XSE10-4-8K question

[DeathRex]

I got a pair of XSE10-4-8K op transformers from coop402. I only have 8 ohm speaker so I don't know if I can even use them. If I hook 8 ohm speakers into the 4 ohm secondary the primary sees 16K, is that right?
http://www.diytube.com/phpBB2/viewtopic ... ansformers

I tried 1 volt RMS into the secondary from another amp's output and got 46 volts out of the primary. Since this one has a screen tap I tried different connections to see what I would get. Between the plate and screen I got 25 volts out with 1 volt in or 25:1. Could I use this as a 5K to 8 ohm now?

[Shannon Parks]

I got a pair of XSE10-4-8K op transformers from coop402. I only have 8 ohm speaker so I don't know if I can even use them. If I hook 8 ohm speakers into the 4 ohm secondary the primary sees 16K, is that right?

Yep.

I tried 1 volt RMS into the secondary from another amp's output and got 46 volts out of the primary.

Makes sense. Square root of 8000 / 4 is 44.7, so your turns ratio is 44.7:1 and 46:1 as measured.

Since this one has a screen tap I tried different connections to see what I would get. Between the plate and screen I got 25 volts out with 1 volt in or 25:1. Could I use this as a 5K to 8 ohm now?

For a Darling or headphone amp, you're probably fine.

Shannon

[DeathRex]

For a Darling or headphone amp, you're probably fine.
Shannon

How about a EL84?

[kheper]

For a Darling or headphone amp, you're probably fine.
Shannon

How about a EL84?

Why not just use 8k to 4ohms with the 8ohm speakers? 8ohm speakers are nominally ohms; They dip below 8ohms. In the data below are el84 amps with primary loads ranging from 3.5k-10k (most above 5k).

http://www.nj7p.org/Common/Tube/SQL/Tub ... ?Type=6BQ5

[DeathRex]

I can always try it.

Would there be a tube even better matched to the transformer, other than a 1626 (I do have some though)?

[DeathRex]

Answered my own question, I found this post
http://www.diytube.com/phpBB2/viewtopic ... 24538bcbac

[kheper]

807s like a high primary load; They can be gotten cheap from ebay sellers in Russia, Lithuania, etc.

[DeathRex]

I have a pile of used 1625s. The STC application report says they can have 6000K impedance in triode mode and pentode mode.