Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: John on August 15, 2015, 01:52:47 pm

Title: Output transformer, short question
Post by: John on August 15, 2015, 01:52:47 pm

If the secondary output tap measures zero (or under 1) ohms to the secondary common, is it dead?

Title: Re: Output transformer, short question
Post by: sluckey on August 15, 2015, 02:05:50 pm

Not usually. The DCR of most 4, 8, 16 ohm secondaries will usually read very very low. It's just a length of fairly big gauge wire.

Title: Re: Output transformer, short question
Post by: John on August 15, 2015, 02:14:05 pm

Whew. Thanks!

Title: Re: Output transformer, short question
Post by: PRR on August 15, 2015, 09:50:00 pm

You want the _DC_ resistance of the winding to be much less than the load, so it don't waste power.

Ideally zero, but we can't have that.

"Much less" than 4-8-16 Ohm speakers is typically an Ohm or less. And most meters won't read 1 Ohms well.

Don't worry about it.

Title: Re: Output transformer, short question
Post by: John on August 16, 2015, 05:35:18 am

Thank you.


I just finished re-building my amp (added spring reverb and such) and had no sound, not even hum. I think I had a bad joint at the speaker jack. Now she sings.


And spring reverb is cooooolllllllll.