Michael & Ultrasonic
Hey Michael, Iāve been building a new balanced cable using silver and pure copper, and Iād love to hear your thoughts on how impedance tolerance could affect signal integrity in a highāfidelity setup.
Sounds like a solid project. For a highāfidelity balanced cable, keeping the impedance tightly on target is essential ā if it drifts too far from the 50ā or 100āohm spec youāll see reflections, loss and distortion. With silver and copper you get a very stable conductor, but the dielectric and geometry are what really set the characteristic impedance. Iād recommend measuring the impedance with a timeādomain reflectometer and aiming for a tolerance of ±1ā2āÆ% of the target. Make sure the shield or braid geometry is consistent, use a stable dielectric, and choose connectors that match the impedance as well. Even a small mismatch can throw off the phase relationship between the two conductors, which is a real headache for balanced signals. Keep the layout tight, test thoroughly, and youāll preserve signal integrity.
Thatās good, but remember the cableās impedance is really a reflection of its own waveform path. If the dielectric isnāt stable, the phase of the two conductors will wander and the balance collapses. Keep the geometry tight, use a braid thatās uniform, and check the whole run with a TDRāany stray mismatch will pop up as a hiss you canāt ignore. And donāt forget the connectors: a mismatched jack is like a bad filter in a highāpass chain, itāll bleed the clean sweep youāre chasing.
Exactly, the whole line is a single resonant system ā any small change in dielectric or spacing throws the phase off. Iād doubleācheck the braid pitch and the connectorās return loss, too. A clean, tight run and a lowāloss jack are the only ways to keep that hiss from creeping in. If you still see imbalance, run a sweep from the source to the far end; the TDR will show you exactly where the stray impedance is. Keep the layout as simple as possible and youāll preserve that clean sweep youāre after.
Youāre right, that whole run is one resonant pulse train. Keep the braid pitch uniform and make sure the jackās return loss is below a dB or two. A TDR sweep is the quickest way to locate any microāimpedance spikes, and once youāve trimmed them out youāll have that clean, hissāfree channel Iām after. Donāt overācomplicate itājust straight copper, steady dielectric, and a tight shield, and youāll hear only the pure tone youāre tuning for.
Sounds like youāve got the right plan. Keep the braid tight, check the return loss, and run that TDR sweep. Trim any microāspikes, and the channel will stay clean. Stick with steady dielectric and straight copper, and youāll get the pure tone youāre aiming for. Good luck with the build.
Glad that hits the mark. Iāll lock in the braid, doubleācheck the return loss, and do the TDR sweep. Straight copper and a stable dielectric will keep the signal pure. Thanks, and Iāll keep the build clean and focused.
Good planāstick with that approach and youāll have a clean, reliable line. Let me know how the sweep turns out.
Got the TDR sweep doneāeverythingās staying right in that 50āohm band, no micro spikes to trim. The line feels clean and ready for final tuning. Thanks!
Nice work getting that clean sweepālooks like youāve nailed the impedance. Now just run a quick test signal through the finished cable, check the phase and amplitude, and make sure the balance stays within a couple of millivolts. Once thatās confirmed, youāll have a solid, hissāfree path. Good luck with the final tuning.
I just ran a sine burst through the cableāphase looks locked and amplitude is within ±2āÆmV. The balance is tight, no hiss. Iāll tweak the lowāpass corner a little and lock in the final gain. Thanks for the headsāup!