"Thing was, I'd grown partial to the place. With its sudden smell fear and the thrill of waiting-up for the end of the world."
--Billy The Kid, I'm Not There

Tuesday, January 3, 2012

Replacing Amplifier Speakers

This may be skill many of you have achieved long ago, but I had to be shown it by a tech as there is no how to to be found on the internet. So presented here, changing amplifier speakers:

The subject will be a CBS Fender Twin Reverb, yes this is the much "loved" Silver Face with the push-pull master control volume. Came to me stocked with the truly horrible Oxford speakers (also called "Oxfarts"). I found that a pair of Ted Weber Signature Ceramic 12" speakers, the British style, would be a perfect replacement set. A nice thing about these is they are fairly cheap and have pretty much rave reviews.

Before surgery!

Of the new speakers as they came to me in the box.
The back of the amp as was.
With top panel removed.
Pulling speaker wires, it is important to remember with colored what goes which where.
The chassis must be pulled so you can get to all the screws holding the speakers in place I pulled the power tubes and laid them out in the proper order before pulling the chassis so I could lay the chasis off to the side without smashing the tubes. **BE SURE TO PROPERLY DISCHARGE THE CAPACITORS BEFORE EVER PULLING A TUBE AMPLIFIER CHSSIS!!! FAILURE TO DO SO CAN LEAD TO SHOCK OR EVEN DEATH!!!** <== I had to say this so people don't sue me! :) EDIT: This is from Wally on the TDPRI guitar board: "With the amp on, hit a big chord [on the guitar] and flip the power switch to off [while] leaving the standby switch in play mode. One will hear the signal dying down to silence [this] indicates that the voltage has been drained from the caps. Unplug the power cord from the power source."
The reverb tank has to come out as well, you can see where it used to be in a dust outline! Anyway, this is the empty cab as it sets. Be sure to scrape out any paper left from the gaskets of the old speakers.
The first speaker is in place. A few notes here: Most good amps have their speaker screws set into the baffle board in such a way that all one has to do is tighten or loosen the nuts that hold the speaker in place. This particular amp did not have such a nice feature with screws. Luckily the gillecloth on these CBS amps is just velcro'ed to the front to the board and you can get to the screws on the other side of the board. Hold them firm with a screwdriver and HAND tighten your nuts down in a crossways pattern.
Both speakers are in place!
Almost got it back together, you can see the exposed power tube sockets, as said earlier, put the power tubes back into the sockets they came out of so you don't effect the bias of the circuit (this is simply a precaution).
And complete.
Thanks for reading (and thanks Wally for the pointers)!

A note here, I will be soon re-purposing this blog. I am returning to Kansas State University this spring and will be using this site as a journal for my activities and adventures there. Stay tuned if you wish.

1 comment:

  1. The SPK-C612 is usually a set of two-way co-axial 8O sound system designed for installation inside roof. The dual-driver coaxial sound system were created having a transformer and also behind-the-grille electric power selector switch along with possibly direct 8O as well as 70/100V area evening out.
    For more detail: http://www.dueltek.com.au/collections/speakers-and-amplifiers