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Post by Deleted on Nov 21, 2011 8:51:02 GMT
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Post by dicky on Nov 21, 2011 12:16:34 GMT
Thanks for the tip, Javier. I saw that little screw and assumed you connected a wire to it somehow to get the ground connection. It seems I don't have a grounding problem - but I'll remove the washer anyway and see what happens. By the way, you should have an email.
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Post by Deleted on Nov 21, 2011 13:40:17 GMT
By the way, you should have an email. Dicky, I've checked and don't have any new mail, are you sure yo typed correctly the address? Cheers
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Post by dicky on Nov 21, 2011 17:46:04 GMT
You should now.
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joethearachnid
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Post by joethearachnid on Nov 23, 2011 23:26:25 GMT
I can't quite fit my jealousy into words right now! That looks absolutely fantastic Dicky, really nice job on the fit and finishing. I now pretty much have the money to put the Panda together, but I'm currently living away from my soldering iron. I wonder if I could persuade the family to buy me a bunch of microchips and an expensive metal box for Christmas...
EDIT: Oh, and I don't think I ever said thanks to Frans for sending me the transistors and diodes for the C.H.AMP. I had quite a lot going on at the time, but I was very grateful and hope to put them to good use soon.
-JoetheArachnid
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joethearachnid
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Post by joethearachnid on Nov 23, 2011 23:49:06 GMT
Also it looks like you could certainly get away with using the 230x170 case from your pictures assuming that I use a regular IEC and a blue ALPS, but I'm thinking that having a 40mm rather than 80mm high one would be pushing it? I'm not bothered about the size of the amp, but the thought of all that empty space gets me for some reason.
(I'll stop blabbering over this thread now, honest)
-JoetheArachnid
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Post by dicky on Nov 24, 2011 6:57:59 GMT
Joe, you would be able to use the smaller case and I considered it for some time. However, I wanted to use the stepped attenuator that would make it very tight. Also, I wanted as much space as reasonable to avoid cramping the mains and signal wiring together. As it is, I have the mains on the right, the screened input signal passes under the board (on 25mm stand-offs) and the output signal passess over the board.
The amp is SILENT apart from the last 2 steps.
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Post by Deleted on Nov 24, 2011 7:38:05 GMT
The amp should be silent with all steps. Are the 2 maximum steps the offending ones and what do you hear ? adding 2 resistors might cure the 'problems'. Also the location where the PCB is connected to ground can induce these not being silent things.
Is the not being silent also present with something connected or with open inputs ?
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Post by dicky on Nov 24, 2011 19:48:25 GMT
Hi Frans,
I don't have any issues with the noise. It is an almost imperceptible hum - I have to stop breathing to hear it! ;D
It was just something I noticed after I built the amp and I was running through the configurations. It was only noticeable if the source was not powered up.
I have just checked and can confirm that wWhen the source is powered the CHAmp it is SILENT at all vol positions.
Regards,
Dicky
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Post by Deleted on Nov 30, 2011 12:53:21 GMT
Finally got my C.H.Amp cased up. A few cables to be tidied. As the Chinese case splits nicely in two I used PC screws to secure the back but I have to find something knurled in a similar way for the front. Its recessed thick plate doesnt make it easy. A great case for this 'access required' HA. This my third Chinese case and I have to say its easily the best yet. Not a mark on it and the front panel has a nicer lustre to it. I've got to reread Frans' superb manual but was a little impatient to get going this morning. Used my Superlux and set the 33 ohm output with jumpers also set for W0. It is simply a superb combination and I'm looking forward to trying the many settings available, with my many headphones Thanks a lot Frans, a great project from start to finish. Syd
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Post by Deleted on Nov 30, 2011 13:50:03 GMT
Looks fantastic Syd, plenty of air arounf components!
I ordered a case like your last 14th so according to their table of estimated shipment times I should be receiving it at the end of this week or early next one.
I have to figure how to enlarge the hp socket hole in the faceplate enough to fit my Neutrik and also drill the holes for the two fixing screws without wreaking havoc...
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Post by Deleted on Nov 30, 2011 16:32:32 GMT
Hi Javier I had to enlarge the hole for my Neutrik too. Its a bit tricky as there is a hole already there. I put the faceplate on a piece of wood on the floor then put a piece of protective wrap on it and held it down with my foot (who needs a vice ). I then used a new 9mm drill bit with a cordless drill held firmly but just touched it gradually judging the centre point. It isn't beautiful but it worked and is covered by the Neutrik. How come you only need to drill two holes? I needed 6. A sharp tap with a punch before drilling worked fine, aluminium is very soft. I still haven't had the courage to drill a hole for the LED Syd
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Post by Deleted on Nov 30, 2011 17:45:10 GMT
My Neutrik is the one at the top of this page, it needs a 24mm diam hole plus two 3.5mm for the two holding screws (top left + bottom right). I don't think my drill would even take such a huge drill bit, the small ones should be easier with a 4mm one. This is what I need to drill:
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Post by dicky on Nov 30, 2011 19:22:46 GMT
Nice one Syd. I wish my pot' could have fitted into a Panda case - it would have saved me a lot of time and money!
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Post by dicky on Nov 30, 2011 19:24:55 GMT
Javier, I'm still nagging the chap that did my machining if you're still interested. He's really busy and very forgetful - it took him weeks to get around to mine Dicky
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Post by Deleted on Nov 30, 2011 20:20:20 GMT
When I got home today I found my new Panda case had arrived. It is spotless, no scratches, no dents, perfect. The bad news is the Alps pot shaft also needs a slightly bigger hole. If I have to drill so much I might just as well make a little extra hole for the LED and use it instead of the case's power button one.
I'm still interested in knowing Dicky but no hurry whatsoever. Eventually I may go for a deeper case and try to fit both the CHAmp and my future PK DAC and WaveIO board.
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joethearachnid
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Post by joethearachnid on Nov 30, 2011 21:51:59 GMT
Javier,
I had that problem when I was building my Panda. I don't know if it's because I got a later production case or if it's because everyone else was using a pot extension rod. I decided to mount my pot straight on to the front and just drilled out the hole a bit. It's only off by a couple of milimetres, if I recall. Not sure if my knob is dead centre now though, but it doesn't seem to stick on anything.
Question regarding the Galaxy cases: If I get a 10mm front panel and want my knob in a recessed hole, is there any easy way to mill this out without having access to a CNC machine? I do have a pillar drill available.
-JoetheArachnid
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Will
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Post by Will on Dec 3, 2011 20:07:51 GMT
Syd,
I've just seen your build, very tidy indeed!
How are you finding it now, you've had a chance to have a good listen?
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Post by Deleted on Jan 18, 2012 16:55:56 GMT
Some pics of the newest member of the CHAmp family (Mick's): Day 1: resistors, diodes, DIP sockets and PS opamps (with my board for comparisson): Day 2: bridge rectifiers and ceramics: Day 3: the rest, ready for testing.
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Post by Deleted on Jan 18, 2012 20:46:25 GMT
Javier Any reason why you have chosen to use what appears to be carbon film resistors which are noisier, and have wider tolerance in their actual values ? Alex
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Post by Deleted on Jan 18, 2012 22:53:44 GMT
The resistors used in the audiosection (where low noise matters) are all low noise metal film SMD resistors. The shown resistors are output resistors and resistors used for DC protection e.t.c. so noise is not of importance there, the opamps determine the noise floor. The tolerance of these parts is also not of importance as gain is determined by the precision SMD resistors as well.
You know there are many subjectivists that SWEAR by carbon resistors and polyCARBONate capacitors. They say they sound more 'organic' to them, more natural. Ofcourse .. they are linear elements so cannot do anything (distort or have a preference for certain frequencies/instruments) except add a very small amount of noise and limit bandwidth (above several GHz). yeah... certain wirewounds act as inductors.. Resistor bandwidths are already 1000x bigger than the bandwidth this design can manage.
I might worry about carbon resistors in low noise mic amps though.
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Post by Deleted on Jan 18, 2012 23:01:18 GMT
Alex, they were the ones they had in a shop two blocks away from my office so basically it was convenience but I asked Frans for his blessing before putting them on the board. He gave me the same answer as above.
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Post by Deleted on Jan 18, 2012 23:31:01 GMT
Javier I couldn't tell from the photo whether you had done as above. It is rare for products from well known brands to use CF resistors these days, except in some non critical areas. Fleabay offerings, can be quite different due to CF resistors costing almost mothing these days when bought in quantity. It's always a good idea to use MF resistors, SM or leaded, in input, current mirror, and gain defining sections.This saves the trouble of matching CF resistors for use in those areas for best results. Alex
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Post by Deleted on Jan 19, 2012 15:47:30 GMT
Alex, I measured each resistor before I soldering it. As cheap as they were their tolerance was mostly within <1%. They also matched to within the 2nd decimal on the higher values, the lower ones being identical in each pair. Probably modern manufactring processes make achiving reasonable quality in such simple parts a non issue (or I was plain lucky). As my knowledge about electronics is next to none I always ask those of you who do know before using any type of part not clearly specified in a BOM.
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Post by Deleted on Jan 19, 2012 22:42:29 GMT
Board finished and ready for testing this weekend.
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