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So many interfaces, so little frequency response. Effects Pedals, Units & Accessories
Old 1st January 2011
  #1
Here for the gear
 

So many interfaces, so little frequency response.

I've been lurking this site for a while now, and have been awed by the caliber of posters here. I am amazed at the community this site has attracted and have refrained from posting so that my amateurish nature does not sully you all.

Alas I have no where else to turn too! Please help me, Gear Slutz, you're my only hope.

I've been looking at getting a new interface and have been patiently studying all of the various manuals (when available) for all of the competing solutions, trying to find the right one for me. I think I've pretty much narrowed it down, but was hoping to get your learned input to help fill in the blanks.

This is what I need and how I want to do it, the setup is Ableton Live on Windows 7 64-bit, with USB 2.0 and Firewire ins.

Outputs:
  • Monitors
  • Headphones (for both Cue or Master, and the ease with which I can switch between these is important)
  • Ableton's Send A (in Stereo)

Inputs:
  • Mic (XLR, phantom not required but would be nice)
  • Guitar
  • Korg Kaoss Pad 3 (back into Ableton from Send A)

This isn't an elaborate set-up, but there is one caveat that is a deal-breaker for most interfaces. I need a deep low-end response on the Headphone out. My muse tends towards some very dark-industrial directions and if I don't keep track of the low-end it will get out of hand in a hurry. I've got a pair of Mackie HR824s for monitors and KRK KNS-8400s headphones, both of which provide great faithful sounds. The KNS-8400s are rated all the way down to 5hz and up to 23khz. On most interfaces with a dedicated headphone jack the response is limited to 20-20.

I've got my eyes on the Focusrite Saffire Pro 24 and the Native Instruments Audio 8, but I'm open to any suggestions. The Saffire has a limited 20-20 response headphone out, so that is unfortunate, but the rest of the package sounds great. The Audio 8 has 10-40 on everything (including the headphones), but doesn't really have any instrument ins. It does have a phono input, so I'm wondering if I can use that for a guitar. The specifications on their website list the impedance on the phono as "To Be Announced" and I cannot locate the manual for this anywhere.

I'm leaning towards the Audio 8 for the huge response and because it is USB, and that would make it easier to use on my laptop. I don't actually do anything on my laptop, and have no immediate plans to, but I like the idea that I could.

I hope I've effectively communicated my needs and wants. Does anyone have experience with the Audio 8's phono jacks with instruments? Which will be easier for changing the routing on the headphones from master and cue? Am I making too big a deal out of the 20-20 vs 10-40 response? How does the Audio 8 manage to cram so many analog ins and outs through USB when all of the other USB interfaces seem to be limited? Have I brought shame upon you all with my ignorance?
Old 1st January 2011
  #2
Hey Byteblock, I don't have any experience with the interfaces you're looking at, but I can answer at least one of your questions.

Quote:
Originally Posted by Byteblock View Post
Am I making too big a deal out of the 20-20 vs 10-40 response?
Yup.
Old 1st January 2011
  #3
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enroper's Avatar
 

Couldnt you just use a monitor controller that has headphone outs, rather than using the dedicated headphone out?
Old 1st January 2011
  #4
Quote:
Originally Posted by Byteblock View Post
Have I brought shame upon you all with my ignorance?
Sorry for the double post here... No, not at all! You might already know that the human hearing range is restricted to 20Hz-20kHz, and my best guess is that most interface manufacturers, regardless of inconsistencies in their products, mark this as the frequency response of the unit just because that's all you'll hear. If someone wants to correct me, that's fine too, but I couldn't imagine so many pro audio products (microphones, interfaces, preamps) having a freq. response of exactly 20Hz-20kHz as is so widely advertised. In my experience, monitors and headphones themselves have the only noticeable influence on frequency response, as many nearfield speakers don't go below 40Hz or so.
Old 1st January 2011
  #5
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trondned's Avatar
 

Without having read the manuals of these products, I would strongly suspect that 40 vs. 20 kHz simply reflects wether or not the product is capable of samplerates up to 48 or 96 kHz.
Old 1st January 2011
  #6
Human sound perception covers a wide range. The very young may be able to perceive sounds as high as 23 kHz-25 kHz, while most adults hearing has degraded to the point where they top out in the 10 kH-16 kHz range or lower. At the bottom, most folks probably cease being able to recognize low frequencies as sound with musical content in the 15-30 Hz range. The lowest note on the biggest pipe organs is 16.4 Hz -- but it's likely that what most folks are hearing is harmonic overtones. The lowest note on a conventional grand piano is 27.5 Hz (that's an A; the lowest C is 32.7).

Synths, of course, are not constrained by 3D world physics and can produce signals far above or below the human hearing range.

As noted, precious few loudspeakers or headphones have accurate repro down to the bottom of the so-called nominal range (generally accepted as 20-20 kHz) -- including your Mackies, which start dropping off just below 40 Hz. Mackie - HR824


The problem of subsonics can be vexing, for sure. (And it's not all from synths, of course; it's not all that hard to end up with subsonic rumble that you can't hear on your 'phones or on your speakers that has been picked up by live mics from highways, machinery, earth moving gear, ground tampers, etc.)

Since few of us have the money (or room) for speakers that can repro down down to 20 or below, one way to keep an eye out for trouble down there is with spectral analysis, with either visual/graphic representation or simply numeric statistics.

As most of us who have wrestled with competitive loudness issues already know, because low frequencies require far more energy/power to reproduce, having low frequency content that doesn't add anything musically or that can't be heard by the intended play back systems 'wastes' power bandwidth that could be used to raise overall perceived loudness.
Old 1st January 2011
  #7
Here for the gear
 

Thanks a lot for all of your responses. My last hearing test was 14 years ago, so I'm not sure where my hearing is at now in my 30s. I believe it to be very good, and while I might not be able to make out tones or any useful information, I have come to rely on some kind of auditory sensation of the lower frequencies in keeping track of where all the energy is, in my mix. I play around a lot with soft-synths that, when not carefully tended, can end up peaking with subsonic low-end. Since they are soft-synths this peaking is problematic not only for the energy/power mentioned by Blue, but also with the limitation of plugins and their propensity to clip. My early en devours were all quite messy and muddy, reinforcing the importance of proper plugin management.

I will be the first to admit that my paranoia is probably erring on the side of irrational. I am an enthusiastic amateur, and sometimes a bit too much of both. I was fascinated to learn my beloved HR824s only go down to 40. Before I could type in "eBay" to find a matching Series 1 sub, I noticed that it too only goes down to 39. This is a lot to take in. I'll probably need some orange wedges and a good lie down.

In the meantime, could anyone elucidate the different impedances necessary for the "phono" and "instrument" line-ins? I know, for instance, that many interfaces offer a selectable switch for going between guitars and other line-in. Is that the same impedance necessary for phonographs or are the two wildly different and any attempts to plug a guitar into one would be warranty voiding foolishness?
Old 1st January 2011
  #8
Quote:
Originally Posted by Byteblock View Post
Thanks a lot for all of your responses. My last hearing test was 14 years ago, so I'm not sure where my hearing is at now in my 30s. I believe it to be very good, and while I might not be able to make out tones or any useful information, I have come to rely on some kind of auditory sensation of the lower frequencies in keeping track of where all the energy is, in my mix. I play around a lot with soft-synths that, when not carefully tended, can end up peaking with subsonic low-end. Since they are soft-synths this peaking is problematic not only for the energy/power mentioned by Blue, but also with the limitation of plugins and their propensity to clip. My early en devours were all quite messy and muddy, reinforcing the importance of proper plugin management.

I will be the first to admit that my paranoia is probably erring on the side of irrational. I am an enthusiastic amateur, and sometimes a bit too much of both. I was fascinated to learn my beloved HR824s only go down to 40. Before I could type in "eBay" to find a matching Series 1 sub, I noticed that it too only goes down to 39. This is a lot to take in. I'll probably need some orange wedges and a good lie down.

In the meantime, could anyone elucidate the different impedances necessary for the "phono" and "instrument" line-ins? I know, for instance, that many interfaces offer a selectable switch for going between guitars and other line-in. Is that the same impedance necessary for phonographs or are the two wildly different and any attempts to plug a guitar into one would be warranty voiding foolishness?
Ah... first, your Mackies are nearly flat to just below 40 (39 Hz, I think, it's in that spec link) and then taper off from there. So it's not like sounds below 40 suddenly disappear. And it's worth considering that specs like that put your Mackies in a quite small class of relatively affordable speakers that combine low bass extension with reasonably flat response. (Sure, you'll find sub woofers that claim -- and may deliver -- lower bass, but it's often likely to be far from flat -- and depending on the crossover system, may introduce other problems.)


With regard to phono, line, and mic level inputs, not only are we talking about different impedance levels, but in the case of a phono input (either on a dedicated phono preamp or the phono input stage of a combo amplifier), there is also the key factor of complementary EQ curves applied during record mastering and then then inverse applied during playback. Just to make things even more confusing, a number of different EQ curves were established for that purpose. In the US, the dominant phono EQ curve was finally established by the RIAA. Europe, the UK, and, I believe, Japan had other, competing 'standards.' (So, you'll often find the phono EQ curve standard used marked somewhere on many/most phonograph disks.) In the 'golden age' of hi fi, it was not at all uncommon to see component hi fi control preamps or combo preamp/power amps with a knob offering a number of 'competing' playback curves -- I have an old Williamson tube amp around somewhere that has, like, 6 different phono curves, a couple I'd never heard of back then.
Old 1st January 2011
  #9
Lives for gear
 

Two things...

The impedance and level is different between instrument, line, and phono inputs. Also, the phono input will normally have some special equalization to "undo" the special equalization used when recording to vinyl.

As far as getting "massive" lows out of your headphones, your best bet is probably going to be setting up a bus in your DAW, doing mondo EQ on it, then feeding it to an external headphone amp. There are some good headphone amps at reasonable (<$200) prices.
Old 1st January 2011
  #10
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Big_Bang's Avatar
 

bdenton, that is seriously bad advice as per OP

EQ'ing would be cool, say, for tracking a bass player or drummer so he gets the feel of what he is playing, but Byteblock need to get his sound right on phones, not the feel for it. Just like a mastering engineer would check the low end for consistency. EQ'ing would misrespresent the point entirely.

For that you need a good pair of reference headphones and a proper headphone amp. What is a proper headphone amp?

One that has the correct impedace match to the headphones! (and fair amount of gain)

If the impedance are mis-matched, the low freq content goes to mush and the hi freq get baked.
If you start EQ'in that to compensate, you steer completely away for any sort of translation.

So yes, impedance is also an issue for headphones if you use them for referencing.

Dont worry about warranties, impedace mis-match is not dangerous to gear (except for power amps to speaker, here be VERY careful!) Many pre's have a variable impedance knob so you can tweak the sound of microphones on the fly!

For guitars, if I am not mistaken here, single-coils are 250k, humbuckers around 500, and all the great classic amp have at least 1 Mohm input, to broaden the bandwidth and promote a proper bridging-law effect (technicalities...) - here is where 99% of people scratch their heads when their amp simulators dont sound the same as advertised. You need to buffer the signal before the interface as the vast majority of combo connectors and sub-par D.I.'s are way below this value, so all your tone and articulation is crapped out (Most interfaces suffer from this too!). There is a very easy trick to do override this. Just run the guitar into a Boss TU-2 and out to the interface and hear your guitar tone open up and sing!

For phono ins, just use a mixer with true phono in's and send the lines to the interface and dont think twice about it. Phono curves are for "decoding" the vinyl to the mixer. Just make sure it sound balanced to your ears. If you start obcessing over the curve differenes, wait until you get into power amp crossover phasing, tube harmonics, transformer distortion... you'll have a blast going nut over these issues as they WILL affect your vinyl sound WAY more that the phono curve used.

So... Welcome to Gearslutz !! May you obcess and lust over gear, go nuts, spend tons of money, and finally realize... in the end all that ever matters is how the music sounds.
Old 1st January 2011
  #11
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Do some frequency sweeps in the bottom few octaves and get a feel for where things drop off (or peak). Likely there will be response below the fall off but at lower levels. At some point you'll see the cone (cones? ..the Mackies have a passive on the back?) moving- but no longer sounding.
Proceed as needed with that -compensating as we all do with what we learn about our chain.

..I want to add, and unless your room if fantastic, for a real eye opener try it from about 300 or 400Hz down from different listening spots (as little as a foot or so different up there!)
Old 1st January 2011
  #12
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Big_Bang's Avatar
 

Oh, but getting back to the topic of freq-response... This is a can of worms.

Fourier theory (NOT the audio sampling theory, that is Nyquist-Shannon)...
Fletcher-Munson curves...

Humans hear sinewaves from 20-20k... that means the vast majority are within these limits as a general rule, for the general audio spectrum of life. It is what we percieve, which is VERY DIFFERENT from what we hear.

We also "hear" vibrations below this range, but we dont percieve them with the ear! But they DO influece you. Also the same to be said of freq's way above 20k.

So the Nyquist-Shannon theorem certainly DOES work and yes sampling at 96k does make a HUGE difference (especially acoustic material) but only if the entire chain can support the bandwidth, from mic to pre, interface, DA and speakers.
Old 1st January 2011
  #13
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Big_Bang's Avatar
 

Quote:
Originally Posted by Wayne View Post
..I want to add, and unless your room if fantastic, for a real eye opener try it from about 300 or 400Hz down from different listening spots (as little as a foot or so different up there!)
+1000000

That would be the Colombus-Egg Theorem LOL

Very true, room is always a prime culprit (unless referencing on phones of course...)
Old 1st January 2011
  #14
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Quote:
Originally Posted by Big_Bang View Post
+1000000

That would be the Colombus-Egg Theorem LOL

Very true, room is always a prime culprit (unless referencing on phones of course...)
'Colombus-Egg..? (I feel I'm missing out on some fun here..
Old 1st January 2011
  #15
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LOL dumb attempt of a joke... You do know the story of the egg of colombus right? Point being, everything is logical and simple, once you know how!

the learning curve you get once you actually work in a treated room.

You start hearing the "truth". Everything seems so logical, dialing in dynamics and eq's, mixes start sounding great outside the studio... you actually stop obcessing you need need need this or that to make your music sound pro. You get more more done in less time. Work is fun and less tiresome. The studio smells better, even if you fart. Like being in a womb.

Maaaaan I love studios! heh (especially mine, finishing off my very own first lol)

Oh, and happy new year! (I think I may still be slightly intoxicated from yesterday evening, had a huge blast!)
Old 3rd January 2011
  #16
Here for the gear
 

Quote:
Originally Posted by Wayne View Post
Do some frequency sweeps in the bottom few octaves and get a feel for where things drop off (or peak). Likely there will be response below the fall off but at lower levels. At some point you'll see the cone (cones? ..the Mackies have a passive on the back?) moving- but no longer sounding.
That was a brilliant idea, I can't believe I've never thought to try that before. I made a little Sine with adjustable pitch in Reaktor to play around with it. The results were damned impressive. I could "hear" down to 8hz, and the Mackie's went down to 4hz (I couldn't go lower than that with my little Reaktor gadget) with the cones vibrating.

Along the way I also discovered that a B-2 Sine is a frequency that, while not painful, makes my ears greatly appreciate any tone outside of that frequency. I spent the next hour with a wonderful new appreciation for every sound that was not that one.

Quote:
Originally Posted by Big_Bang View Post
We also "hear" vibrations below this range, but we dont percieve them with the ear! But they DO influece you. Also the same to be said of freq's way above 20k.

So the Nyquist-Shannon theorem certainly DOES work and yes sampling at 96k does make a HUGE difference (especially acoustic material) but only if the entire chain can support the bandwidth, from mic to pre, interface, DA and speakers.
This is something I learned very early on in my studies, and the reason for my paranoia. My production has always teetered on the brink between grim-dark-grime and beauty. Before getting those KRK KNS-8400s mixing and sound-design in headphones was out of the question because I couldn't keep track of the "dark energy" in my low-end.

This test with frequency sweeping has validated my belief that, while I cannot perceive tones down to 8hz, I can still hear something to let me know it's there and... critically... how much!

At the same time this test has also validated what you guys have been trying to tell me; in that I should ignore the manufacturer specs on response. My Mackies went down a factor of 10 lower than the spec.

Excellent work all around, guys!

Now my quandary is simply do I want a USB interface sans a proper guitar input, or a FireWire interface with limited compatibility. I think I'm leaning towards the USB, as I've read a lot of horror stories about FireWire in Windows 7 64-bit and frankly think it is going to obsolesce soon. With NAMM just around the corner, I'll be waiting to see if a more complete USB option becomes available. Thanks a lot, guys!
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