Rumble 115 Cabinet - Rumble 800 Head Wattage Question

#3
CarlosAlmodovar said:
Hello,

The Rumble115 cabinet is 300W continuous and 600W Program at 8 ohms.
The Rumble head at 8 ohms has a 400W output.

Is it safe to do a gig with this setup?
Click to expand...

Yes if you use a little bit of good judgement and common sense.
 
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#5
CarlosAlmodovar said:
Hello,

The Rumble115 cabinet is 300W continuous and 600W Program at 8 ohms.
The Rumble head at 8 ohms has a 400W output.

Is it safe to do a gig with this setup?
Click to expand...
Simply taking the published specs at face value does not necessarily provide the correct answers to the question.
It may depend on what you do with EQ and how loud you need to play.
If going for a lot of low end, you might need to significantly lower your expectations of how much power the cab can handle.
 
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#6
CarlosAlmodovar said:
I won't pass half of the volume for sure.
Click to expand...

Half way on the volume knob does not necessarily correlate to half power. And in many cases it isn't even close to that.

It is commendable that you will limit the output, but going by knob position isn't likely to give you any kind of accurate reference for determining power output.

You'll need to try and listen for speaker stress (farting out) and hope you notice it before any permanent damage is done.

This sounds like a very good application for using a High Pass Filter. If interested in more info about that, just do a search here on TB for HPF.

Broughton and Fdeck HPF's are a couple of brands to consider. @fdeck is also a TB member and good resource for information.
 
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#7
.
Carlos, in addition to keeping the volume low to protect your 8 ohm 300 watt Rumble 115 cab with your 400 watt at 8 ohm Rumble 800 HD amp head, you can also set the Impedance Switch on the back of the amp to 2 ohms. This will reduce the output to something less than 400 watts. It's uncertain just how much less, unless @agedhorse knows, so do still keep the volume low to be safe. :thumbsup:

You can also come talk about it in the Fender Rumble Club and get a free membership. :D .
 
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#9
I'm not sure that's how the impedance switch works on this Rumble amp. Never measured one.
 
#14
Old Garage-Bander said:
Half way on the volume knob does not necessarily correlate to half power. And in many cases it isn't even close to that.
Click to expand...
So, is it more or less? Or either? Gosh young people these days just don't give enough detail to know what they are saying!
"you might need to significantly lower your expectations" Oh yes, significantly lowering expectations is always recomended. That way you will be amazed at how loud it gets ;)
 
#15
Old Garage-Bander said:
Half way on the volume knob does not necessarily correlate to half power. And in many cases it isn't even close to that. ... ... ... u
Click to expand...

BassBrass said:
So, is it more or less? Or either? Gosh young people these days just don't give enough detail to know what they are saying! ... ... ...
Click to expand...


The Master control is your friend to safely run a lesser rated cab with a higher rated amp. But those knobs are hardly ever linear. I've read some claims that, on many/most amps, just halfway up can be 80% to 90% of full power! Possibly much more power than you think you're sending to a lower-power cab. :woot:

So, for safety's sake, just assume that halfway up on the volume knob is 90%, or more, of full power. But you may never really know at what point on that sneaky volume knob the power comes roaring on, so please be very careful. :cool:
.
 
#16
G-Dog said:
The Master control is your friend to safely run a lesser rated cab with a higher rated amp. But those knobs are hardly ever linear. I've read some claims that, on many/most amps, just halfway up can be 80% to 90% of full power! Possibly much more power than you think you're sending to a lower-power cab. :woot:

So, for safety's sake, just assume that halfway up on the volume knob is 90%, or more, of full power. But you may never really know at what point on that sneaky volume knob the power comes roaring on, so please be very careful. :cool:
.
Click to expand...
Thanks that makes sense, although not knowing that, in over 30 years I blew only one speaker and the rule was if 1/2 way up isn't Really Loud, I need more speakers and or watts. Before I could afford that, a compresser was a must for using an amp louder than is safe, it was part of the early 90s sound.
 
#17
On an amp that has controls that operate truly linearly, 1/2 way up may only be 20% of the full electronic range. When a gain and master control are linearized, 1/2 way up could be 10% of the power. This is because the impression of volume is an exponential (or inverse exponential) function, so the control has to be exponential to linearize it.

So the answer is “it depends”. This is why common sense and good judgement are so important, and the myth of 1/2-rotation is an old wive’s tale on some amps.
 
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#18
CarlosAlmodovar said:
Hello,

The Rumble115 cabinet is 300W continuous and 600W Program at 8 ohms.
The Rumble head at 8 ohms has a 400W output.

Is it safe to do a gig with this setup?
Click to expand...




A local player runs a passive, 4 string, Fender Jazz into a Peavy MiniMega head then into a old, 8 ohm, Hartke 115XL cabinet.

Guessing at 8 ohms, that's probably 750 watts from the MiniMega head into a 200 watt rated cab.

He plays in a country/rock group playing in local bars, pubs and animal clubs, no FOH support.

His band members don't "try" to see who can be the loudest, drummer plays drums.....he doesn't beat them.

His outfront bass sound is great!

As others have said, listen for any distress from your drivers, if you hear any, back off the volume and bass.
 
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#19
BassBrass said:
So, is it more or less? Or either? Gosh young people these days just don't give enough detail to know what they are saying!
Click to expand...

I hope what you meant to say was:

Gosh young people these days just don't give enough detail for the rest of us to know what they are saying!

That was my take on it. But wanted to clarify so others know what you are saying. If I was wrong, please accept my apology.

With seven decades in the body that I currently occupy, and five of those decades working as an electronics technician, my most youthful answer to your question is the same as my most elderly... it depends.

Without measuring the broadband power output of the amp with knobs at the midway point, there is no certain way to tell if halfway on the knob is higher than half power, or lower, or right on the money.

One factor that can affect this are the differences between linear pots and those with an audio taper. And then with audio taper, how much taper is involved?

Another factor to consider is if the knob was properly affixed to the shaft of the pot. Or was it rotated away from an equidistance position between pointer location when set to minimum vs maximum when installed.

I hope the additional information is sufficient.
Best Regards,
OLD Garage-Bander, with the emphasis on OLD.
 
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