bass speaker help

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As most bass players want a clean sound it is important not to use the overdrive section of the amp.


Another thing: Does the power-amp stage have an output capacitor ?

Regards

Charles


Would a bad output cap cause the amp to fart out when you dig in?
I'm playing bass through a 65 watt Peavey guitar amp (clean channel). I'm using the emminence Basslite 2012 (150 watt) in a home made cab built to Emience specs. It sounds good until I crank it up loud enough to play with drums. Then it distorts and sounds farty - almost like it's blown. Any ideas? I did notice a couple of large caps in the output section. Could they be the problem?

Don
 
I'd suspect the driver's bottoming out.

Watch the driver as you play. If it starts moving a lot (I mean more than 10mm p/p), you need more drivers, or a driver capable of moving further in a linear fashion.
Apart from that, the amplifier may be clipping.

As a comparison, I use 1x10" and 1x12" in seperate cabs for guitar use, to keep up with drums. With around 80w into them (~40w each). They keep up, but there's not much headroom.
1x12" to go down to 41Hz (bottom E) at drum levels doesn't seem enough.

I can't find detailed cabinet specs for that driver, what did you tune the reflex port to?

Chris
 
Well, I built the cab to factory specs. I even talked to a factory tech a couple of times while building it.

I'm thinking it may be a defective speaker. I read a review on this speaker where another person was having the same problem as me, farting out at moderate volumes on the lower notes.

On a positive note, keyboards sound fantastic with this speaker. Even when turned up loud enough to play with drums. I've had two other bass players bring their guitars over to try it with the same results. The only way I can get it loud enough to play with drums without distorting,is to turn the treble up and the bass down. Maybe it's just a POS - at least for bass. Maybe I should try the smaller sealed back cab design from the Eminence website? It's tiny though, only about a couple of inches larger than the speaker.
 
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I've had two other bass players bring their guitars over to try it with the same results.

rock drummers have always been loud, havent they :eek:well, and sometimes bass players too :D

well, its a long time since I played with anyone, and it wasnt bass
but from memory, my estimate is, you will need about 6x 12"

and another guess would be that your Eminence woofer with its 2" voice coil is best suited for the more quiet player
to keep up with a loud drummer, those woofers need to be top pro quality, with bigger voice coils
and lots of amp power
 
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maybe its a bit more than just about Xmax ratings

well, I guess you can give it all the Xmax in the world, and it wouldnt help any bit if the "motor", magnet and voice coil isnt strong enough

a 2" voice coil with a small magnet (high Qts) might simply not be strong enough to control the cone
and further, your power amp may even have highish output impedance, to make things even worse

but I wonder if the specced 4mm Xmax of your woofer is one way or P-P
but fore a loud playing rock band its hardly gonna work, either way

btw, PE has a 21" Pyle on sale, but no Xmax specs
 
It always depends what one wants to achieve. There are situations where one 10" driver would be enough (like accompanying acoustic instruments on a small stage).
And it also depends on the instrument and the sound one wants to achieve. If your bass is overtone-rich it would automatically sound louder with a given maximum displacement compared with the one who wants the typical muffled reggae bass sound (Which would need loads of 18" drivers).

Michael Manring for instance uses two 2x10" speakers on stage which is by far enough for what he does (he has a very overtone-rich sound and plays a lot of harmonics and does a lot of melodic stuff). OTOH not even an amateur player in a heavy-metal band would probably be satisfied with the same rig.

I once built a tiny practice amp ( "Brüllwürfel" for the German speaking ones). It has just about 4 Watts and a small full-range speaker by Monacor. It also has asymmerical clippig and some bit of compression. With my old overtone-rich Kramer DMZ 6000 B it sounds astonishingly loud in a living room when driven hard. It also employs an output cap that interacts with the speaker such that its output level is enhanced a little in the area of the cutoff frequency. Below that the response dropps off with 18 dB / octave.

When I plug my newer six-string bass into it and play the open low B I hear nothing but some farting sound. I.e. the amp goes into clipping but nothing of the first harmonic is reaching the speaker and also the second harmonic is greatlyy reduced. That's why I asked about the output cap BTW.


Regards

Charles
 
Why not just add a steep low cut filter below port tuning?

The driver unloads below Fb, but still within the range of a standard-tuned bass (bottom E is 41Hz). If your amp doesn't have one already (to cut out effects like string handling), then this would be a worthwhile thing to do.
 
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