In Reply to: Is phono cartridge a " balance " device ? If so, why is 99.999% phono preamplifer single ended ? posted by adnut on January 4, 2001 at 11:51:55:
***Some phono guru told me that phono cartridge is basically a " balance " device.It is not. It is neither balanced nor single-ended. It is correctly called "floating" source that can be used either way. Much like a battery. The connection to the circuit defines wether it is now a balanced circuit or whatever.
But all this is really not important, or at least far less important than in the case of say, a preamp interfacing with a power amp. Why? Because the catridge has no ground reference, while the preamp and power amp do. Connecting two chassis always creates some issues that floating sources simply don't have.
The funny part is that floating sources can be connected to single-ended inputs and still behave like trully differential ones. I would much rather use the term differential, because it is better defined than the "balanced" - that has many definitions. We have built single-ended circuits with 140dB dynamic range that behaved completely as you would expect from differential circuits. The trick was - they were floating. Much like the input circuit in your DVM doesn't need to be trully "balanced" or "differential" (and they usually are not) in order to not have your typical single ended nastiness.
All this simply means that one should not get stuck in some terminology black hole, but rather do what is right. One particular case - tube inputs in phono stages. There, given the floating nature of the cartridge, it is more advisable to connect it to a single-ended input, gaining 6dB better noise performance (for the same resouces) that is extremely valuable in tube phono stages working with MC cartridges.
Again, each case is different and every designer sees it in a different light, and two products from the same designers might be different. All thank to the floating nature of this source.
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Follow Ups
- Something to ponder - Victor Khomenko 12:36:22 01/04/01 (5)
- Many thanks - Aurel 00:42:37 01/05/01 (0)
- i'm confused...please explain. - mikel 22:02:21 01/04/01 (3)
- Understanbly so - Victor Khomenko 05:19:58 01/05/01 (2)
- thanks victor! and one more question. - mikel 07:29:13 01/05/01 (1)
- Re: thanks victor! and one more question. - Victor Khomenko 07:57:50 01/05/01 (0)