I'm still a little surprised you have this (very real) problem on a Lundahl. My experience is mainly with Mike Preamp i/p transformers and the big Lundahls for Line Outputs. All from the days of Broadcast Mixing Desk designs for the BBC and other broadcast organisations in da previous Century.
In my experience, the good trannie makers, Sowter, Jensen, Lundahl, are usually better for slight imbalance than lesser makers.
The example I have this Millenium is microphones that draw P48 from only one leg (eg some Behringer ECM8000 versions and also my SimpleP48 designs) Only about 500uA imbalance.
The Lundahls in old Sound Devices seem to shrug this off without problems.
BTW, it's simple enough to use Audacity to create a test signal which faded up and then down at whatever rate you want.
In my experience, the good trannie makers, Sowter, Jensen, Lundahl, are usually better for slight imbalance than lesser makers.
The example I have this Millenium is microphones that draw P48 from only one leg (eg some Behringer ECM8000 versions and also my SimpleP48 designs) Only about 500uA imbalance.
The Lundahls in old Sound Devices seem to shrug this off without problems.
BTW, it's simple enough to use Audacity to create a test signal which faded up and then down at whatever rate you want.
Well it's worth a couple caveats/notes, before anyone considers this the official word on anything.
Next step is to get some actual tube circuits setup, like 6W6 or 5687's to drive those Edcor interstages, or some DHT's I have using the LL1674's as a parafeed headphone output, and measure the performance of tube & transformer together, as opposed to just a resistor & transformer. I also need to, you know, listen to these a bit. I like having this measurement setup mainly to make sure I don't have anything grossly incorrect, verify there's no obvious problems hiding at different frequency ranges, compare distortion profiles, and examine changes between operating points. If THD was the #1 thing I cared about I wouldn't be messing around with tubes and transformers obviously.
- I only have one decent sound card, the Scarlett 2i2
- I only really have REW (Room EQ Wizard) setup for testing
- Other than seeing that loopback tests look clean, I don't have a means to calibrate/verify the performance of the system
Next step is to get some actual tube circuits setup, like 6W6 or 5687's to drive those Edcor interstages, or some DHT's I have using the LL1674's as a parafeed headphone output, and measure the performance of tube & transformer together, as opposed to just a resistor & transformer. I also need to, you know, listen to these a bit. I like having this measurement setup mainly to make sure I don't have anything grossly incorrect, verify there's no obvious problems hiding at different frequency ranges, compare distortion profiles, and examine changes between operating points. If THD was the #1 thing I cared about I wouldn't be messing around with tubes and transformers obviously.
