Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: isaac_teller on April 13, 2019, 04:13:14 am

Title: unusual transformer
Post by: isaac_teller on April 13, 2019, 04:13:14 am

Shalom. First time poster. I obtained a transformer from a powered speaker that used an EZ81, EL84 and EF86. The primary is a nominal 220 volt. The secondary side has 3 tags-2 of them are 6.3 volts and 2 are 250 volts. The middle tag is common to both the 6.3 volts and the 250 volts. Is this safe to use for a guitar amp? There is isolation between the primary side and the secondary side. Thank you for any advice.

Title: Re: unusual transformer
Post by: sluckey on April 13, 2019, 06:56:51 am

It's safe but I would not use it. The 6.3vac  winding and the 250vac winding have one end of their windings connected together and share a common terminal. This common terminal will have to connect to your amp circuit's ground. that your filament circuit will have an unbalanced reference to ground and may hum a bit and there is nothing you can do about it. And, you must use the EZ81 as a half wave rectifier. Either of those facts would make me just say no.

Title: Re: unusual transformer
Post by: isaac_teller on April 13, 2019, 10:01:43 am

Thank you.