Rod Elliot's 300W sub amp design

Discussion in 'Home Theater Projects' started by RichardHOS, Jun 27, 2003.

  1. RichardHOS

    RichardHOS Second Unit

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    Have any of you ever built a sub amp following Rod Elliot's design? If so, how do you rate its performance? Also, assuming the PCB was purchased from Rod's site, what would you estimate the total cost to complete one would be (including all components, heatsinks, etc.)?

    And for the final question... are there other DIY sub amps of that general power rating that are more highly recommended?

    I'm trying to compare the cost of DIY solutions to some of the less expensive prosound amps for bass amplification.

    TIA
     
  2. Michael R Price

    Michael R Price Screenwriter

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    Many users have reported successfully building and enjoying the P68 amp. I wish I could tell you more, but... it's from Rod Elliott, who apparently has well-designed products and good support.

    I think that unless you really find good deals on parts, a 350 watt plate amp, or a QSC RMX-850 (2 channels) will be cheaper. Here are my guesses for the costs. The PCB will cost you something like $20. The electronic parts to put on them will be $30 or so. A surplus heatsink will cost you $10-20... and the toroid transformer would be like $50 for the recommended power. Then you have to figure in whatever you want for a chassis, which could be a lot. Why so expensive? You would be doing this way, way better (in terms of parts quality and design implementation) than a usual amp around that price point.

    I think that it's still better to just use commercial amps to power subwoofers, where power is more important than anything else, because DIY amps can be more trouble and money. On the other hand, DIY is definitely worthwhile for hi-fi amps.
     
  3. Dave Milne

    Dave Milne Supporting Actor

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    Richard,
    I haven't built Rod's design, but I've built a few other power amps - some of my own design and some from published papers. If you have to buy all of the parts at retail (even with savvy shopping for discounts), the total cost will likely be higher [​IMG] than cheap pro amps or used amps from, say, AudiogoN.

    A nice chassis is often the most expensive part - you're looking at $100 or more. If you can live without that, the heatsinks and power transformer will be the major cost items. A 1KVA toroid transformer is probably going to be upwards of $100. If you want a quiet (no-fan) amp, then you're looking at a lot of heatsink area to get down into the 0.2 degree C/watt range. For example it will take you two Wakefield 345-1046-NDs from DigiKey (at $105 each) to get there. Power supply filter caps can add up, too... but you can usually find these pretty cheap at surplus outlets.

    Building power amps is a lot of fun and can be a great learning experience. I highly recommend it. However, if you're just doing it to save money, I think you'll be disappointed.
     
  4. RichardHOS

    RichardHOS Second Unit

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    Thanks for the advice guys. Yeah, I'd need 8 channels so I was thinking that if it were a little cheaper per watt, then it could offer enough savings to be worth the effort. Looks like that isn't the case at all.

    I'll stick with the prosound options then for my subs, and perhaps play with a really nice high-end DIY amp down the road just for the hell of it.

    [​IMG]
     

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