Hello all,
I have a Tektronics oscilloscope and arbitrary function generator which I use for analysis of my builds, but I'd like to complement that with some PC-based measurement tools, such as frequency response, distortion, non-critical scope functions, etc. I mostly build tube-based audio equipment, but solid state creeps into the picture occasionally as well.
I have a budget of $1000 or so (somewhat flexible) to buy a laptop/netbook to dedicate to this purpose. I do not need fancy graphics, big high-resolution displays, 3D-video, killer audio playback, gaming et al - what I want is a small (to conserve bench space) "laboratory instrument" grade computer with the best sound card for measurement purposes that I can afford to stuff inside it.
So, can anyone help me in my quest for a "lab instrument" PC? What would be the ideal sound card to make audio measurements, with a wide frequency bandwidth so I can see down to 2Hz and up to 100kHz or so? One that can actually make and display a clean square wave would be nice. What would be the right small laptop to stick it inside? Windows-based preferred.
Any advice is greatly appreciated!
.
I have a Tektronics oscilloscope and arbitrary function generator which I use for analysis of my builds, but I'd like to complement that with some PC-based measurement tools, such as frequency response, distortion, non-critical scope functions, etc. I mostly build tube-based audio equipment, but solid state creeps into the picture occasionally as well.
I have a budget of $1000 or so (somewhat flexible) to buy a laptop/netbook to dedicate to this purpose. I do not need fancy graphics, big high-resolution displays, 3D-video, killer audio playback, gaming et al - what I want is a small (to conserve bench space) "laboratory instrument" grade computer with the best sound card for measurement purposes that I can afford to stuff inside it.
So, can anyone help me in my quest for a "lab instrument" PC? What would be the ideal sound card to make audio measurements, with a wide frequency bandwidth so I can see down to 2Hz and up to 100kHz or so? One that can actually make and display a clean square wave would be nice. What would be the right small laptop to stick it inside? Windows-based preferred.
Any advice is greatly appreciated!
.
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A laptop is probably not the best computer to make a test instrument. You cannot use internal soundcards (or the range is limited if you use PCMCIA) and you must use USB.
Better to try a fanless PC, WinXP, with (dual) atom core. fanless pc | eBay
This will allow you to use one of the high quality cards such as the Asus Xonar Essence or ATI Juli@.
While the soundcard's bandwidth may extend down to 2Hz, it will only run up to 96kHz.
A soundcard generated square wave will always have problems as the highest harmonic of 1kHz available is 64kHz so the the square wave will contain at most 6 harmonics and will have a wavy, not flat, top. Better to run a soundcard generated sine into a comparator and generate a square wave that way.
Better to try a fanless PC, WinXP, with (dual) atom core. fanless pc | eBay
This will allow you to use one of the high quality cards such as the Asus Xonar Essence or ATI Juli@.
While the soundcard's bandwidth may extend down to 2Hz, it will only run up to 96kHz.
A soundcard generated square wave will always have problems as the highest harmonic of 1kHz available is 64kHz so the the square wave will contain at most 6 harmonics and will have a wavy, not flat, top. Better to run a soundcard generated sine into a comparator and generate a square wave that way.
Thanks for the input.
I'd really like to avoid using a tower PC for this, as I want the portability of a laptop, and the ability to take my files with me wherever I go. Even in late 2012, are there no laptops capable of making good measurements using an internal soundcard? No one has come up with an aftermarket card that will fit into a laptop yet?
I have used TrueRTA on an IBM thinkpad in the past but that left a lot to be desired, and laptops have evolved quite a bit in the 4 years since then, so I was hopeful that perhaps I could work out a decent solution now.
Am I still SOL?
I'd really like to avoid using a tower PC for this, as I want the portability of a laptop, and the ability to take my files with me wherever I go. Even in late 2012, are there no laptops capable of making good measurements using an internal soundcard? No one has come up with an aftermarket card that will fit into a laptop yet?
I have used TrueRTA on an IBM thinkpad in the past but that left a lot to be desired, and laptops have evolved quite a bit in the 4 years since then, so I was hopeful that perhaps I could work out a decent solution now.
Am I still SOL?
This would not meet your specs for a test platform, but if you are doing strictly audio measurements, why not try REW (Room EQ Wizard) (free) with your choice of laptop and external sound box. For example, I use a 2008-era HP Compaq F762NR (Win XP), for sound interface I use
PreSonus | AudioBox USB
and a Behringer ECM8000 mic for measurements. Assuming you already have a laptop, or even a netbook, the additional hardware should cost you no more than $200 (USA prices). Of course, then you'll need to buy a parametric EQ to tame the peaks, and then you'll need to buy a.... and so on ...
PreSonus | AudioBox USB
and a Behringer ECM8000 mic for measurements. Assuming you already have a laptop, or even a netbook, the additional hardware should cost you no more than $200 (USA prices). Of course, then you'll need to buy a parametric EQ to tame the peaks, and then you'll need to buy a.... and so on ...
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If you're determined to go with a laptop then look at the E-MU 0204 USB interface but note that it has a claimed 113dB input SNR as compared with 124dB for the Asus Xonar Essence.
I doubt that you can get a meaningful recommendation for a particular laptop as regards performance as a test instrument using internals or USB, pick one that has features desirable to you in the other uses that you envision. Or simply buy the cheapest you can find, it'll run a USB soundcard.
One factor possibly affecting USB sound performance is the quality of the USB power supply, so an interface with an external supply might be something you want to look for (I can't suggest one off the top of my head) or somebody might be prepared to suggest a particular laptop on that basis, but I would be cautious of any recommendation not backed up with test results.
I doubt that you can get a meaningful recommendation for a particular laptop as regards performance as a test instrument using internals or USB, pick one that has features desirable to you in the other uses that you envision. Or simply buy the cheapest you can find, it'll run a USB soundcard.
One factor possibly affecting USB sound performance is the quality of the USB power supply, so an interface with an external supply might be something you want to look for (I can't suggest one off the top of my head) or somebody might be prepared to suggest a particular laptop on that basis, but I would be cautious of any recommendation not backed up with test results.
Thanks. I already have TrueRTA 1/24 octave version for room measurements with a mic mixer board and Behringer mic, and I use that for room response measurement with OK results. I'm looking to be able to do better measurements on the electronics I build, however. When I had the aforementioned Thinkpad (work issued leased laptop), it was barely adequate; that has since been "refreshed" with an HP that is simply atrocious with the same software, and rolls off early at both ends even on a loopback measurement. So it's time to cough up some dough and buy something better for myself.
So maybe I should ask "what laptop with internal card could allow me to make reasonably good measurements". I have the scope and function generator for more critical work.
Thanks. I'll look into that USB interface. Still wish I could find a good internal card solution, though, but maybe the tech isn't there yet.
Edit: the E-MU looks pretty good for the price, and may end up being the most workable solution, too bad it's one more box to fit on the bench...maybe I need to get better organized like my wife says...
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I doubt those products are getting anywhere near these numbers. The Roland quad has a measured noise floor of -91 dB at 48Ksps (~5 to 20 KHz), and it's a very well respected product from a company that has been doing high end audio forever.
http://www.spectraplus.com/Downloads/QuadCaptureTestReport.pdf
What about a PCMCIA or ExpressCard sound card, anyone have a positive experience using one of those for routine measurements?
How about something like X-Fi Xtreme Audio Notebook?
Amazon.com: Creative ExpressCard Sound Blaster X-Fi Xtreme Audio Notebook-70SB071000000: Electronics
That would eliminate the extra box and still provide a better tool than an internal sound card, right?
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How about something like X-Fi Xtreme Audio Notebook?
Amazon.com: Creative ExpressCard Sound Blaster X-Fi Xtreme Audio Notebook-70SB071000000: Electronics
That would eliminate the extra box and still provide a better tool than an internal sound card, right?
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There's not many high-quality ExpressCard sound cards around. I bought an Indigo IOx, for the ExpressCard slot on my Sony Vaio laptop. The Indigo has a much higher noise level on one input channel compared with the other, and Echo did not even respond to my emails on the question. I can't be sure if the noise is associated with the Indigo card, as the ExpressCard format never took off in laptops as a Cardbus/PCMCIA replacement, so I don't have access to another laptop to try it. Neither of my USB soundcards show the noise problem though, so I guess it is a problem wth the Indigo.
Well thought I'd check back in - the E-MU 0204 was a huge bust! They claim it works with Windows 7, but not on my laptop (Dell Inspiron 15R, Core i7). Once the driver software is installed, the laptop freezes constantly and not even task manager can get me out of it, have to power down completely. I messed around with it all day and determined that the E-MU drivers are definitely the problem. I even re-imaged the entire computer thinking I may have had some corrupted system files, but as soon as the E-MU stuff went back in...CRASH.
It's on its way back to Amazon.
It's on its way back to Amazon.
As you have discovered most internal sound cards are pretty poor. I did get decent results from the internal audio in a Dell XPS M1330 but not up to high performance audio for what you are after. Win 7 is a major roadblock since the audio subsystem has been completely redesigned and works very differently. The E-Mu card works OK on XP and can get decent measurements with care. Perhaps you should set up for dual boot with a 32 bit XP partition for audio measurements. You can then optimize it for audio by removing unnecesary junkware and shutting down drivers you don't need. There is a program called fidelizer I think that does just this when you need it. In the long run you will have weeks of your life back . . .
You will still need some sort of interface to match levels and dynamic range to the limits of the sound card inputs. There is Samuel Groner's listed on this forum and there is a probe with an audio connector on eBay for starters.
You will still need some sort of interface to match levels and dynamic range to the limits of the sound card inputs. There is Samuel Groner's listed on this forum and there is a probe with an audio connector on eBay for starters.
Plan B is to just use the interface that is recommended by TrueRTA, which is the audio analysis software I have. The interface is the Behringer UCA202, and it's about as simple as you can get, 2 RCA in and out and a USB plug (about $30 on Amazon, so no big risk). Not high resolution but all I really NEED to do at this point in time is take audio band frequency response measurements for the new preamp I'm building. I have a good scope and function generator for the other stuff like square wave testing.
I don't have a lot of time to fool around with other options. My hobby is building tube audio gear, not test equipment. I just want my tools to work when I need them then go back in the drawer, like a screwdriver or a hole punch. Computers don't seem to be there quite yet...
I don't have a lot of time to fool around with other options. My hobby is building tube audio gear, not test equipment. I just want my tools to work when I need them then go back in the drawer, like a screwdriver or a hole punch. Computers don't seem to be there quite yet...
I use laptops all the time for measurements with varying results. One of the problems with my older HP laptop is interrupts. It gets busy doing other things and drops audio. Turning off Wi-Fi helps.
Some more recent laptops don't seem to drop audio, including my little HP netbook that runs Windoze 7 Starter. I use the M-Audio band USB cards. USB cards all seem to be limited to 48KHz full duplex, or 96Khz one way. 24 bit is possible. Firewire gets around this problem. Maybe there will be some faster USB cards out soon.
Some more recent laptops don't seem to drop audio, including my little HP netbook that runs Windoze 7 Starter. I use the M-Audio band USB cards. USB cards all seem to be limited to 48KHz full duplex, or 96Khz one way. 24 bit is possible. Firewire gets around this problem. Maybe there will be some faster USB cards out soon.
My old M-Audio Transit is like a better-quality version of the Behringer UA202, but it's not made any more. It also is limited to 48kHz sampling in full duplex. My more expensive E-MU 0404 USB is happy to run full-duplex at 96kHz sampling with the latest Windows 7 driver, but E-MU seem to have withdrawn this excellent unit from the market!
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