Adding a PS choke -- where did you put it?

[jrebman]

fFor those who have added the c7x choke to their Eros preamps, where did you end up placing the choke so as to not add any noise or cause any other problems with heat or whatever?

I see there are some pictures posted of how people did this, but no description, and that's what I'm looking for.

Now for the really important question: should I paint the top plate a hammertone copper or forest green (to match the Shindo amp the Eros will be paired with)?

 

[grufti]

There is really just one place where it will fit in the Eros: right next to the power supply heatsink. debk posted a picture some time ago. That placement also seems to work with regard to hum for those who have added the Triad choke right there. I would hesitate to use another choke because even the Triad is such a tight fit.

 

[Noskipallwd]

Hey Jim, as grufti said there is only one place it can fit. I mounted mine on standoffs and as close as possible to the heatsink side of the ps board. If you don't want to modify your base then you have to mount the choke with about 3 to 4 mm between the bobbin and the board. As debk stated in her post I ran a ground wire from one leg of the choke to the transformer star ground. I don't know if mine actually functions though, I just finished assembly and getting ready to do all the resistance and voltage checks, the ps and regulator tests were fine so that is a good sign. As far as what finish to use, I used copper hammertone on mine to match my Crack, with an ebony stained base. I am using gold colored tube shields and I mounted a gold colored tube protector around the 12bh7, these all match well with the copper.

Cheers,
Shawn

 

[jrebman]

Thanks Shawn and Hans.

I'm sure it will all become more apparent when I actually can see the parts all together in proximity.

As for the color, of course I was just kidding -- just trying to decide between the two. I really need to see how close of a match the green is, but either will look fine I'm sure.

Thanks both,

Jim

 

[Grainger49]

I PMd Deb to ask about her installation.  She said she needed to use a Dremel on the base because she hadn't remembered about the overlap of the base and top plate first.  I think others have gotten a nice snug fit without any woodwork.

I expect when I mount the choke for mine I will have to cut a hole in the base.  Measure once, cut twice.

 

[jrebman]

Ok, starting to make much more sense now.  No biggie as I'll eventually build a custom base for it -- maybe plyboo, walnut, or ash with an inlaid macassar ebony istrip.

I know you folks probably think it's a bit strange thinking about the cosmetics at the same time as the technology, but it's the way I work, or perhaps better stated as how I seem to be hard-wired.  One of the reasons why this stuff is just such a blast for me -- not to mention the results.

-- Jim

 

[debk]

I had to take a couple mm from the inside of the base to get it to fit.  Took just a few seconds with a dremel.

Very simple to do.

I think it perfectly normal to think about cosmetics.  I want my projects to look as great as they sound.

Deb

 

[jrebman]

Thanks, Deb.  Sounds easy enough.

And, of course the better the gear looks, the better it sounds .

-- Jim

 

[Brillo]

Just finished installing a Hammond 159M choke.  Judging from pix that debk posted, the 159M is considerably larger than the Triad C7X.  I put it next to the heat sink in the PSU board, but had to move it towards the front of the chassis a bit.  I put it on stand-offs as it straddles the vents in the chassis. There is a tiny bit of hum with volume cranked, but barely noticeable unless I put my ear right up to the speaker.  Negligible really. 

The most notable improvement is in the upper frequencies - better detail and clarity.  Very crisp, but not harsh or brittle.  A worthwhile and relatively simple upgrade, without question.  Now I need to find a way to cram this same choke into my Crack.

Chris

 

[Grainger49]

   .  .  .   There is a tiny bit of hum with volume cranked, but barely noticeable unless I put my ear right up to the speaker.  Negligible really.  .  .  . 

I kind of think this is cheating yourself.  First, this is not a good listening position.  Second it is like saying your car does 0-60 in four seconds flat if you could put in a Corvette engine. 

My opinion is that if you can't hear noise at your listening chair, you are good to go.  Audio reviewers brought us to this.

   .  .  .   Now I need to find a way to cram this same choke into my Crack.

Chris

Doc makes us say silly things like this.

 

[Brillo]

Just describing the result Grainger, and hoping to encourage others to set aside fears of hum and try this modification.  I placed the choke in a slightly different location, but with positive results. 

Frankly, I don't follow your Corvette analogy.  If there's a point in there somewhere, it's lost on me.  It's replies like this that make me think twice about posting.  Maybe that's your point?

 

[ALEXZ]

Just finished installing a Hammond 159M choke.  Judging from pix that debk posted, the 159M is considerably larger than the Triad C7X.  I put it next to the heat sink in the PSU board, but had to move it towards the front of the chassis a bit.  I put it on stand-offs as it straddles the vents in the chassis. There is a tiny bit of hum with volume cranked, but barely noticeable unless I put my ear right up to the speaker.  Negligible really.  

The most notable improvement is in the upper frequencies - better detail and clarity.  Very crisp, but not harsh or brittle.  A worthwhile and relatively simple upgrade, without question.  Now I need to find a way to cram this same choke into my Crack.

Chris

Chris,
Verify that your coupling and RIAA capacitor are connected outer foil to the lower impedance . I.e. RIAA caps connected outer foil to the ground and output caps outr foil to the plate  of the 6922.
That reduses susceptibility to hum.

 

[Noskipallwd]

Chris, I believe Grainger was trying for a little humor. I wonder if it is the Hammond choke and it's size that is causing hum. I have the Triad and the eros is dead silent. A tube phonostage is very susceptableto hum, my Cornet II has some. I feel the same as Grainger, if the hum does not exceed the surface noise from the TT then I don't worry too much. I feel the choke is a worthwhile modification.

Cheers,
Shawn

 

[Grainger49]

Nah, Chris got a PM trying to explain my off kilter slant.

I understand Chris's point, that you can't hear anything until you do something unrealistic.  I.E. turning it all the way up and putting your ear to the speaker.

That amount of hum is inconsequential.

 

[Noskipallwd]

Hey Chris, did you have any hum before the choke? The reason I ask is many builders have had complaints of noise. I don't know if I just got lucky but mine has been quiet from the start. Even with the EH tubes I could not detect any noise until I cranked the crack to about 3 oclock. I ended up using 1" standoffs to mount the choke in the crack, I am very happy with that mod as well.

Cheers,
Shawn

 

[Brillo]

No.  No noise prior to installing the choke.  Regardless, it really is negligible.  From the listening position, all is well.  I'm more concerned with my stupid refrigerator and it's constant noise than anything coming out of my system. 

 

[shelby1420]

Ha, took me two days to figure out the fridge in the garage was causing a low level buzz, annoyed the hell outta me!!!!

 

[Grainger49]

Rick is lucky, the fridge near my Seduction caused an earthshaking thump and burp to come out of my system.  It pretty much jolted me out of the listening chair every time it happened.  It is an extremely old 1950s vintage refrigerator.  Lots of current drawn when it cranks up.