Acoustic B200 Bass Amp Output Circuitry

[TomCarlos]

Hey Friends....

I picked up an Acoustic B200 bass amp. This chassis was mounted in a similar cabinet that would hold the B200H version of the amp. So I really do have the chassis that would go with the combo amp. After some cleaning, soldering, TLC, the amp is working fine. So it sits there as a head only.

On the back of the amp, there is a 1/4" "Speaker Output". Just above that, there is a switch for the "Horn." Now keeping in mind that the B200 Combo amp had a 15" and a horn", it makes sense that the button would connect or disconnect the internal horn. But I am wondering how this works if you are running an extension cabinet only? BTW, I did not see an extra set of wires that would go to an internal speaker. Maybe I need to look more closely at the chassis. Those wires must have been removed.

I know that Acoustic B200H version does not have the "horn" button on the back. Instead, the Acoustic bass cabinets have the horn button build onto the input jack boards.

The image (below) of the back panel has a note #1 - "Speaker Out: Two-conductor....etc" So that would mean it is a stereo output jack or is the note merely stating it is a (+) and (-) connection only?

On the circuit diagram (see attached pdf file), there is a note that states "EXTENSION JACK IN SERIES WITH INTERNAL SPEAKER." So if I am looking at this correctly, J3 is the speaker output. If nothing is connected to the output jack, the jack acts as a short so the signal then goes to the internal speaker. The horn switch then connects a piezo speaker (and protects that horn with the 47 Ohm resistor). But that only applies to an internal horn if I was using the Acoustic B200 cabinet. Correct?

So in my case, connecting a speaker cable to the output gets me an output - and the horn button is irrelevant. Correct?

Thanks in advance. Tom



B200ComboOutputBoardTweeterRevE14Jan2008.pdf

[Enzo]

Don't overthink it, two conductors means just that, hot and return.

The switch only affects the internal speaker.. As I see it, the external is in series with the internal, but that doesn't disconnect the horn. So the horn switch ought to continue to function for the tweeter in the cab. If you are using the chassis as just a head, then there is no horn connection to start with, so the switch does nothing.

[TomCarlos]

Thank you Enzo....

And I now see a four pin connector that has nothing connected to it. So that is where the wires run through the chassis, through the cab, and to the internal woofer and horn. Thus the horn would be connected in circuit using the push button.

For now, I am using an external cab and it works fine. Since I am a fan of Speakon connectors, a future change would be to remove the output board, open a larger hole, and install a 2 Pole Speakon connector.

Much appreciated...

[Enzo]

Your schematic shows that connector, and in fact the layout drawing does as well, clearly.

[michaelfpattison@gmail.com]

TomCarlos - i know your post is a couple years old, but I just joined. I have both a B200 and B200H. Yes, on the B200 the speaker wires went out the bottom of the chassis into a hole in the top of the cabinet to the internal speaker. Poor design as these wires were at risk to crimp sliding the chassis in and out. I just added a jack onto the back of the combo cabinet and mounted the horn bypass board/button there, added a second jack on the back of the chassis to fill the button hole.

[TomCarlos]

TomCarlos - i know your post is a couple years old, but I just joined. I have both a B200 and B200H. Yes, on the B200 the speaker wires went out the bottom of the chassis into a hole in the top of the cabinet to the internal speaker. Poor design as these wires were at risk to crimp sliding the chassis in and out. I just added a jack onto the back of the combo cabinet and mounted the horn bypass board/button there, added a second jack on the back of the chassis to fill the button hole.

Thanks Michael....