how to reduce wattage on a 5150

B

bklixuz

New Metal Member
Jul 21, 2010
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hi! new here...
I dont know where to post this its like a billions of forums here so I hope im on the ryt forum...

how do you reduce the 5150's 120watts down to 60watts?
I've tried pulling out the outer and inner tubes but still loud...
reason for this is so that I can reach post gain 3 to 5. my cab is 4x12 and I can barely get pass the post gain 2 coz over that it will break the glasses.
dont suggest me on attenuators they say the amp does not like playing into an attenuator.
dont suggest me on replacing the amp on a lower watt head or combo.

another question is if the 5150 on 120watts is it ok for a 2x12 cab 60watts/16ohms each?
 
Neither will really help you. The difference between 60 and 120 will be barely noticable. You'll mostly notice a difference in "feel" when you are playing. The 2x12 setup might help slightly. You should be ok with a 2x12 as far as how much power it can handle - I used to do this with my 5150. I doubt it will make the difference you need though.

Joe
 
Yeah, pulling the tubes will drop it down to 60 watts, but it'll give you a volume drop of 3dB, which is pretty much nothing. I know you said we shouldn't recommend attenuators, but honestly, it's a high-wattage, high-gain, all-tube metal amp we're talking about, and it just isn't intended for bedroom use. You could try the 2x12 solution, but my Windsor running into a 2x12 with tubes pulled was still waaaay too loud to be cranked in an apartment. Anything over 2 (and the scale on it's knobs go to 12) would have been ridiculous.
 
Traditional attenuators like the hotplate, Weber stuff, etc. would probably not work very well for an amp with preamp gain. Those are usually intended for non-MV amps like Plexis and such. I know Ola used a hotplate with his Savage I believe with favorable results. I used a hotplate with my Plexi and was 'meh' about it. If you attenuate as low as 8 or 16 the tone is degraded too much for my taste. The hotplate sounded good at 4, but even then it was pretty loud.

I used the Ultimate Attenuator which works in a total different way than the others and that thing kicked ass with my non-master volume Plexi, yet they are kind of expensive.

Joe
 
2x12 is fine but it wont help your volume issues. The 5150 is an amp made to be played on a stage. Even in the live environment I never see a reason to go beyond 4 or 5 on the post gain. There is no way other then an attenuator to quiet this beast down.
 
Jarkko Mattheiszen said:
Yeah, pulling the tubes will drop it down to 60 watts, but it'll give you a volume drop of 3dB, which is pretty much nothing. I know you said we shouldn't recommend attenuators, but honestly, it's a high-wattage, high-gain, all-tube metal amp we're talking about, and it just isn't intended for bedroom use. You could try the 2x12 solution, but my Windsor running into a 2x12 with tubes pulled was still waaaay too loud to be cranked in an apartment. Anything over 2 (and the scale on it's knobs go to 12) would have been ridiculous.
Click to expand...

This would be my response as well.
 
when you pull two of the tubes you bring down the volume by 3db, and you have to half the impedance selection switch on your amp, for example if you are running a 16 ohm load the selection on the amp needs to be set at 8. What you get in the end is the ability to hit power amp saturating at half the perceived volume, and if that still isn't much and you need more the only real option is an attenuator. You received slanted information regarding attenuators as they degrade the sound when you used heavy levels of attenuation, however, using mild to moderate settings will not take away any of the tone.

I should add to some of the others than mentioned, using a 212 will not reduce the volume at least anything that would be noticeable because when you add more speakers, they all collectively share the load which means each speaker now works a little bit less or gets quieter. If you have one speaker and play at one volume, then add another speaker, the original speaker will be 3db quieter and so will the new one, when you add the volumes together, they create a total volume of the original one speaker setup. This has a lot to to do with the reactive properties of a voice coil (inductor). When you cut current in half the inductance kick of the coil will be reduced by half, resulting in a lowered volume for that speaker. If two speakers are sharing the load, the amp only sees the equivalent circuit of one larger speaker that has the load of both of those speakers combined. Be more worried about speaker sensitivity as this will help reduce volume. Talking earlier about reactive loads, the higher the reactive load of the coil is, the louder it will be to a relative signal. So a speaker that has more of a passive load (DC resistance) will have a lowered sensitivity and a lowered volume, this is why some people notice a difference in volume when they change change speakers in their cab (ex. swapping out v30's to t-75's).
 
guitarguru777 said:
At this point words cant even describe ...... You just love trying to prove people wrong about shit you know nothing about..... wtfever
Click to expand...

I actually happen to be and electrical engineer, so telling an EE that they nothing about the electronic world, is just retarded, and oh just to let you know, EE schooling implies learning physics.
 
Well something about making more money than your obviously uneducated ass working with electronics, I think that pretty much speaks for itself. So I lost the point of giving a fuck.
 
TheWinterSnow said:
you have to half the impedance selection switch on your amp, for example if you are running a 16 ohm load the selection on the amp needs to be set at 8.
Click to expand...

Not according to Kevin O'Connor, who apparently knows his shit: http://www.londonpower.com/faq.htm

This is something that has been troubling me for a while. I've tried it both ways and noticed little to no difference.
 
LOL ....

Something about you THINKING you make more then I do made me lol IRL .....

So you know all about physics, know all about vehicles and torque curves vs Horsepower vs gear ratios, know all about vintage rogers drums, and make more money then I do .... Yet your Myspace looks like a 5 year old designed it, your little banner ad in your sig looks like an amateur job in photoshop. So what do you do with all these hundreds on thousands of dollars that you make every year? You obviously don't spend it on trying to look or sound professional.

Oh ... and FYI Mr. electrical engineer, any time you attenuate a signal in any fashion you change its tonal characteristics which alters the tone, even if only by the slightest margin. In addition to that Mr. Wizard, as you turn up the amp once said attenuation has been applied the preamp and power tubes work harder which also changes the tonal characteristics of the signal therefor altering the tone of the amplifier.

I think you need a refund from whatever school you went to cause they seriously didn't teach you dick.
 
Jarkko Mattheiszen said:
Not according to Kevin O'Connor, who apparently knows his shit: http://www.londonpower.com/faq.htm

This is something that has been troubling me for a while. I've tried it both ways and noticed little to no difference.
Click to expand...

have you ever messed around with the impedance switch with the same load to see how different the amp sounds? It makes a huge difference in tone, the lighter the load is, the more bright/brittle, lacking bass the tone will have. Quick explanation, as I couldn't find what you were talking about in the FAQ, but the tubes are connected in parallel with each other, which means they receive the same voltage drop and the total current is controlled by the number of parallel connections. Since you remove half of the tubes, you reduced the output current by half. The two tubes that are still in the amp will be conducting the same current each regardless of how many tubes are in the amp (this is an effect of parallel circuits). What happens is that your load will not give you the same current because the voltage does not change, you have to match the load so that the current on the secondary tap matches the current you want the tubes at, and since you do not rebias and you want the current the same, that means the load has to change, it has to double. To compensate, you can use the same load if you drop the voltage in half, producing the correct current (the dissipation will now be equal on both sides).

Now unless their is something that I am forgetting offhand regarding transformers, that is correct. This also means that, if using ohms law on the situation on a load circuit, if you remove two of the tubes and keep the load unchanged, since the tubes were in parallel, the remaining tubes will double their current to compensate as the amount of current they pull will be determined by the load. This means that a 100 watt amp with 4 tubes on 16 ohms will also dissipate 100 watts with 2 tubes at 16 ohms. I can also say that is why manufactures specs for solid state amps specify the power dissipated depending on what type of load you use (ex 250w @ 16ohms, 500w @ 8 ohms, 1000w @ 4 ohms, 2000w @ 2 ohms) because SS power amps do not have a transformer, they cannot be adjusted for, so their maximum output is determined by the load.
 
guitarguru777 said:
So you know all about *blah blah blah I talk shit on the internet*

Oh ... and FYI Mr. electrical engineer, any time you attenuate a signal in any fashion you change its tonal characteristics which alters the tone, even if only by the slightest margin. In addition to that Mr. Wizard, as you turn up the amp once said attenuation has been applied the preamp and power tubes work harder which also changes the tonal characteristics of the signal therefor altering the tone of the amplifier.

*more shit talking*
Click to expand...

and if you were smart you would know...power tubes change their tone when driven harder because they are actually distorting AND transformers have a lot to do with the tone because they are two inductors connected to the same core. They have special filtering characteristics which are the reason matching impedances are important to getting a good sound. Maybe you shoudl research on matching impedances for transformers

and just to save a waste of typing, ima say your grade school comeback that I know your going to retort with: "Maybe you should research on shutting the fuck up"
 
slashvanyoung said:
How is that possible when your regular 6L6 anode (for example) has a max. dissipation of 30 Watts?
Click to expand...

it was a hypothetical for the most part

The ratings on a tube types are just a recommendation for maximum idle current dissipation for a true class A circuit. Tubes actually dissipate more as they are being used and are amplifying a signal. The recommendations are actually the lowest bias that you can get class A on, anything more is unnecessary, you could push the tubes harder and they will do it, but their life won't be maximized that way.
 
Isn't the whole point of getting an amp with 100 watts or more so you can have the headroom to retain a good tight end without too much sag, and so you don't have to induce unnecessary compression from the poweramp?
Correct me if I'm wrong, but I'm pretty sure that's like, half the reason why someone would buy a 5150, JSX, Dual/Triple Recto etc etc in the first place.
 
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