Sex amp with 4 ohm speakers

[johnvb]

I read in the intro of my Sex build manual that the amp can drive 4-ohm speaker loads, but couldn't find any particulars. Is this the case, and does anything need to be done internally mod wise? Is there any power rating change? Also, if so, can a powered sub still be fed off the speaker or amp terminal ala SEXy style?

Thanks, John

 

[JC]

You will need to change the tap used on each of the output transformers to the 4 Ohm one.  I'm sorry, I am away from my amp/manual for a few days, so I can't give you the specific colors; maybe Doc or Paul can chip in.  So, that's just two wires to change out, total.

Everything else should remain the same after you make the change, AFAIK.

 

[Paul Joppa]

If the speaker impedance is not very flat then you might hear some coloration, in which case you'll want to use the proper tap. But first, just try the 4-ohm speaker on the 8-ohm tap. It won't hurt anything, and will likely give a bit more power.

The 4 ohm secondary tap is gray; the 8 ohm tap is white. You can leave the white secondary attached to the black primary (common) and the headphone jack, but run the gray to the speaker binding post - if it's not long enough, or was cut short in construction, you might have to splice a longer wire to it. If possible, keep the wire close to the ground wire that goes to the other terminal post, so it does not create a loop that might pick up magnetic-induced hum.

 

[johnvb]

Thanks Guys!