Preamp for a single XLR measurement mic

[john61ct]

The P48V supply, presumably a voltage doubler affair, isn't particularly hard to overload and drop out of regulation, though it took multiple mics if memory serves.

Another advantage of going bigger for the same price ;-)

I don't think I'll go for the 60mm faders though, gets a bit too unwieldy for my taste.

TBH I REALLY would prefer a small standalone preamp-only for portability and DC-powered, maybe even from a USB powerpak. But thin on the ground, quality ones are hundred$, I guess portable recorders also get built-ins.

...

I also looked at Allen & Heath GSPre ZEDi series, hybrid mixer / interface but concluded the Mackie Onyx path suited measurement usage better, AND better routing option. In case I do ever want to use it as a mixer.

...

Any chance you know:

> Rolls is decent quality?

> Rodyweil RO-04 and Polsen MP60 ?

anyone else?

 

[john61ct]

Thanks for such a detailed response BTW

The bar graph level display is on the output, so if you turned down the main mix substantially for a good match of internal levels to an onboard chip that can take little over 1 Vrms, the indication won't go very high. (The mixer can take +16 dBu without breaking a sweat, so you need roughly -12 dB of output gain in such a case.) There are extra clipping LEDs at the 1/2 level pots to gauge internal level.

even if this is not part of the preamp-only use case. In case I do ever want to use it as a mixer 8-D

> I would not be surprised if the preamps themselves were capable of excellent performance

That seems very clear, and I do agree no need to output hot, the interface TRS inputs impedance is 10kΩ and can be set for -10dBV (consumer) level

which since the direct "channel insert" Sends are SE will likely be best. Max V peak kept well under +6 dBV, I figure ~2.0Vrms will be plenty

Personally I don't think this setup should even be compared to Behringer though. Even if that grade were "good enough" - I am striving here for champagne relative to my beer budget.

 

[Everett T]

I plan to use an Echo Audiofire 12 for REW and other measurement / filter design tools.

It is I/O only, includes neither HPamp nor mic preamps.

I have UMIK-2 but have decided to also get a calibrated XLR mic in order for both the signal output and the measurement precisely clock-sync'd by the one interface.

I have been looking at both standalone single-channel preamps with 48V phantim power

and separate portable mixer / interfaces that include one or more mic preamps

I believe the latter are better value, given they are multi-function.

Note that this latter will NOT be involved (as an interface to the PC) in the measurement / convolver process, only analog connection

mic --> preamp --> Audiofire12

Mackie VLZ series mixers include highly rated Onyx preamps, specifically 402-VLZ4 (402VLZ4) has two and available at affordable prices.

So, not only feedback wanted on any of the above, but suggestions on "better value" units, including singleton standalone units.

portability and DC-powered, even from a USB powerpak would be a plus.

Rolls is decent quality?

Rodyweil RO-04 and Polsen MP60 came up on the google...

You still have a firewire card for the Echo? I have Mackie 12ch portable mixer that has been dependable and the mic preamps are decent, especially for the price. They aren't the same quality as the desktop PreSonus but wouldn't expect them to be at the $2900 price difference.

 

[Keith_W]

1. Your Echo Audiofire 12 only has analog inputs. None of these analog inputs have 48V Phantom Power. There are NO digital inputs.
2. For it to record the output of a microphone, you will need a mic preamp, as you have correctly deduced.
3. If you use an interface, the mic signal will undergo an ADC->DAC stage in the mic preamp, and a further ADC stage in your Echo Audiofire.

You DO NOT NEED another interface. All you need is an analog mic preamp with 48V. Google the term "analog mic preamp with 48V" and you will find something like this. All yours for $32.50. I can't vouch for the quality of that unit, some ultra-cheap equipment may have weird noise issues. But it's cheap enough to be worth a punt.

Ultimately I think it's better if you had bought what you needed in the first place - a multichannel interface WITH a mic input built-in.

 

[john61ct]

1. Your Echo Audiofire 12 only has analog inputs. None of these analog inputs have 48V Phantom Power. There are NO digital inputs.

Well other than the Firewire LOL

edit: and MIDI but then I dunno what I'd use it for.

But yes, I have to keep pointing that out to people

from the OP > it is I/O only, includes neither HPamp nor mic preamps.

I didn't realize that this aspect was so rare! I guess that's why they are so cheap, I've averaged well under $5 per TRS port so far including shipping.

> 3. If you use an interface, the mic signal will undergo an ADC->DAC stage in the mic preamp, and a further ADC stage in your Echo Audiofire

I am not "using" another interface, making sure whatever box contains the preamps, lets me go out direct, very cleanly bypassing all other circuitry.

> https://www.amazon.com.au/Microphone-Preamplifier-Booster-Condenser-Microphones/dp/B0F6LTK5S3

Eww. The Mackie Onyx built-into-a-VLZ4 path I so far like best is head-and-shoulders better performing in many ways. I know measurement doesn't "need" top notch SQ, but then I don't mind overkill in that department, certainly doesn't hurt if it actually costs less!

And **it does costs less** per-preamp.

And then I've got a great 12-channel mixer for free.

In case I do ever want to use it as a mixer. ;-)

Champagne on a beer budget, so far so good...


> Ultimately I think it's better if you had bought what you needed in the first place - a multichannel interface WITH a mic input built-in.

48 channels of super clean SQ I/O costing less than one family dinner - I'm all ears?

EDIT: sorry if you perceive my tone as argumentative or snarky, trying to keep it light is all. I am VERY sincerely and deeply grateful for your so generous sharing of your expertise, and am fully mindful of my noobie grasshopper state. So, thank you for taking the time...

 

[john61ct]

You still have a firewire card for the Echo?

Haven't even started the PC build, but I'm an IT veteran, came up when Linux first emerged, network "engineer" and server admin so looking forward to wrassling chipsets and drivers again (not). Might even need to go Mac yuck, apparently late 2009 to mid-2010 is optimal.

we'll see.

 

[john61ct]

Yes there are a few 1202VLZ4 out there seem very clean proven working, could likely score for not much over $120 delivered plus $10 tax

I have Mackie 12ch portable mixer that has been dependable and the mic preamps are decent, especially for the price. They aren't the same quality as the desktop PreSonus but wouldn't expect them to be at the $2900 price difference.

 

[john61ct]

This looks like a great option especially buying direct so the bundle getting calibrated together.

Besides it being a little more costly especially with that shipping and then ?unknown? tariffs

I think the so-far-leading Mackie contender just delivers a lot more multi-functional value even if I never use it as a mixer.

Finally max PP at 24V again may never be needed, but I prefer the full standard 48V.

That battery powered portability tho!!

This shop offers calibrated measurement microphones and a matching MPA-102 microphone preamplifier, which can also be calibrated as a set.
However, you can also buy the IMG Stageline MPA-102 individually everywhere.
https://shop.hifi-selbstbau.de/produkt/messtechnik-pack-mm-1c/
https://shop.hifi-selbstbau.de/produkt/messmikrofon-mm-1c/
https://www.thomann.de/de/img_stageline_mpa_102.htm

 

[Keith_W]

48 channels of super clean SQ I/O costing less than one family dinner - I'm all ears?

Depends on how large your family is and whether they insist on oysters, lobsters, and steak every night

You might want to check in the Acourate forum with Uli before you buy any hardware. Here is someone else struggling with non-standard hardware.

Computer audio is already difficult. You have to use multiple programs and hardware devices and connect them all together. IT BREAKS OFTEN. Sometimes it's a setting on your interface, sometimes it's something really weird. For e.g. my uBACCH VST has stopped working for a few months now. I can't be bothered trying to diagnose what went wrong and fix it. I just bypass it and that's that. You really do not want to make it more complicated than it needs to be. It's not so much a question of whether it works or not, I am sure you can get it to work. But when something goes wrong, it makes diagnosis so much more difficult.

 

[Roland68]

This looks like a great option especially buying direct so the bundle getting calibrated together.

Besides it being a little more costly especially with that shipping and then ?unknown? tariffs

I think the so-far-leading Mackie contender just delivers a lot more multi-functional value even if I never use it as a mixer.

Finally max PP at 24V again may never be needed, but I prefer the full standard 48V.

That battery powered portability tho!!

As I mentioned before, with standard measurement microphones that have permanently polarized condenser capsules, it doesn't matter whether you operate them at 12, 24, or 48 volts; you gain no advantage at 48 volts.
You only need these for normal microphones with non-permanently polarized capsules.

I didn't see where you live, but you should Google whether there's a company in your country that calibrates and sells measurement microphones. In Germany/the EU, that's just one of several options.

 

[john61ct]

Depends on how large your family is and whether they insist on oysters, lobsters, and steak every night

2x 24-port interfaces for $100 each, wouldn't buy much steak lobster around here...


> Computer audio is already difficult.

Yes, TBH if I can stick to analog only after the preamp I will. But IF it turns out I do need DSP, I'll want it for all channels, and simply cannot pay those prices for proprietary hardware.

I've always been willing to suffer for a more "open" approach anyway, so even if I had an extra grand I'd rather upgrade my speakers or give some to John Mulcahy or Uli.

The PC side complexity is within my comfort zone, far more than the audio DSP stuff. I might even go gor a TB3 external conversion rather than putting a firewire card into the host itself.


>You might want to check in the Acourate forum with Uli before you buy any hardware.

The issues in that thread are exactly why I'm pursuing a simplistic interface based on ASIO.

 

[john61ct]

As I mentioned before, with standard measurement microphones that have permanently polarized condenser capsules, it doesn't matter whether you operate them at 12, 24, or 48 volts; you gain no advantage at 48 volts.
You only need these for normal microphones with non-permanently polarized capsules.

Yes, got that, but I want full 48V PP as I may need the preamps for different uses in future - buy once cry once.


> I didn't see where you live, but you should Google whether there's a company in your country that calibrates and sells measurement microphones. In Germany/the EU, that's just one of several options.

ASR Acourate users

Cross Spectrum Labs "Premium calibrated" Dayton EMM-6 looks a good value. https://www.cross-spectrum.com/measurement/calibrated_dayton.html

www.audiosciencereview.com

 

[levimax]

buy once cry once.

Have you purchased the new MIC yet? If not you may want to consider getting a "good one" that will last you a lifetime. Interfaces will come and go but a good MIC can be forever. I was looking to upgrade from a UMIK-1 and several of my choices were not available and I was feeling a little flush and ended up buying a Earthworks M23. While more expensive than other options the money does not just go into beautiful craftsmanship and workmanship, the MICs are also low noise, low distortion, high overload, and for me the best thing is they do not need a calibration file (they come with a calibration file for super fine work but for most work they are guaranteed to be accurate without a calibration file). Not having to mess with a calibration file is just one less thing to worry about especially if you are using different software, the low distortion and high overload margins also come in very handy. Tools don't make the craftsman but they can help.

 

[Esprit]

1. Your Echo Audiofire 12 only has analog inputs. None of these analog inputs have 48V Phantom Power. There are NO digital inputs.

Are you sure it doesn't have powered mic inputs? I have an Echo4 in a drawer and it looks like it does.

P.S. It also has a digital input.

P.P.S. I checked online and there are no powered microphone inputs on the AF12, how strange.

Echo Audiofire 4

If you have a compact setup, you might need a compact audio and MIDI interface. Is Echo's Audiofire 4 just the thing for the spatially challenged studio?

www.soundonsound.com

 

[Roland68]

Are you sure it doesn't have powered mic inputs? I have an Echo4 in a drawer and it looks like it does.

P.S. It also has a digital input.

P.P.S. I checked online and there are no powered microphone inputs on the AF12, how strange.

Echo Audiofire 4

If you have a compact setup, you might need a compact audio and MIDI interface. Is Echo's Audiofire 4 just the thing for the spatially challenged studio?

www.soundonsound.com

View attachment 519173

The Echo Audiofire 12 is a completely different device.
It only has analog line inputs and outputs, MIDI, word clock, and FireWire. No microphone inputs, no phantom power.

 

[olds1959special]

Don’t use a transformer-coupled preamp.

 

[Keith_W]

for me the best thing is they do not need a calibration file (they come with a calibration file for super fine work but for most work they are guaranteed to be accurate without a calibration file).

Here is a comparison of the calibration file of an Earthworks M30 (in red) vs. a Behringer ECM8000 (green). Note the vertical scale of +/- 2dB.

To obtain the Earthworks cal file: go to the Earthworks website, enter the serial number of the mic, and you will get the cal file. For the Behringer ECM8000: go to the website and download a generic file (applies to ALL ECM8000's, not just yours!!!). To be fair, we are comparing a AUD$80 microphone vs. one which is 15x the price. You could send the ECM8000 to a professional calibrator and still save hundreds of $$$, so the question really becomes: are there any advantages to spending so much money on an Earthworks?

For one, look at that severe roll-off above 10kHz for the ECM8000. And not shown in the graph is the difference in sensitivity, I need to increase the gain on my preamp by about 10dB with the ECM8000.

And here are three measurements of my tweeter with 3 different microphones - a Dayton UMM-6 USB mic with no calibration file (that's why it looks wonky!), my Earthworks M30 with individual calibration file, and a Behringer ECM8000 with generic calibration file. Both XLR mics are straight out of the interface with no adjustment in gain.

 

[Rja4000]

Hi
I've been using a first generation Mackie 1402 VLZ as pure preamp at some point.
The trick for best performance is to isolate the mic preamp from the other mixer circuits by using the insert out to feed your interface's line inputs.
You have to insert your 1/4" plug half way in the "insert" to achieve that- this is described in the manual - and you get an unbalanced output.

That method makes a significant difference in noise.

But the insert I/O is only available from the model 802 (and above).

To get better performing preamp will cost you some money.

RME has a 4 channels microphone preamp (Quadmic II) that could run on 12V batteries - something I do with a Power Delivery powerbank and a cheap PD-to-12VDC cable nowadays.

If a rack mounted device works for you, then explore second hand market - and measure before buying.

E1DA also proposes a purely analog APU that may be used as pure fixed-gain mono preamp with 48V phantom power available. Quality is excellent, but you'll have to have enough with a fixed gain.

I use a Millennia HV-3C as reference analog preamp nowadays - a high performance but expensive option.
Looking at the specs only, I'd also have a look at Cranborne audio Camden if I needed a replacement today.

To be fair, good interfaces' preamp tend to be as good as separates nowadays: as examples, my RME 12Mic-D or a last generation RME UFX are excellent.

Other than that, Topping Pro has a few cheap interfaces with truely excellent mic preamp.
But, again, those are full interfaces...

 

[AudioJester]

Have not tried it before, but looked at this previously when I was finding a solution

SWAMP Microphone 48V Phantom Power Supply

Get the best performance from your mic with SWAMP's 48V Phantom Power supply for XLR microphones. Includes 18V AC power supply.

www.swamp.net.au

 

[john61ct]

Don’t use a transformer-coupled preamp.

None of those mentioned appear to be