advice on converters

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advice on converters

Postby kassonica » Thu Jul 28, 2005 2:49 pm

I'm running a small project studio using a Motu 828Mk 2 and a G4. I want to buy a nice converter so I don't have to sum in the daw. It would have to be firewire based so I could play the mix out of the motu feed it in to the converter then into my other G4. I'm using all balenced lines
Thanks in advance

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Postby Kris » Thu Jul 28, 2005 4:23 pm

I have a similar set up and am considering a second hand Apogee AD8000 with the ADAT output card. That way I can still use the MOTU but also gain 8 channels of Apogee via the MOTU's adat i/o.
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Postby chris p » Fri Jul 29, 2005 9:51 am

Hi there Kassonica, and welcome to the small studio subset of the TRM forum.

Firstly, a quick note to Kris - could I suggest instead the RME Fireface 800, which you could then use as your main firewire interface and clock source? Its a step up from the Motu, and probably about the price of (or cheaper than) an Apogee with an ADAT card (which will only run at 48kHz, remember, so the AD8000 is a bit overspecified as a simple 8 channel ADAT front end). Alternatively, you might go for the Frontier Design Tango 24, which is a simply 8 channel line to ADAT converter.

Back to Kass - By "sum", do you mean mixing multiple channels into one or more stereo pairs? If so, that's quite a different function to an AD/DA converter, although many converters (including the Motu) allow you to set up the various analog paths into a sort of mixer.

As I understand it, the summing boxes that are being hyped nowadays claim that digitial mixing in the DAW is too glassy, and so provide an analog box that really does the same thing using bits of wire rather than 1s and 0s. Its a sort of cutdown mixer without any line setting, gain, eq, etc, and is supposed to be a magical analog warmth solution for the alleged coldness of the digital world.

Rick wrote an excellent article on this phenononem in Audio Technology just a couple of issues ago - his conclusion (and forgive my paraphrase, Rick) is thats it a load of hype and little substance unless you are willing to sell your car to finance it. To be any good, the bus bar must have a large cross section (and therefore is highly susceptible to RFI) and run at high voltages, and neither is conducive to a 1U box.

From my own experience, I would add that I really don't see the problem with digital mixing per se. Its problem is that it is mixing sound that generally has been recorded without any tubes, transformers or transistors in the signal path, and then twisted through plug-ins of varying quality before being mixed with other similarly recorded channels. The key to more warmth in your mix is more likely to lie at the front end of your mix, in the mics and preamps, and in more judicious use of plug-ins.

Failing that, have a look at the Cranesong HEDD for adding analog warmth to a stereo mix. Or do what I do - get the client to pay for quality vintage analog mastering.
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Postby Adam Dempsey » Fri Jul 29, 2005 12:22 pm

Well put, Chris.
;)
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Postby Howard Jones » Fri Jul 29, 2005 12:24 pm

"As I understand it, the summing boxes that are being hyped nowadays claim that digital mixing in the DAW is too glassy, and so provide an analog box that really does the same thing using bits of wire rather than 1s and 0s. Its a sort of cutdown mixer without any line setting, gain, eq, etc, and is supposed to be a magical analog warmth solution for the alleged coldness of the digital world."

Here's my 2 bob's worth... people seem not to realise that you can't just add layer upon layer upon layer inside a DAW without evil effect. When mixing on an analogue console, you know that you have to pull all the faders up to around the same level, then trim them to suit the mix and use the VUs to keep an eye out that you aren't overloading. Some consoles will have an overload LED flashing at you if you go over.

Frequently these elements are missing in a DAW - they don't have the equivalent of a pair of VUs across the internal mix bus. Therefore, people just pile track upon track, leading to distortion. With a DAW, you kind of have to start backwards - you figure out what is the greatest volume you can get away with on the internal mix bus, then apportion a piece of that volume to each element in the mix. Just because it's digital and you can't see the overs, doesn't mean you aren't distorting the mix.

I think this is the cause of a lot of graininess and fuzz on mixes made inside workstations.
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Postby mfdu » Fri Jul 29, 2005 1:11 pm

howard - i couldn't agree more on the source of crispiness and graininess being due to overloading the digital summing. and the DAW encourages filling up any track with heaps of excess bling, only exacerbating the problem.
i run eight stems out of protools, through the tape returns on my console and then back in again as stereo. not a top-notch console, but it still makes a difference.
not only does it sound heaps more *real* than the same mix done *in the box*, but i also have a chance to play with outboard stomp boxes FX etc on the way through - makes me feel like i'm working!

$0.02

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Postby rick » Fri Jul 29, 2005 1:14 pm

"to be any good, the bus bar must have a large cross section (and therefore is highly susceptible to RFI) and run at high voltages, and neither is conducive to a 1U box."

not quite, in that article i was stated the historically best mix busses where big things and asking for rfi interference.

if you only have 8 chn and no bells or whistles a 1 unit box would work out fine - but nobody does this

the tubetech summing box i saw recently (2 units) had a big mix matrix and was followed by simple makeup amps ( tube) .
pity it cost as much as a car and isnt as useful.

in todays market my feeling is that converters are a hoax
save you money and buy something useful
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Postby kassonica » Fri Jul 29, 2005 2:48 pm

Hi all
Thanks for your advice.
What I want to do is take the main outs from the motu when I'm running a mix (usually at 48/24) and run it in to the other converter at 44/16 instead of bouncing/converting/ dithering in the box. Although DP 4.5 does this very well I would like the nice top end conversion. So I really only need a stereo converters.
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Postby Linear » Fri Jul 29, 2005 5:00 pm

Hi,

I still don't understand what you're trying to do, if you're trying to sum outside the box you'll need more than two channels. But anway.

My opinion has changed slightly in the past couple of weeks. I just finished recording an album for a band, we did 9 tracks on 2" 16 track and 1 on a DAW. The one on the DAW was mixed in the box too.

The difference is there, less bottom end, less sheen on the top. But it's quite marginal and not as much as I expected. And using less than 16 tracks I don't think it's really noticable.

I think the problem isn't digital summing, it's a combination of front end, and doing too much because you can in terms of compression and eq. Manipulating audio in a DAW really really messes with it, and turns a nice clean audio file into a noisy, muddy mess x 24. Like I've said before, unlike analog summing (summing discrete voltages), digital summing is summing numbers which leads to rounding and truncation = ugly.

I'll also be interested to see how much difference there is between summing on my existing console (ribbon cable buss/opamp summing/class AB/electronically balanced) vs the new console (buss bar/discrete transistor/transformer balanced/class a). my feeling is it will be less than i'm hoping.

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Postby Adam Dempsey » Fri Jul 29, 2005 6:57 pm

Sorry Mark, I can't answer your original question. But the main contributors to a cold, flat sound when mixing in DAWs: over-processing, cumulative truncation & lack of VU metering as per above discussion, but also often hidden DC filters. Even the classic $40k Sonic Solutions used to default to 20Hz - across all inputs with 16 bit rounding.
(edit) Actually, from memory, I think it was a 7Hz dc filter, but it was gentle enough to eat into the lowest octaves - definitely not something to pass your music through unnecessarily.
Last edited by Adam Dempsey on Mon Aug 01, 2005 3:15 pm, edited 2 times in total.
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Postby Howard Jones » Fri Jul 29, 2005 7:44 pm

"doing too much because you can in terms of compression and eq.... unlike analog summing, digital summing is summing numbers which leads to rounding and truncation"

Compression & EQ are part of the level problem I referred to previously. People add EQ or compress then normalise without apparently thinking about the fact that it is both easy & possible to overdrive levels inside a DAW*, with the only reference point being your ears. This is partly a generational issue - the first generation of users coming to DAWs are/were mesmerised by graphics displays and lessened their trust in what their ears were telling them. I think as younger users rise up through the ranks, they will get a better balance on this.

Truncation can be overstated. All digital devices use floating point math processing which is very adept at manipulating without too much truncation. Don't forget that, when recording to analogue tape, your truncation has already occurred (if you drive the record electronics heavily) by way of tape hysteris - such "analogue" truncation has been held to be more pleasing to the ear.

* Overloads in a DAW are likely to be audible if they occur for any length of time and the operator would react accordingly. Where a mix gets fuzzed is when overs occur for, say, 7 or 8 samples. This is pretty unlikely to be directly detected by the ear, but the overall effect is to take the edge off the sound.
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Postby chris p » Fri Jul 29, 2005 8:53 pm

OK Kassonica - I now know what you want to do, but its not "summing", which is what had us all confused. Its just reclocking and dithering. And I'm sorry, it won't give you that "high end sound".

Why? Well first and foremost, converters can only convert what they get in. The sound after high end conversion is not better than the sound going in - what you get is accuracy, not euphonics. What you can get in cheaper converters is clock jitter, which sounds like a little blurring of the stereo soundfield, sort of like the guitarist is jumping around a bit on stage rather than being at a highly definable spot. It matters to audiophiles, but I bet your band can't even hear it.

So a bad mix reclocked and dithered through the best converter in the world is still a bad mix. Similarly, a great mix through moderate converters like the Motu is still a great mix. Ask Rick - the magic of mixing is knowing when you've got a good arrangement well recorded, and then take your hands off the controls. Its not in high end converters.

I'd come back to my initial suggestions - look at upgrading your mics and preamps, and as others in the thread have said, look at your plug-ins and levels inside your DAW. Don't fret about the MOTU, its likely to be fine for what you're doing. Another hint - record at 44.1, 'cause then you don't have to reclock. Keep the 24 bit wordsize though, that's important for definition and decent DAW mixing. And give your mastering guy a data disk with the 44.1/24 files and let him/her worry about mortgaging their soul for the high end converters.
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Postby wez » Sat Jul 30, 2005 3:27 pm

good one chris, you've got it in one;-)
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Postby kassonica » Sat Jul 30, 2005 10:21 pm

Hi all

thanks for the advice I've learnt a lot.

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Postby heathen » Mon Aug 01, 2005 7:35 pm

I was using an 828 mk2 as the front end for my pc (for mixdown from my o2r's stereo out) so I could do digital routing from its virtual mixer in my pc to outboard gear such as comps and eq's back to the 828 analog ins,all I found was it muffled and distorted my sound,as I was doing to many ad/da conversions.It sounded ok but I just could'nt get my mixes to sound right in the low feqs and high freqs.My solution was get a real patch bay and some nice converters (apogee psx 100se) and just patch in the analog gear I use.Instantly a whole new world of sound opened up nice tops and accurate low's,now I only use the 828's toslinks to and from the apogee.I could'nt believe the difference,even my girlfriend noticed the diference immediately in an a/b comparison with the apogee and motu's ad conversion.I'll happilly never use the motu's analog ins again. 8)
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Postby heathen » Mon Aug 01, 2005 7:43 pm

Not trying to hassle motu was just emphasising the importance of good ad/da conversion to feed my analog signal chain and repesent it correctly when it comes to ad conversion again.Using nice analog gear with digital mixers and recorders are a combination I am very happy with,best of both worlds.
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Postby Chris H » Tue Aug 02, 2005 10:26 am

Hey heathen, try the MOTU's converters but using the apogee as the master clock. Let me know if you can still hear a difference between MOTU and Apogee converters. Also i have read that the apogee's analogue filtering rolls off the top end a smidge giving a nicer sound.
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Postby heathen » Tue Aug 02, 2005 11:34 am

I did notice a small difference clocking the motu to the apogee in recording to my pc through the motu's analog ins,but the difference was more prominent wnen recording through the apogee and playing back through the motu's main outs which sounds reasonably good.Using the motu I was never happy,I thought it was my mixing,I was spending hours just trying to get the tops and lows sounding smooth.Then I thought this is not right so started reading articles on converters and came to the conclusion that motu (828 anyway)suffers from the jitters. As soon as I mixed down one of the songs in through the apogee analog ins I instantly felt relief and was finally happy,as I said even my girlfriend noticed instantly in an ab comparison. The 828 mk2 is really a usefull tool in theory but is let down by its ad converters and clock I would say,if it had better converters it would be an essential tool in every studio I reckon.Also recently the drivers became a bit unstable and required a few re-installs of the software,which fixed it.All this was done at 44.1-24 bit.Also for fun I did record a few songs in at 88.2-24 bit,then src inside my computer which yeiled a better result on cd than straight 44.1 using only the motu.Most of the stuff I've read should be the reverse of what I just said in the last sentence but it did please my ears more,not nearly as much as the apogee at 44.1-24bit though (then dithered to 16 bit of course with powr3).
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Postby Chris H » Tue Aug 02, 2005 5:30 pm

Thanks for that. I'm just reaserching options for adding another converter to the 896 i have. My work in the school is not critical etc, as in mastering comercial releases but i'm critical and like to get the best option. I have been happy with the 896 when used with my outboard pre's ( i bring in my own collection of preamps for the important recordings for the school) and even the on board pre's for easy setup recordings with the powerbook. Im leaning towards getting a Fireface 800 as apple's Tiger softwarer will support multiple devices with Logic,supposedly. The safer option would be to continue with MOTU hardware as there are no problems in daisy chaining firewire devices and adding Adat optical hardware for the odd job where lots of tracks are needed. One issue is MOTU dont have a firewire 800 device and i'm hoping to hear on the grapevine that one is on the way. If the Fire face option is a viable way of expanding the set up i would rather use it for clocking as this seems an area they have the edge over MOTU. I won't be purchasing anything untill March 06 or there abouts so ive got time to try a few options etc.
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