Anyone interested in a low cost DC blocker box?

mark funk · « **Reply #60 on:** 24 Jan 2013, 10:04 pm »

Frank, I'll take one also. But I has one of those dam IEC things on it!

Barry_NJ · « **Reply #61 on:** 24 Jan 2013, 10:27 pm »

Quote from: avahifi on 24 Jan 2013, 03:23 pm

Even to do the DC blocker in a stock chassis box, we still would need to have a metal shop do the metal work for the IEC input and line fuse, the AC output hardware, and add all the necessary mounting holes for the other stuff. By the time we pay to have all that done, they might as well just do the entire enclosure and the cost of the raw metal is not all that significant, its the tooling, setup, and handling time that is expensive.

If we were pretty sure of 10 orders, we could do them at $125 each.

Regards,

Frank Van Alstine

I'd be up for one, maybe 2, and I'll send the money up front. I'd love to get the transformers in my power amps to quit their humming!

roscoeiii · « **Reply #62 on:** 24 Jan 2013, 11:00 pm »

Heck, I am not having DC on the line problems in my current place, but I am tempted anyway...

Speedskater · « **Reply #63 on:** 25 Jan 2013, 12:34 am »

For those interested in learning more or just getting more confused, a few links:

DC Blocking

Variations of DC Main Filter against buzzing Toroid Transformers - what is the right?
http://www.diyaudio.com/forums/power-supplies/161428-variations-dc-main-filter-against-buzzing-toroid-transformers-what-right.html
100 posts

dc filter
http://www.diyaudio.com/forums/solid-state/2080-dc-filter.html
298 posts

Noisy transformer
http://www.diyaudio.com/forums/power-supplies/149330-noisy-transformer.html
43 posts

Powerline DC blocking and conditioning circuit
http://www.diyaudio.com/forums/power-supplies/83784-powerline-dc-blocking-conditioning-circuit.html
83 posts

also see:
Blocking Mains DC Offset
http://sound.westhost.com/articles/xfmr-dc.htm

Wolfman · « **Reply #64 on:** 25 Jan 2013, 02:38 am »

I read through the thread and saw that this blocker was used on a 20 amp line. If it'll handle a full 20 amps unlike some of the others out there,I'm definitely in for one,sir!

Mountain-ear · « **Reply #65 on:** 25 Jan 2013, 03:48 am »

Count me in! This is an easy one. Let me know when you want the $. It sounds like a bargain.

Steve

munosmario · « **Reply #66 on:** 25 Jan 2013, 01:24 pm »

Quote from: Speedskater on 25 Jan 2013, 12:34 am

For those interested in learning more or just getting more confused, a few links.............

Speedskater, in one of those links you warn that finding DC in modern AC power lines is unlikely, implying that cause for transformer humming can be a different one. IME you are absolutely right. I used to experience mechanical vibration in all the transformers in my two main systems. Particularly my six SET mono blocks: four Cary 805’s in a bi-amped system and two custom-made Japanese units (handmade pure silver output transformers) in a single amp system. I thought it was DC in the AC line but that was not the case. My problem was a clipped AC sine wave due to a faulty street transformer. I had the power quality analyzed by the utility. They came to my home with measuring instruments including an oscilloscope. Instead of DC (zero DC presence) they discovered that my AC power’s sine wave signal was clipped due to a fault in the street transformer feeding my house. The clipped sine wave was causing mechanical vibration in all of my systems’ many transformers. However, despite the technicians’ request, the utility refused to change the street transformer...a bit costly and because the utility's service contract does not guarantee perfect sine wave, plus I happened to be the only one complaining about the problem.

My solution was to go the power regeneration route (I first tried a Humbuster but it did nothing). I currently own three quality units from reputable manufacturers serving my systems: 1 from PS Audio and 2 from Pure Power. The PS Audio is a P5 Power Plant and the PurePower ones are APS PurePower models 2000 &1050. As I am sure you very well know, these are AC regenerators, not just power conditioners. They basically reconstruct the AC to a noiseless, perfect sine wave (a detailed explanation can be found in the web pages for PS Audio Power Plants and/or APS PurePower). In any event, although seemingly expensive, this resulted into a very effective solution….much less expensive and cumbersome than trying to implement an off-the-grid all battery power solution (no need to elaborate on additional actual/subjective sonic benefit, suffice it to say that units perform as claimed).

Mario

Speedskater · « **Reply #67 on:** 25 Jan 2013, 03:22 pm »

A interesting paper on the subject:

MEASURING ACOUSTIC NOISE EMITTED BY POWER TRANSFORMERS
Menno van der Veen

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/MEASURING_ACOUSTIC_NOISE_EMITTED_BY_POWER.pdf

werd · « **Reply #68 on:** 28 Jan 2013, 05:35 pm »

Just out of curiosity Frank, If this (dc blocker) doesn't work what do you think the problem is? I have a sub that does this. Initially it was the servo link from the amp to the sub that came less that made it buzz pretty good but it still buzzes even after fixed.

sfox7076 · « **Reply #69 on:** 30 Jan 2013, 01:01 pm »

I will take one.

avahifi · « **Reply #70 on:** 30 Jan 2013, 02:11 pm »

Werd, the normal process to locate a system problem of any sort is to first simplify the system.

In your case, disconnect all inputs from the powered subwoofer and plug it into AC separately from anything else in the system and find out if it "buzzes" then.

This will tell you if the issue is originating in the subwoofer or is an issue with interfacing it with the rest of your system.

If it is an interface issue, then start adding components one at a time until the issue reappears.

Start with the driving preamplifier alone and only with the interconnect cables between the preamp and the subwoofer.

Make all changes with the equipment turned off and unplugged to AC.

Let me know when the issue returns
Frank

gregcss · « **Reply #71 on:** 3 Feb 2013, 06:30 pm »

Would this clear up the hum/buzz from a linear power supply? I have Bolder modded Jerome power supply.

Folsom · « **Reply #72 on:** 3 Feb 2013, 07:01 pm »

Quote from: gregcss on 3 Feb 2013, 06:30 pm

Would this clear up the hum/buzz from a linear power supply? I have Bolder modded Jerome power supply.

It would, if DC is the problem.

Mountain-ear · « **Reply #73 on:** 12 Feb 2013, 01:23 am »

Frank -

Any further thoughts on this project? I went through the list, and it looks like there are 15 expressions of interest (Jackman, Resonance, JerryM, Underdawg, Rollo, Big Red Machine, Martyo, Devil Doc, 2Gumby2, ALN, Mark Funk, Barry NJ, SFOX 7076, Rocket, and yours truly). I think your minimum quantity was 10 so it looks like there's enough interest to reach that level even if some folks ultimately decide not to order.

Still hoping for an AVA solution before I start looking at alternatives.

Thanks.

Steve

avahifi · « **Reply #74 on:** 12 Feb 2013, 02:23 pm »

We actually ordered a short run of DC blocker enclosures that should be ready for us any day now.

We will report here at AC when they are available.

Thanks for your interest.

Frank

rcag_ils · « **Reply #75 on:** 13 Feb 2013, 04:22 am »

Since I don't come to the Circle as much any more, is it too late to put in for a "DC blocker"?

mtruong34 · « **Reply #76 on:** 13 Feb 2013, 02:54 pm »

Hello,
If it's not too late, I would be interested in the DC Blocker as well.

--Mike

avahifi · « **Reply #77 on:** 20 Feb 2013, 07:42 pm »

We can build the AVA HumDinger (DC hum blocker now). Give us a call at 651-330-9871 if you want one.

The unit has: IEC 3 conductor AC socket in and power cord, two x 3 conductor standard AC sockets out. 10 amp slow blow fuse on the incoming AC line. Size is 6" x 2.5" x 4.5" in heavy steel chassis with black powdercoat finish.

What it will do:

Block low level DC voltage sitting on your AC power line because of other devices on your line using power asymmetrically. The low level DC tends to make toroid power transformers hum, but not limited to just toroids.

The HumDinger also has a transient surge absorber on its incoming hot circuit that will somewhat reduce turn on surge currents in your equipment, prolonging power switch and electronic component life.

Plug your power amplifier into one of its AC outlets, and your preamp or a AC terminal strip for the rest of your equipment into its other AC outlet and DC related hum will be dinged.

What the HumDinger will not do:

Provide RFI or line over voltage protection. You need a dedicated suppressor for that, the simplest being an AC outlet strip designed for computer AC line protection.

Cure hum issues causes simply by a defective noisy power transformer or hum from your speakers caused by any number of grounding or system defect issues.

Note that the 10 amp slow blow fuse is provided as a very conservative first step with this product. Under normal conditions the high current, high voltage internal diode bridges won't even get warm. We can't run our system loud enough here with a Fet Valve 600R attached to heat the HumDinger up and don't blow the fuse then either. Sustained very high current demands may get the HumDinger hot. We recommend that only a single high power amplifier be connected and turned on at any given time.

The Humdinger is inexpensive, solidly made, it works, and its available now. The price for now is $125 plus $15 shipping. Again, call us at 651-330-9871 and we will build you one promptly. Standard AVA warranty and satisfaction guarantee applies.

Frank Van Alstine

mtruong34 · « **Reply #78 on:** 20 Feb 2013, 07:51 pm »

Hello Frank,

What's the configuration to hook-up a pair of mono amps?

avahifi · « **Reply #79 on:** 20 Feb 2013, 08:18 pm »

Mono amps, how powerful are they? If you don't routinely blow the 10 amp slow blow fuse you are probably fine with just one HumDinger. Otherwise, you might need two of them. Try one first of course.

Frank