DHTGUY
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Posts posted by DHTGUY
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I can't believe I just soldered this - it's unbelievably tiny. Seems to have gone well, though.
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Yes, it weighs 15 Kg (33lbs) - 200 x 110mm. It's from a swedish company, but I can't find specs on the internet. Two would be preferable for monoblocks but I can get this one for a good price.
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I have found a transformer with the following spec:
2 separate 36v secondary 30A (seller states 60A, I presume 30A per winding). I will need further transformer(s) for the lower voltages. Is one transformer for both channels OK or better one for each channel ?
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Is anyone (apart from me) intending to use the 4D Systems dispay and to amend the code from Kerry?
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Soren, All arrived thanks. Have to stay off the coffee to have steady hands for this one
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I would like to echo that and thanks to Kerry for the explanation. Thanks Søren
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I seem to have solved the problem. The instructions state that the directory should be saved as a subdirectory of library - it has now worked with a subdirectory renamed genie and just the file genieArduino.h in there without the other subdirectories and files. The genie library can now be included in the Arduino sketch with #include <genieArduino.h>. I hope this is of help if anyone else plans to use a 4d display for the digital attenuator
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I am having issues with the 4d display (uLCD-24PTU) and Arduino. I am trying to intall the 4D systems library in the arduino software, but it says it is not a valid library. The Arduino software is the latest from www.arduino.cc and the library is https://github.com/4dsystems/ViSi-Genie-Arduino-Library. I have tried unzipping the downloaded file to /documents/arduino/libraries and also the menu install a zip file from the arduino software. Both give error messages. Any help would be appreciated.
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I want to put together a spreadsheet to check the attenuator values. I have replicated figures from Kerry,
For 0.5dB attenuation
The voltage ratio K = Vin / Vout (L attenuator) for 0.5dB = 10 to the power -0.5/20 = 1,0593
For Z = 50k , R Series is 2797 Ohm, (50.000 x (K-1)/K R Parallel is 843829 (50.000 x 1/(K-1) (These values match Kerry's and also several web sites)
Now taking these two values
V Out / V in = Rpar / (Rpar+Rser) = 1,0033
dB attenuation is 20 x Log10 (1.0033) = -0,03
Where is the mistake?
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Soren - thanks - please put me in for combined shipping attenuator and Überamp
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Am I too late to be in for 2 Uberamp boards ? The excel sheet is locked - please put me down for two (stereo)
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Thanks everyone- looks like l know where to start. I would be really grateful congo5 for some MPSWs - will you pm me? I checked the 1486 - the metal side is above the hatching on the silkscreen, so I think it was a reflection.
On 1/4w and 1/2w - I will check again, but some of the smaller resistors are rated 1/2W. They are vishay or xicon. I used thick film due to the following statement by Kevin Gilmore "
"...The standard dale 1% rn60 resistors are all spiral trimmed to value and
are therefore slightly inductive, and the inductance changes with the value.
I have found that the absolute best resistors for this are the thick film on ceramic substrate. But they
are very fragile (crack easily if you overheat when you solder) and 150 times the price of regular resistors."
Why should they not be a great idea?
Any ideas if the board is going to be ruined?
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I've got +450 and -450 on the output at the stax socket on the one board I have connected. They are rev 0.63 amp boards. The PSU is 450v and running fine (rev 1.0). All LEDs are lit, but the one between the two MPSw06 (I am using 2SC2240 in there) is a lot brighter. The servo is not connected, the jumpers are on global feedback. The PSU is not drawing much current ( less than 1A). I got most parts from Mouser, I am using the SA1968
I am not using the transistors on the silk screen (right), but the ones on the left in the list below - I had an excel list in which these were given as equivalent.
2SC2705 / MPSW42 2SC2240 / MPSW06 2SA970 / MPSW56 2Sc1815 / MPSW06 I got the 2SA1486 from little diode in the UK. I previously posted pictures, and changed a number of resistors to half watt.
I'll try the other board to see if that is OK or not, and post some better images back & front when I have removed the board.
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I have finally plucked up courage to turn on one channel --- no smoke, but the LED in the middle near the SA1486 is very bright, others much less, so, and after power on for ca. 30 seconds I could smell hot components (but perhaps that is normal). Any suggestions? Just go for it? I have the global feedback jumper, no server connected, and I have adjusted each trimpot to roughly the middle.I can hear a relatively quiet b-b-b-b sort of noise for 10 seconds or so, which then goes away - but apparently no signal (I have about 100mV 1Khz test tone on the input) and measured in through to the input on the amp board.I would just it all to go up in smoke at this stage.....
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Hmm - perhaps I'll do another board with the 10m90s again (I managed to damage (fry) the one I made by not waiting long enogh for cleaning solvent to evaporate ). Thanks all - just a cap before the divider makes sense.
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0.01uF 250v tiny enough? Should it be on the bias out side of the 4.7M ballast resistor (then the storage is important agreed) - or on the divider side? I'm interested to know the advantage of the 10m90s
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Thanks John. What is the reason for the 10M90S (I should work it out from the data sheet I suppose), if a divider works OK? (the 2 x 178k are just what I have available). I suppose the calculated 225v above is near enough to 230 to be fine
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Like this?
and thanks for your help
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This must be a record slow build, but I now have a working PSU (+448v -448v) and all is fine - Pro Bias also OK. I need normal bias as I currently only have Sr5. For normal bias, I tapped the circuit where the 500v option jumper connects (on the same side as the pro bias connection) and duplicated the circuit from the 10m90S to outpuit, with a 230v zener string. I presume if I was going to tap the circuit on the other side of the jumper (straight off the bridge without the voltage doubler) it would need another 15k? resistor in series Which side should I tap?
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Oh dear - guess I'm going to have to swap out the 1/4W for 1/2W. Anything else?
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Better late than never... I am getting near to finishing my KGSSHV and I would really appreciate it if anyone can spot anything incorrect before I fire things up. (I still have to put in the op amps and remove the servo jumper on the amp boards).If I could do it again it would be with RN60D resistors. I know - the dissipante case for on board version is a bit unnecessary, but it was never going to be portable
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I would also be interested if there is another GB for the carbon. My KGSSHV is near complete, so I'm intersted in a set of carbon boards. Is there a list I can put my name down on for interst in a further GB?
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Sorry - I read for gauging interest, so I put my name down. I'm not ready to order - perhaps a later group buy. I'll take my name off as the order has been placed already.
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I'm getting closer to being able to fire up everything. I only have SR5 gold with normal bias - so I either need to build with both normal and pro bias, or I need to buy a pro bias headphone. I don't really want to buy the pro headphone until I know the amp is not going to go up in smoke. Question - any reason I shouldn't test the amp with SR5 and normal bias? Double Bias or Ebay pro phone for testing?
I'll post PSU and Amp board pics shortly and would appreciate any "that doesn't look right" comments
and now for something completely different part 3
in Do It Yourself
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What size heatsinks do you have? I want to build a stereo set up which I presume will need to dissipate about half the power.