Hi, i'm new in those things, this circuit would work well for converting balanced or unbalanced audio from condenser mics to a fully differential balanced signal? the balanced output is meant to be plugged to a mixer or interface TRS input. the 20uF caps are solid polymer ones on anode to anode configuration to work as non-polarized, my concerns are about the SSM2019 driving the transformer, idon't know if i did everything right, i will respond to any question.
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will this fully isolated preamp work?
- Thread starter Morph1214
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solderdude
Grand Contributor
So the idea is to have a (phantom not switchable ?) mic input to isolated to line-level balanced output.
Why did you deviate from the SSM2019 datasheet ?
SSM2019 does not like to see < 600ohm loads.
For very low frequencies the load might become too high.
Is the transformer properly driven from 47ohm (no HF peaking roll-off ?)
Have you prototyped the transformer output only ?
Why did you deviate from the SSM2019 datasheet ?
SSM2019 does not like to see < 600ohm loads.
For very low frequencies the load might become too high.
Is the transformer properly driven from 47ohm (no HF peaking roll-off ?)
Have you prototyped the transformer output only ?
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The SSM2019 datasheet measured all values with 2k load resistor. Output may be shorted without a problem. But what distortion will appear when load is below 2k ?
If the mixer input is in the range stated in the schematic it should not be a problem. But what is known about the primary inductance of the output xfmr at say 10 Hz ?
If the mixer input is in the range stated in the schematic it should not be a problem. But what is known about the primary inductance of the output xfmr at say 10 Hz ?
If it is the ED8 xfmr I found at aliexpress then the primary inductance is 2 Henry. At 20 Hz then the impedance is around 250 Ohm which seems to be low for the IC.
The ED8 spec there states bandwidth 200 Hz to 20 kHz which seems to me as not good for a mic-preamp. Probably a much better xfmr should be used.
The ED8 spec there states bandwidth 200 Hz to 20 kHz which seems to me as not good for a mic-preamp. Probably a much better xfmr should be used.
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Speedskater
Major Contributor
It's always suspect when the XLR connectors have pin 1 miswired.
That's what AES 48 is all about.
That's what AES 48 is all about.
DVDdoug
Master Contributor
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Are you sure you need isolation? A balanced connection gets you most of the benefits of isolation and good transformers expensive and "impedance sensitive".
Jenson is known for high quality audio transformers. I assume you can trust their specs They have a wide selection so you should be able to get one with the desired impedances and turns ratio. This one would probably work for you.
Jenson is known for high quality audio transformers. I assume you can trust their specs They have a wide selection so you should be able to get one with the desired impedances and turns ratio. This one would probably work for you.
