Fender Rumble V2 Uses Same IcePower as Rumble V3, but Power Increases?

corvettedcg

corvettedcg

Aug 19, 2017
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#1
I was looking at the schematic for the Rumble V2 150 watt amp and comparing it to the Rumble V3 200 watt amp. Both use the IcePower 50ASX2 in BTL mode, yet the V2 claims 150 watts and the V3 claims 200 watts. See schematics below.

Rumble V2 150 - Adi Final Icepower 50asx2 Rumble 150 2010 Schematic Rev-B

Rumble V2 200 - http://www.fmicassets.com/Damroot/Original/10002/Rumble 500 V3 Schematics-Diagrams.pdf



Same for Rumble V2 350 watt and the Rumble V3 500 watt. Both use the IcePower 125ASX2.

Rumble V2 350 - http://rudn-free.nodevice.com/8232a1b828cb280b09b02394c5ca6869

Rumble V3 500 - http://www.fmicassets.com/Damroot/Original/10002/Rumble 500 V3 Schematics-Diagrams.pdf

I'm curious how the 50ASX2-BTL puts out 150 watts in the V2 150 watt amp yet it puts out 200 watts in the V3 200 amp? (Same question for the 350 watt V2 and 500 watt V3 using the same 125ASX2 IcePower module).
 
#3
The 150 uses a 4 Ohm speaker and has no provisions to add a second cab so it's only rated output is for 150 watts.
On the other hand, the Rumble 150 head (not combo) has provisions for two cabs. You can connect one 4 Ohm, or two 8 Ohm cabs.
It's still rated for 150 watts at 4 Ohms. But that would be using the internal pre-amp.
If you choose to drive the amp module harder by means of a separate pre-amp at the effects IN and have cabs that will handle more power than the combo, you might get more out of the 150 head. Though I would caution anyone against doing that.

The 200 by itself is rated for 160 watts/8 Ohms. You don't get 200 watts out of the 200 unless you have a second 8 Ohm speaker (4 Ohm total).

Obviously the 150 and 200 use different speakers. There can be more to these differences than just the nominal impedance rating.

The cabinet design can also affect how much power a speaker can handle.
I know the 200 has speaker rated for 300 watts. I don't know the power rating for the speaker in the 150.

The same amp module can produce lower power levels if it's input levels are limited somehow, perhaps by how hard they allow the module to be driven by the pre-amp. Perhaps Fender had to ramp down the drive to the amp module in consideration of the speaker/cab power handling combination of the 150.

Go on over to the TB Rumble Club and ask those guys. They may be able to offer more definitive answers.
 
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#5
B&O IcePower modules have self contained power supplies.

Comparing apples to apples, here are the published specs for the two amps that use the IcePower 50ASX2-BTL:
  • 150 V2 - 160 Watts into 4 Ohms @ <0.1% THD, (I couldn't find specs for 8 Ohms)
  • 200 V3 - 200 Watts into 4 Ohms / 140 Watts into 8 Ohms

And here are the published specs for the two amps that use the IcePower 125ASX2:
  • 350 V2 - 370 Watts into 4 Ohms @ <0.1% THD, (I couldn't find specs for 8 Ohms)
  • 500 V3 - 500 Watts into 4 Ohms / 350 Watts into 8 Ohms
 
#6
I remember reading some of agedhorse's posts about how these sort of modules can be worked with using different approaches to limiting, etc. So it's not just "this module puts out 150 watts at 4 ohms and that's that" ... an engineer can tweak things that will affect power. Obvious disclaimer here is that I have absolutely zero personal knowledge of how any of this stuff actually works, lol.
 
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#8
Any amp module can be enhanced with signal processing, limiting, feeback, etc.
Take a look at the Fender schematics and you'll see a feedback path from the output of the modules back through some custom circuitry Fender added. You'll also see some other signal conditioning they added for things like soft clipping.

Fender was good enough to publish their schematics, but it looks like they recently pulled them off public access at their site.
It makes sense to pull them if people are going to look at them and get confused on how the same module can be rated for different power.
 
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