question about ampeg B-25B

[Xeroid]

Hi does anyone know if these amps are good and if I would be able to plug in 8 Ohm speakers into it if it states on the output 16 ohms? Im looking for that ampeg tube sound.. Hoping these are good if anyone knows thanks

 

[rjmsteel]

HA! These are cabinets. The B25B cabinets are 16 ohms only Each! I should know I`ve owned a pair since 1973. They pair only with an 8-ohm head with BOTH cabinets plugged in. How do I know that? Because I got the magic smoke once by only plugging in a single 16-ohm cabinet instead of hooking both up to bring the impedance down to 8 ohms. These cabinets have 2 @ 15" speakers in EACH Cabinet are low wattage and are not very efficient.

Again, the Ampeg model you are referencing is a Cabinet and not an amplifier.

 

[JSandbloom]

The B-25B is also a head. Even tho the b25 and b25b are effectively the same, they branded the B for bass with the B cab. The B25b head can be used for 8ohms if you use a dummy plug with a 8ohm cab. Thats been the work around for decades. It's worked great on mine.

 

[eniac]

A bit of probably useless trivia here: Long ago I used to run into the occasional B25B cab with a 4/16 impedance switch. Can't recall whether the one I had in the mid '70s had the switch.

 

[coreyfyfe]

A bit of probably useless trivia here: Long ago I used to run into the occasional B25B cab with a 4/16 impedance switch. Can't recall whether the one I had in the mid '70s had the switch.

The earliest models were without switch but after the first year or so they all had the 4/16 option so they could sell the B25B cabs with other heads.

The B-25B is also a head. Even tho the b25 and b25b are effectively the same, they branded the B for bass with the B cab. The B25b head can be used for 8ohms if you use a dummy plug with a 8ohm cab. Thats been the work around for decades. It's worked great on mine.

Yes, the first year models were B25 for guitar and B25B for bass, the B25 guitar amp was then renamed to the V3.

For 8 ohm operation a dummy plug in the extension jack is all that is needed, but I wired my own amps with separate 8 and 16 ohm jacks as an alternative option.

 

[Xeroid]

The B-25B is also a head. Even tho the b25 and b25b are effectively the same, they branded the B for bass with the B cab. The B25b head can be used for 8ohms if you use a dummy plug with a 8ohm cab. Thats been the work around for decades. It's worked great on mine.

So what you are saying is plug my 8 ohm cab to one output and a dummy plug in the other? But does the dummy plug have to have resistance of some sort? What about this . What if I plug two 8 ohm cab to this head ,,,would this work??

 

[Xeroid]

The earliest models were without switch but after the first year or so they all had the 4/16 option so they could sell the B25B cabs with other heads.



Yes, the first year models were B25 for guitar and B25B for bass, the B25 guitar amp was then renamed to the V3.

For 8 ohm operation a dummy plug in the extension jack is all that is needed, but I wired my own amps with separate 8 and 16 ohm jacks as an alternative option.

What if I plug two 8 ohm cab to this head ,,,would this work??

 

[Xeroid]

B-25B

 

[JSandbloom]

There's probably someone a lot smarter than me that can explain the mechanics behind it. But yes, a dummy plug is all you need. You can do two 8 cabs if you want to smoke the amp or else 1 8 ohm load is the lowest it'll go.

 

[coreyfyfe]

What if I plug two 8 ohm cab to this head ,,,would this work??

The amp would likely tolerate the mismatch just fine, but the better solution would be a series connector.

I used to run my B25 with a pair of 8 ohm 112s using a Palmer speaker merger in series mode.

 

[JSandbloom]

The amp would likely tolerate the mismatch just fine, but the better solution would be a series connector.

I used to run my B25 with a pair of 8 ohm 112s using a Palmer speaker merger in series mode.

This would put the load back to 16 ohms or keep it at 8ohms?

 

[Xeroid]

This would put the load back to 16 ohms or keep it at 8ohms?

sound like an idea . Thanks

 

[coreyfyfe]

This would put the load back to 16 ohms or keep it at 8ohms?

Two 8 ohm cabs in series using something like the speaker merger would present a total 16 ohm load.

 

[Xeroid]

Two 8 ohm cabs in series using something like the speaker merger would present a total 16 ohm load.

thanks perfect

 

[Deleted member 271037]

thanks perfect

Make absolutely sure that you understand the difference between series and parallel though, and always double check that you don't plug the amp into the parallel input by accident. Two 8 ohm cabs in parallel will present the amp with a 4 ohm load, which will will be a VERY costly mistake.

 

[_One//Man//Mutiny_]

If you get one of them speaker mergers itll make life easier for ya, that what I used when I had one! I think that may have been my favorite Ampeg head I've ever had, sounds really good. If you do happen to get the matching B25B cab, it's an absolute beast. It was made in a time where instead of going deeper they made the cab wider and taller, it's a really, really, big 2x15

 

[Xeroid]

Make absolutely sure that you understand the difference between series and parallel though, and always double check that you don't plug the amp into the parallel input by accident. Two 8 ohm cabs in parallel will present the amp with a 4 ohm load, which will will be a VERY costly mistake.

i will put tape on that output thanks

 

[Xeroid]

If you get one of them speaker mergers itll make life easier for ya, that what I used when I had one! I think that may have been my favorite Ampeg head I've ever had, sounds really good. If you do happen to get the matching B25B cab, it's an absolute beast. It was made in a time where instead of going deeper they made the cab wider and taller, it's a really, really, big 2x15

thanks for help guys!