CAD Trion 7000 Ribbon Mic + Preamp Question

[PoeticIntensity]

I've read everything I can find about the whole "Do I need a specific preamp for my ribbon mic" issue, and I still am finding myself quite perplexed. I just need to know if I'm going to okay or not.

I just found a killer deal on a CAD Trion 7000 ribbon mic (brand-new on ebay for $100.00), so I bit the bullet and bought it. It's not here yet, and I can't wait to try it myself, so I thought I'd ask to see what you all think of my set up and whether it's going to work or not.

I'm planning on recording some acoustic guitar work, and I'd like to try my hand at mid/side recording. I bought the CAD mic for the side, and am planning on either an SM57, or an Audix F15 SC for the mid.

My preamp is a Focusrite Octopre, and here is where my head explodes.

I've read about the Hi-Z / Low-Z weirdness with the ribbon mics, and found that my new ribbon mic is going to have an impedance of 940 ohms. My preamp has Hi-Z and Low-Z inputs. The low-Z (mic) impedance is around 150 ohms, and the hi-Z (direct in) is above 1000.

The max mic gain on the octopre is 60dB for both the mic (lowZ) and the instrument (Hi-Z).

So... Should I be worried about having an impedance mis-match for this mic? Will I have enough gain to record the mid in a M/S configuration for an acoustic guitar? Has anyone had similar experience with similar hardware?

I just need to stop stressing about this, but I thought this forum would have some insight for me.

Thanks for your patience with me. Learning loads as a I go along...

 

[Sonixx]

the answer is yes and no.

the mic should work Okay with any decent pre. But if you are recording a low level source, you'll want a low noise pre with a lot of gain.

I've used my T7000 with several pres including an AEA TRP and it has work fine with each.

note, there was some issues with loose ribbons on these mics. I have two and both were fairly loose. I'm no ribbon expert though. I did open up one and tightened both ribbons. did it make a significant difference? not that I can tell with the sources I'm recording.

 

[MichaelJoly]

...I just found a killer deal on a CAD Trion 7000 ribbon mic (brand-new on ebay for $100.00)..I've ...found that my new ribbon mic is going to have an impedance of 940 ohms...The low-Z (mic) impedance is around 150 ohms...So... Should I be worried about having an impedance mis-match for this mic? Will I have enough gain to record the mid in a M/S configuration for an acoustic guitar?...

First answer - No. No mic preamp has an input impedance of 150 Ohms. Perhaps the spec implies that the preamp input impedance is high enough (1500 Ohms or greater) to work with a mic of 150 Ohms...Second answer - probably. The M/S mic is going to hear mostly room sound reflections. In a small room the energy of the room reflection energy will only be down maybe 6-10dB from the direct sound. In a large auditorium it will be down more than that relative to the direct (M) sound.

Just understand this - whatever the microphone output impedance is spec'd at, the preamp input impedance should be 10x that number in order not to appreciably load the microphone and change its sound or level.

The bigger issue with the CAD Trion 7000 ribbon mic is the dual ribbon design - it introduces a phasey quality due to arrival time difference between ribbons and also has a very broad proximity effect "Q" because of slightly different resonant tuning frequencies of the two ribbons.

 

[PoeticIntensity]

First answer - No. No mic preamp has an input impedance of 150 Ohms. Perhaps the spec implies that the preamp input impedance is high enough (1500 Ohms or greater) to work with a mic of 150 Ohms...Second answer - probably. The M/S mic is going to hear mostly room sound reflections. In a small room the energy of the room reflection energy will only be down maybe 6-10dB from the direct sound. In a large auditorium it will be down more than that relative to the direct (M) sound.

Just understand this - whatever the microphone output impedance is spec'd at, the preamp input impedance should be 10x that number in order not to appreciably load the microphone and change its sound or level.

The bigger issue with the CAD Trion 7000 ribbon mic is the dual ribbon design - it introduces a phasey quality due to arrival time difference between ribbons and also has a very broad proximity effect "Q" because of slightly different resonant tuning frequencies of the two ribbons.

Thank you for your response! Sounds like you know your stuff about mics. Sound like I may have assumed too much about this mic being as good as the reviews say it is. Would you recommend another mic instead of this one for around $100.00? (I know it's a heckuva stretch finding anything worth snuff at that price, but I thought I'd ask anyway...)

Thanks again!

 

[dgatwood]

Thank you for your response! Sounds like you know your stuff about mics. Sound like I may have assumed too much about this mic being as good as the reviews say it is. Would you recommend another mic instead of this one for around $100.00? (I know it's a heckuva stretch finding anything worth snuff at that price, but I thought I'd ask anyway...)

For general recording? Apex 205, but I'd probably spend another $80 for a Lundahl transformer and toss out the stock transformer.

Just to be clear, the Trion is not a bad mic. For some sources, the dual ribbon can impart an interesting effect. IIRC, they get a lot of high praise on guitar cab, for example.

For mid-side work, though, you probably want something less colored, with no offset. I think Michael or Marik are probably about the only people who could say what's what in that regard.

 

[MichaelJoly]

...Just to be clear, the Trion is not a bad mic. For some sources, the dual ribbon can impart an interesting effect. IIRC, they get a lot of high praise on guitar cab, for example...

You know, that makes me think...it might be really interesting to intentionally tune the two ribbons to an interval, say a fifth apart and hear what that does for guitar cab recording. Mod the mic into special purpose "effect mic" in other words.