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When is a 120w combo amp NOT 120w?

tubatodd

tubatodd

Oct 31, 2004
2,456
4,424
Birmingham, AL
#1
....when the cone installed is only 75w. Found this in my Hartke kickback 10.

IMG_20200308_145402.jpg
 
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#3
Actually, if you were to delve deeper into the way speakers are rated (specifically by Eminence), you might find that Eminence provides a "nominal" power rating that's not necessarily very close (or even reasonably close) to being accurate. It's up to the manufacturer of the end product to do their own testing to determine the actual power handling that they feel comfortable with for their specific application. Generally, I find that the ratings are higher than the real world results, especially when a HPF is incorporated into the amp, but in the case of the Fender driver being used, the testing that they do is pretty conservative compared with most. I also believe that there is a gap height error on that spec sheet and may not actually represent the production driver. Also, the power amp is 100 watts RMS at 8 ohms, no question about that.

I wouldn't expect much different by Hartke either, the nominal "power number" is not the actual real world power rating. It's up to the manufacture of the end product to determine that.
 
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#4
a 120 watt amp is basically just that. 120 watts

but bass unfortunately goes pretty deep.

unfortunately the bad news is
there is also " 250" watt or even" 350" watt speakers
that will hit 10% distortion at only 80 to 120 watts

its a rough ballgame for a speaker below 100hz

as far as the hartke speaker
looks like a stamp steel, with dam good sized magnet.
probably a reinforced cone.

looks like a fun driver, im not too shocked i know what one speaker or a single driver does with 100 watts.

120 watts would be alot more than you think if you used 2x

not the point
a manufacture might have rated it for what it is. conservatively 75 watts
as i said with typical 3m to 4mm drivers distortion gets up around 60 to 80 watts anyways.

the actual voice coil could be good for " 150" to " 250" watts.


just tell me what it does....oh 75 watts....cool
ill take 8 of them lol

their is also 300 watt or 500 watt combos.
and it doesnt hurt my feelings. I already know the internal speaker
cant handle all that power.
 
#6
When it's an old heavyweight Peavey from the 90s on back! I still have a TKO75, and have used it in the rare occasion for rehearsals and small jams. Noticeably louder than its rated 75w.
 
#9
Just in case you aren't aware, the power rating of a speaker is nothing to do with the actual amount of noise it delivers, its purely a measure of how much energy can be put into it before it breaks.

A 12" 50w speaker and a 12" 500w speaker receiving 50w from an amplifier will deliver roughly the same volume. So provided it doesn't break, your 75w speaker will give you just as much volume in that amp as a 150w one would do. (Possibly a bit more if we went into subtleties I'm trying to avoid!)
 
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#10
Raf Seibert said:
When is a 150W amp not a 150W amp? Whenever you’re not driving it to its fullest power. Just as your 150mph car isn’t doing 150mph while you’re driving around town, neither is your amp giving its maximum rated power all the time.
Click to expand...
I think he meant 120W amp.. but still. ;)

I think a better analogy would have been to use Horse power rather than top speed.

Like, Your car is not delivering its "claimed" 310HP when you're starting from a stop sign. (under normal driving conditions ;)). More likey it'd be closer to *30 HP when starting from slowly from idle around *1500 RPMs. The 310HP would be after it revved up to say.. 5500 rpms. (* = or so/ish/roughly)

Though, your point is still valid to an extent. :)

I'm here to help.
T$
 
#11
OP here...

So I guess what I was asking was really about what the numbers and the math mean. So the 120w is the rating of the head only. The cone rated at 75w tells me it can't handle the full load of the head. And the only way to get the full 120w load out of the head is to use a cab that can handle the full load.

Is my understanding of these numbers correct?
 
#12
tubatodd said:
OP here...

So I guess what I was asking was really about what the numbers and the math mean. So the 120w is the rating of the head only. The cone rated at 75w tells me it can't handle the full load of the head. And the only way to get the full 120w load out of the head is to use a cab that can handle the full load.

Is my understanding of these numbers correct?
Click to expand...

No. Re-read my post #3, I laid it all out there.
 
#13
agedhorse said:
Actually, if you were to delve deeper into the way speakers are rated (specifically by Eminence), you might find that Eminence provides a "nominal" power rating that's not necessarily very close (or even reasonably close) to being accurate. It's up to the manufacturer of the end product to do their own testing to determine the actual power handling that they feel comfortable with for their specific application. Generally, I find that the ratings are higher than the real world results, especially when a HPF is incorporated into the amp, but in the case of the Fender driver being used, the testing that they do is pretty conservative compared with most. I also believe that there is a gap height error on that spec sheet and may not actually represent the production driver. Also, the power amp is 100 watts RMS at 8 ohms, no question about that.

I wouldn't expect much different by Hartke either, the nominal "power number" is not the actual real world power rating. It's up to the manufacture of the end product to determine that.
Click to expand...

Re-reading post #3 as you suggested.

<<It's up to the manufacturer of the end product to do their own testing to determine the actual power handling that they feel comfortable with for their specific application.>>

So they labeled the head 120W and the same manufacturer labeled the cone as 75W. That's the part that confuses me.

<<I wouldn't expect much different by Hartke either, the nominal "power number" is not the actual real world power rating. It's up to the manufacture of the end product to determine that>>

Which numbers is that? The 120W or the 75W.

I'm assuming Hartke makes their own cones. If they were sourcing them, then I totally get the potential mismatch.

At the end of the day.........I like the amp. :) It punches well above its weight.
 
#14
The number on the part doesn't matter, it's a very nominal number. It's how the manufacturer applies the part that matters. For example, integrating an effective HPF into the combo might double the effective speaker's power handling.

I agree that printing the number could be seen as confusing, unless you realize that it doesn't matter. If it didn't have a number on it, and it held up fine, would it bother you less?

Understand that in the case of the Fender part, I know more than most about how Fender tests their products and IME they are both honest and conservative.
 
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#15
agedhorse said:
The number on the part doesn't matter, it's a very nominal number. It's how the manufacturer applies the part that matters. For example, integrating an effective HPF into the combo might double the effective speaker's power handling.

I agree that printing the number could be seen as confusing, unless you realize that it doesn't matter. If it didn't have a number on it, and it held up fine, would it bother you less?

Understand that in the case of the Fender part, I know more than most about how Fender tests their products and IME they are both honest and conservative.
Click to expand...
Thank you for providing clarity. I understand now.
 
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