S.E.X. 2.0 iron upgrade kit now available

[jrebman]

So, it is looking that one will still have to configure the new iron as an autoformer -- is this a correct assumption?  If so, I'm also guessing that balanced mode would not be possible with that configuration.

-- Jim

 

[fullheadofnothing]

That is correct, it remains an autoformer configuration.

 

[Natural Sound]

Will the instructions be posted online or something? My kit didn't come with any.

 

[Paul Birkeland]

There is indeed a manual for the kit.  If you PM me your e-mail address, I'll send you a link so you can download it.

-PB

 

[Natural Sound]

Paul,

I got the manual, thanks. I have a couple more questions if you don

 

[Paul Birkeland]

Yes, blue and red for the #45, with heatshrink over the black wire.

As far as the impedance goes, you will want to use the OT-2 transformer, but not quite as-wired in the SEX.  The SEX amp uses the transformer to provide an ~8K reflected load to the plate of the output triode, while the Paramour wants to see 4K. 

Consequently, for something like an 8 Ohm Orca, you can wire the OT-3 transformer for 16 Ohms to reflect the correct load.

-PB

 

[Natural Sound]

Yes, blue and red for the #45, with heatshrink over the black wire.

As far as the impedance goes, you will want to use the OT-2 transformer, but not quite as-wired in the SEX.  The SEX amp uses the transformer to provide an ~8K reflected load to the plate of the output triode, while the Paramour wants to see 4K. 

Consequently, for something like an 8 Ohm Orca, you can wire the OT-3 transformer for 16 Ohms to reflect the correct load.

-PB

Got it, thanks!

 

[jrebman]

Along the same lines as Tom's questions -- can the opt be configured for 4k primary and 16 ohm secondary?

Thanks,

Jim

 

[Paul Birkeland]

Yes.

-PB

 

[jrebman]

Ok, now on to the plate chokes... will these new plate chokes work as ps chokes in the paramour -- 2a3 or 45, and would they be an upgrade over the triad c7x?  Gears are turning.

-- Jim

 

[Paul Birkeland]

Ok, now on to the plate chokes... will these new plate chokes work as ps chokes in the paramour -- 2a3 or 45, and would they be an upgrade over the triad c7x?  Gears are turning.

-- Jim

The C7-X has 10H of inductance, the upgrade iron has 20 or 40H, depending on the tap used, so I would use the C7-X for power supply duty. 

-PB

 

[Paul Joppa]

The plate chokes are 2 or 3 times the resistance of the C7-X, so they drop more voltage. And they are designed to handle the output tube plate current. Of course they handle some AC current as well, so they can handle a bit more DC as long as the AC is small (i.e. not in a choke-input filter). At first glance the temperature rise looks OK.

 

[jrebman]

Thanks, Paul, just an idea and I really didn't know the Rdc specs for the various chokes except the c7x, which every bottlehead probably knows is 270 ohms ;-).

Another opt question: is there a way to configure the opt for an 8 ohm load with a primary closer to 5k, instead of 4 or 8?  I knew there are some intermediate taps in there somewhere but no idea what they are.  I'm seriously thinking of putting this opt in the sr-45 as the nickel with the 45 tube seems to be just a bit too sweet.

-- Jim

 

[Paul Joppa]

You can get 5K:16 (roughly) but nothing else.

 

[jrebman]

Thanks Paul, but after thinking about it a bit I decided that I really didn't want to back myself into the 16 ohm speaker category.

-- Jim