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Class D Switching Power Amplifiers and Power D/A conversion

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Old 20th February 2013, 07:58 AM   #71
Fynn is offline Fynn  Germany
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Yup, mine were swapped too. Simply switched them around when i installed new RCA jacks. (To keep the color-coding correct at least)

http://i.imgur.com/BbmPu.jpg
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Old 20th February 2013, 08:22 AM   #72
xrk971 is offline xrk971  United States
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The RCA is fine, it is the 3.5mm that needs switching. If you switch the RCA's to match the 3.5mm, they will both be wrong.
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Old 20th February 2013, 03:27 PM   #73
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I must have a newer version with this fixed. When I change the balance, everything is correct. My speaker outputs are wired correctly.

If you want to be sure everything is correct from PC to speaker, you can use: Speaker Test (Left and Right), Ensure that your left and right speakers are connected correctly. - YouTube
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Old 21st February 2013, 01:43 AM   #74
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Default A_Backwards

Red Board

Click the image to open in full size.

A dremel to cut the traces and P2P wiring will fix.
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Old 21st February 2013, 02:05 AM   #75
xrk971 is offline xrk971  United States
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I am too lazy to eff with it - I will just use a 3.5 mm to RCA cable and avoid the input Incredible how something like this makes it pass the circuit routing Q&A before going to production. But hey, who's complaining because the whole thing costs $20. It costs me $70 to fill up my car with gas so I keep in all in perspective I am glad mine wasn't a solo lemon board though.
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Old 21st February 2013, 03:45 AM   #76
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Why not just reverse the speaker leads? You don't need an adapter for that.

Mine has the input fixed:
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File Type: jpg input_jacks.jpg (153.2 KB, 307 views)
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Last edited by Redshift187; 21st February 2013 at 03:51 AM.
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Old 21st February 2013, 06:05 AM   #77
xrk971 is offline xrk971  United States
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That works too. You have to remember that it is switched if you go back to RCA inputs. With my way of not using the 3.5 mm input, it will be correct... But you have to remember not to use the 3.5 mm, so maybe it is the same thing.
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Old 22nd February 2013, 12:20 AM   #78
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Default pre amp section

I've had a couple of the NOS 6111WA tubes collecting dust. I found a decent schematic for a preamp and built it into my Gainclone. With a gain of 20, it added a nice little boost to the GC and a slight 'crispness' (to me) of the LM3886. Not going to tear it out of the GC but would like to build another to replace the sad opamp section in the Lepai. I can see using this Lepai board like Mardis did with the original T-amp. Mount it in a slightly larger enclosure and add a couple 10k uF caps to the resevoir cap, 2.2uF input caps and off board all connectors, switches and volume pot to better, case mounted dealios.

Tell us your plans!
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Last edited by tamasic1; 22nd February 2013 at 12:24 AM.
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Old 22nd February 2013, 12:57 AM   #79
xrk971 is offline xrk971  United States
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Tamasic,
Wanna share the tube preamp circuit and photos with us? I have sometimes thought of making a faux class A manly manly man amp with huge heatsinks and thick slabs of aluminum on the front with galvo gages and lights but with nothin but a measly class D TPa31xx inside, or a Tripath 2020. Have a class A aficinado listen in an AB blind test and see if he can pick out the real class A ( without touching the fins to see which one will burn his hands).
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Old 22nd February 2013, 04:19 PM   #80
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Quote:
Originally Posted by xrk971 View Post
Tamasic,
Wanna share the tube preamp circuit and photos with us? I have sometimes thought of making a faux class A manly manly man amp with huge heatsinks and thick slabs of aluminum on the front with galvo gages and lights but with nothin but a measly class D TPa31xx inside, or a Tripath 2020. Have a class A aficinado listen in an AB blind test and see if he can pick out the real class A ( without touching the fins to see which one will burn his hands).
Hey xrk!

I'm going to cobble together something similar, except I plan to build an ultra-low budget hybrid integrated (tube pre and 2020 power).

I already own a 2020 and I have ordered a $21 "YJ" single 6N3 pre-amp kit, some switches and other small parts, an $8 power supply, etc. About $33 in total. Going to bypass the volume control on the 2020 (already bypassed the tone and opamp) to turn it into a straight power amp and then wire the pre-amp directly to the 2020. Stick it all in a homemade chassis and maybe even integrate a USB DAC.

I don't expect it to challenge an expensive amp, but it'll be fun as hell to build!
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