Newbie(ish) here-Bass Guitar Cab modification

[s6g2k]

Hi all
I say newbie-ish because it has been a very long time since I hung out here. I have gained a lot of valuable information and knowledge at PE in this love of mine - audio hobbying. I noticed one thread where bass players were characterized as cheap. Sticking my hand up!

I have encountered a situation and i am looking for a bit of advice. Recently, I was blessed with a smokin' deal on a Warwick 4x10 bass guitar cabinet. I did mostly some cosmetic upgrades on it (refinishing, rewiring (just for higher gauge)). It looks to have 4 eminence Gamma 10s (Qts=.46, Vas=1.2 cu.ft., Fs=68hz, 200W each) in it, probably some Warwick specified variant anyways. The cabinet is probably about 1/3 undersized for a ported box, however looks to be appropriately tuned when modeled according to the gamma 10 specs for a box that size.

Well, I got to do some serious playing with it this past weekend. The bottom end, which sounds awesome in a domestic setting, is not so good at the higher levels of keeping up with drums and loud guitars. Playing through a 250W Trace-Elliot amp I get a lot of distortion AND I am concerned about damaging the drivers.

Driving back from the practice, I thought of a few things to remedy this.
1) Provide some big capacitance filtering/protection, say around 50 hz. I do intend to supplement this with a 15" cab.
2) Maybe(?) seal the ports? The box is a little shy of 4 cu ft. which is about .5 cu ft bigger than WinISD suggests for a sealed box.
3) I remember reading here about adding some distributed weight around the dust cap to lower Fs (at the expense of sensitivity). Is this worth it? I don't mind losing a little SPL, but wouldn't want too much.


any thoughts on this?

[brianpowers27]

I think you need to cut out the rumble somehow... (>40hz) Can you do this with your amp head or external processor? If not then prusue option 1. Option 2 could work and it is easy to try. I don't know about option 3. It could work but it seems counterintuitive since most PA gear needs the sensitivity to avoid driving amps into distortion at realistic volumes.

Was the distortion coming from the amp or drivers? How do you know?

P.S. I would seriously consider using an 18" in the bass guitar rig. The lower FS and large displacement would help on the low end.

[s6g2k]

thank you very much.
I am able to EQ (12 bands on the head), though I wouldn't want to lose the low end when I am fully equipped.

I am pretty confident that the distortion was from the drivers as it was specific to low frequencies. Once i got to the A-string, it was pretty good. I did some tweaking with the pre-amp gain (which is metered for optimum level on the amp anyway). Once I compensated with master for volume, it was the same.

Yeah...an 18" would be fun. Maybe next year! I am not a serious gigger and have a day job. This little band we are developing is for a family music event later this year.

[brianpowers27]

thank you very much.
I am able to EQ (12 bands on the head), though I wouldn't want to lose the low end when I am fully equipped.

I am pretty confident that the distortion was from the drivers as it was specific to low frequencies. Once i got to the A-string, it was pretty good. I did some tweaking with the pre-amp gain (which is metered for optimum level on the amp anyway). Once I compensated with master for volume, it was the same.

Yeah...an 18" would be fun. Maybe next year! I am not a serious gigger and have a day job. This little band we are developing is for a family music event later this year.

--An 18" should cost about the same as a 15..
--You may be clipping the amp. Oftentimes the amp will have a clippind indiciator.
--Use the 12 band and cut the very bottom band and leave the others alone.
--Good luck!

[billfitzmaurice]

Gamma 10s only have 1.6mm xmax, so they're displacement limited to about 20 watts each through most of the power band below 100 Hz. Frankly they never should have been used for electric bass, but what sells cabs is watts, not xmax.

[s6g2k]

thanks Bill (remembering you from before)

I had once experimented with the off the shelf gamma 10 and no, I would not characterize it as a bass guitar speaker. that said, it is Warwick-ified but is very similar to the G-10 I own.

Brian
The 15 I am referring to is one that I own and use already. I am planning on making it into an identical sized, ported cabinet as the 4x10, which models well according to the specs I have. The amp has a tool for meetering the preamp level, identifying under and overdriving. I turned it down to way underdriving and it still had similar performance. I will soon check how it sounds with the current configuration of the 15". i just don't have it with me now. I can then see how it performs with reduced low frequency EQ.