Rameish 0 Report post Posted September 1, 2003 Hear is a rig created to test drive the so called "direct part". Hmm...it had very poor results with several headphones ranging from the Philips HD-910 (low impedence/high sensitivity) to Senn HD-600 and Beyer DT-931. With the Rotel RCD-971 regular output (based on the Burr Brown OPA-2604) the sound was muffled, there was a marked loss of dynamics, very poor control of the transients - verdict? Not worth the solder used IMO. A quick look at TI's webpage and I read the words 600 ohms in despair for the OPA-2604. However, hope springs eternal and I said a silent prayer to ye audio gods. All that was left in the quest of the so called "direct path was open heart surgery to the Rotel. yes it was operated upon and IC sockets (of the berrilium copper - gold plated variety were installed). Out came the venerable JRC4556 - an op amp known to drive low impedence cans like Grado ;-). No prizes for guessing where else it's used LOL. Unfortunately things did not improve - so snaching at straws - another op-amp was called into service - the OPA-2227P. Alas things did not improve. Part 2 below... Direct_PathJPG Share this post Link to post Share on other sites
Rameish 0 Report post Posted September 1, 2003 Here's the open heart surgery on the Rotel. Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 1, 2003 hey great that you tried it out Rameish! hmm..wonder what went wrong. JaZZ, your thoughts? Share this post Link to post Share on other sites
Rameish 0 Report post Posted September 1, 2003 (edited) So...the lesson here is the op-amp does not seem to matter - rather the CD output seems to designed for input into an amp - as should be. However, not one to be easily daunted I had another card up my sleeve - the Marantz CD-6000 OSE. Here the so called "direct path" fared a little better however once again lost out to Marantz's onboard headphone out. Right now - I am extremely reserved and cautious about the so called direct path. However, I do acknowledge that it is possible that some CDP may be able to do a little better. With that, I invite others who have different CDP to bring their CDPs to my home for further evaluation of the so called direct path. If you are wondering why I call it the so called "direct path", well, it's because it isn't a direct part really - you do have op-amps in the way. However these op-amps seem to be amplifying signal not for driving transducers but as inputs to amplifiers. My mind is as always open to new discoveries - however this one seems to be a red herring for 90% of people. It's always possible that your CD player may behave better or I do not have the right headphone for the job. Nuf said. Bring me your CDP Muhahah. Edited September 1, 2003 by Rameish Share this post Link to post Share on other sites
N@Z 0 Report post Posted September 1, 2003 Why am I not surprised? Share this post Link to post Share on other sites
ablaze 0 Report post Posted September 1, 2003 Why am I not surprised? hate it when skeptics turn out right. JaZZ, say somethin' Share this post Link to post Share on other sites
jtfoo 0 Report post Posted September 2, 2003 Heng ar.. Sign of relieve.. Share this post Link to post Share on other sites
fishball79 0 Report post Posted September 2, 2003 The only viable candidate i know of was my old Denon as it uses 2 opamps per channel for buffering. I was reccomended by a friend who owned the same player to use a passive pre you see... So basically only cdplayers that output MORE than the standard 2v got chance... Share this post Link to post Share on other sites
N@Z 0 Report post Posted September 2, 2003 Why am I not surprised? hate it when skeptics turn out right. JaZZ, say somethin' I wouldn't say I was a skeptic but theory doesn't always work out that way in practice. It's actually great that Rameish went to all the trouble to test it out. Ablaze it doesn't matter whether you were right or wrong at the end of the day you decide for yourself. I just happen to favour the amped way, until such time that I am able to hear for myself that the direct path is actually better. Share this post Link to post Share on other sites
Rameish 0 Report post Posted September 2, 2003 Anybody with CDPs that output 4.5 volts? Pls bring them over - I promise not to open it up :-). Hmm...now that one of my Rotel CDPs has IC sockets installed, I'm gonna get a bunch of chips and try op-amp rolling the AD825 and LM6172 seem to be ideal candidates according to a few guys at Audio Asylum - then maybe a clock upgrade. Anyone have a nibbler I can borrow?? Share this post Link to post Share on other sites
Mackie 0 Report post Posted September 2, 2003 (edited) Rameish, U'll need cdps with XLR balanced output as signal is normally double of that from single ended output of 2V. Edited September 2, 2003 by Mackie Share this post Link to post Share on other sites
headphonecrazy 0 Report post Posted September 2, 2003 Rameish, U'll need cdps with XLR balanced output as signal is normally more than double than that of single ended output of 2V. Lengcm's 1.1 has a pair of balanced output. Share this post Link to post Share on other sites
Rameish 0 Report post Posted September 2, 2003 Hmm, it wasn't as much as volume (i listen at low levels) but the muddy sound that has sorta put me off. Share this post Link to post Share on other sites
fishball79 0 Report post Posted September 2, 2003 Ram, Having higher voltage output means more current on tap too, that was what's lacking in your experiement. Low power = muddy sound. Share this post Link to post Share on other sites
Rameish 0 Report post Posted September 2, 2003 (edited) Fish, voltage = current??? Edited September 2, 2003 by Rameish Share this post Link to post Share on other sites
