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Maximize the Thump

Alexander

Alexander

Aug 13, 2001
3,359
3,609
Seattle, WA
#1
I like the thump of my PBass and was happy to get a similar sound with my Tribute L-2500. I'm wondering what I can do to bring this thump out even more. People have said to get more growl, you need to boost at around 800hz. Is there any way to bring the thump out more by tweaking?
 
#2
Shouldn't this be in basses...or setup?

Anyway, how about a low mass bridge (like a P) and only 4 neck screws (also like a P)?

I suppose Thump is like anti-sustain. Undo sustain adding qualities and you could enhance thump...

How about lowering the pickup(s) and/or raising the action or adding relief?
 
#3
I am more asking about changing amp settings to maximize thump, which is why I posted this here. I've read a lot about how to hot-rod a bass to get there, but I don't want to do that with my L-2500 (I want to keep it stock and flexible to other good tones - of which there seem to be many with this bass). Thanks for your advice, though.
 
#8
to me seem like two different things. Thump is quick development of the fundamental and quick decay, like a kick bass drum. Growl is the upper partials (harmonics) bumping into one another. Mutant is right about using damping techniques and boosting the bass. This will give you the quick boom and decay you need for thump. I don't think plugging up the port is a good idea. The speakers are designed for a certain vent size and amount of back pressure the air in the box provides. You would be totally negating the efforts of the speaker designer by doing this. Flats will help your thump, but not your growl.
 
#9
Precisely my point about plugging the ports. The cabinet designer was probably aiming for a full range response with as deep a bass response as the woofers and economic would allow.

Amps like the Ampeg portaflex, noted for its thump, has a 15 in. speaker in a smallish box enhancing the thump.

Same thing with the first generation Avatar Compact 15 cabinet, the little cube (very Bag End like) with a Kappa...not a lot of low bass but lots of thump.
 
#11
Originally posted by HeavyDuty
BillyB, now you have me interested in what would happen if I plugged the port on one of my pair of Bag S15-Ds, and left the other open...
Click to expand...
You will effectively lower tuning frequency of the cab. From a frequency response point of view, this will raise the -3dB point. However it will result in a much shallower roll of in the low end. The result will be a bigger area under the curve in the region below F3 and an apparent increase in bass = THUMP.

My concern with this is the changes to driver excursion that will result. You may be introducing unwanted additional speaker cone movement and therefore unwanted distortion or worse. If we had ahe speaker's T/S parameters we could run a simulation.
 
#12
If you have a local music store that has Aphex equipment, you might try one of the Bass Xciter pedals or a rack mount Aural Exciter.
The Big Bottom portion of either can be used to add Punch without affecting your tone. You set a frequency and everything below that frequency briefly "swells" a small amount, giving you additional punch.

Boosting your Low-Mids can also give you additional thump (80hz-120hz seems to work for me), but it affects your tone.
 
#13
Originally posted by Petebass
You will effectively lower tuning frequency of the cab. From a frequency response point of view, this will raise the -3dB point. However it will result in a much shallower roll of in the low end. The result will be a bigger area under the curve in the region below F3 and an apparent increase in bass = THUMP.

My concern with this is the changes to driver excursion that will result. You may be introducing unwanted additional speaker cone movement and therefore unwanted distortion or worse. If we had ahe speaker's T/S parameters we could run a simulation.
Click to expand...
I'm pretty sure Bag End offers a port cover as an option for my cabs, so it's probably OK from an engineering standpoint. I'll give my guy at the factory a call on Monday and see what he has to say about excessive driver excursion.
 
#14
Forgot to post back!

Per Dan at Bag End/Modular Sound, no prob in sealing the port in a S15-D. As a matter of fact, one of the guys at the factory does that in his PA rig to get a (IIRC) 100Hz bump.

I'm going to have to try and find something to temporarily seal one of the ports and see what happens. Pray for me.
 
#16
Originally posted by Petebass
You will effectively lower tuning frequency of the cab. From a frequency response point of view, this will raise the -3dB point.
Click to expand...


trace-elliot had covers for their ported cabs
both open:F3 45hz
both closed F3 55
one open :F3 35
it sounded pretty good in the 2x15 i had when closing the upper one and opening one port in the bottom
 
#17
Originally posted by Petebass
You will effectively lower tuning frequency of the cab. From a frequency response point of view, this will raise the -3dB point. However it will result in a much shallower roll of in the low end. The result will be a bigger area under the curve in the region below F3 and an apparent increase in bass = THUMP.

My concern with this is the changes to driver excursion that will result. You may be introducing unwanted additional speaker cone movement and therefore unwanted distortion or worse. If we had ahe speaker's T/S parameters we could run a simulation.
Click to expand...

I would think that plugging a port would increase the internal (air) resistance to motion by the speaker cone, and result in less cone movement per watt input.

P.S. The BE S15B-D comes with a plug for its port.
 
#18
Originally posted by lo-freq
I would think that plugging a port would increase the internal (air) resistance to motion by the speaker cone, and result in less cone movement per watt input.
Click to expand...
yes but at what frequency are you talking about? Port activity if frequency dependant. Speaker cone movement is at it's least at the frequency the cabinet is tuned to. Ironically that's also where the speaker cone is under the most stress because the air in the cab acts like a spring. Make the spring too stiff and the speaker can't function properly and can even crease the cone if the situation is bad enough.

Excursion is actually quite complicated and I've got a lot to learn about it yet.
 
#19
Originally posted by Alexander
I like the thump of my PBass and was happy to get a similar sound with my Tribute L-2500.
Click to expand...

I've got an L2500. Select the neck pickup, switch it to series and stay passive: BIG thump.

I'm wondering what I can do to bring this thump out even more. People have said to get more growl, you need to boost at around 800hz.
Click to expand...

I wouldn't call 800 Hz "growl." That's more upper midrange snarl and if overused, honk.

Is there any way to bring the thump out more by tweaking?
Click to expand...

Boost around 250-300 Hz for punch and 80-100 Hz for thump while cutting the upper mids (1-2.5 kHz). Leave some extreme highs to avoid total mud, but it's better to cut them at your amp and boost them on the L2500, which has some of the best voiced EQ I've ever heard on a bass.
 
#20
Originally posted by Petebass
yes but at what frequency are you talking about? Port activity if frequency dependant. Speaker cone movement is at it's least at the frequency the cabinet is tuned to. Ironically that's also where the speaker cone is under the most stress because the air in the cab acts like a spring. Make the spring too stiff and the speaker can't function properly and can even crease the cone if the situation is bad enough.

Excursion is actually quite complicated and I've got a lot to learn about it yet.
Click to expand...

Thanks, Pete.
 

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