[wushuliu]

I know this tweak used to be discussed at AC back in the day. I've been using the 193L and M for several years now. It is by far the best tweak/accessory for video I've ever tried. The image quality for TVs and DVD/BR is astounding. This time I gave it a go with my W1070 projector. Here's my post from AVS:

Have been enjoying my 1070 for a couple months so I decided to take things up a notch and use one of my diy power conditioners that I've used with Video gear for the past few years. It's the Hammond 193L/M choke plugged in the wall trick based off a well known and expensive power conditioner. Was very popular in diy circles for a while.

And for good reason. The 1070 looks AWESOME now. The blacks are sumptuous and rich, colors are saturated, greater detail. I could go on and on. I've used these chokes for a long time so I've gotten used to them, so seeing what they do with a new component like the 1070 only re-affirmed how amazing they work. Best of all it's visual so there's no mistaking. It's not subtle. It's amazing.

Unfortunately it IS DIY and although ridiculously easy to try out for oneself it does involve mains voltages which is why it hasn't taken off beyond the fringes. The chokes themselves have also doubled in price over the last few years so it's a $90 tweak not the $40 or so it used to be. Still, it beats the $1000 and up retail option.

EDIT: Just checked and Parts Express has the 193M for half price! Link added

[richidoo]

Link

[wushuliu]

Link

Whoops. Thank you.

[Big Red Machine]

Thanks for the reminder about these.  Had some years ago.  Just ordered 2 more.

[jtwrace]

Is there a DIY thread from back in the day?  Anyone know? 

[wushuliu]

Is there a DIY thread from back in the day?  Anyone know?

There have been a lot more since then but this is the original thread I believe:

http://www.audiocircle.com/index.php?topic=10310.40

I don't know if there was much discussion regarding the visual side. I found that part out over at audio asylum some time back; only later did I realize there were threads here at AC (that was how I discovered AC in fact).

[jtwrace]

Thanks.  You literally plug the thing into the wall where your equipment goes.      Seems way easy.  Never did see if anyone uses a fuse or not...I can't imagine not using one. 

[wushuliu]

Thanks.  You literally plug the thing into the wall where your equipment goes.      Seems way easy.  Never did see if anyone uses a fuse or not...I can't imagine not using one.

Don't think I've ever read of anything bad happening with a choke but I've read comments over at audio asylum saying that a fuse is recommended if one feels unsure. The choke wires are on the thin side so although plugging straight to the wall is doable an enclosure with an IEC like HTCoz did at the end of linked thread would be better or soldering on proper rated wires a couple feet long and then add the plug, etc. Especially if there are pets, kids, etc.

[Speedskater]

I must be missing something?
What do a choke designed for high voltage, low current DC power supplies have to to with AC line power?
The old linked thread is way to long on posts and way to short on safe useable information.

[wushuliu]

I must be missing something?
What do a choke designed for high voltage, low current DC power supplies have to to with AC line power?
The old linked thread is way to long on posts and way to short on safe useable information.

Then feel free to do a search on the many other posts regarding it available both here and elsewhere.

[wushuliu]

For those averse to the search function:

http://www.audiocircle.com/index.php?topic=53953.0

I borrowed a pair of 193m's from Big Red Machine to try with my SS Mono amps, and tried searching for an answer but no luck.   

Both chokes have a pigtail thingy, and i am using two outlets (one for each amp).  It looks like the pigtail plugs into the amp, amp power cord to the end that plugs into the amp, and I assume the other end is where the choke would plug into?   

However, is it appears some people plug the choke into the same outlet as the amp.  I'm not sure what to do, any help would be greatly appreciated.

Pete is out of town, so I can't ask him.  I will be returning the chokes next week and would like to be sure I went about things the correct way.

Mark

As you probably already figured out you put the leads on the choke, thingies, in a male a/c industrial grade plug. I got mine at Lowes for around $9, which are returnable if the chokes don't meet your expectations.

Mine just has two black wires; one goes to the line plug terminal and one to the neutral plug terminal.

Lots of other posts all over.

[Speedskater]

OK, so I read the linked thread, and I still don't understand any of it.

[JohnR]

I think the choke is across the line, not in series. I'm not sure why, but that was what I gathered as the connection.

[*Scotty*]

The choke or unused power transformer with the secondaries unconnected and insulated is connected across the line in parallel with the load.
 As the load draws more current the line voltage tends to sag, when the voltage drops the magnetic field in the choke collapses across the core and a current is induced which acts to keep the AC line from sagging. The same thing happens in a cars' coil. The collapsing magnetic field induces a current to flow out of the coil, same principle at work.
 In effect the choke in parallel with the load stores some energy in the magnetic field and releases it on a near instantaneous basis as transient current demands from the load occur. This is like having a much larger transformer in the power supply of the amplifier. Also for some reason a choke helps out front end equipment operating at line level where it really shouldn't matter, go figure.
If you have a spare transformer lying around 500watts in size or larger it is a cheap tweak to try.
Scotty

[barrows]

OK, so I read the linked thread, and I still don't understand any of it.

Seems to me that one would get much more bang for the buck out of a nice choke like this by using it for its intended purpose:  Put it inside a component, in series with a high voltage (tube) DC supply, where it will block a lot of noise.  Using it in parallel with the H/N of the AC line seems to me like it would have little, to no, effect.  Much like the nonsense of the Richard Gray products ("electric flywheel", please).  For any transformer to store significant energy in its magnetic field, it would have to be enormous.  If one is concerned about voltage sag in one's system, a large capacity AC regenerator is what you need, as it has a large C supply and active output stage which allows it to hold the line voltage constant even under heavy, and fast, transient current demands.

[Quiet Earth]

Wow, this is a really old tweak, and a good one IMO. I'm kind of surprised that some of the regulars here have never heard about it. Here are two of many posts from AudioAsylum, which try to explain what is going on with a choke across the AC line :
http://db.audioasylum.com/mhtml/m.html?forum=tweaks&n=146122&highlight=Hammond+193&r=&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dtweaks%26searchtext%3DHammond%2B193

http://www.audioasylum.com/audio/tweaks/messages/17/172219.html

As for the fuse, Richard Gray used to supply their units with a fuse. I think they have moved to a magnetic circuit breaker now. This is probably the only way they can sell the product UL listed.

[*Scotty*]

Back in the Forties this was called a slave inductor. This concept has been around a very long time.
Scotty

[barrows]

Wow, this is a really old tweak, and a good one IMO. I'm kind of surprised that some of the regulars here have never heard about it. Here are two of many posts from AudioAsylum, which try to explain what is going on with a choke across the AC line :
http://db.audioasylum.com/mhtml/m.html?forum=tweaks&n=146122&highlight=Hammond+193&r=&search_url=%2Fcgi%2Fsearch.mpl%3Fforum%3Dtweaks%26searchtext%3DHammond%2B193

http://www.audioasylum.com/audio/tweaks/messages/17/172219.html

As for the fuse, Richard Gray used to supply their units with a fuse. I think they have moved to a magnetic circuit breaker now. This is probably the only way they can sell the product UL listed.

here is a quote from Al S. from the above link:

"These devices have significant low frequency winding resistance (57 ohms for the 193L and 63 ohms for the 193M), so they do not present a short-circuit to high frequency noise. They appear to work by damping high frequency resonances with the winding resistance, as the core behavior drops out above about 5 KHz."

Now Al is a pretty knowledgable dude, and the wording above does not inspire much confidence in how a choke used in parallel "appear(s) to work".  Or if it really does anything at all.   

[*Scotty*]

The primaries on transformers I use have about 2 ohms of resistance measured with a Multimeter. Being a cheapskate I have not spent the money on one of the Hammond chokes.
I have been using the transformers as slave inducators for about 20 years and they have been a cheap functional tweak that made an overall improvement to the sound of the system. I tend to grade these things on a weight basis. I use a couple of 26lb E core transformers in parallel with the power amp and 12lb. E core on the front end gear. Past a certain weight you hit a point of diminishing returns. Two 26 pounders on the power amp is probably past the point but I have them so why not use them.
Scotty

[wushuliu]

here is a quote from Al S. from the above link:

"These devices have significant low frequency winding resistance (57 ohms for the 193L and 63 ohms for the 193M), so they do not present a short-circuit to high frequency noise. They appear to work by damping high frequency resonances with the winding resistance, as the core behavior drops out above about 5 KHz."

Now Al is a pretty knowledgable dude, and the wording above does not inspire much confidence in how a choke used in parallel "appear(s) to work".  Or if it really does anything at all.

Five seconds of google returned this from Al Sekela (RIP):

Simply wire it to a line cord and plug it in to your audio circuit. It will improve the sound if you have RF noise on the line.
You can spend a lot more money for slightly better performance.

or

I don't have a 193L handy, but I do have a 193H. I connected it to a resistor and a signal generator, and swept the frequency. The choke impedance rises with frequency to 5 KHz, then it drops.

Many power transformers I've tested this way have a maximum frequency in the 40 to 100 KHz range, so Alan is correct that the Hammond chokes are superior as AC noise filters. However, the real reason they work so well is that their cores are not built for wide frequency response

or his very first post on the issue from 2006:

I found that I have a pair of Hammond 193H chokes acquired for another project. These are 200 mA instead of 300 mA, but are the same inductance (5 H). The DC resistance is 65 ohms instead of 57 ohms.
I wired these up with junk cords and plugged them in to the circuits feeding my Atma-Sphere MA-1 monoblocks. There was an immediate improvement in the midrange. It became easier to hear the separate piano strings in the decay of notes on Shirley Horn's _You Won't Forget Me_.

In fact there are dozens of posts with Sekela advising on the chokes for some 3 or 4 years on AA although he eventually preferred a separate method for power conditioning. Those methods however are more related to audio. I am focusing on the choke because of the near immediate and quite visible effect on visual components.