Speaker cab ohm problem

[maxmckee]

Hi. I have a TC Electronic 4x10 bass cab rated at 8 ohms. A few years ago the tweeter broke and I haven’t replaced it as I never really got on with it. I’ve just purchased a n 8 ohm 1x15 cab to use with it and was wondering if it will be ok to do so. Has the 4x10 cabs ohm rating changed now it has no tweeter?

cheers Max

[mybass]

12 minutes ago, maxmckee said:

Hi. I have a TC Electronic 4x10 bass cab rated at 8 ohms. A few years ago the tweeter broke and I haven’t replaced it as I never really got on with it. I’ve just purchased a n 8 ohm 1x15 cab to use with it and was wondering if it will be ok to do so. Has the 4x10 cabs ohm rating changed now it has no tweeter?

cheers Max

I didnt think the tweeter changes the ohm rating anyway…hopefully a more sure answer will crop up here.

[Phil Starr]

You'll be fine. 

 

The 8ohm rating is only an 'average' rating as the impedance varies with frequency anyway. In a properly designed cab the crossover deals with all this for you swapping the signal from the bass units to the tweeter anyway so the amp always 'sees' the right impedance. If the tweeter is out of circuit anyway it will have no effect on impedance.

[maxmckee]

15 minutes ago, Phil Starr said:

You'll be fine. 

 

The 8ohm rating is only an 'average' rating as the impedance varies with frequency anyway. In a properly designed cab the crossover deals with all this for you swapping the signal from the bass units to the tweeter anyway so the amp always 'sees' the right impedance. If the tweeter is out of circuit anyway it will have no effect on impedance.

I’ve just found the tweeter. It’s an eminence asd1001 with an 8ohm rating, does that make any difference?

[maxmckee]

Cheers 

[Phil Starr]

1 hour ago, maxmckee said:

I’ve just found the tweeter. It’s an eminence asd1001 with an 8ohm rating, does that make any difference?

Not if it is disconnected  

 

I'd check the crossover is disconnected too. often it's just a high pass filter with only a couple of components to protect the tweeter but it's possible there is something filtering out the the high frequencies from the 10's. If all your horn is doing is blocking a hole it's probably best to just run a connection from the sockets to the speakers bypassing everything else. Though if you've been using it happily for years it's probably fine

[Bill Fitzmaurice]

5 hours ago, Phil Starr said:

 If the tweeter is out of circuit anyway it will have no effect on impedance.

Actually it does. With no load on the high pass filter it can exhibit a very low impedance within its pass band, which can create problems. The safe way to remove a tweeter circuit is to disconnect the crossover entirely, wiring the woofers direct to the input jacks.

[nilebodgers]

13 minutes ago, Bill Fitzmaurice said:

Actually it does. With no load on the high pass filter it can exhibit a very low impedance within its pass band, which can create problems. The safe way to remove a tweeter circuit is to disconnect the crossover entirely, wiring the woofers direct to the input jacks.

I was just going to post the same - a typical high pass looks like a series RLC when the tweeter is disconnected, so can end up as a very low impedence at the resonant frequency.

[BassmanPaul]

The combination of a 1x15 with a 4x10 is a poor one. The 15 has no hope of keeping up with a 4x10 and will eventually fail.

 

[Downunderwonder]

12 hours ago, BassmanPaul said:

The combination of a 1x15 with a 4x10 is a poor one. The 15 has no hope of keeping up with a 4x10 and will eventually fail.

 

Not just for the power handling imbalance is it usually a fool's paradise of a stack. Most often the 410 has such a superior sensitivity that when it's on top the 115 is completely inaudible to the player, and barely contributing to the overall output out front either way.

[Bill Fitzmaurice]

There are 115/410 combinations that would work well, as in a bi-amped rig with a long throw sub-driver 115 and a 410 loaded with guitar tens, but that's not what you see being used. Even that would be far from ideal, as it doesn't take four tens to match up well with one fifteen. One or two would be sufficient.

[DGBass]

TC Electronic BC cabs use a permanently wired Eminence ASD1001 horn tweeter and a high pass filter printed circuit board screwed onto the inside of the cab.  Curiously the 4x10 BC cabs were mostly 500w 4 ohm cabs. The RS410 cabs were 600w 8 ohm cabs + tweeter. K410 cabs were also usually 600w 8 ohm + tweeter. If you want to use these cabs without the tweeter, it would be prudent to remove the high pass filter wiring from the speaker circuit. You can then be sure it won't interfere with the cab impedance in any way if your stacking another cab with it.