Ampeg B100R External Speaker Mod

[maxsample]

Hi everyone, this is my first post at talkbass.

I just bought an ampeg b100r, and I like it a lot. I have only one problem with it, no external speaker out. I'm pretty sure it wouldn't be too hard to jump a 1/4" jack off the speaker leads but would this cause functional problems? It's currently 100 watts into a 4ohm speaker, would another speaker divide the load between the two at 8ohms? will this actually lower my output? has anyone tried this?

[stiles72]

Because the internal speaker is 4 ohms, you can't run another external speaker. Adding another speaker will cut your ohms down too low to the point you could damage the amp. If you are set on running a separate cab, you'll have to swap out the original driver for one that is 8 ohms, and then the external cab will have to be 8 ohms as well to give a 4 ohm total load.

[RickenBoogie]

+1 to the above post. Combo has no ext spkr jack because amp won't support a load less than what is already has.

[tdub0199]

The above post is correct, the internal speaker is a 4ohm speaker, thats as low as you can run the head without damaging it, you would have to exchange the existing speaker out for a 8ohm speaker and the ext. cab would have to be at 8ohms as well, Total load would be 4ohms....

[Caca de Kick]

Or....

You can always install a switching style jack. One that disconnects the internal speaker when you plug in a larger 4ohm speaker cabinet.

I used to do that with my lower watt combos. Sensible volume for praticing home alone, then plug in a bigger cab for basement jamming.

[maxsample]

cool thanks everyone. I will probably just leave it alone and use the line out into the p.a. when necessary. or get a second one...

[anderbass]

Hey Max, I installed 1/4" jacks and plugs in both my B100R's.
They're just soldered in-line between the amp section and speaker.
(I mounted the jack to a bracket instead of drilling any holes in the combo)


Then I built this Series Y-cord adaptor so I could plug in a pair of 4 ohm cabs and end up with a combined 8 ohm load that's safe for the B100R poweramp. This combos poweramp would only be developing somewhere around half power at 8 ohm but mines still quite a bit louder like this with the additional cab.






The series Y-cord is wired:

The male 1/4" positive (tip), to the first female jacks positive.

Then just loop the first females negative over to the second female jacks positive post.

The second female jacks negative then connects to the male 1/4" ground. (sleeve)

Just make sure you use quality speaker grade plugs/jacks and also keep your combos positive and negative speaker wires connected the same way (proper-phase) through their new plugs.

Here's a series Y-cord adaptor you could buy:
http://procablesnsound.com/items/spe...80#ITEM_623649

This setup also allows me to use my B100R's as cabs with my other heads:

[/quote]

[tdub0199]

^ two 4ohm cabs will not give you a 8ohm load, in fact two 4ohm cabs would be 2ohms which is NOT safe for B100R.....

[anderbass]

Originally Posted by tdub0199

^ two 4ohm cabs will not give you a 8ohm load, in fact two 4ohm cabs would be 2ohms.....

They will if they're wired in series...