Octatrack headroom, MKI vs MKII

Hi.

Could someone compare MKI and MKII headroom ?
Some people asked, and I’m also curious about it…

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About which headroom are you talking? Processing headroom internally before clipping or external “headroom” before the inputs themselves clip due to a too hot signal?

IMHO the internal processing uses the same headroom on both machines (-12dB).

BUT the MK2 can be fed with hotter signals into its inputs (before the A/D converter clips) and it produces hotter signals on its outputs (see specs in the manuals).

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mk2 louder

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That’s my take as well.

I had both simultaneously and MK2 is significant louder. When I was uskng my mk1 I had to turn down the volume of everything else to match its signal.

That’s the thing I’d like to hear about.

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I’ll rant a bit because I feel like this difference is under acknowledged. The difference in headroom is basically the only reason I switched to the MK2.

I’ve owned a MK1, then a MK2, then a MK1 again, and finally settled in the MK2 for good, though i no longer have a MK1 to provide you with objective comparison testing. I know it can seem subtle to some people, but the difference was night and day in terms of how the MK2 allows a much wider range of useful input signals. Because I almost exclusively use the OT for external input sampling/manipulation rather than internally stored samples, the headroom difference was a big deal. And I found this out empirically through experience, since i’m not the audiophile type and at first glance “increased input headroom” sounds like marketing copy describing real-world negligible circuit tweaks an audio interface company does to sell last years product to people who always buy the new thing.

The MK1 works perfectly if you are quite confident about the consistency of levels. But mostly I send the OT 4 signals from my modular (dropped down using line level output modules), and since i don’t compress much inside the modular there’s often a wild range of signals it spits out as I am improvising. With the MK1 I felt It was always a delicate dance to ensure to ensure I don’t overstep into nasty clipping territory, and sometimes this meant sort of ruining the dynamics of a buildup or making a creshendo sound gross.

I truly don’t think this matters for studio use, but I was about to start doing a few live shows/streams and focusing on gain staging during an improvisation was something I wanted to minimize. I view it mostly as a way to decrease stress i guess, which sounds odd but is totally worth it for me.

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I recently switched from MK1 to MK2, and I second this. The difference is substantial. On the MK1 I had to carefully gain stage the levels going into the inputs. On the MK2 I just need to make sure I’m not clipping, and it’s all good.

Would be interesting to see pictures of the mk1 and mk2 side by side, naked in HD. Wondering if there is a complete redesign of the input/output section (and ad/da ?) or just a simple IC upgrade . I’ve been upgrading alot of my unbalanced gear with THAT line receivers and drivers like the 1246/1646 chips, which is a great modern solution that provides a “transformer like” fully balanced/floating i/o. Don’t use much power either, chances are one wouldn’t have to upgrade the powersupply. That combo would, as far I understand, give -6dB(u) at entry/unbalancing end and +6dB(u) at output/balancing end. This is unity gain in total, but would let you run hotter inputs into the OT inputs before clipping theAD. And give a solid output stage that can drive about anything, and provide a fully balanced signal (no need for fancy cables when going into other transformer based floating inputs) that eliminates ground loops.

Steady on

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Why not jsut stick some of these (or a DiY equivalent) in a box and not have to modify your gear?

Not much more expensive, a lot less labor intensive, and no risk of damaging anything:

I wasn’t actually aware of these ICs, but now I’ll proably use some of these off-the-shelf boards to make a multichannel balancing/isolation box for a few pieces of old Roland gear that are especally prone to line noise and ground loops at some point, I’d been putting it off for a long time because of the cost of transformers.

I got a bunch of these made up, works great. Probably same circuit, it’s right out of the datasheet. Theres a version for the 1246 (input side) too on oshpark.

JLM Audio has a nice 8ch solution for both input and output called Palpigrade & Tardigrade using more off the shelf opamps that sounds great too

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Even better, thanks for the link! Looks like the same circuit, but I would rather build them myself and select my own parts (without the trouble of doing it all on vero).