Hi guys and gals. I hoped members here might enjoy seeing an AC mains line filter from ATL Audio I just finished putting together. Having been requested by a forum member to post about this from a discussion in another thread, I decided to do so as promised. Let me explain how this came about. In the other thread I was sharing the progress I had been making on an Aikido tube preamp amp I am building and when I posted pictures of my "power supply" questions were asked. I had been trying to incorporate all of the elements of this AC mains line filter before the power supply of the preamp. As I was nearing completion of the mockup stage I was becoming less and less satisfied with the way it looked and how jam packed the housing was becoming. It would not have been fun to work on, if need be. That brought me to the decision to pull those boards out and create a full separate AC main line filter. Let me start by saying Aleksandar of ATL Audio doesn't offer the line filter as a kit, but my numerous previ0us dealings with him and him knowing I love to build my own electronics led me to acquiring just the boards from him. Eventually after pulling the boards out of the preamp I also acquired the case and other pieces from him. Here is a link to what I assembled: AC Mains Line Power Filter LPF-6000 – ATL Audio Ltd. In the photo below you see the case and the thick front and rear panels. In the photo I have already installed the AC outlets on the rear panel and the rear panel is already installed on the case. Everything goes together without a problem. In the below photo are the boards for the filter. The top 2 boards are actually (4) 2nd stage emi/rfi filters designed for almost everything except a power amp. Power amps tend to draw too much power for these filters. The bottom left board is a 2 function board consisting of a DC blocker circuit and the 1st stage emi/rfi filter. The DC blocker circuit, as the name suggests, block DC voltage on the AC line which is a source of noise. DC can be generated from toroid transformers but is certainly not the only thing in your household that generates DC on the AC lines. The 1st stage emi/rfi filter is similar to the 2nd stage but IS rated for power amps....up to 15 amps total. The corner filter frequency is different between the 1st and 2nd stage as well. The bottom right board is the inlet board and serves 2 functions. First it protects against surges buy using varistors between all the different legs of the AC mains. Secondly there is a bridge rectifier circuit to create a DC voltage to trigger a relay when you want to turn the unit on. This next picture has all of the boards mounted (including half of a 2nd stage emi/rfi output board from a previous build) mounted in the case. Also I have the outlet grounds connected to the ground bus bar. Basically the finished product. 2 things to note though. I have to get another PCB header assembly for the LED output from the first board. I can't stand dealing with the crimp on header pins and 22ga wire. Secondly I connect the grounds on the outputs of the 2nd stage emi/rfi boards, Aleksandar does not. Having spoken to him about this before, he believes it closes in the soundstage and limits dynamics somewhat. It does, to a very small degree. I however believe on my system grounding the outputs of the 2nd stage does a better job of cleaning noise off of the line. Depending on your system, you may get better results one way or the other. You definitely do want to ground the DC blocker/1st stage board and the inlet/relay board regardless. Lastly, a picture of the finished product from the front. I will also note he supplies a red LED. I swap those out for the blue you see so it matches the rest of my system. In my previous builds of 2 smaller versions of this, I added a 12v output trigger for my amplifiers. If anyone is interested I can provide details on how I did this. Hopefully you all found this interesting and useful. Feel free to ask questions if you care to.
Nice work. I have to admit, I'm quite ignorant in the area of line conditioning although I think I have a handle on DC blocking. Do you think something like this is helpful in most cases or only if there are noticeable/measurable issues on the power line? What's the audible effect once cleaned up?
Nice job! Just a minor clarification, toroid transformers don't cause DC on the AC line but they are very susceptible to the effect since there is no air gap in the core, and it can easily saturate and vibrate if DC current is present in the primary winding. The DC is a result of power appliances that draw current from only one half of the AC waveform, such as hair dryers and many types of lighting with adjustable brightness. This imbalance causes distortion of the AC wave and a small resulting DC component. Also just curious about the capacitors, on the link you provided for the assembled unit, it looks like they are using Milflex X1 rated capacitors, are those Wima capacitors in your unit? They don't look like the X1 rated types. Edit: Oh, I see Wima does have plastic film X1 caps with red casings in the MKP series, nevermind, I was only familiar with the paper film MP series. BTW, the MP series are pretty nice sounding for low cost caps, in the sizes up to 0.1uF, the vacuum epoxy encapsulation creates pretty much a solid block, and they sound very neutral. Above that, I don't think the encapsulation is to the same extent, they definitely aren't as nice sounding, but I've used tons of the MP3-X2 series in 0.1uF for power supply bypasses in analog gear.
Thanks! I think it would be helpful in almost all cases. The level of improvement however I think will vary depending on the quality of the system involved, the quality of the AC mains coming into your home and how many electrical appliances that are further contributing to the noise on the AC mains. I think a lot of folks wouldn't necessarily notice that they have noise on the AC until you take that noise away. Then you will surely notice it. I will give you 2 examples at opposite ends of the spectrum. My system consist of Hi Res audio from my computer, an active digital crossover with FIR time alignment/phase correction, 4 Halo A23+ power amp (tri amping and sub), and some very good floor-standing speakers and a transmission line subwoofer that plays flat to the low 20Hz range. That system also had a common "line conditioner" on it which I was using as a glorified power strip with delayed turn on for the power amps. The difference by removing that piece and adding (2) smaller versions of this was night and day. Wasn't just my opinion. I had my son listen to both as well without telling him which one he was listening to. He could pick it correctly 100% of the time. His descriptions of the improvements matched mine as well. At the other end of the scale I had built him a smaller version of this for his system. Computer (no high res audio), decent but small bookshelf speakers and inexpensive desktop amp bricks. The experience was even more dramatic due in part because he went from no line conditioning at all to a smaller version of the piece above. How would I describe the improvements? Tighter bass that seemed to go deeper, highs that were crisper and more detailed without becoming harsh, a sweeter midrange without sounding fake. Sound staging was wider, deeper and more 3 dimensional. But the biggest difference I could describe is what you didn't hear. Between the notes, when no music or vocals were playing you heard NOTHING which made the notes you did hear stand out more without becoming obnoxious or overbearing. I guess everyone's experience will differ but my experience has been confirmed through blind listening sessions by multiple people including some that have been musicians for 40 years. I hope that helps some.
You are of course 100% correct. The toroid transformers don't cause noise in the system but the DC noise in the AC causes them to buzz, sometimes audibly. There are a ton of home appliances and electrical devices that create noise on your AC lines. Some have DC components and some AC components. Very good eye. I had bought the boards before Aleksandar had come out with the LPF-6000 and posted the pictures and added it to his web site. I asked him about the Milflex caps, when I saw this, and this was his response. "What about the Miflex capacitors, actually they were available at some time and I bought several. Then I decided to go with the KEMETs, I haven't made a sound comparison. The number of capacitors was connected with their values." I have used the Wima MKP 10 series caps for a while now. I started using them after I saw them reviewed on this website Humble Homemade Hifi - Cap Test . That prompted me to look for Wima safety caps. I am using the MKP X2 and MKP Y2 series here. I have no idea if they sound any better than the Kemets he has in his BOM or the Milflex in the photos.
While out of scope of audio, the question I have of this thread is if Americans run on 120@60hz or 240@60hz this filter wouldn’t care it would just clean what voltage and signal is present. Now for the second question. Application to cleaning a 3 phase circuit would take for terms legs A, B, C, and ground so would you need three primary stages filter AB, AC, BC, ? Bring them back to cleaned rail legs A, B, and C then do the second of the same as the first stage as I’m more concerned about high amps my application is cleaning power after creating 3 phases through a rotary phase inverter for my cnc machine.
In America we run on 120V @60hz. This is the website I got the boards from. Bare PCB – ATL Audio Ltd. Aleksander does sell products for the worldwide market (different voltages and frequencies) but he doesn't normally sell the whole filter as a kit. His products are geared for audio applications so they are limited to 15 to 20 amps of total draw. I don't think he has anything setup for 3 phase application nor does he have anything for the amount of current draw I think you may be getting into. Having said that I would send him an email and pose the questions to him. He is a super nice guy and may have some work arounds for you. The email is listed on the contact page of the link above. I hope that helps.
Hi Bluezee, I appreciate you writing about this power conditioner from ATL Audio b/c I am very interested in knowing more about their conditioners and company. There is very little information out three about this company and its difficult to make a purchasing decision when you can’t hear the products and they are not inexpensive. Thanks for sharing about the difference on the 1st and 2nd stage filter differences. I noted that you have a 1st stage emi/rfi filter for your amp but I do not see that as an option on any models on their website? In your system it looks like you have the 1st stage filter dedicated to outlet #2 for the amplifier. I have read the difficult part of evaluating line conditioners is it is really system dependent so without trying the product in your system it may not be a good fit. For example, some have claimed amplifiers after power conditioning may limit their peak power potential. This is why as you mentioned that the 2nd stage filter was not used for your amplifier outlet. So how was your overall experience with this vendor? Were there any challenges in receiving the shipping from Bulgaria? Hidden fees? What is your overall satisfaction with the purchase a few months later? The Puritan PSM156 is another power line conditioner that I am considering as a potential power conditioner. I may be able to audition this model. Any feedback from your experience would be appreciate. Thank you.
I appreciate you writing about this power conditioner from ATL Audio b/c I am very interested in knowing more about their conditioners and company. There is very little information out three about this company and its difficult to make a purchasing decision when you can’t hear the products and they are not inexpensive. Thanks for sharing about the difference on the 1st and 2nd stage filter differences. Thanks. This forum was created so we could share information amongst other crazy, and obsessed enthusiasts. Lol I noted that you have a 1st stage emi/rfi filter for your amp but I do not see that as an option on any models on their website? In your system it looks like you have the 1st stage filter dedicated to outlet #2 for the amplifier. The emi/rfi 1st stage/dc blocker board (the very top board in the 2nd and 3rd photos) actually feeds outlet #1 directly and also all the 2nd stage emi/rfi boards. This includes the 2nd stage filter board with the gray capacitors. These were just left over from a previous build. I bought the individual bare boards, though some are not listed on his website. I'm sure he would sell you the boards just like he did for me. His email address is listed on the website. I have read the difficult part of evaluating line conditioners is it is really system dependent so without trying the product in your system it may not be a good fit. For example, some have claimed amplifiers after power conditioning may limit their peak power potential. This is why as you mentioned that the 2nd stage filter was not used for your amplifier outlet. Correct. Too much filtering on high current devices can be detrimental. In their listening sessions they thought the amplifiers sounded best with only 1 stage of filtering. The second reason is the 2nd stage filters are not rated for a full 15 amps like the first stage. So how was your overall experience with this vendor? Were there any challenges in receiving the shipping from Bulgaria? Hidden fees? What is your overall satisfaction with the purchase a few months later? The Puritan PSM156 is another power line conditioner that I am considering as a potential power conditioner. I may be able to audition this model. Any feedback from your experience would be appreciate. Thank you. Dealing with Aleksander was a joy. He endured far more questions than most would have put up with. Never any hidden fees. Shipping was by simple post/mail so it was very reasonable though it did take some time. Week...week and a half if I remember correctly. My opinion of the product has only been confirmed over the last couple of months. I have no experience with the Puritan model, but if you can audition it in your system....that would be ideal.
Assembly was very straight forward. He sells a lot of his boards as bare boards or tested/assembled boards. If you get the assembled boards then it's just a matter of a couple of screws and a bit of wire. I think almost anyone could do it at that point and save a lot of money. With the big, high res photos on his website you have all you need at that point.
Hi Bluezee, I just thought of a follow up question after reading your post again regarding what I belief you describe as a power sequencer which allows your amps to be powered on last. I have as well a power sequencer so I don't have to turn on and off each component at a time and the amps don't harm the speakers. So with all six outlets in your system coming on all at once do you have a work around to sequence the power coming on for the power conditioners outlets i.e. power amps on last? Thank you.
In one system the power amp is a tube amp and it takes about a minute to come up to operating voltages all on its own. In the second system, the 4 Halo amps also have a built in delayed start. The line conditioners don't have that feature own there own. I do believe others sell a time delay board though.
