Making my 5150 60 watts?

[GarethSE]

Got some questions about making my 5150 60 watts...

First: It's either the two inner or two outer power tubes you pull, correct?

Second: I'm under the impression a different value fuse would be needed, any idea what value? I fail at electronics.

Anyone here done this?
Cheers!

 

[alan1990]

as far as i know you only have to pull a set of power tubes, either the inner our outer pair. when doing this the impedance of your amp is cut in half so if you have an 8 ohm cab you would have to use the 4 ohm output.

 

[Last_Confession]

that will fry the tubes dude

 

[Metaltastic]

No it won't, it's totally doable, and it's the outer pair, though the impedance thing is what I'm not certain about, so yu should email Peavey tech support just to be sure!

 

[Last_Confession]

sorry, i thought it did my mistake

 

[RockGuitarX]

No offense, but if you fail at electronics like you say, you might feel safer letting someone with more experience handle it?... :/

 

[JeffTD]

Two inner or two outer, then make sure you use half of whatever impedance you were using before.

 

[guitarguru1969]

1/2 the tubes = 1/2 the ohms. Just remember a drop from 100 watts to 50 watts = 1 Db less. Not much difference.

 

[Jarkko Mattheiszen]

1/2 the tubes = 1/2 the ohms. Just remember a drop from 100 watts to 50 watts = 1 Db less. Not much difference.

Might be off here, but isn't there always a 3dB difference when the power is doubled or halved?

 

[GarethSE]

So no changing fuses?
I'll give it a try as soon as my guitar's fixed then, couldn't hurt to see if it makes a difference.

 

[SuperD]

Try it, see if you like it...it's electrically safe.
You probably won't notice a difference in volume, it's far from significant. You may, however, notice a difference in tone, as removing half of the power drawing transducers from the circuit causes a compensatory jump in voltages, and this you may notice in the character of the tone or in the 'feel'. I can't speak to the change in resistance settings as this is based on tapping windings on the output transformer...and none of this really matters, as I pulled 2 tubes for many years with no problems, and I never changed the ohms to compensate, so feel free to disregard!!

 

[006]

For the record Mesa advocates trying the incorrect ohm output for nearly all of their amps to see what kind of different tones you can conjure. I realize this thread is about a 5150...but it's still a tube amp. Because of them I have a hard time seeing how it really can hurt the amp itself, it may draw more or less from the OT/power tubes and kill them off quicker than if you ran the correct ohm output, but not harm the amp really... I'm no expert though so...

~006

 

[Line666]

Might be off here, but isn't there always a 3dB difference when the power is doubled or halved?

I'm pretty sure it is. It works exponentially.

Although it takes around 10 decibels less for the sound to half in volume to our ears.

 

[Jarkko Mattheiszen]

I'm pretty sure it is. It works exponentially.

Hmm, no. The measurement of decibels is indeed logarithmic, but check the examples here: http://en.wikipedia.org/wiki/Decibel

It states: "A change in power ratio by a factor of two is approximately a 3 dB change."

Here's another nice site with the same info, but perhaps in a less confusing way: http://www.micworks.com/freeinfo/decibel.htm

EDIT: One more, since the site seemed really nice and easy to follow: http://www.homestudiozone.com/sound-decibel.php

 

[Line666]

My bad. I knew the principal, but I was never very good at remembering the names for these things, so yes, you're right, logarithmic not exponential.