I would agree that the pre-amp is at fault, but it is not entirely the fault of the pre-amp. As you say, there are lots of reports of this problem with the Electro Harmonix 12AY7 Preamp. I would say that it was a design limitation as it seems to be a typical issue with this pre-amp, but other pre-amps are quite capable of driving an unbalanced circuit without this problem. The thing to notice is that all the reports of this problem are when the pre-amp is driving an unbalanced circuit. Many of the reviews mention that the problem is fixed by connecting the output of the pre-amp into a balanced circuit.tymime wrote:I can say for certain that the preamp is entirely at fault here. Lots of people have had the same problem.
Actually, no ... I'm not sure what I was thinking when I mentioned that, but in all probability that would not worktymime wrote:Is this what you mean?: http://www.thomann.de/gb/millenium_dia_ ... di_box.htm It does the same thing then?
A passive DI box may work, but an active one will almost certainly not work. DI boxes are actually designed to work the opposite way round to what you require. They are designed to feed an unbalanced signal into a balanced input, but what you have is a balanced signal (from the pre-amp) going into an unbalanced input (the iMic). I've never tried it, but a passive DI box may work when used the wrong way round (it's basically just an audio transformer), but an active DI box is more like an amplifier and it is very unlikely that feeding a signal into the output will produce the required signal from the input.
My other suggestion was not as stupid. A sound card with balanced inputs (XLR sockets) will provide the necessary balanced input. However, such sound cards are generally designed to allow microphones to be connected directly, so you may find that you do not need to use the Electro Harmonix if you have a sound card with XLR inputs (unless you find that you particularly like the "tube sound" that it adds).
Your ribbon microphone, when partnered up with a good pre-amp and analogue/digital converter should be capable of excellent sound quality. The iMic sound cards are capable of "OK" sound quality if you're not too fussy. While it is not the iMic causing the hum problem, even if you can sort out the hum, the recording quality will be nowhere near as good as the ribbon mic is capable of because (in comparison) the iMics are not in the same league. My personal opinion (and I stress that this just what I would do and you absolutely at liberty to disagree), would be to sell the Electro Harmonix and buy a decent USB microphone pre-amp (one with higher gain than the EH).
