Sunday, October 3, 2010

Quad 303 (2nd unit)

Found the following pix(s) of my 2nd Quad 303 which was recapped and re-biased in 2009. Though it would be interesting to post them. 

I acquired a 2nd Quad 303 to enable bi-amping using my Quad 33 and FM3.

I tested the unit after purchase and it was functional but with a slightly lower volume on the right channel.

When I open up the internals, I was shocked (!!!) and surprised it was still functional (Hint: Right channel board)

The are pix of the original unit before it was recapped. Will add pix(s) of the recapped unit once I take it out from storage.
PSU board

Right channel board with broken capacitor!!!

Left channel board


  1. Hi, I've just bought a 33/303. They actually sound surprisingly good given that they look like they're all original inside. I'm intending to recap / tweak them with the Dada kits.

    Would be really interested to hear how you find the biamp sound? I'm thinking I might look for a 2nd 303 later on and try this...

    thanks for the write up.


    1. Hi Jim,

      Good choice!

      Please look at my other posts for the information you are after (see further below).

      I would say the 33 is the weak link. Sounded pretty much the same after the DaDa upgrade but with better volume and some improvements in the clearity with the imaging naturally centred again. Bass was ok but HF seem surpressed. I then added the bypasses to the internal adapter boards in the 1st 33 to improve the HF (see pix in 2nd 33) - suggest to only add the bypass(s) only at this stage.

      For the 303, I have compared my original (late model 303) with the upgraded 303 (with my alterations) and the difference (my 5cents worth)is the increased HF spaciousness and better defined bass. In the 303 I also substituted 2 ceramics for silver mica's.

      For the bi-amping, I did not follow the Quad document as I believe that was a bit troublesome to perform the adjustments and would be like "double work" e.g bias setting after upgrade and add the potentiometer and need to readjust again! Bi-amp setup was thus performed following traditional methodology with the balance control on the 33 used for imaging centering.

      The necessary links are at the following.

      Quad33 (1st unit - with Dada upgrades but I forgot to include pix of the back of the 2 internal removable boards) @

      Quad33 (2nd unit - please try with the bypass added to the back of each board only) @

      Quad303 (after this unit was upgraded) @

      Quad303 Bi-amp @

      Best wishes!

    2. Sorry forgot to add that the review of bi-amping is towards the end of the writeup.