Ohms

[klejst]

Bass combo is 250w stated at four ohms...yet has another jack to connect a external speaker. Hmmm...so correct me if I am wrong as one (or perhaps another or all are correct) but technically you could not/should not...

1. Add another extension cab that was 4 ohms to the combo
2. Adding another cab that was 8 ohms to the combo

Correct?

I guess if you wanted to use an 4 or 8 ohm cabinet with the amp in the combo for some reason you should first disconnect the cable from the combo's speakers from the amp in the back on the combo before connecting the cable from said extension cab? Unless the speakers in the cabinet are 8 ohms then adding a extension cab that is 8 ohms would then equal the 4 ohms full 250 wattage and the combo amp would then work properly and alright with said extension cab correct?

Whew...just wanted to make sure I got things right there.

 

[mmbongo]

What amp is it?

 

[klejst]

What amp is it?

Fender Bassman 250 2x10 combo, extension cab in question, Fender Bassman Neo 1x15, my bad totally forgetting to include this before.

 

[ddnidd1]

From the Bassman 250 MANUAL:

"PARALLEL SPEAKER OUTPUTS
- Use the 1/4"phone jacks and Speakon®
connector in any combination to connect a total speaker load of
4–ohms minimum. Combo units have a 4-ohm
internal speaker load for maximum power output."

 

[klejst]

From the Bassman 250 MANUAL:

"PARALLEL SPEAKER OUTPUTS
- Use the 1/4"phone jacks and Speakon®
connector in any combination to connect a total speaker load of
4–ohms minimum. Combo units have a 4-ohm
internal speaker load for maximum power output."

So I'm guessing no go on leaving both the internal speakers hooked up to the amp while plugging in the external 1x15 cab as well regardless if the external is 4 or 8 ohms?

 

[Lobster11]

So I'm guessing no go on leaving both the internal speakers hooked up to the amp while plugging in the external 1x15 cab as well regardless if the external is 4 or 8 ohms?

Here's an old thread in which someone asked more or less the same question. Check out the first reply:

Fender Bassman 250/210

Seems pretty clear that you can use a different external cabinet, but only instead of rather than in addition to the internal one. That is, the jack isn't really for an "extension speaker."

 

[klejst]

Here's an old thread in which someone asked more or less the same question. Check out the first reply:

Fender Bassman 250/210

Seems pretty clear that you can use a different external cabinet, but only instead of rather than in addition to the internal one. That is, the jack isn't really for an "extension speaker."

This is what I was trying to find out and make sure. Seems weird but understandable. I was just curious how that worked on that particular combo as I have seen other combos that do allow for another cab to connect to it as a true blue extension cabinet to what's in the combo. Thanks for the responses.

 

[ddnidd1]

The explanation is in the excerpt from the manual above.

It's to get the maximum power from the amp to those internal speakers.

 

[klejst]

The explanation is in the excerpt from the manual above.

It's to get the maximum power from the amp to those internal speakers.

Gotcha. Thanks for the responses.

 

[HaphAsSard]

The new Hartke Kickback combos (KB12 and KB15) work the same way, except the head section has only one power output jack, period: it is accessible from the outside and normally connected to the internal speaker, which has to be disconnected, not only for the total load not to fall below the lowest acceptable impedance but also physically, for external cabs to be used.
500 watt Hartke kickback combos. KB12 VS. KB15?
Bought a new Hartke KB12 bass amp can I......

(From the older thread linked to above I see that the reason for the potentially risky two speaker-out sockets at the back of the Bassman 250 combos is the fact that the head section was kept identical to the corresponding stand-alone head in the product line.)

 

[Downunderwonder]

That's messed up.

Some combo amps with 4ohm internal speakers have a series wired extension jack. That's only slightly less messed up.

 

[Nev375]

It's a conspiracy to get more work for Fender qualified amp techs.

 

[Ewo]

It's a conspiracy to get more work for Fender qualified amp techs.

Or maybe it's the latest initiative of the #LiberateTheMagicSmoke movement...

 

[BadExample]

I wonder if they sell an authorized 8 ohm replacement for that combo. Which is also kinda messed up in its own special way.

 

[jcerio]

Another reason not to buy a combo amp...... <ducking under cover.... >

 

[Ewo]

Another reason not to buy a combo amp...... <ducking under cover.... >

+1. When amp heads were all big and heavy, combos made sense. But now that good-sounding micro amps are available at value pricepoints, with high power and good feature sets, IMHO combos don't offer any advantage over head + cab.

 

[Engle]

Gotcha. Thanks for the responses.

Good thing you were smart enough to find out for sure before you connected a cabinet!

 

[two fingers]

That is one of the dumbest designs I have ever heard of. Either forgo the external cab jack or make the internal speakers an 8 ohm load and be done with it.

Stupid....

 

[StatesideRambler]

That is one of the dumbest designs I have ever heard of. Either forgo the external cab jack or make the internal speakers an 8 ohm load and be done with it.

Stupid....

It differs from the mainstream of combo configuration but since the majority of combos never get an extension cab plugged into them it's equally "stupid" to relegate them all to run at permanently lower power. It's impossible to satisfy everyone.

 

[two fingers]

It differs from the mainstream of combo configuration but since the majority of combos never get an extension cab plugged into them it's equally "stupid" to relegate them all to run at permanently lower power. It's impossible to satisfy everyone.

That's why I said just forgo the jack if you wanna run at full power.