Stand Alone Power Amplifiers

Remember, it’s not an instrument amp. It’s just a power stage. It adds gain. You still need a preamp to take care of the instrument signal. Otherwise, the power stage takes line level in and drives down to a 4 Ohm load. The only thing I left out is that the two heads I have also have a little fan. I think you can drive it off the power supply on the amp board.

As far as protection, you could input limit so it doesn’t clip, but digital distortion clipping goes to crap really fast and you can detect that with your ears. I didn’t dig that deep into it yet to see what it’s input stage already has. It’s a fairly complete module. There may be a couple components to add to the input. @terb can likely have some insight.

2 Likes

I know you are using it as an example, and I only brought it up because I have mentioned to people that say, oh, my Fender 200 is not as loud as your 160w amp, and I have more watts.
I tell them it is my understanding that that 200w is max when used between two cabinets, so you have to add the right add on speaker to get the full 200w.

the reason I asked you, is I assumed you had a confirmed answer for me, because I was going off a hunch, or even an educated guess at best.
thanks for clarifying, I just wanted to speak with confidence when talking to others about their equipment.

I know that 500 (350 really) is plenty, and the extra headroom gives most of those that would GET a combo and not go up higher out of need (not want), so they, when using their Amp, alone, not comparing to others, is plenty.
I just think that Fender, and others should do a better job with transparency about this fact, because there are those that will argue to the death that their Fender is now, and always will be, standing alone, without a speaker add on, 500 watts of power.
This is clever marketing for sure.

2 Likes

Please refer to @Gorch How Can I Be Heard Through The Mix.

He talks about practical power levels. I talk about math.

I’ll only say here that an 8 Ohm cabinet will take twice the power amp size of a 4 Ohm cabinet. A cabinet with a 96dB sensitivity will take twice as much power as one with 99dB sensitivity. If you have a 96dB sensitive cabinet at 8 Ohm and you are driving it with a 400 Watt amplifier, I can match your level with my 99dB cabinet at 4 Ohms using only a 100 Watt amplifier.

In audio it’s never possible to evaluate one piece of gear in isolation. It’s a system. If you need more than 350 Watts, it’s no longer an amateur topic. If you buy 800 Watts, they just sit in the amp taking a coffee break, no biggie. If you overpower and drive a cabinet too hard, it will start farting before it breaks. Back off.

4 Likes

I just checked. The Rumble 200 runs at 140 watts without an expansion cabinet.

They don’t put that information front and center but it isn’t buried like with some manufacturers. If you click on the specs link it spells it out clearly.

Yeah, I never get it when people decide they want to fight about the details when they haven’t taken the time to do the research. If I’m wrong, call me out, I’ll be better for it.

2 Likes

That was a fantastic thread. I need to re-read it.

@DaveT The more I learn about all this the more ignorant I feel. I’ve been trying to take it in small pieces but so much of it is part of the intertwined system that I’m not making much headway.

Thanks for this. I’ll keep looking into it.

1 Like

Nope. Neither one. Most, if not all, bass multi effects pedals have one built in. Otherwise, it will be something that is being sold specifically as a bass preamp.

We have this thread… 2020 Bass PreAmp Shootout
And I’ll point you here… Sweetwater Bass Preamps
Some of the stuff that comes up are full amplifier heads. Just ignore those.

1 Like

For the most part, no. If you were to imagine your rumble with only one knob on it, volume, you get the idea of a power amp (and power amps generally don’t even have volume, so you would have to use your bass’s volume knob). A preamp generally let’s you control the input gain, output volume, bass mid and treble settings. So when I have my preamp pedal with all the tone controls on it, I generally don’t need a bunch of duplicate tone controls on my amp, which is why we would like to see a bare naked power amp as it would be cleaner and cheaper.

2 Likes

Yes, I was not trying to bad mouth Fender, or single them out, I was saying the industry in a whole. I think they know the average player is confused about watts and ohms and dbu and all that stuff, so they slap a 200 on where 140 would do just as good if it were industry standard to advertise and name product like that.

2 Likes

Sorry to keep asking dumb questions…

Would an active bass serve as the pre amp in this setup?

2 Likes

Yes, technically. But it would be very rudimentary. If you have a 2 band eq on your bass, you can control bass and treble (and a volume knob). But a preamp (built in to your amp) or a standalone preamp (like a pedal) can give you much more tone control, as you could imagine if say your preamp has a 9 band eq built in or something.

5 Likes

You’ve probably seen amps with 400 knobs on them for tweaking everything under the sun. That’s your preamp.

3 Likes

Almost. The active bass may not be hot enough to drive the amp to full output level if you are operating loud. It may also drive the amp so hard when you are operating at home that you need to keep your bass level set microscopically low. This can be solved by going to a pedal with a gain knob and then to the power stage.

5 Likes

This is an interesting and informative thread. Thank you @eric.kiser

1 Like

There’s certainly no ignorance in this! I only write the tech things that I do in case someone wants to think about it that way. From a practical standpoint, very little of it is necessary to understand to be successful. I’ve had 30 years of practice understanding nothing but this topic and that’s only because I have to say how many and what size amps and speakers are going to be there on opening day before the building construction has started.

In reality, you can just keep adding power until you have what you want. A lot of bass cabinets are rated in the 350-500 Watt range and that’s conservative. So, it’s easy to buy 350-500 Watt amp head and be just fine. The only thing to really realize is that you need a 4 Ohm cabinet to get all the power out of the amp. The only reason to buy an 8 Ohm cabinet is if you plan to run two cabinets off the same amp.

5 Likes

Not dumb at all. This topic is pretty dense to get through.

If someone were willing to volunteer, I would be interested to hear what would happen in two situations.

  1. What happens if you plug directly from an active bass to the FX receive on the amp?
  2. What happens if you plug headphones directly in to an active bass?
2 Likes

I use my headphones directly in my pre amp peavey fury. And its great for practicing without the need of a power source outside of the 9v battery.

But i am buying a portable amp similar to the vox to get a bit more tone control and volume as without it the bass is a bit farty sounding, not that your really trying to put a show on for yourself its just a nice benefit to have a bit more clean sounding tone + volume.

2 Likes

Also plugging directly into FX In doesn’t really do much other than plugging into the preamp or normal input. not quite as loud but overall sounds fine to me.

3 Likes

@Mao Would you classify it as usable but not optimal? Or is closer to useable in the sense it works when you don’t have anything else?

2 Likes

I would say usable and viable in a " I’m home alone noodling" sense. But i wouldn’t try to gig with it. at least not on a rumble 25.

2 Likes

Cool. Thank you for checking that out.

2 Likes