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Old 15th October 2007, 04:37 PM   #1
gongli is offline gongli  United States
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Default laptop->tubes?


i was wondering how people setup their digital players to use with tubes. i have a laptop and an external drive, onto which i rip cd's from my collection. so i have some questions:

1) what is the best format and bitrate? (i use 320bit mp3 and flac, which do you use?)
2) is there any improvement using a usb sound gadget like creative extigy?
3) how to connect to a power amp like dynaco st70? use preamp (ss/tube?), or go directly? (i go directly using 3.5mm->rca cable)

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Old 15th October 2007, 05:18 PM   #2
zigzagflux is offline zigzagflux  United States
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Good questions. I've tried a number of versions over the past two years, and can make the following notes.

1) Best bitrate to use is lossless, without exception. There are a number of threads you can search for regarding the debate between .wav versus other lossless formats, and EAC versus iTunes, etc. Not really much concern to me, I suspect we're really splitting hairs at that point. But I would not recommend compressing your music in such a way as to remove information, so regardless of what you use, I would go lossless.

2) Can't add much here, as I haven't tried external devices. My comparisions were between the iMac analog output and the PowerBook analog output. Essentially no difference, with one exception: the grounding. With both computers plugged into the wall, I received hum and buzz from the ST70 output, due to the common grounding I had. I ended up lifting my ST70 common with a 100 ohm resistor / parallel capacitor, which significantly reduced the noise, though it could still be heard. Of course, running the laptop on battery only was very quiet, but then I only get a few hours of playtime.

I have now switched over to a RAKK DAC with tubed linestage, so all these issues have disappeared. The transformer output has completely eliminated any ground loops, so I can solidly bond the ST70 common with zero noise. Needless to say, the improvement is more than siginificant. It's amazing.

3) If you are not selecting a linestage for other reasons, such as separate D/A, greater drive capability, source selection, phono interface, I see no benefit to adding an additional stage in between your computer output and the ST70. You really can't expect an additional stage to improve the sound of your computer soundcard, with the exception of maybe galvanic isolation. Therefore, I would go directly from computer to amp, and lift the common of the amp a little. Search for back to back diodes or yin yan diodes for some examples.
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Old 15th October 2007, 07:02 PM   #3
Sherman is offline Sherman  United States
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Join Date: Feb 2004
Location: Chicago area
1- What Zigaflux said

2- Don't know how audible it is with MP3 but an external sound card would almost universally be far better than any laptop sound card and better than 99% of desktop internal cards. Personal experience here using external vs. internal sound cards for digital recording sessions. Creative makes some good ones.

3- Again what Zigaflux said. An advantage of some type of preamp might be easier access to the volume control or even a remote volume control depending on the pre. For sound however, the fewer things in the path the better (in general).
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Old 15th October 2007, 07:22 PM   #4
gongli is offline gongli  United States
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Join Date: Jan 2007
Default also compare with cd?

Hi thanks for the replies, Im also interested on thoughts comparing the laptop/hd setup with a semi-decent (ie price is not a nonissue) cd player (i use a denon from about 15 years ago which sounds decent). does lossless from the laptop sound the same as the cd player? what about all the super-linear direct converter jazz written on the outside of the cdplayer? is this what's in a creative extigy/outboard sound card?

personally, i can tell 128bit mp3 from 320mp3 on external 2.1 computer speakers. i think i can tell flac from 320mp3 on 2.1 computer speakers but its not entirely obvious. when im listening to the 2.1 setup im not "listening" critically though so i guess it doesnt matter. telling flac from 320mp3 from cd on the st70/altec i havent tried yet, only played the denon on the st70, in fact im just resetting up the system after moving so i guess thats why im asking.

thanks for the info
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