Internal temperature of s.e.x. amp?

[Jim R.]

I'm considering using the new high temp series of Jupiter caps for the parafeed caps in my s.e.x. amp but don't know what to expect in terms of internal temps.  If it helps, the base of my amp is cut down to a height of 2.5" but will be mounted so that there is probably at least a 3/8" gap all the way around.

Also, if anybody has any experience with a teflon tube socket vs. a quality ceramic (Azuma) I'd appreciate hearing about it.  I have both availble in my stash.  I'm leaning towards the teflon for their reported lessening of microphonics in some amps, but the azumas have hard copper with direct gold plated pins and have a real death-grip on tube pins.

-- Jim

[Paul Birkeland]

I would use the Azumas, but be sure to use a tube that will allow the use of the supplied O-ring. 

As for the operating temperatures, 70 degrees celcius seems reasonably to use in a SEX amp, but I will ramp mine up tonight and plunk the oven thermometer underneath just to check.

-Paul

[Paul Joppa]

For what it's worth, the earlier Jupiters did have problems in the SEX amp, more than once. They were used as parafeed caps, and sounded great but shorted out after a while. There are some in Doc B's big headphone amp which have lasted well for several years; that amp has perforated plate top and bottom for good ventilation.

Personally I recommend 85C ratings for everything under the hood. But I believe a number of people have used the lower-rated M-caps with success. Hopefully some of them will post in this thread...

[Jim R.]

Thanks, Pauls :-).  Looks like the new Jupiters are good for a steady state 70c or approx 160 F, so if I can keep them far enough away from the hotter parts, they may be fine... I think.

No time for building today, time to go and start cooking.

Thanks again,

Jim

[Rick58]

For what it's worth, the earlier Jupiters did have problems in the SEX amp, more than once. They were used as parafeed caps, and sounded great but shorted out after a while. There are some in Doc B's big headphone amp which have lasted well for several years; that amp has perforated plate top and bottom for good ventilation.

Personally I recommend 85C ratings for everything under the hood. But I believe a number of people have used the lower-rated M-caps with success. Hopefully some of them will post in this thread...

I have been using Mundorf Silver/Oils (55C rating) as parafeed caps in my Paramount (300B version) for over a year, no apparent problems. I know the 300B version runs 'cooler' than the 2A3 version. One end of the cap is about 1" from one of the cathode bias/heater resistors. I think these resistors are the hottest things under the hood.

STURMJ is using (new) Jupiters in his as well:   http://www.bottlehead.com/smf/index.php/topic,251.0.html
he has his mounted against the base wall, about 3" away from the resistors, and 'sideways' to them.

[Paul Birkeland]

For what it's worth, the earlier Jupiters did have problems in the SEX amp, more than once. They were used as parafeed caps, and sounded great but shorted out after a while.

Were the old Jupiters foil with wax dielectric, or did they also have paper in them?  I'm wondering if they added paper to somehow stabilize any wax that softened up and changed thickness. 

[Len]

For what it's worth, the earlier Jupiters did have problems in the SEX amp, more than once. They were used as parafeed caps, and sounded great but shorted out after a while.

Were the old Jupiters foil with wax dielectric, or did they also have paper in them?  I'm wondering if they added paper to somehow stabilize any wax that softened up and changed thickness. 

Or maybe they changed the wax. The original Jupiters that I have were advertised as being made from beeswax.

Hmmm, maybe they changed to equatorial bees.