Posted by Ted Conger on May 02, 2004 at 12:05:57:
I wanted to recap all I've gleaned from various posts over the past 6 months or so since I've been lurking in SLOG. It appears to me from various posts that there are four backplate mods that can be done to my A-3's Yes I know all this is probably in the archives in snippet form or has been discussed individually,but I wanted to recap the mods and make sure that I have gotten everything understood correctly.Actually Roy helped me in a private email immensely.
1.)Find the correct setting for the Low Frequency "Bass Comp" jumpers and hard wire them.
1a.) Do the same if your model has midrange jumpers.
2.Through trial and error determine the correct settings on the "Brilliance" control ...meter the pot,... and replace with a value resistor correlating to the metered value of the pot.
2a.) In order of coolness, I will place a "Roys Super Resistor" at the top of this list as being the highest quality part to use here.
2b.) There have been other resistors discussed for this .....considering the wide range of values likely to be needed for each individual.is there a "general" guideline?
3.) Replace the "shunt" resistor in front of the toroid. The stock resistor is supposed to be a "sandcast" unit
3a.)Again a "Roys" should be the best....suggestions for something that works well for more reasonable cost?
4. Replace the 2, 24 ufd Solen capacitors in each backplate.
4a.) Kevin Covi's link for polystyrenes is no longer functioning.
4b.) Has anyone got any "high value" suggestions here?
Finally...taking into account the sonic gains from performing steps 3 & 4...would it be wise to do step 2 last???
For a guidline my speakers are somewhat older units....serial no 173 that have been upgraded to A-3+ with toriods and remylared with copper rings,and Cardas binding posts.