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Interesting conversation about speakers and ohms

#121
So, it's plausible the tech had a point, given: loading a cab that was designed around certain 8 ohm speakers with 4 ohm speakers marketed as "equivalent" will often result in damage. Really not much different than just "swapping" with no regard for box volume or tuning. He theorized and wasn't speaking from knowledge, but experience. Devil's advocate and all....
 
#123
B-string said:
This is also unfortunately not new here.
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True enough. :D

JimmyM said:
Totally. But now and then, sometimes the pressure gets to be a bit too much ;)
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I totally get that and I definitely have my share of snarky posts. I have been trying to not do that so much lately but I've failed as recently as earlier in this thread. :D

ThisBass said:
I'm afraid the myth is going to carry on.
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Without a doubt. ;)


EDIT: Snarky post office? Stupid autocorrect. :D
 
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#124
Oh, wait. I get it now. If you put tube watts through 4 ohm speakers they're going to crease, but if you use solid state watts and mix sizes of 8 ohm speakers it's ok, just as long as they're next to each other and you don't underpower them.

Thanks! I'll be sure to tell everybody I know.

Now off to the bass forum to figure out what bass I should get for my metal band.
 
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#126
JimmyM said:
So we need to dumb down our approach so they understand it? I think not.
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There is a huge difference between dumbing something down and giving consumers the information they need to make wise choices. You should not have to have a degree in engineering or physics to operate a light switch or to pick a cab that is suitable for your amp. And even if you do have a degree in the physical sciences you'd be hard pressed to figure out what the maximum output power of any given amp is from the paltry information that manufacturers give you. Besides, why would you think that giving an honest rating of the maximum saturated output power is dumbing down but giving an honest sine wave power rating is not?

Amp manufacturers don't have to give me either rating. If they tell me enough about their circuit designs I can figure out everything I want to know about their amps on my own. Why should they dumb down their advertising for the sake of you poor bassists who don't have master's degrees in electrical engineering? If you want to play the electric bass you should have studied electrical engineering too. If you can't cut the mustard as an amplifier designer you should have studied the double bass.

At least that is where your fear of dumbing down goes when carried to its logical conclusion. I've seen way too many thoughtful and well reasoned posts from you to believe that this is where you really want to go. Saturated output power ratings would be a Good Thing.
 
#127
khutch said:
At least that is where your fear of dumbing down goes when carried to its logical conclusion. I've seen way too many thoughtful and well reasoned posts from you to believe that this is where you really want to go. Saturated output power ratings would be a Good Thing.
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I don't disagree. They used to give them, though, but then people were angry that their alleged 600w amp only put out 300w cleanly, so most companies stopped. It's the old "can't win for losing" scenario.

Enjoyed your doomsday scenario, BTW :D
 
#128
basscooker said:
So, it's plausible the tech had a point,
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The tech does have a point but his/her conclusions are almost certainly based on too little information. The tech probably sees 10, say, failed 4 Ohm cabs for every failed 8 Ohm cab and concludes from this that 4 Ohm cabs are more prone to failure. If for every bassist in his market area who uses a 4 Ohm cab there is another who uses an 8 then the tech's conclusion is correct, the 4's are failing ten times as often as the 8's. If for every 8 Ohm cab in his area there are ten 4 Ohm cabs then the tech is wrong and in fact the 4 and 8 Ohm cabs are failing at the same rate. And if there are twenty 4 Ohm cabs for every 8 Ohm cab then the tech is really wrong, the 4's are twice as reliable as the 8's. It's not likely the tech has the market statistics needed to make a valid comment on the failure rates even if the tech works in a shop that sells cabs and the tech knows the sales numbers for that shop. The numbers from the tech's shop don't necessarily reflect the numbers for the whole market area.

But most amps will deliver more power to a 4 Ohm cab than to an 8 Ohm so people who change cabs willy-nilly without giving any thought to power ratings will in fact blow 4 Ohm cabs preferentially over 8 Ohm cabs. This could also be the reason the tech sees more 4 Ohm failures. This is not a problem with the 4 Ohm cabs as the tech assumes, it is a problem with the people and with the lack of suitable ratings that would keep them out of trouble. Assuming they pay any attention....

Besides electrical engineering I also have training in black belt quality control techniques. One of the basic principles of QC is that you have to listen to the people like this tech who are directly exposed to or involved in the issue that you are trying to resolve. They are the only ones who can lead you to the correct solution. However you have to be careful to collect their information without becoming biased by their conclusions. They may not understand WHY something happened, only how, when, and where it happened. And that is likely to be the case with this tech's conclusions about cab failures. Depending on the circumstances, as I outlined above, there may not be an issue here at all and if there is an issue it may be with the cabs that present the fewest, not the greatest number of failures.
 
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#129
JimmyM said:
I don't disagree. They used to give them, though, but then people were angry that their alleged 600w amp only put out 300w cleanly, so most companies stopped. It's the old "can't win for losing" scenario.
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What you are telling me is that it was the decision to give only the clean power rating that was the dumbing down! The correct answer to consumer confusion about two power ratings was education, not dumbing down. You should not have to have an MSEE to mate a cab to an amp but you should be willing to learn enough to keep you out of trouble. And yes, I have worked closely enough with consumers to know how difficult a sell that can be.
 
#131
Isn't it one of the most asked question at TB that reads like:

"How can I do to get 4 Ohm load to get full power out of the amp?"

" ... I want have full power of the amp so I'm looking for 4 Ohm cab/speaker BUT the cab (or speaker) are only available in 8 Ohm version"

or sometimes a post reads similar like:

"... so the load is 4 Ohm and the amp will push it's full power"

May be the relationship between amp power and cone surface and gainable loudness is (too often) poorly understood.

May be some folks belive in delusion 350 watt into 112 cab 4 Ohm was just the same like 350 watt into 215 cab 4 Ohm.
Because the amplifier will push it's full power then may be some folks try to blow up a 112 just as loud as experienced previor with 215 ?
Both cabs are 4 Ohm so may be some folks expect by default both cabs as just the same in gainable loudness because the amp will push it's FULL POWER in either case.
 
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#133
CL400Peavey said:
The ratings on cabs are thermal ratings. Which are crap to begin with, and mechanical ratings are well below those points. No big manufacturer posts those, as they are less marketable.
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Thermal ratings aren't necessarily crap.

Mechanical (excursion) ratings would be frequency dependent. That makes them more complicated, which both marketers and customers tend to dislike.
 
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#134
Bob Lee (QSC) said:
Thermal ratings aren't necessarily crap.

Mechanical (excursion) ratings would be frequency dependent. That makes them more complicated, which both marketers and customers tend to dislike.
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For sure Bob.

Where I see thermal ratings failing the consumer, is when they are well above the mechanical limits for an implementation that will be limited by the mechanical limits much quicker. No equipment is 100% safe from all abuse, but many dont understand that when their cab sounds like it going to die, it will, regardless of the huge power handling spec it was sold with. Yes using mechanical limits is more complicated, but the world is full of examples of "it depends". Which 400hp vehicle is faster/quicker? a Porche or a dump truck? How about a porche and an M3? How about if you have to transport 4 adults. I know it goes back to crappy car analogies, but I hope it kind of gets my point across.
 

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