Easy and cheap way to limit volume from analog to audio interface

WarmJetGuitar

New member
Hey guys, its been a while.

Still run a Fostex G16C and DDA Q desk, mixing down to digital 2 track and still working nicely. However it has annoyed me for a while that I have to turn the desk way down low not to clip digital since our EMU 0404 doesn't have a pad.
I had a non-functional MCI working as a buffer for some time but had to sell it. When the MCI was in this function my mixes just sounded better, I suppose it was a mix of better gain staging where the DDA got to work a bit harder with needles on the master out dancing around 0 and probably also the transformers in the MCI.

My question is whether there's an easier and cheaper way to let the DDA work harder without getting digital clipping? Most cheap DI boxes only take jack in so that way I don't get balanced outputs and the good lord knows that if there's one thing a narrow track tape recorder running with NR off it's more noise. Any stand alone units that runs balanced in and out and only has a minus 10 DB pad?
Or even better a dirt cheap unit with some transformers?
Also been thinking about getting a dead A77 or similar but then again I dont get a balanced signal and there's a load of cables crossing each other. Really ruins my mojo putting a mix session to a halt to identify what causes the nasty humm/clicks :facepalm:
 
Hmm...that seems kind of odd to me.

I used to have a G16C until last year, though I had mot used it since maybe 2012(?) when I got my Otari MX-80.

Anyway...I never noticed a level problem running the analog audio to my converters.
That said...I didn't do it like you seem to be describing. I'm not quite sure of how you have your tracking signal flow...?

I used to track to the G16 (which is what I now do with my MX-80) and the console was a TASCAM M3700 console (which now I have a Trident 24 London)...but in either case, the console was purely for my cue mixes during tracking.
IOW...the sources went directly to the tape deck.
If/when for some reason I wanted to use the console for the pres or EQ or whatever....then the sources went to the console and then the tape deck.
The converters got/get their signals from the tape deck...never the console...so as long as I had my analog levels correct at the console, and more importantly at the tape deck....the dump from the tape deck to the converters was always a the perfect level range. Never a need to boost or turn down to prevent clipping.
Are you doing some sort of pre-mix from the tape deck, back through the console, and then to the converters?

The real point here...if you follow your analog gain staging, no matter the signal path, and shoot for acceptable, even somewhat "hot" analog levels...they should not be clipping the converters, IMO...(unless you're totally burying the VU meter needles).
At most, you might be hitting -10 to -6 dBFS at the converters, instead of the recommended -18 that represents 0 VU....but even if you are hitting -3...which is DAMN LOUD on the analog side, it would still be OK for the converters.

Crazy thought....are you maybe having a -10 vs +4 conflict between the analog and digital side?
I know the G16 is all -10...so can you describe in more detail what you are doing and how you have your signal flow and gain staging set up from the G16 to DDA to converters when you encounter this "too much level" problem?
 
That does seem strange, as long as you are going in the line input 1/4 trs on the emu, the level should be right. If you are going in XLR, you are feeding the mic preamps, which will be a problem.
 
If you are going in XLR, you are feeding the mic preamps, which will be a problem.

Good point.
I keep forgetting that most of the home-rec interfaces in use are the all-in-one types, most with those multi-use connectors on the I/Os...and they are not just straightforward converter boxes with line I/O. :)

Yeah...line level signal fed to a mic pre input will be pretty HOT! :D
So then it might be as simple as changing the interface I/O from pre to line....probably either a hard switch or more likely a soft switch in the interface console.
 
Yes. This is the problem I had when I got the MX80 originally - I fed the outputs from the deck into the XLR inputs on the mixing desk, but they all had a +5dB gain or something which could not be disabled.
I fixed the problem by getting 24 XLR->TRS adaptors. The line inputs on the Soundcraft were balanced anyway, so it Just Worked. If the XLR inputs have a gain boost, see whether the TRS can accept balanced inputs.
 
Yes. This is the problem I had when I got the MX80 originally - I fed the outputs from the deck into the XLR inputs on the mixing desk, but they all had a +5dB gain or something which could not be disabled.
I fixed the problem by getting 24 XLR->TRS adaptors. The line inputs on the Soundcraft were balanced anyway, so it Just Worked.

I'm sure you know that you have two level settings for the MX80 in the Inputs and Outputs.
It's on the main Audio Control PCB...there are internal switches that let you set the I/O at either +4 or -8 dBu.
You can use them for better I/O compatibility...though not sure why they went with -8 instead of -10.
 
I'm sure you know that you have two level settings for the MX80 in the Inputs and Outputs.
It's on the main Audio Control PCB...there are internal switches that let you set the I/O at either +4 or -8 dBu.
You can use them for better I/O compatibility...though not sure why they went with -8 instead of -10.

This is true. The inputs were already set to -8, which was good because I was interfacing with the TASCAM's -10 outputs, but the outputs on the 2" machine I intentionally set up for +4 to go into a balanced mixing desk. It wasn't until some time afterwards that I realised the XLR inputs were clipping early, and it took me a while after that to hit the manual and discover why. Switching to TRS was better all round, though - no unwanted bump in the input gain, and no risk of enabling phantom power and blowing up the audio cards on the recorder.
 
Switching to TRS was better all round, though - no unwanted bump in the input gain, and no risk of enabling phantom power and blowing up the audio cards on the recorder.

Huh..?

Not sure how XLR to TRS adapters lowered the input level on the console...? Were there some kind of built-in level pads in the cabling?

Also....not understanding how you would blow up the recorder audio cards by enabling phantom power on the console...?
Plus, if the recorder outputs are connected to the line inputs on the deck...how does the console phantom power even come into the picture?
 
Huh..?
Not sure how XLR to TRS adapters lowered the input level on the console...? Were there some kind of built-in level pads in the cabling?
Also....not understanding how you would blow up the recorder audio cards by enabling phantom power on the console...?
Plus, if the recorder outputs are connected to the line inputs on the deck...how does the console phantom power even come into the picture?

Well, we're digressing, because strictly speaking, the matter at hand is a quick fix for the OP, not a problem I solved two years ago. As Farview points out, going via XLR will often have a different signal path to the line input, even when the line input is balanced. My purpose in bringing this up was to point out that the line input may be balanced at a lower input level than the XLR, which would likely solve the OP's problem without too much hassle, or losing the balanced signal path which he wants to keep. 16 XLR->jack converters is going to cost far less than a pair of 8-way level converters. They're handy to have anyway, so it might be worth testing with one channel first before getting more.

That said, this is what happened with the Soundcraft desk. Looking up the block diagram, it's slightly different to what I was saying last night. The MFXi-20 has XLR inputs, line inputs and inserts. Originally I was running an MSR-24 which has -10 RCA outputs. Those I just plugged into the line inputs of the desk via the appropriate looms.
When I got the Otari I was suddenly faced with the prospect of balanced outputs at a professional level. I made a couple of mistakes in my eagerness to get the new deck operating ASAP, one of which was not realising that the MX80 could be set to accept unbalanced, -10 inputs and as I result I grabbed a trio of DI800 units which I was intending to use as a balancing converter/patchbay combo on the assumption that even Behringer couldn't mess up so simple a function. (They did, the DI800s are sitting boxed in the front room waiting for me to put them on ebay). Also the previous owner had set the machine up to -10 unbalanced I/O, so I left the inputs as -10 unbalanced and set the outputs to +4 balanced, which like the OP, I wanted to keep.

But this is a digression within a digression. The meat and bones of it is, this - the Soundcraft, like a lot of budget mixing desks, is apparently not designed with the expectation that you'll attach +4 balanced line signals to the XLR inputs. They are intended to accept condenser mics, and have a +48v phantom power line. Crucially, the preamp has a minimum gain of +5 which in my case was enough to make the desk clip if you looked at it funny. It cannot be set to unity without modification, and as mentioned, if you accidentally hit the phantom power button (which I removed the cap from to recess it) you will get 48v phantom power into the XLR-attached device.

The 1/4" line inputs have a different signal path. They are not parallel wired into the XLRs, they come later in the signal path, after a pair of blocking capacitors which stop the 48v phantom power getting to them. (I checked this with a multimeter). The other difference is that they go through a -15 pad before hitting the preamp, which in my case was enough to counteract the +5 bump which the preamp adds.

It seems likely to me that whatever the OP is plugging the XLRs into may have similar misfeatures, in which case going via the line input instead of XLR may solve their problems with less hassle and expense than adding a line converter.
 
Good point.
I keep forgetting that most of the home-rec interfaces in use are the all-in-one types, most with those multi-use connectors on the I/Os...and they are not just straightforward converter boxes with line I/O. :)

Yeah...line level signal fed to a mic pre input will be pretty HOT! :D
So then it might be as simple as changing the interface I/O from pre to line....probably either a hard switch or more likely a soft switch in the interface console.

That interface has the combo jack. The 1/4 is line level and the xlr is mic.
 
-8dBu is equivalent to -10dBV.

:eatpopcorn:

Yeah...gotta always check the nomenclature...dBu, dbm, dBV... :facepalm:
I was just so use to seeing +4 and -10 as the two options on most gear, that the -8 on the MX80 threw me....which I should have realized why, seeing how it plugged into -10 gear without any level change. :)


That interface has the combo jack. The 1/4 is line level and the xlr is mic.

OK...that explains it...so by simply using the XLR to TRS...it switched the input from Mic to Line.
Boy I hate the combi-plugs... :D ...and I constantly forget that most of the combi-interfaces use them, which is done for size and cost reasons, though I know some will at least give you both sets of plugs, so you can keep the different cables plugged in, and then you use a switch to move the signal from one to the other, internally.
 
Get two of these:

Little Labs

I have three of them just ahead of my converters. Most useful item I ever added to my transfer studio!

Little Labs makes great stuff...but I'm still not understanding why you would need any kind of attenuation device before the converters, unless your converters have no option for lowering input levels...?
 
It's easy to think the combo jacks are just two ways of getting in to the same signal path, but a lot of times it's two separate signal paths.
 
Little Labs makes great stuff...but I'm still not understanding why you would need any kind of attenuation device before the converters, unless your converters have no option for lowering input levels...?

Correct. My Lynx Aurora(n) converter has no input attenuation. Neither presumably does the OP's equipment, hence the thread.:)
 
Neither presumably does the OP's equipment, hence the thread.:)

Yeah...I got that, but again, to clip the digital input with an analog source...that's a VERY hot analog signal already, and that would (or should) have been a problem on the analog side before it ever got to the digital gear.
IOW, if you keep things even in "good" hot level range on analog gear...it should go straight to digital without clipping it.
I think some people are adding more gain at their interfaces, and causing the problem if their converters are clipping.

I've been moving audio from analog to digital devices (and not just preamps, but tape decks and consoles, etc) for a long time, and to date, I have NEVER clipped my converters once, even when I was running some pretty hot signals, especially coming off my tape deck.
Not saying you can't...but just that those kinds of analog levels wouldn't be the norm.

My converters have a soft console where I can lower either input or output levels, and by default they are set at max gain, 0dBFS....I can't recall ever having to lower them because the output from my analog gear was too hot.
 
Wow, thats a lot of interesting answers... thanks guys :-)
The Little Labs thing seems interesting but is quite pricey for what I'm looking for.

The multitrack is indeed -10 and the desk is +4 but there's no audible problems with gainstaging on the actual desk.
I do run really hot level on tape except sometimes vocals and of course for very transient stuff like shakers which definitely doesn't sound good with the tape saturating.

It's true that the TRS (jacks we call it here) are made for line level. But then I assume I can't run them balanced? But maybe it's not a problem, can keep them relatively short however avoiding them crossing power cables can be a bigger challenge.
 
But then I assume I can't run them balanced?

You are able to.
I've got a lots of TRS connectors in my studio...all running balanced....or XLR <--->TRS and balanced at both ends.

XLR is usually Pin 2 +, Pin 3 - and Pin 1 Ground.
TRS is would be Tip +, Ring - and Sleeve Ground.

That's balanced to balanced.
 
The whole point of TRS as opposed to TS is to facilitate balanced operation. XLR inputs on consoles are almost always microphone inputs. Line inputs for =4 operating level on the console are typically TRS quarter inch balanced. Now, outputs on many consoles from the stereo bus or main output were often XLR male due to tape recorder manufacturers who typically put XLR ins and outs on both their stereo and multitrack machines to signify their +4 operating level. They are not mic inputs and the outputs are not intended for mic ins on the console. So if your desk has XLR male as their L/R bus main out, you are just going to have to cut the end off of two mic cords and wire them to TRS jacks. Better yet, buy cables made for line level operation from someone reputable, mic cables these days are scandalously tiny gauge that last you at least a week, not ideal for your final cable to your mixing destination. Since all interfaces I have encountered observe a different protocol, XLR always mic level, line level usually balanced +4. (but not always) And of course as these combi-jacks are so prevalent now, it is hard to find any interface that has them where the line in signal bypasses the pre-amp, as they tend to be used as inputs from a variety of sources, keyboard outs, mixers that are tyically -10, guitar processors, etc. As for narrow gauge tape recorders with some kind of noise reduction, with the cost of tape doubled and tripled these days, why not just find someone who wants to fiddle but isn't trying to record music very often if at all, and get a couple of interfaces connected by light pipe. It will sound better, and will save you money in the long run. If you think digital conversion is voodoo, gain some understanding of your typical semi-pro NR on these units. As for consoles, I have a very nice English console, please someone offer me five per cent of what it cost new. Faders, knobs, all just pots waiting to start failing, and really no handier to use than a mouse. Add in instant and total recall, quieter operation, hardware emulation you could never afford if you are reading these forums. Free your mindset, the new and improved world of recording has closed the gap between the big boys and basement geniuses in waiting.....
 
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