DIY power conditioner? How to fix dirty AC in shared electrical environment

[Paul Birkeland]

The isolation transformer is most certainly what's called for in your application.  There are also some designs out there that can block DC before it comes into your isolation transformer.

Do your best to find an isolation transformer that isn't toroidal.  You want absolutely horrid bandwidth more than a decade or two over 60Hz.  That will knock out the RF/AF bleed pretty substantially.  List off all the gear you want to put on this thing, then we can help you size the transformer properly.

If you want balanced power, your isolation transformer needs a center tap on the secondary.

Filtering before the isolation transformer can be obtained simply by buying a fancy IEC receptacle that has it built in and sized according to your approximate draw.  More filtering can be added after the ISO transformer, and you may find that specific filtering for outlets feeding switch-mode power supplies or digital devices is a nice idea.  Frankly, after you've bought the enclosure and isolation transformer, none of this other filtering stuff is going to seem particularly expensive. 

Something like a Hammond 169G will do 4A of current at 120V, and it has taps at the output that can help you dial in 120V regardless of what's coming into the primary.  It will not, however, provide balanced power.  Putting a Hammond 1182N60 after the 169G will give you the center tap you need to obtain balanced power.  Such an arrangement has been suggested in the past, and if your wallet can afford it and your floor joists can support it, it seems to be worth a shot!

[Tubejack]

FWIW, I went to a TRIPP-LITE LCR-2400 a few years back and I have been very pleased with it's performance vs. cost.  (<$300)

https://www.tripplite.com/2400w-120v-3u-rack-mount-power-conditioner-automatic-voltage-regulation-avr-ac-surge-protection-14-outlets~LCR2400/

When we lived in El Paso, particularly during the "hot" months, the load on the transformer that serviced 5 houses fluctuated greatly, as AC units and pool pumps kicked in and out.   This unit significantly improved line voltage stability performance, and related spike and noise suppression.

I added a PS Audio IPS-9000 after the LCR-2400, but that was mainly for outlet control, and the geek factor of being able to set delay turn off and turn on times, as well as monitor performance, with a web interface.  The LCR-2400 does the line voltage heavy lifting ...... I believe the IPS-9000 has been retired by PS Audio  http://www.psaudio.com/wp-content/uploads/2011/11/PowerPlay-80001.pdf

[ewingfox]

Thank you everyone for the input!

We worked pretty hard to try ensure that the loud hum (100-120hz) and a bit of high frequency fizz was coming from the power and wasn't a source issue.  This is for a pretty low-fi active studio monitor system that is taking signal directly from an SMSL M8 DAC with linear power supply.  The house power is completely atrocious, but for now (and with no tubes in the mix yet) we have gotten it to a livable level

Turns out the Presonus 5" active monitors have a case of bad case of gain-itis - the line level from the SMSL DAC was hot enough that using the default gain  (it is a rotary adjustment on the monitor) it was amplifying some signal noise (the fizz) and the ~100hz noise from the power supply, and the local country music station.  By dropping the gain setting on the monitors to nearly off - when you back the dial all the way back it goes from low to off - and using a much higher source setting (at the digital level) we were able to improve the signal to noise ratio. Combining this with a Pyle 10 outlet, 2U sequential power /voltage stabilizer/ line filter that we had on hand seems to be enough.

Still a bit of hum when there is no music playing out of one channel (the amp is not the best quality for sure in those, but for under $200/per what do you want?) and he is a happy camper.

What does this mean? Was this thread for naught?  NO!

Once we build the tube setup, we are going to have to address the power quality issues.  I'm thinking medical grade outlets on a dedicated circuit, home brew IS Trans, center tapped for balanced power as an option, with something like a PS unit for outlet control and additional filtering ahead of the BeePree (on order) , DAC and SS amp.  Once we have a better handle on the power draw for the system, expect me to be back kneeling at the BH alter

I am a pretty smart guy - I spend most of my day being a trusted expert at work, and people pay me to be  trusted expert in my consulting business.  I come here, and I am instantly reminded how phenomenal the talent, intelligence and experience the Bottlehead Community has collectively in its ranks.  It is humbling and I am incredibly thankful for how generous everyone is with their time and knowledge. I am happy to take the title of permanent Newb

[Paul Joppa]

It's a pretty good creative community. One of the characteristics of good creative communities is "each one teach one" - you may start as a noob, learning from the more experienced. But as soon as you learn something, you will recognize when someone else is in need of what you have learned, so you share your knowledge. The return on investment in sharing knowledge is a robust community, where everyone is both learning and teaching.

[EricS]

I've been lurking around here for a while, mostly trying to learn about tube amps and just found this thread.  I've already learned quite a bit from many of you, so thank you.

It seems that this problem has been solved, but wanted to share my effort at power filtration for others.  My power box serves a number of functions for my theater system.  It is installed on its own dedicated 30A feed from my breaker box, powers my entire theater system, has a two-stage remote control power up, features two separate turn on delay circuits, has multiple AC line noise filters, has four stages of spike and surge protection,  and provides balanced power to the preamp, CD, DVD, and DAC.

[edit] Hmmm... looks like I'm not allowed to post external links on my first post...  I edited my profile to include the URL of my webpage,  click on the "AC Power Distribution, Sequencer, and Filter" link.

Eric

[ewingfox]

Interesting update to the power conditioning issues!

So - it turns out that the power in the house in question was DEAD SILENT.  The issue was a component in the room that was pumping out RF and also some line noise back into the house circuit - some third party phone system gadget for internet phone service that ties back into the home POTS lines.  This in combination with a pair of presonus studio monitors that have a track record for a nasty high Frq hiss lead us down this long road.

Thank you everyone for the fantastic information - I always say the only stupid question is the one you have to ask twice!!  I am still keeping my eye out for a honking isolation transformer at local swaps and online so I might build up a power conditioning setup anyway just for the experience if I can find the parts on the cheap.

Take care,

Ewing