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A Very Compact Hybrid Amp - Page 22

post #316 of 2213
Quote:
Originally Posted by holland View Post
Ah cool. I like the 8416 tube very much, but it depends on the headphones.

I bought the Context Engineering case from Fry's. ... I'm not sure what the shipping to CO would be.
Thanks. I get to Major Urban Areas with Fry's a bit
post #317 of 2213
Quote:
Originally Posted by wiatrob View Post
Thanks. I get to Major Urban Areas with Fry's a bit
When you buy the cases, make sure it has a little package inside. It contains the screws for the other end of the panel, and that both panels are screwed onto one end. The cases are in a plastic wrap. Sometimes people open them up to size things or returns.

Fry's is notorious for half-opened or returned stuff.
post #318 of 2213
Quote:
Originally Posted by holland View Post
Thanks, cfcubed.
Interesting case. If you can measure the PCB slots (for potential future stuff), I would guess no more than 1/4" off the bottom.
Yes, as waitrob indicated they seem darn nice cases esp. for the price... There's a bigger one (& they come in black too). Got mine fast:



It's about twice the volume of the target case for this project, but I have plans True, has only the two PCB slots centered 3/16" (4mm) off top/bottom. My slots are exactly 100mm (3-15/16") wide so probably takes 98mm-100mm wide PCB.
post #319 of 2213
wow, that material looks *thick*. very nice.
post #320 of 2213
Quote:
Originally Posted by holland View Post
wow, that material looks *thick*. very nice.
OT: here's some pics of the larger case:http://www.head-fi.org/forums/f6/pos...ml#post5463013

Probably fit three CH's in there
post #321 of 2213
Using the Amperex 6189 tube. I disliked this tube on my SOHA 2 as it was somewhat odd sounding, but it seems to fare well in this amp.

Overall I'm getting more impressed with this amp. I haven't come across anything that has a weird presentation. Good job, cfcubed and runeight.
post #322 of 2213
I posted this over at the prototype builder's thread, but I thought I'd update the Head-Fi gang as well.

I finally had enough free time yesterday to work on this beauty of an amp. I got the board populated and did the preliminary start up to check voltages. I'm happy to report that everything checked out first try and now I'm ready to move on to wiring and casing it (hopefully tonight after work).

My advice to anyone attempting the build is to work slowly and methodically, and it is a no brainer. The key here is to check and double check everything as you go, looking for solder bridges along the way, because things can get pretty crowded in their, depending on your layout.

My build is slightly different then the 'stock' build because I decided to try mounting all of the taller components under the board, in order to allow the tube to be fully exposed outside of the case. This worked out fine, and am looking forward to getting it inside of the enclosure to verify that it all fits as planned.

A couple things to note - I decided to switch the positions of the leds. I did this with the idea that green means it is powered up, and orange means it is 'warmed up' and ready for music - plus if any light is sneaking out of the enclosure, I prefer a orange glow as opposed to to green. The other thing is the led's I used are kinda oversized for this board, but they were gathering dust in a parts box, so I used them rather than buying new ones. Also, I like to live dangerously and chose to skip both a switch and a fuse, so S1 - S2 is jumpered with a zero ohm resistor. I wouldn't recommend this in general, unless you fully understand the risks...

The BOM is pretty much stock with the exception of substituting Nichicon elctrolytic caps for the Xicons, and pretty much all WIMAs on the films. I used some Vit Q's I had lying around for the bypass positions as well.

With the tube outside of the enclosure, my hope is that the only big heat producer is the voltage regulator, and there will be enough airflow based on this layout to keep it in limits using the BOM heatsink. I chose to mount it under the board with the pins bent at 90 degrees, and the heatsink pointing down. I'm banking on the notion that the heater reg will stay cool enough without a heatsink based on convection airflow. We'll see once she's boxed up...

Here are a few teaser pics from last night...
LL
LL
LL
LL
LL
post #323 of 2213
Cool, TimJo. I did the same thing with my build. I thought about chopping off the tab of the LM2595 entirely as I didn't want it scraping the top of of the case even after it's bent back or forward as in your picture, not that it would be a bad thing entirely. I couldn't bend it as far as you did. That's when I decided to mount it underneath. I had to bend the legs, but it fit underneath just fine as well. It's a pain to desolder it when mounted underneath as it's very close to some plastic caps.
post #324 of 2213
Yes, cool indeed TimJo... I wonder what case you are targeting. You can make that a surprise

True about the checking/double-checking joints, parts & polarity. I think we may be at the stage where the design, BoM & PCB are fairly proofed. Having one std build, I'm now also going for a deviation/non-std build... And its only happening because I'm very happy with the 1st build

When production rolls around it will be interesting to see how many do a std build (e.g. target case) and how many a non-std build.
BTW I think I'm going to resort to trickery for PCB mounting in my non-std case (proto PCB has no mounting holes)... Going take a perfectly good very small hammond enclosure & cut it into 4 pieces (lengthwise along middle sides + top & bottom) to create nice mountable PCB edge brackets. We'll see. Maybe I'll poke around for other ideas...

Well good luck & I'm sure you'll let us know how it turns out.
post #325 of 2213
I got my PCB today, and the Mouser order finally came too after I managed to "unstuck" it as the heater switch changed from available to backordered in the space from checking out and paying, and Mouser kept quiet until I started wondering why my stuff did not show up.

But, the 88 euros order came with a customs bill attached for 38 euros, which is unbelievably expensive and totally wrong (note that I did not have to pay any duties on previous orders). I spoke with FedEx, and apparently they used the USD amount to calculate customs duties in euros, so I filed a claim and now I'll have to wait for it to be checked before getting my stuff. Bah, maybe next time I should only participate to a proto build if I can source everything from the EU. Sorry for all this, people.
post #326 of 2213
Quote:
Originally Posted by cfcubed View Post
When production rolls around it will be interesting to see how many do a std build (e.g. target case) and how many a non-std build.
I think it might depend on whether or not there are pre-drilled panels, etc.

Quote:
Originally Posted by cfcubed View Post
BTW I think I'm going to resort to trickery for PCB mounting in my non-std case (proto PCB has no mounting holes)... Going take a perfectly good very small hammond enclosure & cut it into 4 pieces (lengthwise along middle sides + top & bottom) to create nice mountable PCB edge brackets.
Interesting. How will they be reattached?
post #327 of 2213
Quote:
Originally Posted by holland View Post
Interesting. How will they be reattached?
The little cut up hammond would create 4 identical L-shaped pieces... The short side of the L having the PCB slots. The long side would get through holes for screws that thread into the (very thick) bottom of that ebay case (using 6/32" drill/tap set), possibly with stand-offs to bring PCB up close to case top. CTH PCB would be centered width-wise & up against the back panel of the case, allowing for 3 PCB edge bracket/contact points (front + sides).
Again, we'll see if I come up w/something better, easier, cheaper, etc. If I don't I'll post pics.

ludoo - Sorry for your shipping difficulties! Good luck.
post #328 of 2213
Quote:
Originally Posted by cfcubed View Post
The little cut up hammond would create 4 identical L-shaped pieces... The short side of the L having the PCB slots..
You might also investigate hobby aluminum channel stock, might save you some cutting... Train store nearby??
post #329 of 2213
Quote:
Originally Posted by ludoo View Post
...Sorry for all this, people.
No need to apologize, your expereince is totally 'bogus' as we say over here!!

Take some solace in the fact that the build sounds quite good when it comes together. Driving my Lambdas as loud as I'd like them right now...
post #330 of 2213
Quote:
Originally Posted by cfcubed View Post
Again, we'll see if I come up w/something better, easier, cheaper, etc. If I don't I'll post pics.
Interesting, but I would probably go for this.

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a good series of them along the edges will do well, IMO.

with these for support

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I actually was going to use this, and make the amp bigger to fit the transformer in the same case with different offboard voltage regulation, before I decided on the Context Engineering case and the external AC transformer. The charm of something small won over the desire to overkill everything these days (Tim Allen syndrome).
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