Kemper Player Teardown
- Thread starter texhex
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L
likitlikeyoulikeit
Guest
He's no Tony McKenzie!!!
Whoa.
First off, there are lots of boards and components in this beast. I had originally thought that Kemper should have priced this lower than they did, but I am now wondering if that is possible after overhead and everything.
Second, I was very surprised to see the vent holes in the bottom. I would have thought that having a metal case, there would be no need to have vent holes in the device to remove the heat. This open design can allow water and moisture into the unit which will can make it fail. Additionally ..... if you are going to have the board open to atmosphere like that without a sealed case, for the LOVE OF GOD the board should be conformal coated.
The USB failure he mentioned is a rookie engineering mistake done by picking the cheapest part you can find. In the case of mechanical USB ports this is a very stupid place to try and save 25 cents.
The soldering failure indicates a lack of process control in the factory and/or an insufficient solder mask or worst of all, poor pad design for the part.
The rest of the design looked OK to me.
I am a little disappointed. As an electrical engineer, I had thought Kemper a better design house than this.
First off, there are lots of boards and components in this beast. I had originally thought that Kemper should have priced this lower than they did, but I am now wondering if that is possible after overhead and everything.
Second, I was very surprised to see the vent holes in the bottom. I would have thought that having a metal case, there would be no need to have vent holes in the device to remove the heat. This open design can allow water and moisture into the unit which will can make it fail. Additionally ..... if you are going to have the board open to atmosphere like that without a sealed case, for the LOVE OF GOD the board should be conformal coated.
The USB failure he mentioned is a rookie engineering mistake done by picking the cheapest part you can find. In the case of mechanical USB ports this is a very stupid place to try and save 25 cents.
The soldering failure indicates a lack of process control in the factory and/or an insufficient solder mask or worst of all, poor pad design for the part.
The rest of the design looked OK to me.
I am a little disappointed. As an electrical engineer, I had thought Kemper a better design house than this.
L
likitlikeyoulikeit
Guest
(laughs in Headrush/InMusic)
Vent holes resemble those in proximity to the wifi chip under the Kemper Stage - maybe less to do with ventilation than transparency to wifi frequencies.
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There's a small "box" that the WiFi antenna goes into on the side of the chassis. You can see it at around 10:55.
Round holes actually block RF. That's what's in the door of your microwave oven and why you can watch your food splatter all over without getting irradiated RF passes through rectangular openings (slots, etc.).
There are two ways to get RF in/out of a WiFi module: use a module with integrated antenna and have the antenna penetrate the chassis (like here); or use an external antenna. Some devices have a physical antenna on the outside of the chassis. Other devices hide an internal antenna behind a chassis opening (i.e. the LCD in a laptop computer).
AFAIK you don't need perforations to create a Faraday cage around a radio source. The rest of your microwave lacks them, for example.
There was a revision to the Stage after its initial release where the holes in the chassis directly under the wifi chip were altered. ( Just checked a Stage and under the revised Stage there are round perforations whereas IIRC the perforations were initially slots).The speculation at the time was that these slots were altered for the reason I gave. Where were you at that time? Not lurking? Say it isn't so!
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Wilson is Chinese, he should use a wooden fork to spite Tony.
Desertdweller
Shredder
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- 1,101
Yep, looks like circuit board, a battery, and some jacks. Enthralling.
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No you don't. The point was that holes don't allow RF through them. A Faraday cage can be solid metal but then you can't see your food inside the microwave oven.
IOW, if you want RF to go in/out of an enclosure you don't use small, round holes.
Wifi at 2.4 GHz has a wavelength around 1/8 of a metre. An effective aerial is 1/4 wavelength (or 1/2) so ~ 3cm is an effective length of an aerial for that frequency and less than half that for 5.4 Ghz. So I guess if you are going to use slots they need to be of the order of a 3 cm long for the 2.4 Ghz band. Small holes of the order of several mm in diameter are effectively screening out longer wavelengths I guess.
No matter how you slice the turkey, the board should be conformal coated if it isn't going to be in a sealed box. I don't know about you guys, but I have got caught in the rain on an outside event before, or gotten splatters from outside of the tent we were playing under. Just the humidity is a good reason to have it though even if the board is in an enclosed box.
TubeStack
Rock Star
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He's no Tony McKenzie!!!
Not gonna lie, I was a little disappointed it wasn't TM...
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No one in this product space conformal coats their boards. It's prohibitively expensive, environmentally toxic and makes rework difficult, if not impossible. It also affects signal integrity so all that time/work/money you spent getting your DDR and USB to work properly can be jeopardized.
Really?
Expensive eh. Never did a board before have you.... Or talked to anyone who has evidently.
I'll give you the rework argument, although I did one today. You do know they make a spray solvent to remove it from the rework area... Maybe not.
What universe do you live in where you can't conformal coat RAM? Sure, you have to mask off contact areas if using DIMMs.
And I literally have several designs with USB that are conformal coated, and certified.... No problem.
What are you talking about?
Expensive eh. Never did a board before have you.... Or talked to anyone who has evidently.
I'll give you the rework argument, although I did one today. You do know they make a spray solvent to remove it from the rework area... Maybe not.
What universe do you live in where you can't conformal coat RAM? Sure, you have to mask off contact areas if using DIMMs.
And I literally have several designs with USB that are conformal coated, and certified.... No problem.
What are you talking about?
MixMinisterMike
Groupie
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As a german .. kemper shouldnt make tjis mistakes. They are very anal about many things in their personalities
KHAAAAAAANNNNNNN!!!!!!!!
Shredder
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- 1,372
Not sure where they went wrong in their thinking on the Player. My foot controller (for my KPA Rack) and the KPA Stage don't have holes in the bottom. I am not sure about the quality of the USB sockets. I use a patch bay on my Kemper Rack so none of the connections on the Kemper are ever connected and disconnected.... just the patch bay connectors.
I am guessing that the biggest difference is the size. Maybe they needed the open ventilation because the Player is so small (and therefore has much less surface area for the heat to be transferred out though).
Fractal's FM3 has vents as well (and more of them). Maybe I am the only one that has been rained on at a gig?
