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help improving/refurb a Fisher k-10 Tube spring reverb

Diggy Fresh

Member
2013-02-19 10:13 pm
Hi! I'm John, new member here!

I'm in the process of refurbishing a Fisher K-10 "Space expander" tube spring reverb.
It's basicaly a consumer tube spring reverb unit made by fisher to add reverberation to home stereos and was sometime used in organs. I've been looking for that sound for my studio.


It's pretty old but looks pretty clean, i haven't powered the unit yet, My goal is to refurbish it and if possible "improve" it for studio use.

attached is the schematic ( courtesy of Dr.Zee) and a pic of the inside of my actual unit.http://www.gearslutz.com/board/atta...round-scheme-tweaks-circuits-mine-grounds.jpg

So far here's a list of what i plan on doing:

1 - replace selenium rectifier by a modern silicon one
2- replace the "can" type capacitors, 40uf, 40uf, 10uf,10uf disconnect the can and mount the new 4 caps inside chassis with small circuit board.
3 - move the power supply transformer outside the chassis
4 - replace the electrolytics, i tested them all and they all test way higher than the expected capcitance and esr. probably dried out..
5 - replace the plate resistor by newer metallic film one for lower noise.
6- cleaning sockets, connectors, new tubes ect..

questions :

1- would any type of full wave rectifier work? as long as its 400v- 600v
is there "better" ones that could improve something ?

2 - the power supply capacitors, should i stick with the original values but maybe use bigger voltage/temperature ones ? is there an advantage in using audiophile high quality caps like Jensen or sprague for the power supply ?? i guess as long as it's low ESR it shouldnt matter..

3- Plate resistors, i read somewhere they often go bad and cause noise, should i "upgrade" them to higher wattage metallic film ones?? I am very concerned about lower noise. or maybe audiophile ones?

4- the heater : it's a 6v tap of the transformer, unregulated. would it be better if i made it regulated ? (for hum) rectifier/caps. but i guess i don't have much room with 6v..



Any ideas to upgrade improve this thing would be veryy helpfull.

Thanks for your time
 
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