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Thoughts on Three Pre-amp Scenarios? Recorders, Players & Tape Machines
Old 15th January 2018
  #1
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Thoughts on Three Pre-amp Scenarios?

I have a Samar VL373A stereo active ribbon. I used it last night on a Baroque orchestra, the first time I had used it in anger.

I used the preamps in my Sound Devices 788T and set them to 40dB of gain. No sound-check. After the end of the performance, I realized that I probably could have gotten away with another 10dB of gain and still been easily within my rule of peaking about -10. So the mic still needs a lot of gain on quiet sources.

What are the thoughts on where to get that gain. I could haul around one of my Grace m108 units. Tons of clean gain there. But that adds to my footprint in a number of ways. I could just reach for the extra gain on the 788T; great preamps yes, but +50dB and more might be getting up into the "tad bit more preamp noise" range, yes?

Or I could add FETHead P48 amps and get another 18dB of gain there. My experience with FETHeads is that they are quiet, but then, a pre-pre and the SD preamps? More noise than without?

Just a little puzzle. What do you guys think?

D.
Old 15th January 2018
  #2
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My ribbons (BBC bronze PGS circa 1953) require full bore gain (80dB ) for distant mic ing
Thus I don't use on public location, modern fig 8s so much easier and don't need my Sonosax mixer
They are excellent in close proximity with a little eq for air
Heavy ,fragile ,vulnerable to damage but still devices that conjure silk like smoothness from many course sources
I use my STC 4033a in front of Gtr amps now , its got battleship qualities, it was designed for 50s boom work and can take stick
Roger
Old 15th January 2018
  #3
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Cloudlifter?
Old 15th January 2018
  #4
RPC
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Doug's got the active version of the microphone, so the regular Cloudlifter is a non-starter. Frankly, I'd start with the 788T at 50dB gain. I'm using SAMAR VL37 (passive) with either a Metric Halo ULN-8 or Sound Devices Mixpre-6 and noise has not been an issue with either.
Old 15th January 2018
  #5
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Quote:
Originally Posted by RPC View Post
Frankly, I'd start with the 788T at 50dB gain.
Okay. I'll try that next time and listen. The man who cuts all these for broadcast edits digitally (natch) so levels sent to him are not, really, an issue. But I also burn CDs for client approval and they never like not being able to listen in their car on the way home ( ) so that is a bit of a problem with last night's recording. Not life threatening of course.

D.
Old 15th January 2018
  #6
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Doug, I know you’re well familiar with the AEA TRP, which of course wouldn’t work for your Samar because it cannot provide phantom power. However, if you still have yours, you can try my Neumann N248 to provide power, then run that into your TRP. Another option is the AEA RPQ which can provide the gain plus P48. I have one of those you could try as well.

A future option will be the Pueblo Audio Isleta, which will have 80db gain and phantom powering. Not sure when Scott is planning to release it, but we are keen on it for doing binaural in Cuba. So hopefully we’ll see it in the first half of the year.

ISLETA - Battery Preamp - Pueblo Audio
Old 15th January 2018
  #7
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What cars still have CD players? I’d have thought that most people would just want a little USB thumb drive. The only CD drives I have in the house now are in computers and just used for ripping to FLAC, WAV, AAC or whatever.

Quote:
Originally Posted by tourtelot View Post
But I also burn CDs for client approval and they never like not being able to listen in their car on the way home.

D.
Old 15th January 2018
  #8
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Doug - take a look at Mogaines. I have tried fetheads and cloudlifters and was not happy with either one. I currently use a mogaine with my Royer 121 and it is awesome. Otherwise you could consider changing the 788 for one of the new SD mixpre 10T units which have quite a bit of clean gain.
Old 15th January 2018
  #9
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Doug, I have a Mogaines, if you want to try it out. It’s a stereo unit. Pretty good, and much quieter than the Cloudlifter. Not as quiet or transparent as the AEA preamps, though. Mogaines have transformers, btw.

Quote:
Originally Posted by jnorman View Post
Doug - take a look at Mogaines. I have tried fetheads and cloudlifters and was not happy with either one. I currently use a mogaine with my Royer 121 and it is awesome. Otherwise you could consider changing the 788 for one of the new SD mixpre 10T units which have quite a bit of clean gain.
Old 15th January 2018
  #10
RPC
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Looking at the description, the Mogaine blocks phantom power. This would not work with an active ribbon. One could put a phantom supply ahead of it, of course, but now the collection of boxes is getting out of hand. Here's a thought for experimentation: take a Y cable from each side of the VL373A. Run one Y out into the 788T (to supply phantom and compare audio) and the other into the Mogaine which would feed another 788T input. You'd want to ensure the Mogaine would be happy with phantom power on its input before you tried it, though!
Old 15th January 2018
  #11
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Quote:
Originally Posted by bwanajim View Post
I’d have thought that most people would just want a little USB thumb drive.
Woulda thought so right? Can not seem to ween them off CDs. (Shrug)

D.
Old 15th January 2018
  #12
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May just be worth dragging the Grace along when I use the Samar (which, in fact, is pretty rare. I'm a condenser man, myself )

D.
Old 15th January 2018
  #13
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Quote:
Originally Posted by RPC View Post
Looking at the description, the Mogaine blocks phantom power. This would not work with an active ribbon. One could put a phantom supply ahead of it, of course, but now the collection of boxes is getting out of hand. Here's a thought for experimentation: take a Y cable from each side of the VL373A. Run one Y out into the 788T (to supply phantom and compare audio) and the other into the Mogaine which would feed another 788T input. You'd want to ensure the Mogaine would be happy with phantom power on its input before you tried it, though!
Or just get a Fethead Phantom, which passes phantom power with 18 dB of gain.

Last edited by jimjazzdad; 15th January 2018 at 11:44 PM..
Old 15th January 2018
  #14
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Also, I believe sandy (boojum) runs his 373a through his 788t and I haven’t heard him indicate any problem with inadequate gain or preamp noise. You might PM him and ask his experience.
Old 15th January 2018
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RPC - if you plague the 373a into Mogaines, wouldn’t it simply operate like a passive ribbon and use the gain supplied by the Mogaines?
Old 15th January 2018
  #16
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Oh yes, you’re right of course. Don’t know what I was thinking. Mogaines do block P48. My bad.

Quote:
Originally Posted by RPC View Post
Looking at the description, the Mogaine blocks phantom power. This would not work with an active ribbon. One could put a phantom supply ahead of it, of course, but now the collection of boxes is getting out of hand. Here's a thought for experimentation: take a Y cable from each side of the VL373A. Run one Y out into the 788T (to supply phantom and compare audio) and the other into the Mogaine which would feed another 788T input. You'd want to ensure the Mogaine would be happy with phantom power on its input before you tried it, though!
Old 15th January 2018
  #17
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Don’t think so, Jim...

Quote:
Originally Posted by jnorman View Post
RPC - if you plague the 373a into Mogaines, wouldn’t it simply operate like a passive ribbon and use the gain supplied by the Mogaines?
Old 15th January 2018
  #18
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Really, that new LiFe Pueblo preamp is going to be great for this application.

Last edited by bwanajim; 15th January 2018 at 11:47 PM..
Old 15th January 2018
  #19
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Chained preamps

I'll don my crashproof helmet here, but who has used the old trick of chaining two preamp channels in series to get massive gain with minimum noise?
Old 15th January 2018
  #20
Here's the thing. If your preamp is clean, what's the benefit of adding additional gain when you've got 120+dB S/N in your recorder? By all means add all the clean gain you want, but I wouldn't sweat the difference between peaking at -20 dBFS and -10 dBFS. I'd much rather have less gain that's clean than more gain and more noise.
Old 15th January 2018
  #21
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Originally Posted by TMetzinger View Post
Here's the thing. If your preamp is clean, what's the benefit of adding additional gain when you've got 120+dB S/N in your recorder? By all means add all the clean gain you want, but I wouldn't sweat the difference between peaking at -20 dBFS and -10 dBFS. I'd much rather have less gain that's clean than more gain and more noise.
Yeah, it's the dumb CDs that are my problem. I will see what I can crank the 788T digital output gain into the Masterlink. It's at +5 but may have up to go.

D.
Old 15th January 2018
  #22
Quote:
Originally Posted by tourtelot View Post
Yeah, it's the dumb CDs that are my problem. I will see what I can crank the 788T digital output gain into the Masterlink. It's at +5 but may have up to go.

D.
Gotcha. I hadn't caught on that you weren't doing post-production with a DAW.
Old 16th January 2018
  #23
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Originally Posted by tourtelot View Post
Yeah, it's the dumb CDs that are my problem. I will see what I can crank the 788T digital output gain into the Masterlink. It's at +5 but may have up to go.

D.
If you're going to bring a 'gain stage' into the equation, it seems like it ought to be just before the CD burner, and not necessarily at the mic stage ! Does the Masterlink have any Loudness Wars type brick wall levelling you can apply before burning the CD's...a preset perhaps buried in the owner manual ?

On a different matter (and I might have missed your posts on it), have you had a chance to audition that small fig 8 condensor mic from 9sbean yet, in a range of settings ? If so, would you be able to share your impressions in a new dedicated thread for the mic ?
Old 16th January 2018
  #24
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So I think there is a gain stage deep in the guts of the Masterlink, but I am usually making these CDs pretty much on the fly. Editing track flags and burning CD #1 during intermission. You all know how much stage crews like to stand around at wrap and can barelty even wait til we throw stuff in the cases, let alone burn CDs. But I will look into it.

Oh, and I think that there is more output in the AES send from the 788T. Kinda sorta looking at all the perceived possibilities.

I do have the B9Audio figure-of-eight condenser and I have put it up a couple of times. I don't know it well enough to use it as my main mic; even the quite expensive and well regarded Samar Stereo Ribbon took a while to make it into the rotation. My initial feeling it that it sounds good, much like the Schoeps which it unabashedly mimics, especially at the price point. I would really like some others listeners to try it out; those who don't have the mics in their locker that I have and almost always pull first.

To someone using Rode cards in XY, it might be a really nice experience to test the CSM88.

With Tony's explicit permission, I would be happy to send the mic off to other test subjects and would be curious to hear what others think. I know this sounds lame, but right now, I am just a bit busy to experiment (and that is a blessing, not a curse.)

D.
Old 16th January 2018
  #25
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Dont dismiss CDs please Doug
Apple has given up on them but they are an important carrier for classical music imho
Push the gain structure into the burner, if its for the car on the way home (what a weird conceit) its not fidelity anyhow, just signal
As for Sound Devices mic amps my 702 had enough gain for ribbons just ,but it was noisy compared to my Sonosax or Nagra, but they are passive ribbons not active.
Roger
Old 16th January 2018
  #26
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Quote:
Originally Posted by TMetzinger View Post
Gotcha. I hadn't caught on that you weren't doing post-production with a DAW.
Hi Tim-

We are doing post in a DAW (ProTools) but digital gain makes for no problem there. But on the "approval CDs," it does.

D.
Old 16th January 2018
  #27
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Quote:
Originally Posted by tourtelot View Post
I could just reach for the extra gain on the 788T; great preamps yes, but +50dB and more might be getting up into the "tad bit more preamp noise" range, yes?
Actually, no . . . it's very common for mic preamps to deliver their best EIN (equivalent input noise) performance at higher gain, and this was the case when I measured those on my 702T. This is because at higher gains, the preamp's feedback ladder usually reflects a lower source impedance back to the input stage, and reduces the effects of the thermal noise from the resistors that set the gain. The overwhelmingly dominant noise mechanism remains the relationship between the preamp's input transistors and the source impedance of the microphone.

If the levels are low enough on the metering, you'll start to see the noise floor of the converters come into play . . . and this is where products like the Cloudlifter may have a distinct advantage . . . that is, they can deliver similar EIN as the mic preamp, and raise the available gain so the converter's noise floor doesn't become an issue. But this mainly applies to situations where the preamp gain is maxed out and you still can't get good levels on the converter (or tape). With my 702T, the converter noise starts to become an issue with peak levels hitting in the range of -30dBFS.

So the take-away is that if you're able to get your levels in the -18 to -12dBFS range with the gain available in the SD's preamps, I can assure you from firsthand measured data that the dominant noise source will be the microphone's own source impedance. It's still possible that you may prefer the sound of other preamps when operating at high gains, as a preamp's distortion and bandwidth will also change as the gain is adjusted, and these are almost always poorer at the highest gain settings. But from a noise perspective . . . there's no need to worry.
Old 16th January 2018
  #28
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Could you just stick a compressor or something between the 788t and the Masterlink?

-Mike
Old 16th January 2018
  #29
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Quote:
Originally Posted by Klimermonk View Post
I'll don my crashproof helmet here, but who has used the old trick of chaining two preamp channels in series to get massive gain with minimum noise?
Rupert Neve.
Old 16th January 2018
  #30
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Plush's Avatar
Just bring out a high quality mic pre with big gain.

It can't weigh that much.

Don't make any compromise on your front end.
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