Recapping the Twin

Posted: May 25, 2009 in 1

Fenders are robust, but like anything else they need occasional maintenance. Her are a few photos of a silverface Twin Reverb I recently recapped.

Sloppier hand wiring is a hallmark of later twins, but they can still sound nice if biased correctly.  Most master-volume era twins I have seen are overbiased - the tubes run cold and sound like it.

Sloppier hand wiring is a hallmark of later twins, but they can still sound nice if biased correctly. Most master-volume era twins I have seen are overbiased - the tubes run cold and sound like it.

I often take a moment to remove all the knobs and give the face a moist cleaning with a soft cloth.  Most customers won’t notice, but we all know a clean car runs faster, yes?  :o)

I prefer to use Sprague caps when I can find them. however I have been hearing rumours that the company was bought out and this series of products are or will be soon unavailable. That rumor jives with the drying up of vendors stocking these. It’s not the end of the world to use something else, but it’s nice to keep the american vibe intact if one can.

cimg8782

cimg8781

 
The vents on older mallory caps start to blister as they get leaky and run hotter than they should.  Waiting too long to replace them can lead to a chemical mess at best and a small fire at worst.

The vents on older mallory caps start to blister as they get leaky and run hotter than they should. Waiting too long to replace them can lead to a chemical mess at best and a small fire at worst.

A bit of high-temp silicon is always helpful to prevent excessive vibration of heavier components

A bit of high-temp silicon is always helpful to prevent excessive vibration of heavier components

1973 Fender Twin Reverb

1973 Fender Twin Reverb

The earlier years of the siverface era still have 100-watt power supplies and do not yet have the ultralinear output circuit that the 135-watt models had. This makes them sound a bit better im my opinion – they break up sooner and have more natural harmonic products in the power stage. Ultralinear topology is great for hi-fi, as it really reduces certain distortions (think McIntosh amps) but is kind of out-of-place in a guitar amp, methinks.  By the way, the ultralinear taps are easy to remove on any later Twin, but the power supply voltages will still be a bit stiff and therefore, loud and clean.

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Comments
  1. Fantastic photos. You helped me out on a customer’s Twin w/master switch in which the resistor going to pin 8 on V3 was burned beyond recognition. Your amp turned very nice, great job.

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