Double Bass Contra isn't handling the low notes on my URB

[matthewbrown]

So I bought a Contra Series iii, with a down-firing 10" speaker. I've been using it for low-volume gigs on electric and ABG with great success. I've now started using it with my new URB, but it's farting out on notes lower than the open A. Above that, it sounds fine. The 10" speaker is intact when I check it, and it sounds fine with the electrics. I'm using an Upton Bohemian all-ply with a Revolution pup. I'm fairly new to amplifying URB, as I used to play an Azola acoustic baby bass, which was very easy to amplify. The Upton sounds better through my electric bass rig -- it doesn't distort -- but still not very satisfactory. Any suggestions for troubleshooting?

 

[carl h.]

HPF - try one of the Fdeck models.

 

[KUNGfuSHERIFF]

Low, light or loud. Pick any two.

Cut those sublows.

 

[Francois Blais]

The speaker cone is probably hitting the grill.
A HPF will likely help, as suggested.

 

[SAlcott]

Your amp has a low cut control-try setting it between 30-50 hz.

 

[brianrost]

HPF - try one of the Fdeck models.

There's a HPF built into the amp already...just use it. Whenever I'm running really loud and hear a fart, I just raise the filter frequency.

 

[Pat Harris]

Depending on how high your strings are, how hot of a signal you're putting into the preamp of the AI, and where the gain on the AI is set, you can also overdrive the preamp in a very non-desirable way.

I'd go with the HPF as a first option. If that doesn't clean it up (because the HPF is applied after the preamp stage), it could have something to do with your gain staging. I used an Fdeck HPF in FRONT of the AI for this very reason-- to not amplify the sub lows in the preamp stage. While the included HPF on the AI is good, it's more for speaker/room control than for tone sculpting, imo.

I think the AI manual tells you to put the Master at noon and then adjust the Gain to control the overall volume. I'm not into this method. Set the Gain to where you're getting the best signal to noise ratio and then use the Master to control your overall volume. By setting (and leaving the Gain alone) you get the most interaction with the EQ section.

 

[james condino]

The Contra has a pretty delicate cab best used for very polite situations. You should be able to pull the head out and use it with a different cab when you need more punch or add a second cab. As much as I like the AI heads (I'm using one on the job tonight), I've had better results pairing them with other cabs.

 

[matthewbrown]

I've tried the contra with an extension speaker. The low E sounds fine; the notes that require stops sound bad. So I think it's a problem with the bass itself and the setup of the bass. I'll keep trying. The suggestions here have helped me narrow down the problem -- thanks!

 

[Les Fret]

Isn’t this what happens with most single 10” combos? When playing a really accented low note they often can’t handle it (?).

 

[matthewbrown]

It turns out that part of the problem was that the fingerboard wasn't completely level. The contra still has problems with accented low notes, but having the board planed definitely helped. The clue was that the open E didn't sound worse at the same level of accent as stopped notes below A on the E string. Adding an extension speaker has helped, too.

 

[Mark Gollihur]

Again - the low-cut (aka high-pass) filter built into the combo should also mitigate the issues you're having.

The 10" speaker in the combos is specially designed for extra low-end extension and should be just fine for a 4-string bass, even at higher volumes. But a piezo pickup can send lots of subsonic content to the amp, which - unless you're filtering it out - the amp and speaker will faithfully try to reproduce.