tardishead
Well-known member
Can anyone comment on the tube input impedance criteria for microphones?
This is something I don't really yet understand. Grid impedance is generally assumed to be infinite so long as the anode voltage is high enough (which it is, in a tube mic).tardishead said:Can anyone comment on the tube input impedance criteria for microphones?
tardishead said:Sony c37a uses 10k:200
That is not true in normal (linear) operation. It is true that the Slew-Rate is different because generally, the tube has the capability to pass much more current than the cath resistor. So unless you are overdriving the mic's head amp, there should be no noticeable difference between positive and negative going edges. BTW, the problem is the same for common-cath stages, with polarity reversed.tardishead said:Klaus Heyne and others who dont like the C37a complain about its smeariness of transients. I've read that in a cathode follower the square wave fall time is not as fast as the rise time.
Just to add on Matt's and PRR's comments.tardishead said:Can anyone comment on the tube input impedance criteria for microphones?
tardishead said:Personally I think cathode followers are very useful and can sound huge.
Really? It just explains how to use them properly. Do you think these CF mics are designed improperly? And if so can you explain whyIt also explains some sonic limitations of some CF mics, such as C12A, or C37A:
I don't want to speak for Marik, but there is a point of discussion there.tardishead said:Really? It just explains how to use them properly. Do you think these CF mics are designed improperly? And if so can you explain whyIt also explains some sonic limitations of some CF mics, such as C12A, or C37A:
Which results in ?? Compression and harmonic distortion at high SPL into low impedance tube preamps? Compared to common cathode same SPL same mic preamp surely both introduce distortion?However, the peak current demand on the tube may be an issue, particularly if the load impedance is on the low side.
This will happen sooner because of the higher ratio of transformer. More ratio-> more current demand for a given output.tardishead said:Which results in ?? Compression and harmonic distortion at high SPL into low impedance tube preamps? Compared to common cathode same SPL same mic preamp surely both introduce distortion?However, the peak current demand on the tube may be an issue, particularly if the load impedance is on the low side.
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