Ampeg B1 combo question

[mickebas]

I have a chance of buying this 90s B1 combo but having a bit of a problem understanding how connecting an extra speaker cabinet works without damaging the head.
How would I go about connecting an external 8 ohm cabinet and still have the internal 12' speaker on?
Is this not possible due to the internal speaker being 4 ohm?
Do I have to disconnect the internal speaker to use an 8 ohm extension cab or is it just the fact that the speakers will be very uneven volume vise?
Since the manual seems to say not to use the combo with internal and external speakers at the same time is this a definite no no or is there a way around it.
The seller says he's been using an 8 ohm extension cab with it together with the internal 12' 4 ohm speaker all the time with good results for years with no problems.

 

[Slevage]

Most tube amps need a load. They can also operate with more load (lower impedance, more speakers in parallel).
Some have multi tapped output transformers to optimize power transfer to the speakers.
These characteristics are not the same with amplifiers with transistor outputs.

 

[G-Dog]

I have a chance of buying this 90s B1 combo but having a bit of a problem understanding how connecting an extra speaker cabinet works without damaging the head.
How would I go about connecting an external 8 ohm cabinet and still have the internal 12' speaker on? ... ... ...

This is specifically prohibited in the manual!​

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... ... ... Is this not possible due to the internal speaker being 4 ohm? ... ... ...

Bingo! That's what the manual says. Stay at, or above, 4 ohms.​

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... ... ... Do I have to disconnect the internal speaker to use an 8 ohm extension cab [Yes, you do.] or is it just the fact that the speakers will be very uneven volume vise? [No, that's not it.]
Since the manual seems to say not to use the combo with internal and external speakers at the same time is this a definite no no or is there a way around it. ... ... ...

The manual does not "seem to say not to ... [do that]". It unequivocally states "DO NOT ... [do that]". Doesn't that "seem" pretty definite to you?​

... ... ... The seller says he's been using an 8 ohm extension cab with it together with the internal 12' 4 ohm speaker all the time ... with good results ... for years ... with no problems.

And what assurance does the seller give you from any problems that may arise from you doing that, as explicitly warned against by the manual? Will they repair, replace or refund it?​

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I understand that you really want to do this. But, it really doesn't look like a good idea. Maybe get a more modern RB-115 to do that.​

 

[mickebas]

This is specifically prohibited in the manual!​

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View attachment 7437480​

Bingo! That's what the manual says. Stay at, or above, 4 ohms.​

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View attachment 7437482​

The manual does not "seem to say not to ... [do that]". It unequivocally states "DO NOT ... [do that]". Doesn't that "seem" pretty definite to you?​

And what assurance does the seller give you from any problems that may arise from you doing that, as explicitly warned against by the manual? Will they repair, replace or refund it?​

​

I understand that you really want to do this. But, it really doesn't look like a good idea. Maybe get a more modern RB-115 to do that.​

 

[Jeff Scott]

Most tube amps need a load. They can also operate with more load (lower impedance, more speakers in parallel).
Some have multi tapped output transformers to optimize power transfer to the speakers.
These characteristics are not the same with amplifiers with transistor outputs.

The B1 had a solid state power amp.

 

[Johnny Fingers]

Follow these two steps and you should be fine:
1. Buy an old amp
2. Blow it up
Repeat, ad nasaeum.
With the added benefit that you will be really well known at the local electronics recycling event.

 

[Slevage]

The B1 had a solid state power amp.

Thanks for the information. I made the wrong assumption that the OP was talking about one of those old flip tops.