AudioNervosa
Electro Stimulation Ward => Power Conditioning => Topic started by: P.I. on August 24, 2016, 12:00:08 PM
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Well, I have taken it all apart and will be commenting on it in the next couple of days. I have already ordered parts to spiff it up.
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Well, I have taken it all apart and will be commenting on it in the next couple of days. I have already ordered parts to spiff it up.
What do you think of the stock unit for $99?
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Well, I have taken it all apart and will be commenting on it in the next couple of days. I have already ordered parts to spiff it up.
What do you think of the stock unit for $99?
If I had DC problems like my customers do in some locales, it would be the first $99.00 I would spend to attack to problem. It is very nicely done. The ISO9001 facilities can and do some great work.
The casework extrusion is top notch as is the powder coating. I like the built in line tester, but that needs to be quieted down. Looks like a reasonable choice of parts and values given its' price. I'll be into it more as I go along. Almost wish I had (shhh, you know) on my AC lines to be able to tell. I'll have to build something to unbalance what I have and go about it that way, I think.
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Dave,
Something that might be of interest.
Try growing some copper sulfate on copper AC connections. Has created lots of line hash and instabilities at my power meter connections.
Just a thought.
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Dave, I'm really looking forward to what you find. My CMX-2 seems to be serving its purpose (thank you Emil!) but I'm eager to learn if you find ways on improving it. And if you need a beta-tester, I'm here for you :thumb:
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Dave, I'm really looking forward to what you find. My CMX-2 seems to be serving its purpose (thank you Emil!) but I'm eager to learn if you find ways on improving it. And if you need a beta-tester, I'm here for you :thumb:
You are my guy, Mike. We've been down this road for a while, Bro'.
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I should have an update to this thread early next week. I've been swamped with life and business and I am thankful for both. Thank you everyone!
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Count me in for beta testing or being an early adopter. I have a CMX 2 as well as a CMX 6 as candidates for modification. I have so many issues with the electrical in my house that I had layers upon layers of power tweaks. For everyone's head scratching or laughing pleasure here is what I did.
Upgraded PS Audio Decora outlet -> CMX-2 with Pangea AC 9 power cord -> modified Isolation Transformer -> Belkin Power strip.
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Here is what a customer of mine has to say: Unit came a day early. This unit definitely works. Took the Majik Buss from an audible buzz I could hear across the room to one that you have to put your ear up to the unit to hear anything. Much better.
Now, all I need to do is figure out how to get the compressor on a wine fridge and larger fridge to not make so much noise. That is all I can hear now."
I told him to drink all of the wine and then turn that one off.
He had just finished a major remodel and almost everything that he installed in the house was a potential source of DC... especially the induction range.
I've been slammed in the shop now that my back is better and will do the first installment on the CMX-2 tonight or tomorrow.
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Dave, that's pretty much the same result I've had with the CMX-2. I can now just barely hear the Uber buzz and even then, only if I get down on the floor next to it. Seems like a pretty inexpensive way to deal with the problem.
Now, what I haven't really attempted to see is if it is having any affect on sound quality. I don't notice any issues but trying to switch it in and out of circuit is a royal pain so just haven't done so (please don't take away my AN credentials ;-)
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OK, I've tried everything I can think of to post a picture from my computer on this threat.
Any ideas?
HELP!
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Dave,
Click the additional options and use the Browse to get the file to attach. Works on IE11.
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Dave,
Click the additional options and use the Browse to get the file to attach. Works on IE11.
Thanks, Rich. We'll see if OS X 10.10.5 works, too.
It'll be headed to you this week... really.
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Thanks, Rich. I at least got an attachment so we can see what will be the mod topic! :thumb:
More tonight. Off to the shop.
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Dave,
Glad it worked.
Check email about the BB.
Best,
Rich
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OK, I'm home riding out some oral surgery and this is the time to begin the discussion of tweaking a CMX-2 for better (YMMV) performance in a high performance audio system or a ROTM system that belongs to a true listener than can hear everything.
Here is the obligatory disclaimer: DO NOT take the modifications that I have laid out lightly. Electrical devices are like weapons: always assume that they are loaded and/or energized. If you are not comfortable with your soldering (especially unsoldering) skills, find someone who is. Always observe marked polarity. Never, never, never insert a polarized capacitor in the circuit backwards. There is an amazing amount of stuff inside an electrolytic that none of us should ever see, especially up close. Bottom line: know your abilities and your limits or you can die. Not my fault: I told you so!
Take a look at the gut shot of the CMX-2 and you will see a very high quality piece for a hundred dollar bill. The case/heatsink is bulletproof and well thought out to be functional and attractive.
Let's buck tradition (Who? Me?) we'll look at the unit from the right to left so you can see the value markings on the PC board.
The end plate: contains a standard IEC 15A connector and a 15A push to reset circuit breaker rated at 15A. The IEC could easily be replaced (or no so easily if you go for a 20A IEC) with your favorite.
Internal wiring and ground is 14a and well done - 4" lengths here.
Next comes the built in circuit fault tester. Great for someone that does not have a $5.00 version from Harbor Freight, but this is the first thing I would gut. Take out the LEDs, D1-D4 and remove R1 - R3.
Next we come to the input filter / first stage of the DC blocker. It is 2 - .47ufd surrounding a 2.5mH common mode choke. There are 4 - .001ufd caps that couple the power rails to ground before and after the choke... all in an attempt to kill incoming RFI. The major problem here is that the choke is comprised of 14 turns of 15a wire. That is roughly 40" of wire with a resistance of 0.01 ohm. Not bad, BUT there are 25A 12ga 2.5mH common mode chokes that have a series resistance of of 0.004 ohm. That is less of an importance than the fact that the 12ga choke is epoxy potted and stiff wire whereas the wire on the choke in the CMX-2 is free to vibrate. Don't want to change the choke? at least hot glue or other wise immobilize the windings on the choke. Magnetostriction and the distortion/noise it makes is a real deal even if small.
After the second 0.47ufd cap are 2 - 470ufd caps that form the next leg of the DC trap They are rated at 16V on the board, but the ones installed in my unit are 10V. DC voltage will run much lower than 10V, but there is just something about the implied security that a 16V cap brings. These should be replaced by low leakage capacitors of your choice with 1000ufd to 1500ufd @ 16V.
In the middle of the blank space you can see the leads for the bridges that are the brains of the DC elimination. These are 50A 600V devices. Combined with the heatsink case reliability should be stellar. The standard KBPC5006W has a reverse recovery time (Trr) of 1-2 microseconds, i.e. a general purpose bridge. I scored some IXYS (one of my favorite diode companies) VBE 55-06 bridges that are 55A 600V packages with a Trr of 35 nano seconds. It is a much lower noise, more efficient bridge to use here. Pinout appears to be identical between the two.
Next comes another filter/blocking filter with the same values as the first bunch. Also are 2 - 470K 1W resistors as safety resistors to drain the onboard capacitance when the CMX-2 is disconnected. There is no on-off switch. Keep the resistors and replace the capacitors just like before.
Last, but not least is a 20A receptacle than can be easily replaced like the inlet.
At first glance the circuit board traces look a tad on the thin side until we notice all of the through hole trace ties that join the top and bottom traces on the board. This not only doubles the conductor cross-section, but increases the capacitance in the AC path to help kill noise and reduce eddy currents.
Pretty much a steal for $99.00 + shipping. Add $35.00 for the bridges, $13.00 - $15.00 for a new CMC - or not - 5 bucks for little caps and stuff and then whatever you want for inlet and outlets and you too can have a marginally approved (by the high $$$ guys :-| ) DC blocker.
OR: you can leave it well enough alone and still enjoy the music.
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OR: you can leave it well enough alone and still enjoy the music.
Come on, what fun is that? 8)
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All kidding aside, my wife had oral surgery last Sat and she was a basket case for three days. Hope you are feeling better soon.
Do you think this unit could handle the transient draw of a large power amp or should it be limited to use on lower wattage more steady state loads like preamps and CD players?
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All kidding aside, my wife had oral surgery last Sat and she was a basket case for three days. Hope you are feeling better soon.
Do you think this unit could handle the transient draw of a large power amp or should it be limited to use on lower wattage more steady state loads like preamps and CD players?
Thanks. This is the second time in two weeks in prep for an extensive bridge rework without killing my will to live. Last time Gayle says: "Did you hear that?" while reading that evening. I said "Whamph?" She said : "Silence". Life can be cruel...
It all depends on what you mean by a large power amp. I SS amp will draw a ton of cueing on loud LF transients, while most tube amp's draw will be almost an order of magnitude less.
I think that one with a replaced CMC will do for 98% of amps out there. I wouldn't plug a solid state Class A 200W amp into one if you have low sensitivity speakers. That might take a bit more of a worker in the terms of trace capacity.
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Thanks for the DIY recipe Dave! Sounds like a fun and worthwhile project. Feel better!
Rich
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Thanks for the DIY recipe Dave! Sounds like a fun and worthwhile project. Feel better!
Rich
Since DC is becoming a major issue it seemed like the best thing to do. It is inexpensive, well laid out and, by all accounts, works well with minimal coloration. The mods I have laid out are a very good start towards transparency and enhanced dynamics.
Thanks for the well wishes, Rich.
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That's why I have an Uber and Digi buss, Dave did all the work for me. :shock: :thumb: I just sit back, sip a beer and listen. :D
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That's why I have an Uber and Digi buss, Dave did all the work for me. :shock: :thumb: I just sit back, sip a beer and listen. :D
:beer: