Speaker wattage ratings... huh?

[avvie]

So I've been posting around here trying to make a decision regarding downsizing my rig. Now I have another idea:

I have a Hartke 7000 head. If i understand correctly, if i run one speaker out only in full range mode it's 350 watts.

I have an SWR Goliath Jr II (2x10+horn)which says it's rated 4 0hms and 250 watts. Now, I ran it this way for about a year and it fried the amp and I had to have it serviced and resoldered. I could hear it sizzling, but I would love to be able to use this configuration again.

MY QUESTIONS ARE:

1- could I just switch out the speakers in the cab and boost the wattage tolerance that way?

2- if so, what speakers would you suggest? Budget-conscious is preferable; I'm on a small island with small stages and only gig a couple times per month for under $100/gig.


HOW IT GOT THIS WAY: I assembled my rig through CL ads and pawn shop deals. The first thing I found was the Hartke amp which is 700 watts. My cabs cannot tolerate that wattage but i was unaware that it would be a problem... I had always bought matched sets previously.

Mahalo!

[BassmanPaul]

Changing drivers always ends up in a crapshoot unless you do the science to find what drivers are suitable. I wouldn't even think about playing a gig with a single 2x10. I always use a pair. When it comes to volume, more speakers trumps more power every time.

With cabinet power ratings, they are usually the thermal rating of the drivers. That's the point where they start to melt. In the real world a driver will run out of excursion at about half of it's thermal power.

[Downunderwonder]

I disagree that 2x10 can't hold a gig together. Outdoors not too flash for sure. I agree two of them makes a fine rig for stage monitoring and even covering a goodly sized bar.

Technology marches on but 350w through a single 2x10 is still bleeding edge. Cone area x displacement determines ultimate volume. Tone suffers when displacement power handling is optimised.

The amp failure wasn't a cab issue in the way you seem to think. I wonder if you might have cooked the tweeter circuit into a dead short that fried the amp. Where are you at with amp and cab?

[avvie]

Dug up a quick photo...

Harke 7000 in bi-amp mode, and as I understand it from the manual:

350 W from amp 1 into a 4 ohm 250 watt SWR Goliath II

240 watts from amp 2 into an 8 ohm 200 watt Hartke 4/10.

Volume rarely ever goes above 3. I never use the on-board EQ.

This configuration works just fine, but the problem is that I have to use this configuration ALL THE DANG TIME. I can't ever just grab the 2/10 and the head for smaller rooms. My footprint is most obtrusive in some of these bars.

[avvie]

BTW, before the amp fried, that 210 was plenty loud and sounded good in outdoor jams.... I was really surprised. It was the backline amp for a weekly outdoor jam in Makawao for several months and I would get to hear it from audience range whenever someone else would stand in.

[Bass_Pounder]

Why would you be in bi-amp mode with 2 full range cabs ?

Why run a 2X10 @ 4 ohms, and a 4X10 @ 8 ohms ?

Nothing about that setup makes any sense.

[Tuned]

You could contact your local SWR dealer for new replacement drivers, their current ones should be fine in the older cab, and they handle 400W instead of 250.

Next time you use both cabs at a gig try unplugging the bottom cab. I bet the 2x10 is enough as long as you get it up above waist level, provided there's PA support.

[avvie]

Originally Posted by Bass_Pounder

Why would you be in bi-amp mode with 2 full range cabs ?

Dunno... just tried it once and it sounded cool... I could control how much was from the 210 and how much was from the 410. Seemed like a good idea at the time.

Why run a 2X10 @ 4 ohms, and a 4X10 @ 8 ohms ?

Nothing about that setup makes any sense.

Those are the cabinet ratings. The Hartke ratings are marked on the cab; the SWR ratings are from http://www.swramps.com/support/vintage.php#procomboamps

[Bmorefoozler]

It may be a smart idea to re-wire the 4 ohm 2x10 into 16 ohms. Check to see if it has 8 ohm drivers, and if it does, change the wiring from parallel to series. Then, equal wattage would be spread accross all speakers.

[avvie]

Originally Posted by Downunderwonder

The amp failure wasn't a cab issue in the way you seem to think. I wonder if you might have cooked the tweeter circuit into a dead short that fried the amp.

Hmm... still trying to grasp.

What I originally thought was that since 350 watts were being pushed into a 250 cabinet and the cabinet impedance was 4 ohms instead of 8 (which would make the amp deliver 240 watts instead of 350) that the excess power was somehow getting slammed back into the amp and overloading something. That was just my understanding from hearsay, and I probably have learned more about it today than any other point in my life, but still I'm not an electronics tech.

The amp never completely died, but it sizzled and popped a lot until I took it in for service. Soon it sizzled and popped again until I bought a second cabinet (the Hartke 410) and it's worked fine ever since as long as I run both cobs.

[avvie]

Originally Posted by Bmorefoozler

It may be a smart idea to re-wire the 4 ohm 2x10 into 16 ohms. Check to see if it has 8 ohm drivers, and if it does, change the wiring from parallel to series. Then, equal wattage would be spread accross all speakers.

Ooooh... that sounds interesting! And much cheaper. That would bring the wattage down from 350 to 145, according to the Hartke manual...

[JimmyM]

Originally Posted by avvie

Hmm... still trying to grasp.

What I originally thought was that since 350 watts were being pushed into a 250 cabinet and the cabinet impedance was 4 ohms instead of 8 (which would make the amp deliver 240 watts instead of 350) that the excess power was somehow getting slammed back into the amp and overloading something. That was just my understanding from hearsay, and I probably have learned more about it today than any other point in my life, but still I'm not an electronics tech.

OK, take a deep breath, and prepare to learn First thing, forget what you've been told so far. Second, read some of the links in the stickies at the top of the Amps forum. Some of the talk gets a little complex from time to time, but it can be broken down into small bits and absorbed easily enough. Third, there is a lot of BS out there about audio. We're pretty good at calling BS on here. Though obviously some things are matters of opinion, there are certain physics facts about how audio behaves, and people try to argue them but the truth can't be argued. Doesn't mean you won't like a rig that isn't set up 100% by the book, but facts are facts.

[Downunderwonder]

Is that biamp setup a true crossover lows and highs split to the two cabs? If so it is no surprise it has the better sound.

The overall loudness in the audience would be similar to the 4x10 alone.

It should be possible to run the amp dual mono. You could lose the 4x10, get another of the swr in 4ohm and run both without losing hardly any volume. Beware, they won't take 350w each without taking out a lot of low end.

The vertical stacking of 2x10 gives the best dispersion.

You didn't say where you are at with the rig. I'm concerned your 2x10 is presently an amp killer.

[Downunderwonder]

Sorry, I'm slow typing, just reviewing new posts.

[avvie]

Unsure what you mean by "where you're at"... posted current rig in photo post above.

And yes, a true crossover. Highs to one amp and lows to another.

[Downunderwonder]

It's possible the amp has an incompatible nature with that 4 ohm Swr. It's not common, never personally had any issue of brand total incompatibility.

It's beyond me to explain but basically cabs aren't uniform impedance across the frequency range. The 4 or 8 is only a nominal average. Older swr could do 2 ohm and possibly less fussy than your amp pushing hard into less than 4 ohm load.

Other possibility, the amp wasn't fixed well enough.

Note that in biamp mode very little power is sent to the cab on high freq duty. Lows use lots of power to get loud, not highs.

If there is a proper tech available you should get an impedance sweep done on the Swr. This will answer to the compatibility question.

[Downunderwonder]

Just to be clear, the amp functions flawlessly until you try to run only the swr alone and hard and then you get the amp doing the frying bacon noise itself, not via the cab?

[RickenBoogie]

I agree with Jimmy. A couple of hours spent reading the stickies and faq's will go a looong way. It's important to understand HOW amps and spkrs work, if you want to make good use of them, and NOT need repairs and replacements. Terminology aside, there are some rather large misconceptions, and an obvious lack of understanding that is apparent in th op. And, agreed again, a 4 ohm 210 paired with an 8 ohm 410 is comletely backwards. Also, makes no sense to bi-amp those 2 cabs. This is but one thing that can be learned by reading those faq's. I urge the op to take the time to read them. Best of luck.

As for the cheapest/easiest fix to the present situation, turning the 210 into a 16 ohm cab, then running each cab full range on seperate outputs from the amp, NOT biamped.

[Downunderwonder]

ugh, it makes every bit of sense to biamp those two cabs. It's two power amps in there, all crossed over. Not everything is about maximum volume.

[Downunderwonder]

He doesn't have a problem with the rig apart from the footprint and carrying it all.