Ng Oon-Ee wrote: Warning: The Transit is a completely different model. If I remember correctly, the Fast Track Pro is not supported at all. That patch is in the kernel. HTH Clemens

Hi, I'm not sure I understand correctly the question... As for 'noise floor' much for example depends on the input signal, environment etc. or are you talking about the intrinsic 'noisiness' of pre-amps on the cited devices?. Maybe if you explain the situation/setup one could have a clearer picture. Anyway, because the SM57 is a dynamic microphone you should be ok with virtually any decent mic preamp: at an extreme limit you could probably even plug it into your computer's "mic in" (but then of course might as well use a 10$ skype microphone or something :) ). Lorenzo.

On Thu, Nov 26, 2009 at 05:55:17PM +0800, Ng Oon-Ee wrote: 40 dB is on the low side, and will produce low levels for some instruments, but more gain would not improve the S/N ratio at all (*). To get a good level you can as well use 'digital gain'. (*) except if the preamp is really very badly designed. Ciao, -- FA Io lo dico sempre: l'Italia è troppo stretta e lunga.

On Fri, 2010-01-08 at 07:46 +0800, Ng Oon-Ee wrote: I was thinking about getting one of those interface just to use Pianoteq with a laptop. Primarily for it's OUTS. I am not familiar with Roland as an interface manufacturer, though. I need it to sound good. Rich...

On Thu, Nov 26, 2009 at 05:07:16PM +0800, Ng Oon-Ee wrote: The question to ask is not how much gain would be required. All these interfaces will provide enough gain to the point that increasing it will not improve S/N ratio. The important question is then: how much noise do we have in those conditions ? Two values are important for this : the self noise of the mic, and the equivalent input noise of the preamp. For the SM57 the self noise is easy to find: Sensitivity = 1.9 mV/Pa or -54 dBV/Pa The reference sound level is -94 dBPa, so the mic will produce -148 dBV at that level. The SM57 is a passive microphone, so its self noise is determined by its impedance which is 310 ohm. This will produce a noise voltage of around -130 dBV in the audio range. Comparing these two numbers, the result is that the mic will produce the equivalent of around 18 dB of acoustic noise. For example if you record a sound of 78 dB SPL, the S/N ratio will be 60 dB. This is a typical figure for a mic of this type, which is not really designed for low-noise use such as recording classical music or soft instruments. It's used mainly for solist voice, amplified instruments and drums. The best low-noise mics would be some 10 dB lower. The second parameter, equivalent input noise, is the noise of a preamp, measured in some operational condition, and assuming all that noise is generated by adding it at the input. For a good preamp this will be very close to reality. It will have the best EIN at max gain, and this level will remain almost constant over a large gain range. None of the four manufacturers provide this information, nor any other data from which it could be computed. This is no coincidence: for most 'consumer' type preamps the EIN is not very good, and manufacturers want to avoid that you compare their performance to the competition. For my Edirol UA-5 I just measured it. For a source (mic) impedance of 150 ohm it is around -120 dBV, at 310 ohm it would probably be around -117 dBV. Now if you compare this to the self noise of the mic, -130 dBV, the conclusion is that the preamp will produce 13 dB more noise than the mic. Not very good, but quite typical for any product in this price range. Combining all this, using the SM57 with the Edirol UA-5 would produce a noise level that is equivalent to 31 dB of acoustic noise. This is, in the end, the only figure that matters, as it determines what you can record with a good S/N ratio and what not. HTH, -- FA Io lo dico sempre: l'Italia è troppo stretta e lunga.

On Thu, Nov 26, 2009 at 07:00:27PM +0800, Ng Oon-Ee wrote: AFAIK there's only one fons in jack-devel, and that is indeed this one :-) For noise levels when using the mic inputs the AD converters won't matter much, the preamp dominates the performance (unless it's a very bad one). The converters could have an effect on sound quality, but most types used today are quite good. I guess that the measured performance of my UA-5 is quite typical for this range of products. If any one would be really much better, the manufacturer would boast about it and provide an EIN figure. Ciao, -- FA Io lo dico sempre: l'Italia è troppo stretta e lunga.

On Thu, Nov 26, 2009 at 07:29:53PM +0800, Ng Oon-Ee wrote: At least they quote an EIN figure: -115 dBu, which is -117.2 dBV. Not really much to boast about, but providing an honest figure gives them bonus points. Compare this to Aphex 1788A -125 dBu RME Micstasy -127 dBu Midas XL42 -129 dBu Of course you pay for those... Ciao, -- FA Io lo dico sempre: l'Italia è troppo stretta e lunga.

ok I will chime in I guess... for your/any mic Centrance makes a clean mic interface called Mic Mate Pro. I love mine, its quiet, has decent pre amp, runs 24 bit and will run with Indamixx at 2msecs in Jack. I am pretty sure Robin Gareus wrote in another respone about 'on soundcard' buiilt in processing with UA EX 25/ others and basically said all that stuff does not add up to a hill of beans..... As far as pre amps in low cost mass market audio devices such as M Audio and Presonus that's all definitely a marketing scam because when we were making Trinity DAW with Echo Audio I got to look at every mfg. design and exactly what they ALL put in these devices and in EVERY bill of materials BOM as a mfg you have 2 choices when building a sound card. 1) The .80 cent part from Maxim or some of the others 2) The high end uber boutique part that will cost you some serious coin What I learned from Milo at Echo is all of these products have noise but Milo is very good at placing other parts on the circuit to cancel and kill noise. Just ask Daniel James at 64stduio because he has one of the original Trinity DAW units and its so super quiet ( you think its not running) Again I would suggest going with UA EX 25 because I think I read in LAU that you can get 24bit mode going on the card. Sorry to break anyone's heart with the 80 cent part fact but that's the tale of the tape. However, now that I know where the difference is measured between audio cards, I would choose Echo because Milo is at the top of his game, AND Echo has been Linux friendly for quite some time. Thank you Ron Indamixx On Thu, Nov 26, 2009 at 3:29 AM, Ng Oon-Ee <ngoonee(a)gmail.com> wrote:

fons(a)kokkinizita.net schrieb: Brilliant™ Mic Preamps: * THAT Corp Silicon o Isolation of discretes o Matching of monolithics o High Slew Rate * Low Noise (-130 dBu EIN) * Crystal clear transparency That's what they say on their homepage Ciao

fons(a)kokkinizita.net schrieb: http://www.echoaudio.com/Products/FireWire/AudioFirePre8/index.php

On Thu, 26 Nov 2009, fons(a)kokkinizita.net wrote: /snip/ /snip/ Fons, thank you for your clear explanation! I got quite an education from that one post alone. Makes me want to go out and measure all the preamps in my environment. So how do I do it? Just off the top of my head, I'm thinking of something as simple as placing a 150ohm resistor across the input of the preamp, turning the gain all the way up, and measurnig the p-p voltage at the output. Comparing that to the '0dB' reference level would give the EIN. Am I even close? On a related note, what is the maximum dynamic range of a 24-bit a/d converter? Each 'bit' of precision represents a doubling of the maximum input voltage, and I remember being told somewhere along the line that 3dB represents a doubling, but I don't remember if that's voltage or power. 3*24 is 72dB, but that sounds too low. I remember being told that 16-bit CD audio is capable of something like 100dB dynamic range, so I would expect 24bit to be capable of something more like 124dB. And the '0dB reference level' isn't the full-scale 24-bit clipping level, is it? So the 'working' dynamic range would be somewhat less. I realize I'm babbling on... I guess the ultimate question is how good is good enough? WHat is the EIN figure that would be unmeasurable with a 24-bit A/D converter? What level (expressed in dB wrt '0VU' is required to make the transition from 0x000000 to 0x000001? I'm displaying my total ignorance here. I don't even know if audio is represented by signed integers, or unsigned integers. Is a shorted input represented by 0x000000, and a minimal signal would oscillate between 0x000001 and 0xFFFFFF, or is it represented unsigned, where a shorted input would be 0xEFFFFF, and a maximum signal would oscillate between 0x000000 and 0xFFFFFF? What's the binary representation of the '0VU' reference level? -- Rick Green "Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." -Benjamin Franklin "As for our common defense, we reject as false the choice between our safety and our ideals." -President Barack Obama 20 Jan 2009

Ng Oon-Ee wrote: Then I didn't remember correctly; sorry for that. Just for the record: It's the Fast Track Ultra that is not supported. Clemens

On Thu, 2009-11-26 at 10:27 +0100, Hans Wilmers wrote: This page (http://alsa.opensrc.org/index.php/M-Audio_FastTrack_Pro) seems to suggest that it is possible with an external page. Full 24bit sampling anda ll.