Threshold FET nine

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R

Renehc

Member
Joined 2019
Hello.

..My first post here :D

I just got a Threshold FET nine. Lovely piece of equipment, a beauty!.

It has a problem..
It does some hizzing/popping noises once in a while. I wrote Jon Soderberg to try and understand what could be the cause. I told him it happened every two minutes or so, but after a bit more listening, it seems more sporadically, than every two minutes!
(Im not a technician).

He told me I should change the electrolytic caps (because of the aging?), and that a Jfet (6 leg can) maybe caused the problem because of static damage.


Now, I think that this is the right place to ask which electrolytic caps that I should be using instead of the ones in place now (I think it is the original ones?)
I dont want to degrade the PRE, so im thinking of the best solution, without it running crazy with the cost. What options do I have?

Jon said that the Jfet could be replaced with two 2SK174 (paired).
Can I get two of those paired in an easy way? (Total newbie you see :) )
I will have someone to look at it, to find the exact problem.

Is there anything else to be aware of? Something else to replace maybe, to make it even better, while still maintaning the PRE in “stock-form”?

Again im not technical..


Looking forward to hear from you.


Regards

René
Denmark
 
R

Renehc

Member
Joined 2019
Hello jfetter.

Thank you for your answer. With that in mind maybe it will be easier to locate the problem, thank you.

Will you recommend upgrading different components in the FET nine?
Jon said new electrlytic caps, which ones would be a good choice for the FET nine?

I will leave a picture here of the FET nine. May be come in handy :)

An externally hosted image should be here but it was not working when we last tested it.



Regards
 
R

Renehc

Member
Joined 2019
jfetter said:
With the information you gave, it does sound like the input pair.

I damaged my sae amp by plugging in rca male plugs while powered up.
Same for one of my Sansui rack mounts.
In both cases I had accidentally damaged them. The symptoms same as yours.
Click to expand...

Btw. I always turn everything off while disconnecting/connecting equipment. But maybe it happened before I got it. Well, its an old pre, a lot could have happened in the years.
Altogether it looks like it was taking good care of since march 1987 :)

Regards
 
J

jfetter

Member
Joined 2012
Speaking from my own observations, depending on age of the unit newer replacement parts are of lower quality.(even parts in mfgr distribution)
The auctions not too good due to so many convincing fakes.
Try to get a new original type input pair.
Caps are a similar with fakes. If you can use mouser,digikey ie the parts come with certificate showing source.
Sometimes a parts donor chassis can be found on auctions. This is ok if one channel is good or its completely dead.
 
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