Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Jatchley on November 09, 2020, 02:11:54 pm

Title: Tube Preamp OT Question.
Post by: Jatchley on November 09, 2020, 02:11:54 pm

So if a preamp has both an unbalanced 1/4” output jack and a balanced XLR Output jack... how does the OT not get burned up if you only use the 1/4in Unbalanced output?

Title: Re: Tube Preamp OT Question.
Post by: PRR on November 09, 2020, 03:02:56 pm

There are many ways.

Specific model? Circuit?

Preamps mostly do not have OTs.

If you are worried about voltage-spikes on an unloaded OT, add a dummy load.

Title: Re: Tube Preamp OT Question.
Post by: AmberB on November 09, 2020, 10:41:30 pm

The OT on the preamp is just an impedance matching transformer.  It converts the high impedance of the tube circuit to a low impedance balanced output for the XLR line out, which is usually a 600 ohm balanced line out.  You're not going to hurt that by using the preamp without the low impedance line connected.