speaker power handling

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zax
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speaker power handling

Post by zax »

Looking to buy a 2x12 cabinet to be powered at different times, by 2 different amps.

1st amp is mesa boogie mk2 B, 75 watts
2nd amp is line 6 flextone HD, 300 watts

I've heard that underpowering speakers can wreck them. Is this the case? Presently, the boogie has a 200 watt EVM which has had no problems.

What wattage of speakers should I consider?
Thanks
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Blackburn
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Re: speaker power handling

Post by Blackburn »

Zax, underpowering speakers cannot wreck them.

For your 2x12 cab, I'd say you'd be fine with a pair of those 200w EVMs running with either amp.

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xtian
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Re: speaker power handling

Post by xtian »

I suspect the OP meant "under SPECIFYING" the speakers. If you crank up your 300 watt amp into a 60 watt speaker, yes, you can wreck it.
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zax
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Re: speaker power handling

Post by zax »

Thanks for the quick replies and info
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NickC
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Re: speaker power handling

Post by NickC »

Generally speaking, it isn't over-powering speakers that kill them; it is distortion from an amp (with insufficient clean output) that is driven too hard into clipping (of course, the previous observation that "300 watt amp into a 60 watt speaker" is asking for trouble).
Last edited by NickC on Thu Mar 20, 2014 6:16 pm, edited 1 time in total.
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Blackburn
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Re: speaker power handling

Post by Blackburn »

xtian wrote:I suspect the OP meant "under SPECIFYING" the speakers. If you crank up your 300 watt amp into a 60 watt speaker, yes, you can wreck it.
You're probably right... Doh! :lol:
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lord preset
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Re: speaker power handling

Post by lord preset »

Blackburn wrote:
xtian wrote:I suspect the OP meant "under SPECIFYING" the speakers. If you crank up your 300 watt amp into a 60 watt speaker, yes, you can wreck it.
You're probably right... Doh! :lol:
The underpowering thing comes from the hifi world. If your power amp isn't big enough one might just turn it up to the point that it's clipping. Sustained hard clipping from a solid state power amp could damage a speaker, but I always found it hard to believe anyone would continue to listen to a stereo that was clipping badly. Could happen though
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JazzGuitarGimp
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Re: speaker power handling

Post by JazzGuitarGimp »

Yes, this comes from the hifi world. Specifically, tweeters are prone to blowing when used with underpowered amps driven to clipping. Square waves (from the clipping) contain a lot of high frequency energy, which can quickly fry a tweeter. Since we don't use tweeters in guitar amps, this really doesn't apply to us.
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Re: speaker power handling

Post by Roe »

zax wrote:Looking to buy a 2x12 cabinet to be powered at different times, by 2 different amps.

1st amp is mesa boogie mk2 B, 75 watts
2nd amp is line 6 flextone HD, 300 watts

I've heard that underpowering speakers can wreck them. Is this the case? Presently, the boogie has a 200 watt EVM which has had no problems.

What wattage of speakers should I consider?
Thanks
if the line6 is 300w into 4ohms, then a 200w 16ohm cab will probably be sufficient
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RCGPNY1
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Re: speaker power handling

Post by RCGPNY1 »

I saw Carlos Santana blow the speakers in his Boogie's twice in one show
at the Fillmore east back in the day( He had to finish the night with a Twin)
I worked in a repair center at the time and a customer walked in with a Boogie with a blown speaker. It had a JBL D120 in it>>>The customer said "Why did it blow ...it's 100 watt speaker in a 100 watt amp. I told him the JBL would only handle about 60 watts in an open back cab and if the signal was distorted it would probably not even handle that. The more distortion you have, the closer to a square wave you get...speakers don't like square waves as they do not allow for an "off" to the wave cycle.
Plus there is also mechanical issues for JBL's in open back cabs. Power handling is more complex than people think. Underpowering,that is, drivinga 30 watta amp into hard clipping will fry a 50 watt unit in the wrong cab.
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rdjones
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Re: speaker power handling

Post by rdjones »

zax wrote:Looking to buy a 2x12 cabinet to be powered at different times, by 2 different amps.

1st amp is mesa boogie mk2 B, 75 watts
2nd amp is line 6 flextone HD, 300 watts

I've heard that underpowering speakers can wreck them. Is this the case? Presently, the boogie has a 200 watt EVM which has had no problems.

What wattage of speakers should I consider?
Thanks
As others stated, the underpowering speakers lore is from the HiFi world where clipping an amp will send lots of high frequency trash to the tweeters, burning them out.
This occurs even with an amp that's rated at below that of the speakers.
It's much less of a concern in a guitar scenario with no tweeter.
Hard clipping can still burn a voice coil if there's not enough power handling reserve.

If you like the EVMs, you should have nothing to worry about.

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pops
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Re: speaker power handling

Post by pops »

Used to play with a bass player that would blow the 10's in his 2X10, 18 cab. He was sending square waves into the cab by the tone and volume settings he was using. Changed the settings and never blew another 10.
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Alan0354
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Re: speaker power handling

Post by Alan0354 »

RCGPNY1 wrote:I saw Carlos Santana blow the speakers in his Boogie's twice in one show
at the Fillmore east back in the day( He had to finish the night with a Twin)
I worked in a repair center at the time and a customer walked in with a Boogie with a blown speaker. It had a JBL D120 in it>>>The customer said "Why did it blow ...it's 100 watt speaker in a 100 watt amp. I told him the JBL would only handle about 60 watts in an open back cab and if the signal was distorted it would probably not even handle that. The more distortion you have, the closer to a square wave you get...speakers don't like square waves as they do not allow for an "off" to the wave cycle.
Plus there is also mechanical issues for JBL's in open back cabs. Power handling is more complex than people think. Underpowering,that is, drivinga 30 watta amp into hard clipping will fry a 50 watt unit in the wrong cab.
I can't help but to chime in. I bought a new JBL K120 back in 1976 and put into the Twin working together with the other stock speaker. Both were 8 ohm so they pretty much share the power. I blew the JBL without even cranked up high. I don't remember I ever crank the amp high ever!!!! The voice coil of the JBL deformed and scraped the frame and make scraping noise.

Don't say 60W, say 30W share between two speakers. The stock Twin speaker worked like a champ, never blown. I was so mad, I was a poor student and $100 per JBL is a whole lot of money in 1976. I only paid $375 for my new Twin in 74!!!!

from my observation, the JBL is like a hifi speaker, it response to low frequency and transient attack. For example, if you slap the strings with you hand on the neck, the cone of the JBL jump, it moves like over 1/4" easily. You do it on the Fender speaker, the cone doesn't even move!!! Seems like it's the ability to respond to the transient attack that can kill the JBL. Never would I buy another JBL, I don't even like the sound, it's very hifi to me. So far, I have two WGS cheap speaker and loving them.
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JMFahey
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Re: speaker power handling

Post by JMFahey »

RCGPNY1 wrote:I saw Carlos Santana blow the speakers in his Boogie's twice in one show
at the Fillmore east back in the day( He had to finish the night with a Twin)
I worked in a repair center at the time and a customer walked in with a Boogie with a blown speaker. It had a JBL D120 in it>>>The customer said "Why did it blow ...it's 100 watt speaker in a 100 watt amp. I told him the JBL would only handle about 60 watts in an open back cab and if the signal was distorted it would probably not even handle that. The more distortion you have, the closer to a square wave you get...speakers don't like square waves as they do not allow for an "off" to the wave cycle.
Plus there is also mechanical issues for JBL's in open back cabs. Power handling is more complex than people think. Underpowering,that is, drivinga 30 watta amp into hard clipping will fry a 50 watt unit in the wrong cab.
Agree and add: the MB MK I/II had a switch to open the cathodes of 2 of the output 6L6 for a "60 W" nominal rating (I think it was even less than that, probably closer to 40W RMS), and the User Manual specifically stated that if the amp was used clipping, the amp had to be set to "60W" or it would blow the speaker.

As of overexcursion with that D120, it had a cloth edge which allowed it to move all over the place , plus a big coil/magnet linear motor to push it; the standard Twin speaker had a much harder all paper cone and a stiffer suspension (much better adapted to an open back cabinet) , coupled to a mucgh smaller coil (38mm vs 100mm) and smaller magnet (130mm vs a big Alnico which later was replaced by a 220mm magnet, go figure).

By the way, the Fender flagship in those days was the Dual Showman, basically the same chassis as a Twin but with two JBL 15" (same magnet and coil as the 12"ones) but in a closed and shallow enclosure, which limited their movement.

Sound was incredibly clean and loud, almost bonecrushing.

By the way, I also saw Santana live in those days (don't ask), he was playing with 2 little Boogies, there were 2 more ready to change if he had any problem, and what I found very funny was that on a nearby table there were 2 or 3 extra speakers , unboxed and face down, apparently ready to be changed during the show (otherwise why would they be already unboxed?).
I asked the stage assistants and they told me they were some Electro Voice model, not JBL.

They were weird, very deep , not shallow like the typical JBL.
Alan0354
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Re: speaker power handling

Post by Alan0354 »

I remember Mesa Boogie Mark? used Electrovoice back in the 70s. I saw Santana 5 times, he did not play that loud, always went through the PA. I am surprised the Electrovoice blows too!!! He couldn't be using over 40W out of the amp.

Seems the cheaper smaller voice coil diameter ones are more rugged. I remember one time I went to a tech to fix my Marshall, I saw a whole basketful of cut JBL voice coil, must be like 20 of them!!! He even gave me two!!!
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