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SWR Deterioration


pusso9tails

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Hey all,

If there are any SWR owners/students out there, I've got a pop-quiz for 'ya.

I recently own an SWR 350X head, and I'm wondering about cabinetry.

The manual states that at 4ohms, it'll run @350watts, which is fine.

My concern is that the manual also states that when you're running it @ 2.6 or 2ohms, "wear and tear" on components will occur faster than normal.

Now, is this wear and tear on the tube and fuse? 'Cause if so, then hey, no problem; they're replaceable.

But, if they are talking about wear and tear on the circuitry, etc., that could be a cause for alarm and it would be a defining factor in my choice for a cab setup.

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If AlembicKoa were still here, he'd say: that means that running it at 2 ohms will cause smoke to come out of the amp, & once the smoke comes out, it's very hard to get it back in. :D

 

Don't do it.

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Originally posted by dcr:

If AlembicKoa were still here, he'd say: that means that running it at 2 ohms will cause smoke to come out of the amp, & once the smoke comes out, it's very hard to get it back in. :D

 

Don't do it.

That's GREAT. Brilliant.

 

However, any amp is going to "wear" more if you run it hot (i.e., run a 4-ohm load instead of an 8-ohm load). Strange wording in the manual, but very true.

 

Run it! Load up that amp! Push that baby till it burns!

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HAAAAAAAAAAA! You guys are crazy!

Apparently the new aluminum chassis on the amp is supposed to act as a heat sink. I just think it's a way for justifying the delicious excess of the shiny exterior. Perhaps I'll grab two 8 ohmers (one Goliath III and one Big Ben) just to be careful. Or maybe one Henry 8X8. I don't know...I just want beefy low end fundamentals with tight high end transients (manual speak).

What do you guys think? Does anyone have any recommendations for cab set ups? I guess in terms of a live gig, I'm running xlr out of the amp's ass and back and into the house, so it doesn't matter for the punks in the audience 'cause they'll get the tone that I dial in anyway. Decisions, decisions...

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I use the SWR 4x10 & 1x15 well enough but I have to turn the horns completely off on both cabs or they just shriek when I pop or play more aggressively, emitting a very unpleasant sound to my ears. Even if I just turn one of them up a bit it sounds garbled to me. I'd just rather not have any horns at all. My amp is G-K 1001 and I use an EB/MM 5. What gives? :evil:
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Really!? That shrieking sounds pretty bad. How high is your treble on your amp and bass? Do you think that has an effect?

As far as the Workingmans' go, what do those puppies cost anyway?

If it's cheaper and just as rockalicious, I might gravitate toward one.

I was looking at Rocco Prestia's rig in the last issue of Bass Player; simple and solid it appears to be.

I wouldn't mind trying out one of those towers he uses. Then again, it's rated to hold something close to 1000watts. My head is only 350watts. Do you think it would be worth it?

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Pusso9tails wrote:

"My concern is that the manual also states that when you're running it @ 2.6 or 2ohms, "wear and tear" on components will occur faster than normal."

 

The output transistors draw more current when driving a lower impedance load. The more current they draw, the more heat they dissipate.

The power supply has to work harder to deliver more current to the output transistors, so the power supply also disipates more heat when the amp is driving a lower impedance.

More current = more heat = faster "wear and tear" on the output transistors and power supply's transformer (and resistors). Excessive heat can lead to more rapid deterioration (or destruction) of electronic components.

A "marginal" output transistor or power supply transformer is more likey to fail when stressed by excessive heat.

That's why it's best not to run most solid-state amps into loads less than 4 ohms.

TB

The more you listen, the more you hear.
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if you want a killer set up with the low end fundamentals. get a goliath 3 4x10 with a SM 500 and eith a 212 or 1x15 with the horn turned off and run it with a small :) QSC. or the 4x10 with the qsc and the 1x15 with the SM 500. that should blow the doors off most buildings and it will still be modular incase you need to break down and play a small gig or rehersal.
I didn't come here to play. I came here to make babies.
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Originally posted by Terry Buddingh:

The output transistors draw more current when driving a lower impedance load. The more current they draw, the more heat they dissipate.

The power supply has to work harder to deliver more current to the output transistors, so the power supply also disipates more heat when the amp is driving a lower impedance.

More current = more heat = faster "wear and tear" on the output transistors and power supply's transformer (and resistors). Excessive heat can lead to more rapid deterioration (or destruction) of electronic components.

A "marginal" output transistor or power supply transformer is more likey to fail when stressed by excessive heat.

That's why it's best not to run most solid-state amps into loads less than 4 ohms.

TB

Whoa! Hey guys - that was Terry B from Bass Player - long time amp tech, Ampeg wiz, and lots of other credentials that I don't even know!

 

Terry - Thanks for stopping by :wave:

Tom

www.stoneflyrocks.com

Acoustic Color

 

Be practical as well as generous in your ideals. Keep your eyes on the stars and keep your feet on the ground. - Theodore Roosevelt

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How about this:

buy two 8 ohm cabs and run them parallel, or a 4 ohm and an 8 ohm (or another 4 ohm), and only bring the 8 out to play when you need to move a little more air (4 + 8 = 12 which is one more than 11! :thu: ). That way you will only put more "wear and tear" on the amp occasionally.

"Start listening to music!".

-Jeremy C

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