Are High End CD Players worth it?
I have looked over the past 10 pages of this thread with near total disgust. While Gene has addressed the room loudspeaker issue I am going to attempt to address other issues that directly pertain to this thread.
The major problem with consumer audio gear is that there is no standard for grounding. Therefore. as far as I am concerned, no meaningful DBT can be used. This has been demonstrated to me on a number of occaisons, as I have demonstrated on a number of occaisons. Early on in my involvement with audio I had the chance to observe the difference between a Denon CD player connected to a pre amp with and without a Jensen Line Level Audio Transformer. The noise floor drop and increase in dynamic range was blatantly obvious using the Jensen Transformer. This basic scenario was done again here:
"First, we played some music and listened to his system. You know... the usual. Then I hooked up my two units in his system. Wow! The noise floor fell so low that both of our jaws dropped. It was that blatantly obvious to the both of us. You could hear so much more of the music. Now mind you, this guy was a die-hard double-blind ABX adherent who kept saying that he heard no differences between records and CD's, and he was out to prove it. He invited me to bring back my D/A Converter for the ABX test but not the pre-amp. I'm sure the reason is because if we used my pre-amp, you would have clearly heard the differences between records and CD's. He also made sure to tell me as I was leaving, that I was not to tell anyone that his system was so noisy! Can you imagine what his pre-amp sounded like?"
The above is from my website and was written to once again to attempt to tell people that because I implement good grounding/shielding practices I can get these type of results.
Once again, I demonstrated to a business associate who was at the time developing small amplified loudspeakers to be used with a PC. I demonstrated my small plastic Boston Acoustic loudspeakers with and without a prototype pre amp. The difference was obvious becasue the prototype pre amp had some of those Jensen Line Level Transformers at the input. The business associate noted the difference and is now using line level isolation transformers at the input to the amplified speakers he is developing. Think about it, who in their right mind would want to directly connect some reasonably sensitive analog directly to the ground inside of a computer.
And again; in the write up I did for the Yamaha T-80, note the photos of the ground straps and note that I used isolated RCA plugs at the output.
The following is a post I put up on few consumer boards about a year ago. I got few comments, from the "intelligentsia". I would heartily suggest that all who have particapated on this thread think about what I have attempted to convey here.
GROUNDING PRACTICES IN CONSUMER AUDIO
As many of us have observed over the years grounding practices in consumer audio have for many of us been a frustrating experience. Compatibility/Synergy are consistently major issues, as well as safety, reducing ground loops, noise and interference. Designers are equally frustrated by this problem. Some of us wish it would go away and others attempt to deal with as best as we know how. There does not appear to be much of any standardization that I, and many others are aware of. Many of us who work in the electronics industry outside of audio who have observed the posts from audiophiles, designers and dealers scratch our heads in near disbelief.
The following is not only an outline for reducing these problems, but a wake up call to this end of the industry. The following is for the application to consumer unbalanced audio, and could well be a possible outline for positive discussion and direction. It is also a way to use Earth Ground to our advantage instead of a problem.
Chassis Grounding:
The following is a technique used in instrumentation for low frequency applications.
The chassis will be earth grounded via the earth ground at the three-prong outlet. The audio signal ground contained in the chassis is not connected to the chassis ground. This will require the design to be electrically isolated from the chassis ground which is easily solved by using nylon stand offs to mount pc boards and isolated bulkhead RCA jacks. (I am going to break this rule later on but bear with me for the moment). The above forces the design to be star grounded at the return of the power supply, which is always good practice to reduce noise and ground loops. However, this does leave the present configuration susceptible to interference from the inputs. This interference can be reduced by the using a simple common mode ac line filter at the AC input and using either a well shielded coax or microphone cable at the line level input. This configuration also poses an additional problem due the fact that we now have two different grounds with two different potentials. In the past I have observed this problem when using a certain brand of rotary switch for a volume control. The rotary switch was not well isolated internally and had enough of a leakage current so that noise was developed when it was used. Moving to a different vendor with higher isolation devices corrected the problem. I have not observed any problem with standard switches for on off applications or anything similar.
I have applied this technique to basic audio chain of equipment consisting of an outboard DAC, line level pre amp, and power amps using the chassis and grounding design I outlined above. The transport that I presently use is a modified consumer device and is equipped with a two-prong plug. The system also has an FM tuner and an old pre amp that is used as a phono pre amp. Both of these devices are standard consumer issue with a two-prong plug. I have observed no compatibility issues with the older style units.
As I outlined earlier I am going to break this rule at one point. The line level pre amp now has a connection from the return of the line stage pre amp power supply to the chassis of the unit. I have now connected earth ground to the analog “center point of the system.” This did not cause a ground loop at all, and to be more precise, for CD playback the inherent ground loops that are typical for unbalanced circuitry simply disappeared. The FM tuner and the old pre amp appear to be unaffected by the center point earth ground. A welcome addition was that the rotary switch that had a leakage problem because of the two different potential levels described earlier no longer had the problem due to center point earth ground.
The use of the system center point earth ground for low frequency applications has been in the textbooks for at least 30 some odd years and has been applied to other low frequency applications. Applied at this level to a simple chain of audio playback equipment, CD playback now has reduced hum and hiss to levels more akin to balanced design than unbalanced design. Playback of FM tuner and Phono pre amp remains unaffected.
One thing that has surprised me relates to the issue of low frequency applications. I was expecting to find problems with the digital portion of this playback chain. I have not found one to date but I think this needs to be investigated further when time allows.
A note to all of the tweakers who read this: I am not recommending any changes to existing designs; in fact I would discourage it.
To DIY folks: You may wish to rethink some of your present chassis/grounding schemes.
To the rest of the industry; this is a subject that not only deserves discussion but an active participation to reach acceptable standards.
The grounding system described above will not address the problem of toroidal transformers mechanically vibrating due to either DC on the AC lines or as I have observed on occasion, low frequency oscillations.
Dan Banquer
I hope that all of you who have particapated in this thread take some time and think about the implications of lousy grounding practices and a near total lack of standards.
d.b.
P.S. Yes I am having a really really bad hair day, so I thought I would cloud the issue with facts.
