Old 07-18-2011, 06:14 PM   #1
boatbassguy
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Default DC Powered Quality Preamp?

Hi All !

I'm starting to think about the option of upgrading to a standalone preamp, up until now I've always used the ones in my interface.
The thing is, I run everything from 12v dc. I can easily bump this up as far as 24v and down to 3v.
So far I've managed to avoid running a 12v dc to 240v ac inverter (... and then bumping down from that.)

So.....

- Does anyone know of a decent mic pre that runs on dc between 3 and 24 volts?

Or preferably...

- Does anyone know if it's possible to modify any pre's such that they will accept dc? For all i know the first internal power stage may be to convert to dc! ...now wouldn't that be convenient.

Thanks in advance, mikey
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Old 07-18-2011, 06:37 PM   #2
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Originally Posted by boatbassguy View Post
Hi All !

I'm starting to think about the option of upgrading to a standalone preamp, up until now I've always used the ones in my interface.
The thing is, I run everything from 12v dc. I can easily bump this up as far as 24v and down to 3v.
So far I've managed to avoid running a 12v dc to 240v ac inverter (... and then bumping down from that.)

So.....

- Does anyone know of a decent mic pre that runs on dc between 3 and 24 volts?

Or preferably...

- Does anyone know if it's possible to modify any pre's such that they will accept dc? For all i know the first internal power stage may be to convert to dc! ...now wouldn't that be convenient.

Thanks in advance, mikey
Well here's some of the more affordable ones, the only ones I would know about. First, ART makes one, look up the ART dual USB, which also works as a standalone -- but I forgot, this runs on 9V. If that works for you. BTW, the USB function is only 44.1/16 and no ASIO support. But it comes with a free copy of Audacity! :-)

And a way of doing it on the cheap also is to get a battery-powered Shure mic mixer, like I use for work a lot, and use it just as a pre. Those also would probably be 9v powered, too. They will probably sound pretty good, in a sort of retro way. And both M-Audio and a couple cheaper brands make a battery powered pre, I think both called the DMP2. All 9v. Maybe get a transformer if you don't like using the batteries?

Cheers, frog

And PS, check out products form RDL. RDL makes stuff for permanent installations mostly, but almost everything they make runs on 24V and they make a couple nice looking portable dual pres, which I haven't tried myself but hope to sometime. And a lot of Shure mixers/pres that don't have battery power have a 30V DC in on the back. Like the M67, a really good old mono 4-mic mixer. You can pick up an M68 or an M268 for a song on ebay and I think they all have that 30V in - but verify and don't take my word for certain because I'm going by memory on that one. And of course we're looking at a mixer/preamp unit that's 20 years old and the predicted lifespan of some of its parts are 10 years or so. But that's some of the more affordable options out there.

But you probably don't want to go the cheap route. If it helps, this is info gleaned from the experience of one who's had to go the cheap route and work upwards from there. I've now got a Shure FP410 that runs on two 9V, if I want, which I usually don't. But it's great also.

Last edited by frog_jr; 07-18-2011 at 06:47 PM.
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Old 07-18-2011, 07:04 PM   #3
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Hey Frog,

Thanks for the reply man. I looked up all those units, and I really appreciate your time, however I'm looking to move up a notch in quality. Also I want to drive a ribbon mic so need more gain than those units offer. The exception being the M-Audio DMP, but that seems to run on 9v - AC - , so we're back to where we started.

Cheers.
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Old 07-18-2011, 07:16 PM   #4
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Hey Frog,

Thanks for the reply man. I looked up all those units, and I really appreciate your time, however I'm looking to move up a notch in quality. Also I want to drive a ribbon mic so need more gain than those units offer. The exception being the M-Audio DMP, but that seems to run on 9v - AC - , so we're back to where we started.

Cheers.
The DMP3 runs on AC. The DMP2 runs on DC. I think. And don't underestimate the quality of Shure mic mixers too fast. But yeah, that's mostly what I learned of stuff I could afford. And I don't need any better than broadcast quality for my work.

-- Correction. The DMP2 made by Pyle is battery powered and the M-Audio is AC, so you are correct, sir. And the Pyle is probably also not as high quality as you would want also. And any Shure mic mixer with a F prefixing its part # is a field mixer and will run on battery.

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Old 07-18-2011, 08:33 PM   #5
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Thanks all the same...
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Old 07-18-2011, 08:56 PM   #6
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http://rupertneve.com/products/portico-5032/
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Old 07-18-2011, 09:11 PM   #7
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Hmmm... Yes! So it is possible to make a truly excellent pre that runs on my kind of power.

You know if money was abundant for me that would do the job just fine I'm sure. I guess I'd always assumed that the truely high end stuff would run on mains AC. Not so!

That definately broadens my search, however I daresay not quite that broad!


Middle ground anyone?
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Old 07-18-2011, 10:44 PM   #8
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RME Quadmic will run off of any of those DC voltages from a transformer power supply or battery power. I just picked up a really great custom mic preamp from http://www.naiant.com/naiant/microphoneamplifiers.html and it is dc/battery powered. He is great to work with and the quality is top notch. There is an astonishing A/B test of one of his pre's against the Lunatech V3.

http://taperssection.com/index.php?topic=124895.45
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Old 07-19-2011, 01:18 AM   #9
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RME Quadmic will run off of any of those DC voltages from a transformer power supply or battery power. I just picked up a really great custom mic preamp from.....
Now we're talking!

These are both aimed at location work which is something that I have no experience with... are they in the same league as the studio gear?
I notice that both still top out at about 60db of gain. I've e.mailed Naiant to see if that can be upped a bit further.
Plush2, you own a Naiant pre? How is it? Are you able to compare it to anything else? Hows the noise level with the gain maxed out?

Thanks, interesting stuff.
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Old 07-19-2011, 11:19 AM   #10
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FMR RNP: http://www.fmraudio.com/rnpFeatures.htm

Quote:
Flexible power supply requirements
The RNP will run off of either AC or DC as long as the voltage range is within 9-12V (and has a current capacity of at least 1.5Amps). Polarity of the wallwart connection is unimportant so that you don't have to worry about that detail either.
Depending on your DIY facility, you might contact one of the kit manufacturers to see if they can meet your needs. I haven't used any of these guys, but they get a lot of thumbs up on various forums, and I think some of them offer built-up modules as well.

http://www.seventhcircleaudio.com/
http://www.fivefishstudios.com/
http://www.hamptone.com/

Fran
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Old 07-20-2011, 03:25 AM   #11
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Hey Fran,

The FMR RNP look like a serious contender. That's exactly the sort of thing I've been looking for. Do you happen to own one?
...and yeah, I'm pretty capable as far as making stuff goes. Mostly timber boats, musical instruments, and jewellery. I been reading a few DIY preamp sites and thinking this could be an option too.

Thanks man.


ps: I'm mid followup on a number of these leads and will post my findings for the value of the future forum searcher.

Last edited by boatbassguy; 07-20-2011 at 05:04 AM.
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Old 07-20-2011, 10:21 AM   #12
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Originally Posted by boatbassguy View Post
Hey Fran,

The FMR RNP look like a serious contender. That's exactly the sort of thing I've been looking for. Do you happen to own one?
...and yeah, I'm pretty capable as far as making stuff goes. Mostly timber boats, musical instruments, and jewellery. I been reading a few DIY preamp sites and thinking this could be an option too.

Thanks man.


ps: I'm mid followup on a number of these leads and will post my findings for the value of the future forum searcher.
I had an RNP back in the days when I believed what I read in internet recording forums. When the RNP came out it was widely hailed as the magic box of the week, an amazing technological accomplishment, the bare minimum of excellence needed to prevent home recording acrudditization at a bargain basement price.

Then I did some careful comparisons, level matched and same performance, double blinded evaluation, and learned that all preamps sound the same to me. So I sold the RNP and use the preamps on my interface.

** Edit - should have said "all the preamps I've tried sound the same to me" and even that is a slight exaggeration. I had a Presonus Somethingbox with preamps that were limited in their gain and noisy when cranked. I should always add the disclaimer that my opinion only holds for preamps designed for transparency and operated in their linear range.

Fran

Last edited by Fran Guidry; 07-20-2011 at 03:34 PM.
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Old 07-20-2011, 02:40 PM   #13
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Then I did some careful comparisons, level matched and same performance, double blinded evaluation, and learned that all preamps sound the same to me. So I sold the RNP and use the preamps on my interface.

Fran
HA! Yeah, that may well be the case for me too! I dunno yet. I've certainly heard a few A/B comparisons that people were glitzing over and thought, "Hmmm, yeah there's a slight difference - Maybe. I do know that my recorded sounds are different from reality in ways that I'm not always keen on.

Thanks for the info. I'm going to dip my toes in the water and listen carefully before swimming.
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Old 07-23-2011, 02:11 AM   #14
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Aerco MP2?

http://www.aerco.net/html/mp2specs.html
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Old 07-23-2011, 04:33 AM   #15
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Cool, thanks Cyrano.

I've been getting a few replies from follow up with some of these pre manufacturers. I've also been learning a bit about gain and noise and how what seems obvious isn't quite so straight forward. Testing the pre's that I do have at various gain settings then normalizing the tracks to get a realistic s/n comparison. My ribbon has arrived and apart from it's sound ( which I'm still very much discovering) it's need for more gain and subsequent noise makes these comparisons so much easier to make!

I will post findings here shortly!
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Old 08-05-2011, 08:57 PM   #16
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This is the follow up post....


I did get several replies from very nice people at Five Fish and Naiant and others. My plan was to post those replies for the future forum searchers.

However, I've spent a bit of time over on Fran's Homebrewed Music site, in particular with his ABX testing and Foobar and I feel the results of this will serve us all better....

I also spent a day with a mate in his studio with quite a selection of pre's to trial. We made a bunch of recordings with a matched pair of mics.

When I knew what I was listening to, I was pretty sure there was a subtle but noticable difference. When I go blind I managed to repeatably pick the difference so infrequently as to be laughable.

Fran, if you read this: Thankyou my friend - for your website, for setting me on the straight and narrow and for saving me some money! I tried to post on your site but it won't let me - some kind of area or locality error. (I can go get the exact words if you like.)


Until I'm clearly shown otherwise, I'm sticking with the pre's in my Focusrite 18i6.

Thanks everyone, Mikey
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Old 08-08-2011, 10:01 AM   #17
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This is the follow up post....


I did get several replies from very nice people at Five Fish and Naiant and others. My plan was to post those replies for the future forum searchers.

However, I've spent a bit of time over on Fran's Homebrewed Music site, in particular with his ABX testing and Foobar and I feel the results of this will serve us all better....

I also spent a day with a mate in his studio with quite a selection of pre's to trial. We made a bunch of recordings with a matched pair of mics.

When I knew what I was listening to, I was pretty sure there was a subtle but noticable difference. When I go blind I managed to repeatably pick the difference so infrequently as to be laughable.

Fran, if you read this: Thankyou my friend - for your website, for setting me on the straight and narrow and for saving me some money! I tried to post on your site but it won't let me - some kind of area or locality error. (I can go get the exact words if you like.)


Until I'm clearly shown otherwise, I'm sticking with the pre's in my Focusrite 18i6.

Thanks everyone, Mikey
Wow, Mikey, thanks for following up on this.

There are scientists who spend a lot of time and energy figuring out the limits of the human sensory system. They have a pretty good handle on what we can hear and what we can't. And there are definite limits to our ability to detect noise, distortion, and frequency response issues. Once a piece of gear surpasses those limits, it becomes transparent - has no sound of its own that we can detect. And while it was once difficult and expensive to achieve transparency, that is no longer the case.

There really are differences between high end gear and prosumer mid range stuff, but they're not audible differences. There are higher quality pots with big knobs that are easy to adjust precisely, better quality connectors that last longer and work more easily, jacks fastened to the chassis rather than the printed circuit board. Lots of cool useful touches that make a difference if you record for a living and want stuff that lasts a long time and maximizes your efficiency. But a preamp that has a sound is either broken or being used as an effects device.

Fran
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