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Philips SACD 1000 / power cords in general

For those of you with SACD 1000's, i was doing some experimenting the other day that you might find interesting.

After repairing a pair of speakers that a friend had dropped off, i hooked them up into my HT system to make sure that they were working correctly. I did this AFTER checking them out VERY thoroughly electrically. Upon listening to them, i was puzzled as to their tonal balance not being what i was used to hearing out of them. The sound was much leaner sounding and lacking bass weight. Since i've always thought that these speakers were somewhat slow and muddy when it came to their bottom end, i began to scratch my head and wonder what i had changed.

At this point in time, my Brother showed up out of the blue. He was also familiar with the speakers and also thought that they were now bass shy. After examining the speakers and finding that everything was as it should be, i began to think that maybe something in the system had changed. I sat back and began to think. A few days prior, i had changed the power cord on my SACD 1000 and never really sat down to listen to it. I mentioned this to my brother and he jokingly mentioned "power cords don't change anything, it's all psycho-acoustics" : )

With the power cord change in mind, i put on a disc that we were both familiar with and gave a quick listen. I then proceeded to swap the original cord back onto the SACD 1000 that i was previously using. Cueing up the disc again brought a smile to both of our faces. The bottom end was back and so was the all too familiar "slow & heavy" bass that these speakers are known for.

As a side note, not only was their much greater bass weight, it seemed as if the highs were a little cleaner and there was better focus throughout the midrange, especially vocals ( it was a male singer ). These differences were SO noticeable to me, that i decided to see if i could measure any differences in tonal balance with an SPL meter. While i had to resort to using my standard unmodified analogue Rat Shack model ( my modified and calibrated RS was out on loan ), i took standard precautions to make sure that whatever "irregularities" appeared in one reading would be the same as those that appeared in the next reading.

As such, the spl meter was situated in a permanent mounting location in a manner that it could not move, yet i could see the meter from a few feet back. I did not want to be anywhere near the meter as my body would cause reflections. In such a case, even slight body movements can change things by several dB's, believe it or not. So as to minimize room interaction, the mic was appr 1.5' away from the speaker and aimed at the center of the baffle between the tweeter and the two mid-woofers that were right below it.

I selected a disc that had calibrated output levels at various frequencies as a point of reference. The jumps in frequency from test tone to test tone were further apart than i would have liked, but i really didn't feel like hooking up one of my signal generators. I was trying to do this as "quick and dirty" as possible yet get repeatable results.

I selected a random volume level and adjusted the output to a point that provided me with a steady state "0 dB" reading ( mid-scale ) on the SPL meter at 1 KHz. I then began to sweep the various tones on the disc while observing and recording the readings on the meter as accurately as possible. When i had done a full frequency sweep, i went back to 1 KHz and verified that i was still at the "0" mark at mid-scale, which i was.

I then proceeded to change power cords as quickly as possible. With the new cord in, i fired up the test disc at 1 KHz and looked at the meter. The reading showed "O". This meant that there was no measurable difference at 1 K in terms of output and that the the meter / system volume were still consistent with the conditions from the first test.

Just like i did above, i ran through all of the test tones one by one, recording the readings as they appeared. I then went back to 1K and verified that everything was still reading consistently. Just as before, it was still centered at "0".

The results were pretty interesting but not quite what i had expected. All of the readings at the very bottom end were identical or within the margin for error that reading such a device would allow. This was kind of puzzling as there really was a noticeable difference in both quantity and extension of bass to both my ears and my brother's. Hmmm...

As i looked at the chart proceeding up in frequency, there was one noticeable divergence in the response. With the test tone centered at 400 Hz, there was bump of appr .5 dB between the two cords. The cord that we thought "sounded fuller" with it in the system showed to have the higher output level. Hmmm... could the added half a dB in the upper warmth or "body" region make that much of a difference ? Could this added "body" have fooled us into thinking that we had greater bass extension ? Maybe. I think that we might have found other differences below that frequency if the test disc wasn't stepped from 100 Hz all the way up to 400 Hz. My thoughts are that there was a hump between 100 Hz and 400 Hz, but i'm just guessing at this point.

As we progressed up in frequency, the readings remained consistent from cord to cord all the way up to 18 KHz. At this point, there was a divergence of .5 dB between them. As we scaled up to 20 KHz, the divergence between the two cords widened to 1 dB. That is, as measured on the meter. The cord that we thought sounded "fuller", sounded more focused and had cleaner highs was the one that was higher in output up top. As such, the cord that was leaner in the lower freq's with less clarity up top actually measured similarly to what our ears were telling us. One cord was actually boosting the warmth region and offering greater treble extension and / or the other cord was losing warmth and rolling the top end, depending on how you wanted to look at it.

While i know the "experts" are rolling their eyes at this "impromptu" test procedure, both cords were subjected to the same conditions on the same system with the same measurement flaws. As such, consistency was good even though it was not done under "laboratory grade" conditions.

NOW for the "kicker". These two power cords are identical in construction except for how the grounds are configured. One cord has the ground spiral wrapped directly against the bodies of the hot and neutral conductors. The other cord is built the same way using the same materials, but the ground is spaced off of the hot & neutral by appr a 1/8" gap. My guess is that the differences in impedances presented by the two cords are what caused the differences in both perceived and measured sonics.

Now for the REAL kicker. The Philips SACD 1000 is not grounded via the IEC jack. This is specifically covered in the manual and states that one has to ground the chassis of this player via a lug on the back IF one wants to ground it. Obviously, the differences in the impedance presented to the hot & neutral have NOTHING to do with the conductivity of the actual CD player being connected to ground. The power cords were basically acting as "telescoping" grounds with this unit. As such, try explaining this one to an EE and watch them roll their eyes....

This taught me a lot and i'm sure that it will raise a few points of interest with others that build / design commercial cables and those that DIY various cables. One should bare in mind that the cords that i was using were not "manufactured" cords but DIY designs that cost less than $50 to build. I'm not encouraging anyone to run out and buy / build power cords, but i am suggesting that there may be a lot more here than meets conventional thinking, even "conventional thinking" of "cable crazy" audiophiles. Sean
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sean
zoya
120 posts
 
Sean, I'll try to put some sense into the results of your test. When you conducted your test you were using test sinwave. But the music is a complex signal - not a pure sine wave. The many harmonics are part of the music that we hear. So additional boost of .5db at 400Hz means that you not only hear louder signal at 400 Hz, but also you can hear clearer second harmonics of 200 Hz and 4th harmonics of 100 Hz - hence the overall improved performance of the entire lower range of the frequency. The same applies to .5 db boost at 18 KHz and 1 db boost at 20 KHz - while we can't here the base signal of that high frequency at all, but it affects second and 4th harmonics of 4.5 KHz, 5 KHz, 9 KHz and 10 KHz. Again, overall improved performance.
I hope this helps. I only have one question - you were not clear about which cord with which ground wire showed better performance. I would expect that it was the one with the ground wire wound around as it should provide a better shield, even if it is not connected on the player's end.
sean OP
6,231 posts
 
Richard: The SACD 1000 is not grounded in this system other than by the grounding that one achieves through the interconnects that tie component chassis together.

As a side note, i would prefer that the chassis of all components were "floating" and NOT tied to signal or "board" ground. If designers were to take this approach and end users had a low resistance path to Earth ground that they could tie all of the chassis to, the end result would be something similar to a Faraday cage shielding each component.

Zoya: What you are describing would be classified as sub-harmonics rather than harmonics. Harmonic's are "overtones" above the primary signal. As such, a signal that was generated below the primary tone would be a "sub-harmonic".

With that in the clear, it would not matter if harmonics were being generated or not. At least, as far as the SPL meter and the readings are concerned. Since the meter is a broadband unit, it samples and averages the results regardless of frequency. As such, a "boost" at 400 Hz that also incorporated harmonics or sub-harmonics would simply show up on the meter as a higher over-all reading than a signal that was a "pure" 400 Hz tone. The output from the multiple signals would be compounded and show up as one reading.

Since such a signal would be highly complex, a simple device like an SPL meter would not do any justice here. You would need something along the lines of a distortion analyzer or spectrum analyzer to really see what was taking place. For the record, i should have a new spectrum analyzer in the next week or so : )

As to which cord was which, the cord with the "air gap ground" was the one that was both "fuller sounding" and offered better high frequency extension. Sean
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eldartford
4,262 posts
 
sean...per your instruction I am responding here. I read your account with interest, and some degree of skepticism. It sounds as if you made very careful listening tests, augmented by spl meter readings. However I have some experience with such spl readings, and I really doubt the accuracy of 1/2 dB changes, and listening, we must agree, is subjective.

The "data" I would like to see relates to the DC power going to the audio circuits. If the power cord has an effect, it must propogate from the cord to the audio circuits via this DC power. If the DC power noise changes with the power cord it might have an audible effect. I don't believe there will be any difference, but my mind is completely open to change if there is evidence to the contrary. Fourier analysis of the DC noise would be nice and is the kind of thing we would do in my business, but I would be satisfied with a couple of oscilloscope photos.
sean OP
6,231 posts
 
I agree that in-depth analysis would be great and would probably shed a lot of light on the subject. I wish i had both the time and equipment to do just that. I have been working towards picking up more lab grade test equipment, but audio is strictly a "hobby" and major expenditures into that area don't pay my bills. As such, devices that are "utilitarian" in nature i.e. usable for both AF & RF are the products i'm concentrating on.

As far as a .5 dB to 1 dB change being "negligible" in terms of accuracy, the scaling of these meters is wide enough to easily be able to see that there were measurable differences, regardless of the absolute quantity of the differences.

In terms of asking others to hand evidence to you on a silver platter, i challenge you to do some personal investigation on your own. As others have mentioned, there are more than a few cable manufacturers / retailers that offer "free" trial periods. With minimal to no cash outlay, you can find out for yourself if there are any sonic differences. I am relatively confident that, as long as you have a "decent" system and an open mind, you'll hear a "difference" ( "good" or "bad", a difference is a difference ) and want to investigate things for yourself. Since you seem to have access to some relatively advanced high tech test equipment, you may end up answering some of your own questions in the long run. That is, if you are willing to take the first step and find out for yourself rather than rely on "heresy" or "doubt". I took that step several years ago and the results were not what i was expecting. Sean
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eldartford
4,262 posts
 
Seems to me that those who are selling the power cords ought to have the objective electrical data. I would like to make the experiment which I suggested, but my neat test equipment is all locked up in classified project labs at work.

Of course, if I don't admit to hearing a difference, my audio equipment is junk. Can't win that one!

Question to you...if I DEGRADE my power cord, say by inserting a 25 foot 18ga extension cord, will sonic quality go downhill? That experiment would be easy.
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