[tomb]

Quote:

Originally Posted by kuroguy /img/forum/go_quote.gif First of all, thanks to the guys who put the kits, cases, and boards together. Group buys are not a way to get rich. Especially when you are machining cases by hand. Now, onto my problem. My SSMH has been working flawlessly for the last year. I recently relocated and when I set up my amp at work the left channel had a 60 cycle hum that gets louder when I move my hand near the left tube. if I touch the tube it is the loudest. If I ground my hand to the casewhile it is near the tube the hum goes away. In face, even a paperclip that touches the tip of the tube and a ground point on the case stops the humming. I switched the tubes around and the hum followed the tube. The room it is set up in has an audible 60 cycle hum without the headphones on. Is this a bad tube or a grounding issue? I suspect some aluminum foil around the tube should solve the problem, but that wouldn't be too elegant. Any comments or suggestions?

I'd have to say that if the problem followed the tube, that's pretty conclusive. Some of these tubes (not ones I've tested and rejected) have intermittent shorts. I've seen a few that changed with a little shaking.

. Just enough metal was flaking off in areas to come into contact with the pins inside - that doesn't mean you'd have to see it for it to be shorted, though.

 

[Tritonpad]

Hi everyone ^^

Just want to say thank you again : I received my ss pack this morning (considering I am French).

I hope I'll have time to solder very soon. Off course I'll tell you when it's finished.

Now I guess I am at the end of the way ^^ Just 1 thing to do : Do It Myself ^^

 

[revolink24]

Just a couple questions for tomb and/or others.

On the BOM it lists the SSMH Standoff Kit and Heatsink kit as being on Beezar.com. I'm assuming this is the heat sink kit (if not, tell me), but I can't find the standoff kit anywhere.

Also, what do you think about using the 50K - 1/4W resistors (high gain) on low impedence/high sensitivity headphones (ie Grados). Also, are there any other modifications requited for the use of the 100k (low-gain) resistors?

Thanks

 

[revolink24]

Just a couple questions for tomb and/or others.

On the BOM it lists the SSMH Standoff Kit and Heatsink kit as being on Beezar.com. I'm assuming this is the heat sink kit (if not, tell me), and where can I find the standoff kit?

Also, what do you think about using the 50K - 1/4W resistors (high gain) on low impedence/high sensitivity headphones (ie Grados). Also, are there any other modifications requited for the use of the 100k (low-gain) resistors?

Thanks

EDIT: Also, you use "heat transfer goo" on your build thread - is standard heat sink compound (ie Arctic Silver) the type needed?

 

[kuroguy]

Bummer. my spare tubes are in Tampa and won't arrive here for another 2 weeks. Looks like I'll be using some aluminum foil for a couple of weeks. Thanks for the response, Tom.

Quote:

Originally Posted by tomb /img/forum/go_quote.gif I'd have to say that if the problem followed the tube, that's pretty conclusive. Some of these tubes (not ones I've tested and rejected) have intermittent shorts. I've seen a few that changed with a little shaking. . Just enough metal was flaking off in areas to come into contact with the pins inside - that doesn't mean you'd have to see it for it to be shorted, though.

 

[TeraHz]

Quote:

Originally Posted by revolink24 /img/forum/go_quote.gif EDIT: Also, you use "heat transfer goo" on your build thread - is standard heat sink compound (ie Arctic Silver) the type needed?

I used Arctic Silver 5 without problems for my build. I'm sure if you have it, you can use it. I believe it is mostly non-conductive (for electricity).

 

[tomb]

Quote:

Originally Posted by revolink24 /img/forum/go_quote.gif Just a couple questions for tomb and/or others. On the BOM it lists the SSMH Standoff Kit and Heatsink kit as being on Beezar.com. I'm assuming this is the heat sink kit (if not, tell me), and where can I find the standoff kit?

No, it's not the same. Sorry it's not there, but I was overwhelmed for a time. I'll have them both up this weekend.

The heat sink kit contains 4 times the hardware. Plus, two of the screws are 1/2" long, not 3/8".

The standoff kit has some metric washers included because they're the only ones with a small enough OD not to short out on the LED resistor.
Quote:

Also, what do you think about using the 50K - 1/4W resistors (high gain) on low impedence/high sensitivity headphones (ie Grados). Also, are there any other modifications requited for the use of the 100k (low-gain) resistors?

It depends on whether or not you have a fetish about being <sorry - Blackberry typo> able to turn the volume knob all the way through its travel. I don't and became quite irritated to find myself racking the volume knob with Senns at anything greater than a one-to-one input/pot impedance. IMHO, 50K input resistance is fine for Grados,too. There are those who disagree, however.
Quote:

Thanks EDIT: Also, you use "heat transfer goo" on your build thread - is standard heat sink compound (ie Arctic Silver) the type needed?

not sure - I wouldn't use anything that dried to a glue-like substance. I don't know if Artic Silver does that or not.

 

[Juaquin]

Artic Silver 5 stays in paste form (although it gels some as it burns in). It's the golden standard for CPU cooling in gaming and watercooled computers. I used it on my SSMH because I have a big syringe full for computer work and it's working great on the amp. But make sure it's AS5 - Artic Silver Ceramique does get hard and glue-like and won't be so great for this amp. You can find AS5 at Fry's or anyone online computer store like Newegg, FrozenCPU, or TigerDirect.

EDIT: In response to the earlier post about AS5 and conductivity - it IS conductive. There are a lot of silver particles suspended in it. It's not a perfect conductor but it's good enough to fry something in the wrong place, like if you got it on pins of the CPU. Of course, conductivity should not be a problem here because both the base and heatsinks are supposed to be at GND.

 

[kuroguy]

Um, the MOSFETS MUST be isolated from ground or you get to buy new MOSFETs.

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif Of course, conductivity should not be a problem here because both the base and heatsinks are supposed to be at GND.

 

[Juaquin]

Quote:

Originally Posted by kuroguy /img/forum/go_quote.gif Um, the MOSFETS MUST be isolated from ground or you get to buy new MOSFETs.

The MOSFETs are isolated from ground by the berguist pads (on the inside of the case). They are not directly attached to the heatsinks.

The case is purposefully set to ground. And then the heatsinks are attached to the case, thus they too are ok to be at ground. Of course, they're anodized so the connection isn't perfect, but either way conductive or non-conductive doesn't matter when it comes to the paste in this application.

 

[kuroguy]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif I'd have to say that if the problem followed the tube, that's pretty conclusive. Some of these tubes (not ones I've tested and rejected) have intermittent shorts. I've seen a few that changed with a little shaking. . Just enough metal was flaking off in areas to come into contact with the pins inside - that doesn't mean you'd have to see it for it to be shorted, though.

I hear what you are saying. I initially thought that since the problem followed the tube that it had to be a bad tube, and it may still be a bad tube. The thing is, this space has an audible 60 cycle hum coming from either one of the air conditioning units or a bunch of cheap lighting ballasts. I think there is also a pretty good magnetic field that goes along with the humming. Is is possible that my body/hand is acting like an antenna? The reason I ask is that the hum gets louder as my hand gets closer to the tube but if i touch one of the heatsinks (ground) the humming immediately stops. I wedged a paperclip into one of the holes in the top of one of the heatsinks and made a loop around the tip of the tube with the other end and the hum has completely gone regardless of the location of my hand.

I'd bet installing a pair of those retainer caps that are held in place with springs would completely solve the problem.

 

[Juaquin]

Also, I wrote a short post on the SSMH kit with a couple pictures here.

For those constructing the kit, here's a little tip. Bend the very end of the MOSFETs a tiny bit forward, so they slide in a bit easier. Here's a picture of what I mean:

 

[Juaquin]

Double post failure. Keep moving.

 

[ethan961]

Does anyone know of anywhere that does have 19J6 tubes in stock? All the places I have tried are out of stock. I do not need a PCB so buying tubes from Beezar isn't the ideal option for me, as I will just have a PCB that sit in a box unused.

 

[Juaquin]

I've looked around online, and besides places that list them for $15-20 each (I didn't even bother emailing them to check stock), everyone seems to be out of stock. Of course, this is just what I could find using a quick google search. I'm sure they're out there if you dig enough.