dip16dac
New Head-Fier
- Joined
- May 9, 2004
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Looks like the jumpers inside do not disconnect the signal from pin 3.
Originally Posted by Ferbose I got my roomate to help me yesterday with some single blind testing. I was comparing RCA output (1250 ohm) via cheapest radioshack 12 ft cable ($6) versus headphone output (0 ohm) via HOSA headphone->RCA adapter ($5) and GE ultra-prograde RCA 12 ft cable ($10). The CD used was Harmonia Mundi/Bach Flute Sonatas vol 1. This CD contains well-recorded harpsichord, very beautifully vibrant. I tried to detect a difference by listening to the subtleties of string vibrations in the harpsichord. In my experience this is a very revealing test for hi-frequency extension. I used the harpsichord solo in the beginning of track 3 (~30 s) to evaluate different connections. Headphone output is set to the same volume as the unattenuated RCA output. I used the input selector on my integrated amplifier to switch between the two. I first did some non-blind testing myself. I was expecting the headphone output to sound better because of its lower output impedance. At first I did not discern any difference. After extended listening I thought I heard subtle differences in two particular notes. I thought with headphone output these two notes sounded more vibrant. Then my friend came in to help me do the blind test. He designated the two outputs A and B and helped to switch them. On those two notes, again I heard some differences. B was more vibrant than A. And 80% of the time I was able to guess if it was A or B being played, when he randomly chose one or the other to play. My conclusion was that B sounded better because it carries more details. But the difference is so subtle I don't think it really matters. Much to my surprise though, B turned out to be the RCA output. Therefore my final conclusion is that headphone output is not as good as RCA output for connecting to amplifier. When I first expected headphone output to sound better due to low impedance, it did sound better in a non-blind test. However, blind test also revealed the same difference but in favor of RCA output. I have learned several important lessons in this test: 1) Blind testing is extremely important. When I was psychologically biased, I heard a difference and the one I expexted to sound better sounded better. During blind test, I heard the same difference but the verdict for the better sound went to what I expected to be worse. 2) Even if there is a difference, the psychologically favored component is likely to sound better. If there is no difference, psycholgical effects can probably still create differences out of thin air. 3) These two outputs are drastically diffrent. Headphone output is NE5532/BUF634/0 ohm and RCA output is NE5532/1250 ohms. The differences are so subtle and could hardly be discerned on two particular notes on a very special recording. I don't think such differences have any relevance in real-life listening. 4) If extra IC in the signal path and huge discrepancies in impedance only affects audio signal so little, I wonder what difference can cables make except for better contact at the connectors? |
Originally Posted by Ferbose Cosmopragma, so you heard that headphone output sounded better than RCA output, how is it different? Is it big? |
If I got this correct, your setup was like this: headphone jack of DAC1-->passive preamp-->Stax headamp-->Stax cans RCA out put of DAC1-->passive preamp-->Stax headamp-->Stax cans |
The setup is really quite different. Maybe that is why we heard opposite things. |
Originally Posted by jsiau If necessary, the output pads can be installed. The pads will raise the output impedance (see manual) but it will still be much lower than that of the RCA outputs. |
Originally Posted by Kurt I checked the manual but could not find a answer. What are output pads? TIA |
Originally Posted by jsiau As explained in the manual, we set them high enough to tolerate "Y" cord mono sums, and the inevitable misswiring of two outputs to each other. One of the design goals of the DAC1 was that it must tolerate a short on one ore two outputs without degrading the performance of other outputs. The manual discusses these issues, and also suggests maximum cable lengths as a function of output impedance and cable capacitance. BTW you don't have to be a DAC1 owner to download the 39 page manual. Lots of useful tidbits. |