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Among other issues, my new Xfinity X1 DVR CATV box features an outboard switch-mode 12 volt DC power supply. When compared with the performance level of a high-performance regulated linear power supply, the presentation sounds sterile and too aggressive via the switch-mode PSU, without subtle listening cues to appreciate, not to mention a level of unacceptable switch-mode power supply pollution within the rest of my audio system. Taking advantage of an otherwise unfortunate audio configuration has always been a key factor as it applies to DIY modification projects, so a 12 volt DC input jack can be an opportunity for sonic betterment, and in this case it's been a worthwhile audiophile experiment.I found a Newmar 115-12-6E 3.5A regulated linear power supply intended for high-end marine communication and navigation purposes within my audio gear collection to perform substantially better than the stock switch-mode power supply, and the barrier spade outputs of the 115-12-6E PSU makes it easy to build custom DC umbilical builds, along with a Switchcraft 762 2.1mm ID DC barrel connector terminated at the load end of the cable for this upcoming DIY cable project. While the Switchcraft 762 is not on par with a SOTA Oyaide DC connector, it's considerably better than a sub par, too fragile Radio Shack DC plug, IME.
Other than two other DIY experiments based on 16 AWG and 18 AWG mil-spec twisted pair wires, the next DIY project will be constructed with a 2 foot length of Connex BL-Ag solid core silver with foamed Teflon dielectric and foil shielded cable for use with the 3A rated device. The Connex BL-Ag is a custom-made by DH Labs interconnect cable for Parts ConneXion priced at 50% off at this time, which makes it a very affordable choice for a non-critical listening, but still-worthy DIY audiophile cable project.
Note: The following voltage drop calculator result indicates a 2 foot, 23 AWG pure silver conductor cable provides a less-than 2% voltage drop for a 12V DC 3A load, which is a fine figure to expect for a DC power supply application:
http://www.calculator.net/voltage-drop-calculator.html
I plan to post an AA report down the road, along with other details about the particular application.
See link:
Edits: 09/20/16Follow Ups:
I'm not really sure about what improvements (If any for Audio)I might be getting from my X1 box plugged into my PSA PP & then attached to a DVDO Edge(which is also going through the PP).
What I do know is that visually the X1 is just exceptional. I don't know why but I just can't get that excited about "better Audio" from my "Video System". I suppose whatever "Audio" I'm getting from Edge processor> Denon AVR> Focal speakers "works" for me.
Now the Video output I'm getting from my X1> Edge still has me scratching my head a bit. This is rented Xfinity equipment after all (& it's pretty unusual to be impressed by what I expect to be "Consumer Level" in quality)
Does line conditioning compensate for switching power supply defficencies ? I ask this because I wonder if my Equitech 1.5Q BPT is also compensating for the switching power supply my Auraliti PK100 uses ? Beforehand I would occasionally notice some "Dynamic Sags" when listening ,whereas now I don't experience those "sags" anymore. The only thing I hear now is a constantly very low "Dead Quite" Noisefloor (Which just works fantastically with following the inticate scoring of Orchesral Music)(This is in my Audio System;Which why my PSA PP is now placed in my Video System)
(Sorry, I think I went off topic)(I get going with a "flow" of thought & keep going with it)
While a nominally isolated or separate filter bank of a power line conditioner can help to mitigate switch-mode power supply noise from polluting the AC delivery to other gear within a system, radiated noise (airborne noise) can still be an issue regardless of effective AC noise filtering. If there were no other choice but to use a switch-mode power supply for an audio application, I would likely use a true isolation transformer for the purpose rather than ordinary AC power line filtering.
Okay,I think I can follow that,& I'll probably investigate changing from the switching power supply that is feeding the X1 coming out of the PSA PP.
As I'm not using the X1 at the same time that I'm listening to my Music System,it might be interesting to see if this might pull "double duty" for my Auraliti PK100 DFP.
My question is "Can I tell what my power requirements for the PK100 would be from the information printed on the power switching transformer it currently is using ?" (Mind you,this is not to say that I honestly can detect any type of "noise" coming from my playback on my Audio System,just a music signal that seems to go deeply back into source material being played; If this can be "improved upon" though I suppose I'll never leave my house)
The stock power supply should have both the voltage and current rating printed on it...
Duster, After you have had the NEWMAR ps and Connex umbilical in your system for quite a while, I dare you to get rid of the Switchcraft 762 and female jack of the NEWMAR. Solder the umbilical direct to the circuit board. You will be VERY surprised how much you will gain! It will NOT be "splitting hairs".
The Switchcraft DC plug is for use with the Xfinity X1 CATV box, which is not allowed to be modified in that way since I don't own it. The Newmar PSU features a high quality barrier strip for use with spades, but if the Connex BL-Ag DC umbilical is a keeper and I don't want to swap-out anymore cables, I might consider a hardwired connection at that end.
Edits: 09/20/16
Why such a small gage wire on a power supply? I would be thinking 16 awg would be a better choice. Also the principles of signal wire do not apply to power cable. The shield and drain you should reconsider.
I really think changing the source would have a more profound effect than 2 feet of wire. But you're the expert.
Also you need to revisit your voltage calculator. You put in 3 amps as your load current, a pretty large load (look on your CATV box and see if it gives a number, I don't think it would be anywhere near 3 amps). That number is in fact the available source current(continuous or peak?). The voltage drop in the case you put forth is actually negligible.
Edits: 09/17/16
The stock switch-mode power supply is rated at 3A, of which one might assume is intended for peak current capability. I would never implement an aftermarket power supply with a lower current rating than a stock power supply. The modern Xfinity X1 DVR CATV box is essentially a computer with current hungry processors, and with a 3A rated power supply, it actually involves less current demand than a typical laptop computer with say a 15.6 volt 8A rated power supply.As for a short-length 2 foot cable with 23 AWG pure silver conductors (with higher conductivity than a copper conductor), I simply did the math to find out if it might be acceptable in terms voltage drop, which is the only important factor I considered in order to choose the cable as a DIY DC umbilical. Since the Newmar 115-12-6E 3.5A regulated linear power supply output measures 13.3 volts without a load, a minimal amount of voltage drop will be insignificant. Another factor I found when evaluating a 16 AWG vs. 18 AWG DC umbilical is that the smaller 18 AWG conductor sounds better than the larger 16 AWG version for the Xfinity X1 application. Bigger is not always better when it comes to various DIY experiments.
In regards to the foil shield, I've had good success with shielded DC umbilicals, so this project is no exception. I'm expecting the twist ratio of the Connex BL-Ag cable to be fairly lazy, so the foil shield should be an effective factor against RFI, and to a lesser extent EMI which can be further mitigated by keeping the DC umbilical away from AC power cords.
Edits: 09/20/16
Please tell more after you've had it in service a while. A couple of months back when all my Uverse hardware got replaced with wireless receivers, I pulled my old King Rex PSU out of storage and hooked it up to the receiver that feeds my Pio plasma. Sound quality out of my sound bar took a definite step forward and PQ seemed better too. Unfortunately, because of space/setup and length of cables I had on hand, I had to put the receiver and PSU inside the credenza the plasma sits on and the wireless reception suffered. So I didn't get enough stick time with the picture to do a proper evaluation before I was forced to move the receiver to the top of the credenza to improve reception, and as the cable I had from PSU wasn't long enough now, I had to go back to the wall wart. I've been meaning to take that up again and get a longer cable. Maybe reading about your project and results will get me motivated.
Thanks for posting.
From what I gather, you need a somewhat long-length DC umbilical in order to use the King Rex PSU. A 23 AWG DC umbilical should only be used for a very short-length application, since DC delivery is very sensitive to conductor size and length, so another cable option will need to be considered for your situation. What is the current rating of the stock wall wart? Perhaps you could provide a link to the receiver that you mentioned.
Duster,Yes, a longer umbilical will be needed to accommodate my setup and allow for use of the KR PSU. Something in the 4' to 6' range, rather than the 18" one I have. The set-top box is the CISCO ISB7005. The wall wart that came with it outputs 12V 1.67A. The model number of the wall wart is ADS0202-U120167. I've not been able to find much past the install guide for the CISCO box, but a sticker on the bottom of it also specifics the same 12V 1.67A. I may go ahead and reconnect the KR just to further assess things, just that I will need longer cable to clean up the final appearance of the setup. Too many boxes and wires are ugly ... at least she says so.
Thanks
Mike
Edits: 09/19/16
A good bulk-length commercial interconnect cable to build a longer-length 5 foot DIY DC umbilical (with an acceptable 1.42% voltage drop for a 12V DC 1.67A load) would be the DH Labs BL-1 (not to be confused with the Connex BL-Ag) featuring 20 AWG silver plated stranded copper conductors with FEP Teflon dielectric and foil shield with drain wire. While it's not a solid core pure silver cable, it's well-respected for low-current DC umbilical applications according to Darren Hovsepian of DH Audio, and the 5.5mm outer diameter of the BL-1 is slim enough to terminate with a Switchcraft DC plug.
Duster,
Thanks a bunch for the recco. I think I have a new project.
Best
Make sure to cut-back both the exposed foil shield and the drain wire all the way to the end of the cable jacket at the load end of the cable (the component end of the DC umbilical) so the foil shield and drain wire are no longer at risk of accidentally touching the DC plug contacts. The drain wire should be soldered to the ground contact of the DC plug only at the source end of the cable (the power supply end of the DC umbilical).
BTW, now is the time to buy a Switchcraft DC plug, since Arrow Electronics is offering free shipping during the month of September. Make sure to know the size of the DC plug that is required for your specific application, since there are two different sizes to choose from: 2.1mm ID or 2.5mm ID. A typical 2.1mm ID DC plug is the Switchcraft 762 that I posted a link to, but a 2.5mm ID version is also available from Arrow Electronics.
See link to the 2.1mm ID version:
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