Pre amp impedance for CAD trion 7000

[Harq]

Hi,

I've read on the forum that people have used the CAD trion 7000 ribbon mic with the N72 and were very happy with the result.
I've tried mine with my J99 and N72, but I'm not so happy alas! The microphone starts distorting at low SPLs (not very loud singing) and I'm thinking it's the mismatch in impedances between mic and pre (all pres are tested and work fine).
The CAD microphone has a high output impedance of 940 ohms. Following the multiply-by-five rule, it would like to see at least 4.7k from the preamp and that is of course, not the case.
Does anyone have the same experience? Also, would there be an easy way to solve this?
I'm new to posting here, but any help would be greatly appreciated!

[tpryan]

Do you get distortion even at minimum gain/maximum trim settings? Have you tried using a wind screen or backing off the mic? Are you certain the distortion is at the preamp and not the recorder/converter? You could test your theory by adding a pair of 4.7K resistors on each phase of the output. It will reduce output dramatically and add noise, but if the distortion goes away that would be a clue.

[Harq]

I have tried a windscreen and backed off the mic. Another thing is that this only happens with the trion mic, so I'm thinking it's either the mic or the impedance mismatch. I'll run some other mics trough the preamps again, just to back up what I'm saying here. I'll also try the resistors and the minimum gain/maximum trim setting and post what I find.
Thanks for now and I'll be back!

[Harq]

Hi again.
I tested a lot of different microphones in different settings only to find out that the one real factor influencing the distortion on the Trion 7000 is the distance from the soundsource (my voice).
Even when using a windscreen, it will distort at a distance of about 4 inches, especially on long notes. It does so way below the clipping level as shown in the DAW. When backing off enough, the problem is gone.
I've also tried maximum trim settings and 4.7k resistors on the output, but to no avail.
So I'm quite sure the distortion is not at the preamp or the converter. I suspect I have a disfunctional microphone.
It has produced some interesting subjective results about the character of the different preamps though, and I plan to do a more objective test just for the preamps soon, also including the a12.
Any thoughts are still highly appreciated.
Thanks for the help!

[tpryan]

What does CAD have to say?

[Harq]

So far: nothing. Alan from Front end Audio has been very helpful though.
Anyway, thanks for all the advice!!

[fairweather]

I'm a little late to the party here but I had a similar problem with my 7000. Audio was distorted, muddy and generally bad. I took it apart and noticed that the cover on one of the magents had come off and ripped one of the ribbon elements. I sent it into CAD and they fixed it. I think I paid for shipping and that was it. On a side note, I still haven't found anything to use the mic on. It's very dull. It would be my go to mic if someone asked for the sound to wrapped in a blanket. Good luck!

[Harq]

That doesn't sound very promising soundwise....
I haven't taken my 7000 apart yet, because it might void the warranty, but now I'm extra curious.
As to the sound: I've been told that ribbons like high impedances on the pre amp side. That's why the AEAs and such go up to 10k. Appareantly the higher the impedance, the more the sound will 'open up'. As a rule of thumb the impedance of the pre should be as least 5 times that of the mic. Since the 7000 already has a very high output impedance (940 ohms), you're sort of forced into using a special ribbon mic-pre amp. Of course I learned about this after I bought the 7000.
Anyway, maybe it's worth an experiment to try the 7000 on a super high impedance pre amp, hopefully taking off the blanket.

Cheers!

[Curtis]

Impedance is probably not the problem. It sounds like your ribbon may have damage or too much slack in it. This can be caused by someone breathing too heavily, or even if the mic is stored on its side. Ribbon mics are just an entirely different beast, and require different techniques. (And the cheap ones coming out of China right now are even more finicky.)

Just FYI, I own ribbon-specific mic-pres, and they subtly change the color of the mics, but it's a purely subjective difference. Running my RCA 77 through the C84 sounds great, and provides more than enough gain.

[Krakatowa]

I'm a little late to the party here but I had a similar problem with my 7000. Audio was distorted, muddy and generally bad. I took it apart and noticed that the cover on one of the magents had come off and ripped one of the ribbon elements. I sent it into CAD and they fixed it. I think I paid for shipping and that was it. On a side note, I still haven't found anything to use the mic on. It's very dull. It would be my go to mic if someone asked for the sound to wrapped in a blanket. Good luck!

I've found using the 7000 to track an upright bass, specially using a bow, gives the recording so much air or breath, some may call this a growl, but boy, I wouldn't use anything else but..