Watching this with great interest.
ruffrecords said:So they can and often are asymmetrical? Maybe this explains the poor HF response I have been having with some OEP 1:10 input transformers?
mjrippe said:20kHz is -19.3dBm
at 20kHz it is essentially 1:1.
CJ said:try it without the shields connected...
CJ said:try it without the shields connected...
mjrippe said:Everything exactly the same until...
10kHz is -0.85dBm
15kHz is -9.78dBm
20kHz is -17.75dBm
So we gain 1dB of top end. Again, this is sitting on my bench with ~1 meter of Canare star quad cable going to alligator clips each way.
BluegrassDan said:Thanks for running these tests. Makes me feel better that I was testing it correctly as we have similar results.
I have a whole pile of old transformers to test this evening. I'll report back.
rackmonkey said:I have a bunch of response curves for various transformers in a Google Drive folder I shared on GDIY a couple of years ago.
BluegrassDan said:Here are two sweeps of the Peerless with different situations. The red line is with a -30dB PAD line-level attenuator (150 ohm) between the interface output and the transformer input. The blue line is straight from the interface output (5 ohm) with the levels attenuated -30dB digitally.
[The upload folder is full, so here is a dropbox link.]
https://www.dropbox.com/s/qtmm5n4bx73iygp/Screen%20Shot%202020-06-13%20at%204.08.46%20PM.png?dl=0
BluegrassDan said:Well, here are a few more interesting examples from days of yore.
An RCA N-6567 and some little rectangular transformer with "TE 5266 F" on the side. The top lettering is worn away.
https://www.dropbox.com/s/7624lpd1i63ll5z/RCA%20N-6567.jpg?dl=0
https://www.dropbox.com/s/5v5pqs5vt0e1r26/TE5566F.jpg?dl=0
EmRR said:TE goes to RCA MI-9268 / MI-9285 / MI-10289-A mag film preamps. Probably Hollytran. 30Ω primary; that's why it looks bandpassed.
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