Golden Ages MK II Passive Ribbon Mic Mods/ Suggestions?

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littlemerl

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Golden Ages Project R1 MKII Passive Ribbon Mic

I bought one of these mics awhile back because I wanted to have a Ribbon mic to play around with. It has decent reviews and all that and it was reasonably priced so I went for it. I like it for vocals alright but the low-level noise is significantly higher than any other mic I own. I have read that it is a bit noisy but no review ever indicated that it was a big issue. I have tried it on my two low-budget pre-amps, a Behringer mixer with Xenyx pre-amp or Yamaha MD 8-track with built in pre-amp. I use a Triton FetHead to boost the signal. I was wondering what is the most likely component in the mic that causes so much noise? Is there a known mod to combat the problem or any other suggestions out there?
 
Have you run side by side comparisons with other mics to be certain you're not hearing the noise floor of the preamp?

With something like a behringer mixer, you'd think most mics noise levels wouldn't be an issue?
Maybe I'm wrong.
 
I'd guess the noise is coming from the FETHead (though I know nothing about it) or the preamp. Ribbon mics take lots of gain, so if you have the preamp cranked you're amplifying the preamp's first stage noise and everything upstream. A ribbon mic has no active components (just a ribbon, a magnet and a transformer) so I'd think its noise is negligible.

The way to find out is to connect a different ribbon mic and see if there's any difference. If not, then the problem is after the mic.
 
I have run comparisons with a Shure sm58 and an audio technica dynamic vocal mic which require roughly the same gain to get up to recording level. Since the gain is almost all the way up for all three mics I am definitely hearing the preamp's noise but the Golden Ages ribbon is at least twice as noisy. As far as the FEThead, all it really does is allow me to use less preamp gain (almost half) to get the same recording level and it doesn't really reduce or add to the noise when used on any of these three mics.
 
The noise of any dynamic mic is thermal noise, which is a function of resistance. Ribbon mics in particular need to have very low resistance transformer primaries because that noise is stepped up in the transformer, and then added to the thermal noise from the resistance of the transformer secondary, whereas the much lower-ratio moving-coil transformers are less worried about that.

For example the Lundahl 1:37 ribbon mic transformer has primary resistance of 0.05 ohm and secondary of 69 ohm, so that's (0.05 * 37^2) + 69 = 137 ohm, which using this handy calculator:

Noise calculation calculator calculate Thermal noise Johnson noise voltage level Nyquist dBu dBV signal-to-noise ratio S/N temperature bandwidth noise figure - sengpielaudio

is -134dBV.

Now, let's say the unknown transformer in your mic is 0.2 ohm/150 ohm, that means the thermal noise is -129dBV. And if the mic is say a couple dB less sensitive than a 58 (260 ohm I think), you'd have signal-to-noise that is 4dB or so worse.

Take some more precise measurements and see what you've got.
 
ribbon mics should not excert much more noise than an ordinary dynamic imo, not that i'm an expert.
When you say the low level noise do you mean the proximity effect ? when you get up close are the bass sounds much more pronounced? is that what you're reffering to?
If so this is normal for a ribbon mics.
just checking it's not this you are reffering to and not the noise floor itself.
i have some behringer pre's and if i where you i'd stay away from the tube warmth adding feature and stay on the fet side of things as the tubes distortion will cloud the sound and make it sound muddy too.
 
After some of your suggestions, I decided to do another closer comparison, though no more scientifc, of the sm58 vs R1 MKII Ribbon. I used the behringer 1002fx mixer with it's built in xenyx preamps and did not use the FEThead. I started with the sm58 and set the gain to get the highest recording level without clipping. Then I plugged in the ribbon and set the gain to the same sm58 level for reference. To get the same recording level as the sm58 I had to turn the gain up almost a hatch mark or a few degrees. I guess the lower sensitivity is enough to explain the approximate doubling in noise floor. From the data sheet the stated sensitivity of the sm 58 is -54.5 and the R1 MKII is -52 which I am not sure if that jives with my observations or not I don't understand the sensitivity units.

I don't know how to measure transformer resistances, can I measure off the XLR pins? I don't want to open up the mic at this point I am a little shy of the ribbon inside.

Low-level noise: poor choice of words I didn't mean proximity effect. It sounds like it is called noise floor: The back ground hiss when you are not playing, singing ,etc.

I am only using this solid state mixer, not tubes in the equation. I don't think there is a tube simulation setting on the mixer

So it sounds like the most likely way to decrease the noise floor is to use a cleaner preamp
 
i should say its the mixer thats causing the noise then. Behringer mixers are know for being noisy in the first place.
it sounds like the 2 mics are also reasonably close in terms of gain needed which is good news. as this is my experiance too.
 
If the mixer's input noise is significantly higher than the mic's thermal noise (say 3dB or more), then the mixer is the dominant noise source, and the difference can be explained by the difference in sensitivity. Note that the spec indicates that the ribbon *should* be more sensitive than the SM58, but clearly it isn't. Either the spec is thus wrong, or the mic is far out of spec.

Set the mixer to max gain--contrary to popular belief, that is usually the setting with lowest input noise--and unity on the faders, and measure the noise and sensitivity of both mics. That will tell you the relative difference in both, and you can draw conclusions as to whether the mixer is the dominant noise source. That would be if there was no change in noise, but there was a difference in sensitivity. If that is the case, try to find a known-very-quiet preamp for the test instead.

If the noise is different with the mixer at the same max setting, then you'd start worrying about excess thermal noise from the ribbon mic's transformer. You can directly measure DC resistance of the secondary, but you can't measure the primary while it's attached to the ribbon, and even if disconnected ideally the resistance is too low to measure with a standard multimeter--you need a special instrument for that (called a wheatstone bridge, you can build one, see wikipedia and get yourself three precision 0.2 ohm resistors, an AA battery, and one 10 ohm series resistor to drop the battery voltage as a current limiter).

That said, if you do measure an increase in resistance on the primary with your multimeter (compared with shorting the multimeter leads together), that means the resistance probably exceeds 0.2 ohm, which is likely a source of excess noise.

In the end it might be that you have hit the theoretical maximum possible signal to noise, and the ribbon seems noisier because it has lower sensitivity. There isn't much you can do about that, except to buy a more sensitive ribbon mic.
 
that's me ! i'm out of my depth here but i'm going to look into the wheatstone bridge thing.
 
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