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Post pics of your builds....
Apr 21, 2007 at 1:34 AM Post #2,011 of 9,811
Freq Band - Incredible work. I am reminded of a line from Waynes World.
cool.gif
 
Apr 21, 2007 at 7:34 PM Post #2,016 of 9,811
esh0. is that some sort of uber Cmoy with dedicated power circuit?

Oh... I see another chip in the bottom of the PCB, now it looks like TPA6120 amp using OP275 as a buffer. Am i right?
It looks great, good job.
 
Apr 21, 2007 at 7:44 PM Post #2,017 of 9,811
Seaside - exactly. As we know, TPA6120 works fine with 2v/v gain (that's written in app note) - it's good for low imp. headphones. For higher imp. higher gain is needed. So that's why i used preamp before tpa. Another reason for this, is that TPA is some kind of "clean" headphone driver. It doesn't add anything from itself - so now, opamp can change sounding
smily_headphones1.gif
OP275 is the best in my opinion.
 
Apr 22, 2007 at 7:34 PM Post #2,018 of 9,811
Freq Band,
What music did you use for your first test? I would have been unable to resist playing nothing but nine inch nails eternally.
 
Apr 22, 2007 at 11:39 PM Post #2,019 of 9,811
My Modified Linkwitz Crossfeed built around the PCB sold by Tangent.

Click the picture for the full set @ Flickr.


Enclosure is a cheap $2.50 plastic box from the local electronics parts store.
I'll be using an identical enclosure when I can get a CMoy built that works
properly (messed up the first one by being in too much of a hurry, ended up
with a broken left channel).
 
Apr 23, 2007 at 12:52 AM Post #2,020 of 9,811
... is my first DIY audio project. Well, it's not completely true, since I assembled one radio kit as a kid some 15 years ago. Anyway, a few shots of a somewhat ghettoish Millett: Panasonic pot, OPA551 for buffers, no bypass caps (neither films nor cathode bypasses), front and back panels by "Cardboard Panel Express" (top cover didn't arrive yet). Powered by Jameco linearly regulated wallwart it rocks pretty well.



Edit:
Those who consider building one of these amps for themselves might like to know, what's the cost. In my case it was $94 in parts as shown in pictures (including PCB, the Hammond case, all connectors, volume knob and the wallwart). The capacitors I left out for now would add only some $8 more. So far so good, but I ended up paying $32 for shipping from 5 different places. Now, that sounds really silly, doesn't it? Well,
  1. Mouser doesn't carry any appropriate volume pot (not really true, but I didn't find this post by tomb soon enough), also the Silmics at Digi-Key are so tempting for C7
  2. Digi-Key has no phone jack to fit the pads on the PCB (of course, I could use some outboard jack and/or pot, but PCB mounting is way more convenient for me)
  3. I couldn't find any 24V linearly regulated power supply at either Mouser or Digi-Key (that popular Elpac is discontinued and sold out and all new models seems to be switched)
  4. vacuumtubes.net has 12FK6 tubes for just $2, but no PCB mount tube sockets there this time
  5. Tube Depot has nice ceramic sockets but tubes itself twice as expensive as at vacuumtubes.net, that would still be favorable if one wanted only two tubes, but it is surely desirable to have at least a spare pair
 
Apr 24, 2007 at 1:32 AM Post #2,024 of 9,811
Here's my latest DIY adventure, which took 4 months and costed $1000:
m85665294.jpg


m85665302.jpg


In there is one of Welborne Labs' remote controlled stepped attenuators. It's powered by a 5V regulated power supply next to the power supply for the amplifier (47,000uF @ 10 x 4,700uF capacitors). The transformer is an Avel-Lindberg 530VA @ +/-40V AC. Through the power amp's supply, it delivers a +/- 55.7V DC unloaded. I cracked the acrylic in the back panel putting in the AC inlet... I felt stupid doing that. Originally, I planned on using relays to completely power on and off the amp, but for some reason, the relays fried (I know it wasn't the amplifier, because the sound coming out is extremely clean and undistorted). The relays were rated at 8A/250V. I was too lazy to make another board, so I left them in there. They're currently powering a pair of Yamaha NS-527 speakers.

Oh yeah, a MAJOR thanks goes out to the USAFA electrical engineering department for providing me with the tools to make the amplifier.

One more thing:
m85665310.jpg

I made that interconnect. The C-Store (where all cadets, including myself, buy stuff on base, pretty much) didn't sell a 1/8 mini to 1/8 mini stereo cable, so I made it.
 
Apr 24, 2007 at 2:00 AM Post #2,025 of 9,811
Quote:

Originally Posted by Polaris111688 /img/forum/go_quote.gif
Here's my latest DIY adventure, which took 4 months and costed $1000:
m85665294.jpg


m85665302.jpg


In there is one of Welborne Labs' remote controlled stepped attenuators. It's powered by a 5V regulated power supply next to the power supply for the amplifier (47,000uF @ 10 x 4,700uF capacitors). The transformer is an Avel-Lindberg 530VA @ +/-40V AC. Through the power amp's supply, it delivers a +/- 55.7V DC unloaded. I cracked the acrylic in the back panel putting in the AC inlet... I felt stupid doing that. Originally, I planned on using relays to completely power on and off the amp, but for some reason, the relays fried (I know it wasn't the amplifier, because the sound coming out is extremely clean and undistorted). The relays were rated at 8A/250V. I was too lazy to make another board, so I left them in there. They're currently powering a pair of Yamaha NS-527 speakers.

Oh yeah, a MAJOR thanks goes out to the USAFA electrical engineering department for providing me with the tools to make the amplifier.

One more thing:
m85665310.jpg

I made that interconnect. The C-Store (where all cadets, including myself, buy stuff on base, pretty much) didn't sell a 1/8 mini to 1/8 mini stereo cable, so I made it.


My hero. Beautiful.
 
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