Finished Gain Clone Amps

Discussion in 'Home Theater Projects' started by Ken Cline, Nov 10, 2004.

  1. Ken Cline

    Ken Cline Stunt Coordinator

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    It's been a while since I've frequented this forum. I just finished 2 mono block Gain Clone amps and wanted to share them with all of you.

    These are easy and fun to build, although the case took longer than the electronics. They sound quite wonderful for what they cost. It would be easy to build an HT amp with these boards. If you've been living under a rock and don't know what boards I'm talking about [​IMG], go here... http://www.chipamp.com

    [​IMG]

    There are more pics here http://photobucket.com/albums/v521/kecline/?
     
  2. Patrick Sun

    Patrick Sun Moderator
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    Brian Bell demo'd his gain clone amps at DIY Atlanta this past weekend. For me, the enclosure is the biggest stumbling block to giving it a shot. If someone has some pointers in the enclosure portion of the project, it could motivate others to give it a shot too.
     
  3. Mitch N

    Mitch N Stunt Coordinator

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    The enclosure portion is easy.

    You can use just about anything. many people have made intricate wooden boxes. You can use an old receiver, a cigar box.

    BTW, I love my gainclose from Brian as well. However I bought a pre-fab enclosure from Peter Daniel

    More pics of other gainclones can be found on Brian's site.

    http://www.briangt.com/gallery/nigc
     
  4. MarkRoberts

    MarkRoberts Stunt Coordinator

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    Hey Ken,
    Nice job! I was poking around on the link you provided and am very interested. What would you say the total cost in parts is? Not just the 55.00 kit cost but the other components needed? How much power do they put out? I didn't see any mention on the site. I might have over looked it though I am on my lunch break [​IMG]. Looks like your box is made from 80/20 or similar aluminum extrusion. Looks tough.
     
  5. Patrick Sun

    Patrick Sun Moderator
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    Brian said that you get about 35W into 8 ohms per channel, but there's also bridging possibilities with the amps.
     
  6. Ken Cline

    Ken Cline Stunt Coordinator

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    According to the spec sheet it's 56W into 8 ohm. http://www.national.com/pf/LM/LM3875.html

    I figured I have roughly $80 for each block. But of course I went extreme overkill on the case. However, I got the 80/20 stuff from a local distributor for about $7.50 for each side. Avel Lindberg 2 X 25V xfmr's from Apexjr.com $17.95 each. That alone is a great bargain. The rest of the 1/8" & 1/4" aluminum I got at a local metal shop at scrap cost ($2.25 lb.). Check the remnant area at your local metal dealer.
     
  7. Allen Ross

    Allen Ross Supporting Actor

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    i would love to get a few of those, what sites did you use for the power supply?
     
  8. Joe Hsu

    Joe Hsu Supporting Actor

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    Man, I was eyeing those for the longest time...I'm not EE, but I do have a head for that type of stuff. I just never got around to it, and I would probably look for something with a little more power. I'm personally refurbing an old Parasound right now, so we'll see how that turns out, but in January I'd like to look at making a Pass Labs amp.

    How long did it all take you?

    And for others interested, there's also:

    diyaudio.com
    passdiy.com (most of his stuff is at diyaudio anyway, as Mr. Pass posts there himself)
     
  9. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    Those are beautiful! I am definately interested in building my own amps for the HT I am creating. How suited are these amps to HT use? I was considering building Adire 281s for my mains, but they are 4Ohm. Would something like your amp be able to power these?
     
  10. Ken Cline

    Ken Cline Stunt Coordinator

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    Thanks Jordan. You can run the amps with a 4 ohm load but you have to use a lower voltage transformer.
     
  11. Allen Ross

    Allen Ross Supporting Actor

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    I think i just found my next project, its relatively inexpensive, you can modify it in countless ways, I am thinking of designing it for 4 ohms with a beefy torrid and possibly bigger caps, with the premium stereo kit then bridge

    Now i need to get my learn on and start asking some question over at DIY audio.

    let me know if i can pick your brain with some emails Ken.
     
  12. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    I hate not being able to see how these perform in person!

    I have a few questions...

    First, do you have any info on what kind of speakers these amps are suited for? I looked everywhere but could not find much info.

    What is the difference between the 4780 kit and the 3875, offered at chipamp.com?

    Last, I see the kit does not include a power supply. Any ideas where I could find more info on different types and how they perform?

    I can follow circuit diagram, and build them, but I must admit I have no clue when it comes to designing them myself.
    I would like to make either a 5 channel amp or 5 monoblocks, as it will be for theatre use. My only worry is that these wont have enough "umph" for theatre use.

    Thanks!
     
  13. Allen Ross

    Allen Ross Supporting Actor

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    thats prob depends on what you are going to be powering, i imagine these can't really be used for DIY subs. but if you are going to use them to say power some ELF's or mini monitors, I imagine they would rock.
     
  14. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    I was planning on building Adire 2x281s LCC and 2x81s. 4 ohm loads. I'm keeping my fingers crossed, as these look like a lot of fun to build.
     
  15. Ken Cline

    Ken Cline Stunt Coordinator

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    The only thing you need is the transformer. The kit comes with the rectifiers, caps for the unregulated power supply section. Check out Brian's manual, http://www.chipamp.com/nigc_kit-users_guide.pdf should help you with some of your questions.
     
  16. Jordan_Brulotte

    Jordan_Brulotte Stunt Coordinator

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    I checked the specs on the 4780 and it says it can be bridged to 120w mono. This sounds like it could be great for HT use.

    I see that you did not use volume control with your amps. Using only your preamp, how much control do you get over the volume? I'm new to this but by reading it sounds as though you can set the gain on the amps even without a volume controller. Any tips would be appreciated!
     

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