Can I wire a Combo Bass amp to an active sub?

[dahveed]

Hey guys, brand new to this forum. Been looking for an answer for a while on the internet, but no luck.

I have a Behringer BXL 450 (no pre out) and an active 15" sub - its a little old but pretty powerful - that someone gave me. My little 45 watt behringer has trouble keeping over the drum kit in the garage, so I was wondering if I could wire them together? It has a speaker wire output on it. I'm thinking just splice the speaker wire into a 1/4" and plug it into the combo amp, but I don't want to damage it by sending unwanted electrical signal.

Please help, and thank you in advance!

[Ed Storer]

You need to attenuate the signal from the speaker by at least 20 dB.

Use a DI Box. Behringer makes one that does what is should and is priced reasonably.

The DI box takes an input from a speaker out and reduces it to levels usable by mixers, etc.

[steve_rolfeca]

As you suspected, connecting the speaker output of your Behringer to the input of an active sub, will fry the input of the sub.

If you're handy with a soldering iron, you could make up a simple DI circuit using a couple of resistors, to divide the signal so that the Behringer will still see a safe load, and the Sub will receive a more reasonable level. However, that would sound like crap, as you wouldn't have a proper crossover.

In order to use a sub properly with any bass amp, the amp MUST have pre out and power amp in jacks, or a serial effects loop.

[RickenBoogie]

+1 Maybe you'd be better off just getting a bigger, better amp. Speaker out is NOT for anything other than a speaker. Without a PREAMP OUT or EFFECTS SEND, you're outta luck.

[dahveed]

Wow, thanks for the speedy advice, guys. I'm looking at getting a new bass amp. maybe a behringer, but i've heard some horror stories. know of any o.k. ~100w amps that have a preout? i wouldnt mind stringing the amps together. or would i need a DI box for that too?

as far as the jerry-rig, ive actually hooked up the sub with a couple of old floor speakers and a 70's home theatre amp/mixer, and it didnt sound as horrible as i thought. the sub works at 40 hz, so it can play everything i need it too, and it gives me a LOT of rumble. shook the garage really well. it'd be nice if i could string it to my amp and hopefully give it the tone it was lacking, but im not sure what to do yet.

[dahveed]

also, would a Behringer DI400P work? or do i need an active DI?

[fingerbun]

I've heard horror stories about Behringer too, but everyone I know who has owned it have found it ok. I've owned a few pieces of Behringer kit myself (including the same amp as you) and had two problems, both with pedals, and one was my fault. I have no doubt that there are more robust options out there, but if I had to work at a low price point I would personally consider Behringer.

But if I were you I'd start looking for a cheap seconde-hand Peavey TNT combo. Peavey is generally regarded as tough and loud, and their preamps are reasonably versatile, so depending what model you get it will have features the Behringer is missing. Lots of good players own Peavey at some stage on their way to stardom. The main downside with Peavey is it's usually heavy.

If you want to persist with your home theatre amp you can start looking at preamps. Behringer make an amp modeller, Vox do the Amplug..things like that. Note that I haven't used either of these, I use a product called a Sansamp which does the same thing but is more expensive. Honestly, if the bigger amp is within reach I would save for that. Better result. But if a new amp is too big a stretch, you can have a lot of fun working out ways to get the best result out of what you have.

Good luck. Been exactly where you are. Good times.

[billfitzmaurice]

Originally Posted by Ed Storer

You need to attenuate the signal from the speaker by at least 20 dB.
.

Not necessarily. Many powered subs have speaker level inputs. The dead giveaway is that they would be labeled 'speaker level input', as opposed to 'line level input'.

[dahveed]

mine does have both speaker level and line level inputs, i dont remember which is which right now, but one is rca and the other is speaker cable.

[fingerbun]

Originally Posted by billfitzmaurice

Not necessarily. Many powered subs have speaker level inputs. The dead giveaway is that they would be labeled 'speaker level input', as opposed to 'line level input'.

What does that do for impedance.

I own the same model amp and it doesn't come with an extension speaker out, so I am assuming someone has hacked the OPs amp.

Or what he is describing is the headphone out.

[jungleheat]

Ultimately you should just get a new amp. Behringer stuff pretty much sucks, unless you just want something that will "do the job" and aren't worried at all about quality.

But a cheap way to use both the combo and the sub, would be to get a DI box. But I'm not sure why people are telling you to run the DI from the speaker out on the combo. That's a lot more complicated than it needs to be and is almost sure to result in crappy sound. And I imagine in most cases it would just fry your DI box anyway.

Instead, you put the DI IN FRONT OF the amp, and send parallel outputs to both the combo and the sub. Depending on the jacks available on the particular DI you use, you may need an XLR to 1/4" adapter, or to run the signal through a mixer or something first (although maybe your sub has an XLR in in which you would just need a standard microphone cable).

[dhsierra1]

Originally Posted by fingerbun

....But if I were you I'd start looking for a cheap seconde-hand Peavey TNT combo. Peavey is generally regarded as tough and loud, and their preamps are reasonably versatile, so depending what model you get it will have features the Behringer is missing. Lots of good players own Peavey at some stage on their way to stardom. The main downside with Peavey is it's usually heavy.

big +1, you can snag things like the TNT 130 in decent shape for around US$100 to 200 (max) all the time on CL etc. Save yourself the hassle and headache. And if you find the tone not quite to your taste (I like them just fine) you can always do what lots of folks here on TB do and plug a VT pedal into the effects loop.

[fingerbun]

Originally Posted by jungleheat

Ultimately you should just get a new amp. Behringer stuff pretty much sucks, unless you just want something that will "do the job" and aren't worried at all about quality.

Half agree. The 450 is not pro level, but is actually a good little practice amp (useful feature set, acceptable sound for acoustic practice considering its size, and mine has been a trouble free unit for years) and cheap enough that I won't slit my wrists if it gets stolen from my car. I might not replace mine if it died because I have a 100w cube nowadays, but I definitely have had my money's worth from it.

But no way is it big enough for gigs.

Originally Posted by jungleheat

But a cheap way to use both the combo and the sub, would be to get a DI box. But I'm not sure why people are telling you to run the DI from the speaker out on the combo. That's a lot more complicated than it needs to be and is almost sure to result in crappy sound. And I imagine in most cases it would just fry your DI box anyway.

Instead, you put the DI IN FRONT OF the amp, and send parallel outputs to both the combo and the sub. Depending on the jacks available on the particular DI you use, you may need an XLR to 1/4" adapter, or to run the signal through a mixer or something first (although maybe your sub has an XLR in in which you would just need a standard microphone cable).

This is true provided op doesn't need the preamp sound from the Behringer.

[billfitzmaurice]

Originally Posted by fingerbun

What does that do for impedance.

Nothing, as they typically have an input impedance in the hundreds, if not thousands, of ohms and present no additional load to the amp.

[dahveed]

while i liked all these ideas, on my way to a local music shop in daytona, i was thinking about the crossover and how it wouldnt sound so excellent, and ended up getting a behringer k3000fx keyboard amp and subbing out my bxl450 with the subwoofer port. theres even a clipping monitor so i can eq that speaker, and i spend about an hour eq'ing the sub too. the only things i dont like are:
the eq obviously is more suited for any other instrument, and
i lose the punchiness of a smaller speaker (it has a 15)
but overall, its an amazingly cheap solution, that doesnt really sacrifice tone with the sub. thanks for your input though everybody, although i realize now it was a stupid idea. lol