Power amps with bass cabs... anything to worry about?

[smurfco]

This might be a dumb question, but if you look at a rackmount power amp (for example a Crown XS500) that has a rating of 400W at 8 ohms, can I use that with a similarly rated bass cab (Mesa Subway 1x15 in this case)? Or is there something about these general power amps where the rating means something different than it does for a bass head designed specifically for bass?

I assume it's all the same thing, but I don't want to blow anything up. I'd like to use my BassRig as a preamp going into a clean power amp and then into my bass cab.

Thaaaaaanks!

 

[31HZ]

Short answer (and input sensitivity aside), it's all the same thing.

 

[agedhorse]

Should be fine provided your preamp has the necessary output level to drive the amp to rated power.

What preamp are you using?

 

[smurfco]

BassRig 64 Black Panel 64.

BASSRIG '64 Black Panel

The BASSRIG '64 Black Panel is an all-analogue amp recreation of one of the worlds most iconic bass amps!

origineffects.com

Thank you both!

 

[agedhorse]

BassRig 64 Black Panel 64.

BASSRIG '64 Black Panel

The BASSRIG '64 Black Panel is an all-analogue amp recreation of one of the worlds most iconic bass amps!

origineffects.com

Thank you both!

I looked at the owner's manual and there's no mention of nominal or maximum output level on either the unbalanced or balanced outputs... this information is required in order to determine suitability driving a line level power amp directly.

I suggest that you call them and verify that it can drive at least +10dBu which will give you between 3 and 6dB of headroom (not much).

 

[smurfco]

I looked at the owner's manual and there's no mention of nominal or maximum output level on either the unbalanced or balanced outputs... this information is required in order to determine suitability driving a line level power amp directly.

I suggest that you call them and verify that it can drive at least +10dBu which will give you between 3 and 6dB of headroom (not much).

Thanks, I will and I'll post what I find here in case anyone else is wondering.

 

[4-stringB]

Ran this rig for years. Bass to mixer. mixer to EQ, EQ to mixer, mixer to amp. Amp to speakers.

 

[jnewmark]

The sensitivity match up, as Agedhorse mentions, is the most important aspect when you go to a rack mounted power amp. I always used a rack mounted, bass specific, preamp, never went the pedal route, but its been a long time. Good luck!

 

[smurfco]

The sensitivity match up, as Agedhorse mentions, is the most important aspect when you go to a rack mounted power amp. I always used a rack mounted, bass specific, preamp, never went the pedal route, but its been a long time. Good luck!

Thanks! It is designed as a preamp, not just a typical dirt pedal, so I'm hoping it's able to do this.

I have submitted the question to Origin Effects and will report back when I receive a response.

 

[Killing Floor]

Yep. Any time you swap gear like that start with levels down and you’ll be fine.

 

[dbsfgyd1]

This might be a dumb question, but if you look at a rackmount power amp (for example a Crown XS500) that has a rating of 400W at 8 ohms, can I use that with a similarly rated bass cab (Mesa Subway 1x15 in this case)? Or is there something about these general power amps where the rating means something different than it does for a bass head designed specifically for bass?

I assume it's all the same thing, but I don't want to blow anything up. I'd like to use my BassRig as a preamp going into a clean power amp and then into my bass cab.

Thaaaaaanks!

As long as you cab(S) are not rated less than the output of the power amp, you should be fine.. You will need a preamp that can provide a signal at or above the sensitivity level of the power amp. I've used a rack mount rack system for over ten years with a power amp for years. It's served me well, but at age 72, just a bit heavy in this day of FOH support. But outside when I can crank it, there is nothing like it.

Hope this helps.

 

[hennessybass]

I've used a power amp (with a rack mount preamp) at different times.
If you are smart about things, it's OK if you power amp has a little more power than you cab is rated for. My power amp is putting out 1000w into a cab rated for 800w. But I mute things and keep volumes low before I power up, and I don't expect my gear to do something that it's not designed to do.

Just FYI, from Origin...
I'm sure they will respond. I had a CS service thing with them, and they were pretty great to work with - super responsive.

 

[smurfco]

I've used a power amp (with a rack mount preamp) at different times.
If you are smart about things, it's OK if you power amp has a little more power than you cab is rated for. My power amp is putting out 1000w into a cab rated for 800w. But I mute things and keep volumes low before I power up, and I don't expect my gear to do something that it's not designed to do.

Just FYI, from Origin...
I'm sure they will respond. I had a CS service thing with them, and they were pretty great to work with - super responsive.
View attachment 7033718

Thank you! I'll still report back if they give me actual numbers but that seems to answer my question.

 

[tom-g]

Actual numbers is what is needed. Not all power amps are made alike. What may work for one may not work for another.

 

[hennessybass]

Actual numbers is what is needed. Not all power amps are made alike. What may work for one may not work for another.

Agree... better to actually know.
I think the OP might want to be more concerned about the power amp side of things (input sensitivity) than the output of the BassRig.
Especially if the OP already has a BassRig and wants to make that work.

I can never remember how the input sensitivity works. Lower (~.75) is more accommodating than higher (~1.5)?? Is that right?

 

[darwin-bass]

Origin's answer is a good start but falls short. Yes, of course, you can feed the input of a power amp from the output of a pedal. The question is whether the pedal has enough output to drive the power amp to full power and OE's answer doesn't address that.

Worst case is your preamp isn't loud enough and you get less than full power out of the power amp when everything is maxed. But if that is loud enough for your needs then you're there.

My son did this for years. Used a Line 6 Bass POD to drive a power amp feeding a 4x10 bass cab. I have no idea if he got full power but he was loud enough for the rock band gig for several years.

 

[David Morison]

I can never remember how the input sensitivity works. Lower (~.75) is more accommodating than higher (~1.5)?? Is that right?

In your example the second amp would need twice as much signal from the preamp (ie +6dB) to be able to reach full output. So, I guess you could say the first is more accommodating in that there may be a bigger range of models of preamp that can fully drive it compared to the 1.5V option.

 

[agedhorse]

It’s important to understand the actual numbers for BOTH outputs combined with the input sensitivity of the amp.

Also, sometimes the input sensitivity of the amp will be 6dB lower with an unbalanced signal than a balanced signal. This is often where comparability issues become serious.

It’s important to understand what the numbers mean and how they apply to your preamp and power amp.

 

[smurfco]

@agedhorse What is the input sensitivity on the Aux In on the back of the D800 out of curiosity? I've been using that but I don't want to have to keep moving it to and from rehearsal, hence looking for a cheaper power amp I can leave at the practice space and not worry about.

 

[hennessybass]

Might check out a used Quilter BB800.
Pretty reasonable, small, and great as a power amp kind of thing. Also just a killer amp.