Just finished recapping my SA/1's with four CDE DCMC104M100DF2B 100,000uF, 100V from Digikey per chassis to replace the 39 year old Mallory's 29,000uF 80V.
They still have an inventory of those so all Threshold SA/1 - SA/2 - SA/3, S/200, S/300, S/500 and S/1000 owners can order fresh ones.
These were even lower in height than the old ones but fitted perfectly in the 3" clamps and the groundplate drilled holes.
Would the 100,000uF per can be a problem?
Although they were manufactured/shipped from the CDE factory this year to Digikey I still softstarted them within three hours from zero to 220 volts with a variac. I start the Thresholds always with a variac (but than in a few seconds ;-)) for minimal stress especially for the on/off Airpax circuitbreaker.
The FET Eleven/g (a FET TEN 'e' series for the German market) has two Sprague Series 53D 35V 15,000uf axials and replacement for those is hard.
The best I could find were Vishay/Sprague 25V 18,000uF axials. Over the old ones I measured 23 Volts DC with 230 Volts AC.
Would that be a problem?
They still have an inventory of those so all Threshold SA/1 - SA/2 - SA/3, S/200, S/300, S/500 and S/1000 owners can order fresh ones.
These were even lower in height than the old ones but fitted perfectly in the 3" clamps and the groundplate drilled holes.
Would the 100,000uF per can be a problem?
Although they were manufactured/shipped from the CDE factory this year to Digikey I still softstarted them within three hours from zero to 220 volts with a variac. I start the Thresholds always with a variac (but than in a few seconds ;-)) for minimal stress especially for the on/off Airpax circuitbreaker.
The FET Eleven/g (a FET TEN 'e' series for the German market) has two Sprague Series 53D 35V 15,000uf axials and replacement for those is hard.
The best I could find were Vishay/Sprague 25V 18,000uF axials. Over the old ones I measured 23 Volts DC with 230 Volts AC.
Would that be a problem?
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But do you think the 100,000uF rating (0.4F in total per channel) is a problem?
And the 25V rating for the pre-amp Sprague axials?
And the 25V rating for the pre-amp Sprague axials?
This is the original PSU for the First FET Ten HL
It has apparently a 6VA Toroid by Avel Lindberg and 2100uF for every rail.
The 'e' series, allegedly instigated by John Curl, has a 80VA toroid and 15000uF capacitance per rail.
I can get 10000uf 50Volts Vishay/Sprague 53D's that are 5000uF less than the original 'e' series per rail but still 7900uF more than the original PSU for the FET TEN HL. I'm reckoning 10,000uF is still more than enough but I could be wrong.
My Krell KRS-2 pre-amp had 200,000uF capacitance in total and Anthony H. Cordesman from Stereophile called it a 'real world pre-amplifier' 😉
It has apparently a 6VA Toroid by Avel Lindberg and 2100uF for every rail.
The 'e' series, allegedly instigated by John Curl, has a 80VA toroid and 15000uF capacitance per rail.
I can get 10000uf 50Volts Vishay/Sprague 53D's that are 5000uF less than the original 'e' series per rail but still 7900uF more than the original PSU for the FET TEN HL. I'm reckoning 10,000uF is still more than enough but I could be wrong.
My Krell KRS-2 pre-amp had 200,000uF capacitance in total and Anthony H. Cordesman from Stereophile called it a 'real world pre-amplifier' 😉
Hi Robert,
I updated a set of SA/1's to 4x 100mF back in late '21. They are running very well with that, but I also did include a soft start / inrush limit in each.
I was not completely happy with the hum/noise though - and this later turned out to be the GND lift resistors fitted on each input of the amps. These were two std. 1/4w resistors in parallel, and one set of these had increased to 1.5k - from 10ohm
Whether these were installed originally or added later in the life of the amp we do not know.
After that correction it is now dead quiet 😊
For the Spragues, consider the mains voltage tolerance of up to +/-10% ? this would be borderline and voltage actually has a high impact on capacitor life.
Looking good the update 👍
I updated a set of SA/1's to 4x 100mF back in late '21. They are running very well with that, but I also did include a soft start / inrush limit in each.
I was not completely happy with the hum/noise though - and this later turned out to be the GND lift resistors fitted on each input of the amps. These were two std. 1/4w resistors in parallel, and one set of these had increased to 1.5k - from 10ohm
Whether these were installed originally or added later in the life of the amp we do not know.
After that correction it is now dead quiet 😊
For the Spragues, consider the mains voltage tolerance of up to +/-10% ? this would be borderline and voltage actually has a high impact on capacitor life.
Looking good the update 👍
Thanks Norgaard.
Regarding the FET 11 preamp I will probably order the 50V 10,000uF caps to be on the safe side. They have the same physical dimensions as the original 35V 15,000uF pair so that will be an easy task.
Did you anything else with the SA/1's liker snubbers on the rectifiers?
Regarding the FET 11 preamp I will probably order the 50V 10,000uF caps to be on the safe side. They have the same physical dimensions as the original 35V 15,000uF pair so that will be an easy task.
Did you anything else with the SA/1's liker snubbers on the rectifiers?