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Metric Halo LIO-8


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The new software will run on Windows (not sure which ones).

As far as the bus powering, I hadn't read that (and there's a million rumors out there so I'll just wait till the release).

Anyway, if you're doing serious recording, you don't want to be running off of bus power anyway (my ULN-2 just barely runs on bus power).

If you're doing "informal" recording, a hand held flash recorder is fine for most folks.


However you cut it, it's kind of a waste of time debating possible configurations of something that's "soon to be released" IMHO.

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  • 11 months later...

Picked up some nice info about using a Metric Halo unit for a phono preamp.

There was a discussion of this on the MIO mailing list and this email came from BJ (Metric Halo's designer).


So, the ULN-2 has 3 ways to get audio in analog:
1) Mic Input on XLR of the combo jack. This is 1.65k from each leg to ground (3.3k between the balanced legs)
2) Line Input on TRS of the combo jack. This is 100k from each leg to ground (200k between the balanced legs) with a DC path to ground.
3) Send Return. This is 100k from each leg to ground (200k between the balanced legs) AC coupled from the connector (no DC path to ground on the connector side).

1 + 2 have selectable gain.
3 does not.

The gain on path 2 is less than the gain on path 1 for the same gain setting. For large gains the difference is about -9.5 dB. For small gains, it is less.

What this means is that you can have a max gain of about 72-9.5 = 62.5 on the line input, with a 100k bridging impedance when you are running single ended.

This allows you to adjust the bridging impedance with a resistor between hot and ground. Adding an additional 100k in parallel will give you about 50k bridging impedance (which is probably fine, if you want exactly 47k then the parallel resistance needs to be 88.679k [or as close as you can get]).

Putting resistance in series with the input is not really what you want to do because you are adding a noise source to the high gain path.

So on the ULN-2 the best approach is to use the Line In with a bridging impedance to match what your cartridge wants to see, plus appropriate gain, plus the RIAA filter in the EQ. You can use the RCA to TS adapters for this purpose, or you can put TS connectors in place of the RCAs on the turntable leads.

You definitely need to short the turntable grounding lug to the chassis ground of the ULN-2.

For the ULN-8 and LIO-8 we have a factory mod available for the DI board that sets the input impedance and gain properly to use as a turntable input.

You can, of course just use an external phono stage and come in line level as well. That being said, we do have a bunch of feedback to the effect that using the ULN/DI input + the EQ as the phono stage is one of the best sounding configurations around; it is certainly substantially less expensive than any external phono stage that is in the same range of performance (if you already have the MIO, that is -- and maybe even if you don't)!

Hope this helps.

B.J. Buchalter
Metric Halo

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  • 1 year later...

I have the "lite" version of Foo and I use it everyday for all sorts of stuff related to mixing/mastering but I've never used it for room measurements.

I use FuzzMeasure for room/speaker measurements. I've actually been using the demo for years but I keep meaning to upgrade to the paid version.


Forgot to mention that I use Behringer ECM 8000 calibration mic with it. 

According to some folks, the QC of these mics is terrible these days. If I was going to buy one now, I'd consider one of these;


BTW, these are condenser microphones so whatever interface (or mic preamp) you use, you'll need 48V power for the mic.

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I don't see a way to load a file directly into Foo although I'm sure there's a way to add something to the Generator.

I'm not sure if there's an advantage to doing that as opposed to recording the file into a multitrack (as many tracks as you like) in Record Panel of the MIO Console or just playing it in iTunes through a couple of daw tracks to an output in the Mixer.

But, I'm certainly no expert when it comes to room measurements Marc. That's one of the reasons I like "all in one" solutions like FuzzMeasure.

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  • 1 month later...

Has anyone utilized these insert connections for anything?

"balanced analog inserts (S1, S2, R1, R2 jacks) which are post preamp but pre A/D.You can use the inserts to patch in analog processing between the preamp and the A/D converter.The send jack can also be used to send a mult of the input signal to another device while still using the A/D section of the ULN-2.This allows the ULN-2 to be used as an active mic splitter."

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  • 2 months later...

You probably could do that but if you're using a hardware eq, you'd just be using the ULN-2 for gain and/or digital conversion. In which case, why not just go from tonearm to your phono pre to the main inputs. 

XLR or TRS will depend on how much gain is needed.

I think that jp11801 has done a good bit of experimenting with this stuff and he has the RIAA eq settings too. I believe he was most happy with the digital eq over any of his analog phono pre's.

Give him a pm and see what he's tried.


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The disadvantage of the Send and Return inputs is the lack of control over levels.  They're designed for items like compressors that have a good bit of gain (+24db or more) and level controls. These are passive signal paths (no gain).

If that doesn't present a problem, you could use them. It just seems like extra complications (4 additional RCA to TRS adapters with possible load adjusting resistors). I know that doing that stuff would be child's play for you so it's up to you.

I would contact jp. He's been at this for a while.

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The main difference between the Monitor outputs and the Analog outputs is that the Monitor has a front panel level control and is paired with the headphone output. 

And the analog output has a front panel level meter and the levels are controlled digitally. 

The front panel Monitor pots aren't the greatest so the left/right balance isn't perfect until you get to 9 oclock or so.

There is no dithered digital volume control so when the Analog output is taken below 0dB, the signal is truncated.

The way I use the two;

My studio monitors are connected to the Monitor outputs. I change the levels constantly so having a physical pot is the only way to go. The signal is routed through the Monitor Control app. The powered monitors are guaranteed to be within 2dB of each other and they are actually about .7dB with their physical placement and room treatments. Monitor Control allows this difference to be set internally. My monitors work best when the input is -10dB so that is also done in the Monitor Control app.

The Monitor Control also allows me to create a second signal path. This path is for headphone listening so it doesn't need any compensation. I can switch to this path with a single button in the floating Monitor Control window.

Of course, any pot introduces some noise but for the most part, I'm mixing or producing music in my studio so the quality is so high that the tiny difference the pots make is insignificant.

The Analog outputs are always set at 0 dB. Those go to a pair of +4dB transformer inputs I added to my main stereo preamp in another room. 

These outputs seem to be the equivalent to the output of a DAC where it is expected to be seeing an analog pot (maybe that's why the call it the Analog Output?).

So, I can't say this is the way the designers meant these outputs to be used, but this is works for me.


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ok, yet another question.

So, I'd like to take advantage of the FuzzMeasure Automatic Correction feature. I have an extra mic-pre input I can use (analog input 2 via XLR). Where can I plug the other end of the cable to create a loopback? I'd rather not use the Analog output, as that's what I'm driving the right and left channels. Could I use the receive? If so, how can I assign a channel to that that can be selected by FuzzMeasure? I think there is some routing magic that needs to happen here.


Screen Shot 2016-11-12 at 2.12.33 PM.png

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You want to use the Same signal path that you'll be using to do your measurements with. The Send/Return i/o have a much shorter path so the time correction won't be the same as using either the left (channel 1) or right output that your speakers will be seeing.

You can only do one channel at a time so select either 01 or 02 for the playback channel.

Here's a good video for this.


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  • 2 years later...


Installed the 3D in the Amarra/LIO-8 I bought from Al a while back and I'm loving it.

So far the public beta software (pb8) still has some glitches but if you don't need the mixer/ console, you shouldn't have any issues.

Aside from the bugs left, they just need to finish the Windows version and the software will come out as a general release.

Sure is nice to be able to run down to Staples and pick up a cat6 cable (up to 200ft I believe) instead of fiddling with firewire!

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MH had said that the sonics would be improved on all upgrades but the older the unit, the more significant. 

In any case, the Console 5 software is 32 bit so anyone wanting to upgrade to Catalina will have to upgrade to 3D (at least for now).

BTW, I haven't tried it yet but I heard that the 3D Record Panel will track stereo?

I've been waiting for the General release before I dive into the new mixer/routing.

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