an experiment ..and a surprise (fooled by logic)

[mpmarino]

I have always enjoyed listening to my Sony cdp 508ESD using the variable rca out directly into my power amp. I always thought it sounded way better than running the optical out into my Sony sdp-ep9es pre pro and letting that complicated computer/box do the d/a stuff. I have all EQ and 'processing' turned off on the pre pro. I am using monster interlink 400 for the rca and a 49 cent radio shack toslink cable for the optical.

Today it occured to me that the pre pro has a 'bypass' in. With the push of a button I can switch to an external analog signal with just a set of relays in the way. So, 'normal' is using the pre pro as the dac/pre/level and 'bypass' is the cdp as the dac/pre/level. Upon switching between the two there is barely an audible click, about as quick as a relay.

I got everything hooked up, matched levels by ear, and sat down. With remote in hand I closed my eyes and listened to a bunch of Grusin stuff that I know exactly how it sounds. I've listened to, and enjoyed Grusin for many years. I had no idea whether I was in 'bypass' or not unless I opened my eyes. Good and fair test it seemed to me.

To my surprise, every time I opened my eyes to see which one I was listening to, as it was obviously better, it was the pre pro. Better bass, clearer highs...etc. The player's dac sounded rolled off at both extremes and lifeless. Maybe, and probably a player with a better dac would do better. This player has always sounded great IMHO.

Why do I post this? Well, because I was fooled by what 'seemed' to be true. How could a player feeding a mass produced mediocre pre/pro with a 49 cent OPTICAL cable be better than a direct connect? Dunno, but it is.

[Nixie]

Someone really needs to build a switchbox that can be controlled by a computer program such as abchr. That would make doing proper blind testing of hardware extremely easy.

[clem_o]

The variable level output of the player sounds worse than the "full" line level output - at least that's the feeling I get on my X33ES. On digital in via optical, the high frequencies do sound louder - but also a lot more harsh, usually - due to jitter. The low frequency difference could be due to signal coupling capacitors being too small (on the analog side).

Cheers!


ps: I have tried the same test - except that my "bypass" mode still runs through the volume control of the amp.

[mpmarino]

Thanks for the comments. I have since tried the 'fixed' output of the player thinking the pot on the variable output is lousy. I once again matched levels by ear, and although having rather high spl levels at that point, it still sounded better thru the 'computer pre/pro'. Genuinely better IMHO. I don't know whether to find a new cd player or just be happy that I like it with the es digital pre in line Being happy sounds good right now

[clem_o]

Originally posted by mpmarino
I don't know whether to find a new cd player or just be happy that I like it with the es digital pre in line Being happy sounds good right now

Hehe - definitely be happy for now. Then go out and borrow some high-end player when you feel the possibility of spending... !!

:-)

Cheers

ps: or, perhaps time for some mods on your player!!

[phn]

Your 49 cent radio shack toslink cable is as good as any digital cable. From what I can tell, everything makes perfect logic.

[eleson]

Here's a link to swedish test (Danish origin?) of the DAC-1.

http://www.benchmarkmedia.com/dac1/sweden.pdf

they note that there is no audible difference between
20m el'cheapo toslink and balanced XLR inputs.

To me it confirms what a one is a one and a zero is a zero
no matter how it is transported.

So it is just a matter of where the better D-A converter is placed.
And to me it sounds that you have where I would like it to be,
i.e in the pre-amp.

Cheers
Erland

[analog_sa]

With the push of a button I can switch to an external analog signal with just a set of relays in the way.

I'd be very suspicious of any switching arrangement as well. Your CDP dac may be no good but comparing through the pre pro (whatever that might be) is hardly ideal.

The CDP volume control may be horrible, or you may simply need an active preamp. Your experiment proves nothing.

[mpmarino]

Hi Charles,

I have the service manual for the processor. The signal indeed does go through relays and just relays.

The experiment proves to me that the setup sounds better using the pre/pro (preamp/processor) as a dac and pre than the way that I was using it.

The other points you made may be right on. the cdp analog out may be lousy, but it always sounded very good to me...not as good anymore. Maybe an active pre will make the difference, I will hopefully find out soon.