1484 Silvertone Trem mod

[angelodp]

Hi, I have a nice 1484 amp here and wondering if the tremolo can be modified to take the speed on the trem down to a more slow rate. The caps are buried under the power caps and tricky to get to. That would be C20-.01, C21- .01, C22- .02 ...

[jjman]

Yes, change one of the .01 to .02. I would try c21. Then c20 also if more slowdown is needed.

[angelodp]

Ok, I'll give at a go…. am I right that they are buried pretty deep.

[Stevem]

If you double the value of two .01 caps you can really get that slow southern swap type trem happening, but you may need a really good strong trem osc tube to get the bugger kicked over and running.
If you still have the stock red paper cased filters in the amp its high time to cut them out and stuff in new ones anyway!

[angelodp]

Yes I was thinking that those red caps need to go. They are in pretty near perfect shape externally. I know - its time.

Any suggestions on the trem tube. Current stock... sovtek LP?

Thanks- Sure is a sweet sounding amp.

Cheers Ange

[Stevem]

A JJ from Euro tubes that test in at atleast 88%.
Note with these amps if you are still lucky enough to have the stock OT in it that the amps bias circuit is very much on the edge of having enought bias voltage to tame a good set of outputs.
As such if the the outputs red plate or short out from red plating when the amp is cranked the OTs are quite prone to failing.
While you are down in it and replacing all the filters cut open the cathode ground on each output tube add a 1 ohm 1% 2 watt resistor between pin 8 and ground on each output tube socket so you can check the bias current.
You do not want the tubes idling at more than .030 to .035 amp.
Up rate the bias filter(s) to 100 uf which will give you a bit more bias voltage to work with.

[angelodp]

Thanks for the input. I'll be digging in soon.

Best Ange

[dorrisant]

Thanks from me too. Gotta order a replacement OT... Might as well up the bias cap as well.

Tony

[angelodp]

Ok went ahead and made those changes. Two .01uf on the first and second caps in that trem circuit. I paralleled each cap. Slowed it down a fair amount and is quite useable now.

Thanks

Ange

[Stevem]

Cool!
Now you might want to add a 22uf 25 volt cathode bypass cap to the first gain stage in whichever channel you pick, also making one channel into a a brite channel is a nice thing and then use a A/B floor switch to go between them.