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need some serious input in regards to amp/speaker/synth bass

S

SoundBomb

Apr 24, 2011
10
0
#1
hey guys, long time lurker first time poster. heres my question and any input or experience anyone might have will be much appreciated. here is the scenario ..

i play synth bass in a band. im using a moog little phatty and using pretty guttural/girthy bass patches. kind of a metal kind of thing. im using a fender 800 pro bass amp pushing 800 watts into a 4 ohm cabinet. the cabinet houses 2 JBL 15s rated at 600 watts a piece. the sound is amazing however i am getting slight clipping at the power amp. im not hearing distortion (in fact, the speakers and sound is quite clean and sounds very much like the direct signal of the synth, just very loud), yet the clipping lights up faintly. im not running a tweeter and ive read alot of places that the tweeter is the first thing to fry in a situation like this. ive heard large speakers can usually handle this slight clipping.

i guess to summarize: is 800 watts into a cab thats rated at 1200 watts seriously underpowering the speakrs? secondly, am i safe running the amp this way around 40 minutes continuous once a week? the JBls are 2226Hs and ive read they were designed to push air away form the coils and prevent burning them up. im just loving my tone and so are my band mates. id hate to be a speaker serial killer.

argh, sorry for so much info. if you can decipher what im trying to ask please feel free to drop your two cents in.

thanks!
 
#5
Your jbl's have some pretty good excursion but modern LF drivers have more. The thermal rating is nearly always moot in reflex cabs. Your main concern is sending frequencies that require too much excursion to be heard. You can wind up creasing your cones.

A high pass filter is usual for PA subs and becoming more appreciated by bassists in their rigs these days. Check out F-deck's hpf.

Be extra careful with new patches if you don't get a hpf. The amp may have some of its own since you haven't killed anything yet.
 
#6
No such thing as "under powering".

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Seriously though, if you want to get a bit more headroom out of the amp, you could get a subsonic filter/high pass filter, or even just use a graphic Eq to dump everything way down on the 30Hz slider. You should still get plenty of lows and punch, but you'll keep the speakers a little happier and not push your amp quite as hard. But if the clip lights just flicker a bit, that's fine. If they come on and stay on, that's bad.
 
#7
OP, if you are running a true synth bass, it does not suffer the low frequency limitations of electric basses.
It will deliver ALL the fundamental at 32 Hz, or whatever note you are playing.

Used with any appreciable power, this will drive the snot out of your speakers.
Been there, done that.

I suggest adding more drivers to distribute the load.
If you are digging the two JBL, add two more.
Bass synth will easily over drive your speakers.
 
#8
thanks for the all info everyone.

and yeah, bgavin: i figured i was already pushing frequencies that were out of the range of most electric basses. i have a 18" peavey cab thats missing the speaker. i was thinking of trying to find a jbl 18" at 4 ohms and dropping it in. ive read my amp can push 2 ohms stable aT 1200 watts. i might give it a shot. the speaker shop down the street from my house are really cool about cutting me good deals on speakers people get repaired but dont pick up within their 1 year hold agreement.
 
#11
SoundBomb said:
i was thinking of trying to find a jbl 18" at 4 ohms and dropping it in.
Click to expand...
I own a JBL E155 18".
I did a real nice job replacing the dented chrome dome with a genuine JBL part.
While installing the bolts, I dropped the wrench and dented the new dome... it sits in the garage, a testimonial to being a dumb@ss.

But... the E155 is a typical JBL: very sensitive (loud) and no bottom.
 
#13
Downunderwonder said:
Even if it's got more bottom the 2x15 cab would still suffer and you'll beam your mids terribly. You should use seperate amping.

If I was you I'd get a gnarly big subwoofer set and a crossover and extra amp. Or forget about the low fundamentals and save.
Click to expand...

i have been toying with this idea. im actually getting plenty of bass. im just like every idiot that likes a cabinet mountain behind me. the 2x15s are plenty enough. i can feel the bass through my feet and torso when im playing. my synth patches are pretty brutal.
 
#15
Adding a real subwoofer to carry just the 30-40hz to about 100-120hz area only will take the vast majority of the pressure off your current cab and allow you to run it as loud as it can go, might need 2 subs to keep up with that though.

If you're currently hitting the clip light only occasionally on the hardest, lowest notes, you may be fine as is if you're careful, or just adding 1 more 15 to the stack would likely solve the issue all together. That amp should be quite happy driving 3 speakers (2.67 ohms). I'd rather do that than run 4. Just gives me a bit of confidence knowing I'm not pushing it to it's absolute limits all the time (reliability, longevity, etc.)
 

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