volume (that is at a certain level) you need a lot more watts to achieve a audible difference.

300 watts or 400 watts don't make much of an audible difference at all. Try it if you don't believe me.

Or try this: turn up your volume knob on your KB very slowly to about 2/3. You'll a here a noticeable difference in volume with each increment.
Then turn it up all the way. Not much difference.

Regarding the overheating problem: I own 3 Mackie SRM450, 2 for the audience, 1 as a monitor.
We just had an outdoor gig at a french festival. It was very hot and we played at a good volume. No overheating noted.
The Mackies are clean and loud.
As far as I remember, Uncle Dave is the only one who had that problem in the past, with a speaker that was placed on the floor.
Corect me if I'm wrong.

I still give the Mackies 2 thumbs up
But of course only with the 9000Pro

Eric

You're wrong Eric.
Donny had the troube more than once, and I was at an outdoor show and saw it in action again. The heatsinks need to be redesigned, or the amp must be made more efficient.

I know they sound good, but I can't take another chance till I see improvement. Today my setup is the JBL Eon10s(G2) with the G2 sub...run by a DBX Drive Rack. I love the flexibility and the sound so far.