solderdude
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Post by solderdude on Jul 4, 2014 14:48:12 GMT
These would appear to be non isolated judging from the piccy, but have one here as well (use it in my Kameleon) and it can be used without problems as it is isolated from the metal mounting ring.
The DCDC converter also provides electrical isolation.
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Post by chinook9 on Jul 4, 2014 14:50:48 GMT
Excellent! Thank you.
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Post by chinook9 on Jul 11, 2014 2:03:51 GMT
Frans, I am going with the Option 4 power supply and just discovered the inductors I have are 100uH and not the 150uH indicated in the power supply schematic. The BOM indicates these are OK but I thought I would confirm with you. They are rated at 320mA. Please advise.
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solderdude
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Post by solderdude on Jul 11, 2014 10:59:39 GMT
100uH is more than fine !
As long as they mechanically fit you will be O.K.
The difference has NO influence on the SQ.
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Post by chinook9 on Jul 11, 2014 13:24:56 GMT
Great! Should be testing pretty soon. Biggest problem I've had is getting holes in the front/back of the Hammond enclosure. I found that I could not easily get metric drill bits in US so I had to improvise with drills and round files. Not the way I usually like to do things but it works. Have a good day!
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Post by chinook9 on Jul 12, 2014 22:29:09 GMT
Finished the filter last night and it worked right off the bat. Not a complete surprise but satisfying nonetheless.
The filter transforms the T50RP into a different headphone. I have only listened for half an hour but the "slight veil" I had always perceived in the T50RP is gone. I tried four different settings on P101 201, 102, 202 and ended up with them fully CW. Not sure I'll leave them there, but I do like slightly bright headphones so that setting may stick.
I couldn't get the PCB to slide in the slots in the enclosure but it ran with no hum sitting about 18" away from my Sunrise II. I ended up isolating the DC connector with a bit of electrical tape and a couple of thin fiber washers. Worked fine.
I will put in the 3PDT to switch the filter and maybe add an LED, but I wanted to test the filter initially with the least number of variables that I could mess up. I plan to sand the sides/edges of the PCB ever so slightly so it will slide into the Hammond. If I can ID a way to do it I would prefer to enlarge one of the slots in the enclosure but I expect that may not be easy to do with the tools I have.
Thanks you Frans for the really well written guide. Part of my responsibilities in a previous life was to manage a group of technical writers and you write as well as any of them and better than most.
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solderdude
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Post by solderdude on Jul 12, 2014 23:07:48 GMT
Glad to hear it fired up and worked right of the bat.
Today 'deepfunk' paid me a visit to have some cans measured and treated him on some (filtered) headphones.
He had owned/heard the T50RP in the past and didn't like it... with the filter he loved it.
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Post by Deleted on Jul 14, 2014 13:13:37 GMT
I have a couple of questions if that's alright. Would it be possible to use one of these boards with an O2 amp? Are there any pics of the Hammond enclosure? Would it perhaps fit inside an empty O2 enclosure?
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solderdude
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Post by solderdude on Jul 14, 2014 14:47:37 GMT
yes, it can be used in front of an O2. The filter has unity gain for 1kHz but if the boost for instance is +10dB for lows this might overdrive the input stage of the O2. Fortunately the gain of the PCB can be lowered. pics: www.diyah.boards.net/thread/92/headphone-correction-filter-board?page=2 4th post on this page. And yes, would fit in there but it won't slide in there as it is much smaller. You could mount it in there in other ways as the PCB also has 4 screw-holes |
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Post by chinook9 on Jul 24, 2014 15:02:32 GMT
Hello Frans. I wired the 3DPT switch and the LEDs and put the whole filter board into the enclosure.
When the power and/or the filter is switched off the sounds goes through.
When the filter is switched on the sound goes through if the 12V supply is connected but does not go through when the power is disconnected.
However, I am hearing no difference in SQ.
I want to confirm that I might still be getting unfiltered sound through the filter if a few of the components are not soldered correctly. If this is true, I will resolder all of the joints. Please advise.
I could have caused this problem when I was making everything fit into the enclosure which seems rather small after the switch, LEDs, and all the wires are connected.
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solderdude
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Post by solderdude on Aug 2, 2014 9:03:50 GMT
Hello Frans. I wired the 3DPT switch and the LEDs and put the whole filter board into the enclosure. When the power and/or the filter is switched off the sounds goes through. When the filter is switched on the sound goes through if the 12V supply is connected but does not go through when the power is disconnected. However, I am hearing no difference in SQ. I want to confirm that I might still be getting unfiltered sound through the filter if a few of the components are not soldered correctly. If this is true, I will resolder all of the joints. Please advise. I could have caused this problem when I was making everything fit into the enclosure which seems rather small after the switch, LEDs, and all the wires are connected. Maybe some pics can make things clearer. With the power on and switched from bypass to filter there should be a substantial change (T50RP filter). The filter itself cannot stop filtering certainly not on 2 channels at the same time. Perhaps check the wiring |
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Post by chinook9 on Aug 2, 2014 12:26:21 GMT
Welcome back Frans I hope you had a nice holiday.
I will check the wiring. I would have done so already but my wife broke her arm so my priorities have been changed for a bit.
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Post by chinook9 on Aug 5, 2014 19:59:53 GMT
I plan to take everything out of the case in the next day or two and double check all the wiring. I have to wait until I can take some time and really concentrate and thats not something I do very often in old age.
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Post by chinook9 on Aug 10, 2014 3:02:02 GMT
Well Frans, I checked the wiring and everything seems to be as it should.
The switch and lights all appear to work as they should but no difference in sound with the power on and the filter switched in or out. When the power is disconnected there is no sound with the filter switched on but there is sound with the filter switched off.
Could the problem be caused by a cold solder joint here and there? If so, I could resolder all joints.
If resoldering the joints makes no difference, my next step would be to take out the switch and rewire the input and output jacks.
Anything you could suggest.
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solderdude
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Post by solderdude on Aug 10, 2014 9:16:07 GMT
This is really weird.
Which filter are you using ?
In case of the T50RP the difference should be considerable.
When we are looking at one channel:
input connector should be going to the PCB input + one of the outer connectors of the switch.
The output connector should be connected to the middle contact of the switch.
The remaining switch contact must be connected to the out of the filter PCB.
There is no possibility that the filter stops working on both channels.
There are ways to check operation though.
A: is there a (slight ?) level difference when switching on/off ?
B: while the filter is on and while shorting R102/R202 does the signal go away as well ?
Simply place a wire or pliers across one of those R's and the signal in that channel should disappear ?
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