An isolation transformer will not pass DC voltage.
If that were the case the output transformer of a tube amp would not prevent the high B+ DC voltage, that is fed through the primary winding of the xfmr to the plate of the power tube, from passing to the secondary.
An EI isolation transformer will block the DC offset from reaching the secondary.
Will your DC blocker do the job? YES.... But the OP may not have the skills to build one.
He is looking for a plug and play iso EI xfmr.
Maybe the two of you could get together by email and he would pay you to build a DC blocker for him...
I still say the OP would be smart to take the preamp to a couple of friends houses and check out the mechanical hum.
It could be just a noisy Torrid xfmr.
http://en.wikipedia.org/wiki/DC_bias
.
If that were the case the output transformer of a tube amp would not prevent the high B+ DC voltage, that is fed through the primary winding of the xfmr to the plate of the power tube, from passing to the secondary.
An EI isolation transformer will block the DC offset from reaching the secondary.
Will your DC blocker do the job? YES.... But the OP may not have the skills to build one.
He is looking for a plug and play iso EI xfmr.
Maybe the two of you could get together by email and he would pay you to build a DC blocker for him...
I still say the OP would be smart to take the preamp to a couple of friends houses and check out the mechanical hum.
It could be just a noisy Torrid xfmr.
http://en.wikipedia.org/wiki/DC_bias
.