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Question about wattage and speakers

#21
David A. Davis said:
How does distortion increase power?
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Distortion, by itself, does not generate more power.
It is the how a distorted signal affects your amp's average power over a period of time that is the problem.

If you have a lot of peaks in your signal but the overall average signal is low, the power will be lower over a given period of time. Your amp doesn't work as hard, doesn't create as much heat, because it has time to recover from the short bursts that are the peaks of your signal.

If the average signal is high compared to the peaks as can happen when the peaks are clipped off at the top, which is distortion, the power will be higher over a given time period. Your amp will not be able to shed the excess heat as well, and if it overheats components will be damaged, either quickly or over longer periods of time.

Think of a like hot potato. You can juggle it back and forth between your hands allowing the empty hand to recover from the heat while the potato is in the other hand. You might be able to do this all day. But if you try to hold the potato in one hand you get burned because your hand can't shed the excess heat.
 
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#22
what is your tone setting? it takes a LOT more power to replicate the lower tones, and boosting the bass knob will send more power to the speaker.

also measure the internal dimensions of the cab to determine if the speaker will work. talk to someone @ Eminence, or US Speaker, and they can guide you to what speaker will work best in that box.
 
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#24
Old Garage-Bander said:
Distortion, by itself, does not generate more power.
It is the how a distorted signal affects your amp's average power over a period of time that is the problem.
So are you saying that a distorted signal will heat the speaker coil more than a clean signal given the same volume?
If you have a lot of peaks in your signal but the overall average signal is low, the power will be lower over a given period of time. Your amp doesn't work as hard, doesn't create as much heat, because it has time to recover from the short bursts that are the peaks of your signal.

If the average signal is high compared to the peaks as can happen when the peaks are clipped off at the top, which is distortion, the power will be higher over a given time period. Your amp will not be able to shed the excess heat as well, and if it overheats components will be damaged, either quickly or over longer periods of time.

Think of a like hot potato. You can juggle it back and forth between your hands allowing the empty hand to recover from the heat while the potato is in the other hand. You might be able to do this all day. But if you try to hold the potato in one hand you get burned because your hand can't shed the excess heat.
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#29
Old Garage-Bander said:
Sorry, I didn't notice at first that you had imbedded a question within my quote.

Your Question:
"So you are saying that a distorted signal will heat the speaker coil more than a clean signal given the same volume?"

My answer:
No. I did not say that.

Please re-read my post.
I discussed AMPLIFIER heating.
I said nothing about voice coils in this post.
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Ok, the op’s topic is more about a damaged speaker, is it not?
 
#32
So let's address the distortion/voice-coil issue.

If you imagine a sine wave, the current in the voice coil will gradually rise to a peak, then fall off, pass through zero gradually, and go to a trough.

If you have maximum clipping, you're driving a square wave: the current is at maximum, stays there for half the cycle, then swings wildly downward to negative maximum an stays there for the rest of the cycle. For you pedants, I'm ignoring the inductance of the coil, the capacitance of various components, the physical momentum of the speaker cone, and any acoustic resonance in the cab.

So a pure sine wave means the voice coil is only at peak current for a tiny moment twice a cycle, whereas a square wave means it's at peak current 100% of the time.

Thus, a non-sine signal heats a speaker more even for the same amplitude. To the extent that your overdrive pedal is altering your waveform to be more "square," it is increasing the total power in the voice coil even thought he amplitude is the same.
 
#34
You cannot just cramp a higher rated driver in your cab. It is designed around the old driver. (TS parameters) Your Eminence didn't have much damping and much X-max to begin with. Put that in the wrong cab and damage occurs fast. Your new choice, the Peavey has only 93.7dB. You will thus turn up the volume and same problems happen all over. And why 18"? For show? So, buy a proper cab to go with your new amp, or let someone calculate a replacement driver for you. ;) (and dont forget the ohms story)
 
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#35
OP, I won't pile on but will advise I was where you are 6 or 7 years ago before I joined TB. What I've learned here which were my biggest takeaways -
1. Volume on an amp is not necessarily linear to how many watts are being sent to your speaker.
2. Ratings on a speaker are likely thermal limits and not mechanical limits.
3. 'Smiley-face' eq is likely hard on your speakers. Mids are your friend.
4. Speaker cabs are designed around their speakers. Placing other speakers as replacements in your cabinet is a crapshoot.
After heeding appropriate advice, I have not blown a speaker since joining this forum. Prior to that, my 15" speakers were being replaced about every other year.
 
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#36
One more (slightly related) question; if I'm using an overdrive pedal would it be a good idea to use the active input of an amp? Until recently I always used a bass with active pickups so I never really put much thought into it, but the bass I've been using doesn't have active pickups. Since I'm using an overdrive pedal (and a Thunderbird, which isn't active but seems to have high output for a passive) I'm wondering if setting my amp to the "active" input would generally be a good idea, regardless of what cab I'm using?
 
#37
JRA said:
i think https://www.talkbass.com/members/old-garage-bander.
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Megaton Aaron said:
One more (slightly related) question; if I'm using an overdrive pedal would it be a good idea to use the active input of an amp? Until recently I always used a bass with active pickups so I never really put much thought into it, but the bass I've been using doesn't have active pickups. Since I'm using an overdrive pedal (and a Thunderbird, which isn't active but seems to have high output for a passive) I'm wondering if setting my amp to the "active" input would generally be a good idea, regardless of what cab I'm using?
Click to expand...
The only difference between the so-called "active" and "passive" inputs, is that the active input is attenuated somewhat related to the passive input. It has nothing to do, directly, with using active or passive pickups, or what pedals you might have.

If you have a hotter than normal signal going into your amp, you may want to use the active input so it doesn't overdrive the pre-amp in your bass. Otherwise, you may like that overdriven sound. It really boils down to what works best for you.
 
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#38
Pardon me for injecting a bit of power and watts reality in at this point. Your amp is capable of producing 1000W of power. Your speaker apparently had a rating of 800W.
Note that these are maximum capability ratings. There is also the reality of the signal coming off of a bass, and of music in general. If you are Lemmy playing straight 16ths with as much distortion as possible, at full volume, you may approach that 1KW output. Any music with dynamics and your actual average output is probably closer to 100W. That would still be quite loud btw.
Overpowering implies that the actual output by your amplifier, during use, is greater than the speakers ability to handle.
Underpowering is when you have to push the amp so hard to get the required spls that your output signal is a heavily clipped waveform at all times even though that power level is less than the speakers power handling capability. Effectively the speaker is seeing a square wave which can translate into a high level of dc current through the voice coil and the voice coil isn' built to take that.
Please note that in both cases it is the way the amp/cab is utilized that will put you into an over or under power scenario. Not the ratings tag stuck on the back of the box.
 
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#39
Megaton Aaron said:
I really didn't expect it to be as big of a difference as it was. I knew it would be a bit louder, but the 700 I usually ran about halfway up, while the 1000 I've only had up past 2 a couple times while playing bigger venues.

Thanks for the help everyone. I'm going to try to replace the speaker with a higher rated one and see how it goes.
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To get twice as loud by increasing power that increase has to be ten times. If you need more volume increase the speaker count.

Replacing the driver without doing the math to ensure it’s a good match to your cabinet is a fool’s errand. You’ll be back where you are now in a fairly short time.

Edit: It’s advisable to derate your power level by 50% if you are using a distortion device.
 
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