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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