Focusrite Liquid Pre transformer loading

I picked up a Focusrite Saffire 56 which comes with two "Liquid" preamp channels.

Only one of my mics--an AT4050/CM5--when plugged into either of the Liquid channels generates a low frequency "heartbeat" signal peaking around -18dB until I disable the "transformer loading" feature on that channel.  It literally sounds--and the waveform looks--like an electrocardiogram plot!  For a minute I thought by looking at the VU that it was picking up my hearbeat; but the gain was all the way down.

I understand the transformer loading is intended to simulate mic-to-pre interaction of classic preamps.  I haven't worked with many iron-based units yet--that is until I actually have time to complete some of these projects still in pieces on the workbench.  :  

I'm just curious what's going on here electrically.  I'm sure CJ would have his finger on the pulse* of the explanation for this.  (*pun intended  ;D)

-Bob

Besides the loading issue, what do you think about the Focusrite 56?  Have you recorded anything of use yet or are you still just testing it out?

kml23956 said:

Besides the loading issue, what do you think about the Focusrite 56?  Have you recorded anything of use yet or are you still just testing it out?

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My first impressions are very good.  The DAC side is very nice.  Smooth and precise--an order of magnitude beyond the old Mackie hardware I was using.  Recording-wise, I like the sound on my own voiceovers--the Class-A 2A (Neve 1073) model suits it quite well.  The trial by fire is yet to come.  I am recording an amazing singer this evening--a theatrical/operatic soprano. 

Thank you for the information. I would be very interested to hear how that turns out.  I need a new interface and I have been serious thinking about this one after reviewing the specs.  Will you be using it in 96k/24bit mode?

kml23956 said:

Thank you for the information. I would be very interested to hear how that turns out.  I need a new interface and I have been serious thinking about this one after reviewing the specs.  Will you be using it in 96k/24bit mode?

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Probably not.  It's for a website demo to be tracked over an existing session produced by the arranger that she's bringing with her.  I haven't heard it yet; my guess it's 44.1 - Well, I hope it's at least that.  :

Either way, I am still interested in the results.

kml23956 said:

Either way, I am still interested in the results.

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First track - the Burt Bacharach sampler

Tracked vocal over client-provided backing track. 44.1K  Mic is AT4050/CM5. Used Saffire 56's Neve 1073 emulation (CLASS-A 2A) Harmonic control at 4 

stickjam said:

kml23956 said:

Either way, I am still interested in the results.

Click to expand...

First track - the Burt Bacharach sampler

Tracked vocal over client-provided backing track. 44.1K  Mic is AT4050/CM5. Used Saffire 56's Neve 1073 emulation (CLASS-A 2A) Harmonic control at 4 

Click to expand...

That made up my mind.  I like it.