Helium - a true micromonitor

[Herman Trivilino]

Re: Helium - a true micromonitor

If you have a router you can cut the hole any size you want. If you're using a drill one option is to drill the hole too small and then file out material to make it the right size. Another option, and this is my choice, is to drill the hole too large, but not all the way through. Then use an epoxy filler to cement the pipe in place. After it dries drill a small hole all the way through from the other side, and then cut away the remaining material with either hand tools or a router. Using a round over bit on the router gives nice results.

[scottsehlin]

Re: Helium - a true micromonitor

http://www.amazon.com/Mibro-460271-C...le+hole+cutter

I used something like this in a drill press. Herman's method sounds good, or one could start with a 1" hole and file out until the tube fits.

[Naught1]

Re: Helium - a true micromonitor

... or one could start with a 1" hole and file out until the tube fits.

That's what I had to do, but I used a dremel tool with a sanding tube. It took a very light touch in order not to make it too big.

I think that in general, pipes and conduit are purposely sized to be between common tool sizes, so it's easy to pass them through materials.

[Herman Trivilino]

Re: Helium - a true micromonitor

You can also get the 4 uF capacitor and a terminal cup from Dynavox.

Did you happen to measure yours before you installed them? I received the inductors and caps today. The 2 μF capacitors and the 1.0 mH inductors measured just fine (measured a DCR of 0.8 Ω on the inductors, by the way).

But the 4 μF caps actually measured to be 8 μF.

I have notified Dynavox.

[scottsehlin]

Re: Helium - a true micromonitor

I will check mine this weekend and report back.

[scottsehlin]

Re: Helium - a true micromonitor

I bought 10 of the 4 uF capacitors from Dynavox. 2 are in my speakers, so there were 8 available to measure. 6 of the 8 measured in a nice tight band between 4.25 and 4.39 uF on my Centech DMM courtesy of Harbor Freight. I tried a couple of tighter tolerance caps from Mundorf and Wonder, and they also measured a little high, so I would consider those 6 caps well within tolerance. One of the Dynavox caps measured 4.05 uF, which in reality is probably a little low, but still in the ballpark. I did find one outlier that measured 2.31 uF - so approximately half of what it should have.

My conclusions:

The 4 uF caps aren't mislabeled 8 uF caps in general.
There is the potential for outliers; so if you use these, make sure you have some way to check them. This is what I used.

http://www.harborfreight.com/ac-dc-d...ter-37772.html

[andykriech]

Re: Helium - a true micromonitor

Scott, did you put any damping material in your boxes?
I, for one, would love to see a pic of the box innards (I am building mine now and with the boxes mostly glued up, see how really small they are for all this stuff (specially the ports...).
Thanks, Andy.

[Herman Trivilino]

Re: Helium - a true micromonitor

Andy, look back at Post #47. Scott said he didn't use any damping material but he is interested in hearing from folks who try it. I'm getting ready to start and I'll post pictures as I go. To deal with the small spaces I plan to not make crossover boards. Just glue the inductors to the cabinet walls on the inside corners, and then wire the caps and resistors in line. I've got the smaller wire-wound resistors and plan to use just one 2-ohm and one 15-ohm in each cabinet. Likewise I've got small 2 μF and 3.9 μF caps.

Scott, thanks for measuring those cap values. I picked up some 3.9 μF NPE caps today at a local parts store. Weird that the Dynavox cap values are so scattered. I guess they're selling factory seconds at bargain basement prices, so you take your chances when you buy from them. I'll update this post if I get a response from them.

[johnnyrichards]

Re: Helium - a true micromonitor

How is the ordering process through Dynavox? A few years ago I tried to order something, and it calculated $100 in shipping or something. Curious to try some of their stuff...

[Herman Trivilino]

Re: Helium - a true micromonitor

I placed my order on a weekend and they shipped it out on Monday or Tuesday. I opted for first class postal service and it took almost two weeks to arrive.

[johnnyrichards]

Re: Helium - a true micromonitor

Cool - looks like they got their shopping cart woes under control. Interesting company.

[Herman Trivilino]

Re: Helium - a true micromonitor

Paypal is the only payment option.

[Herman Trivilino]

Re: Helium - a true micromonitor

These are the caps I bought at Ace Electronics in Houston to replace the Dynavox 4 μF caps that were actually 8 μF.



I suppose they'll be alright but do you think I should plan on replacing them with either the PE NPE caps that are 4 μF and 100 V or the PE poly caps?

[Herman Trivilino]

Re: Helium - a true micromonitor

Got started today. These are so tiny!






This is the material. It was on sale at Lowe's for $31. It's not half inch, it's actually 12 mm.



I had trouble with the router making the woofer cut outs. The piece kept jumping around. Maybe cause I was using a half-inch bit.

So I had to resort to a jig saw.

[scottsehlin]

Re: Helium - a true micromonitor

I wouldn't worry about using the 3.9 uF cap. It is well within tolerance.