DIY amps for Linkwitz Orion

Discussion in 'DIY Discussion' started by Hamilton, Jan 8, 2009.

  1. Hamilton

    Hamilton

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    I'm planning to start building 2 x 4-channel amps for my Orions shortly. I've been using them with Alesis amps since I finished them and they sound great, but (a) there is a bit of low level noise (not audible during music but I know it's there) (b) I'm interested in testing out Linkwitz' assertion that all reasonably competent amps sound the same with Orions (c) I can save a bit of space and increase WAF by getting the amplification into two smaller boxes, and (d) I fancy the challenge. I've just completed a 41Hz Amp 6 kit to check out my soldering is up to the job and it sounds surprisingly fine with a pair of little Tannoy 603's I picked up off e-bay.

    So... the plan is to do this with 4 LM3886's per side (1 each for treble and mid, 2 for bass), and seperate trannies/power supplies for bass, mid and treble. I'm going to use the 'CarlosFM' circuit (see http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonesnub.html) for the amps and 'snubberized' power supplies with increasing amounts of capacitance going from treble to bass.

    There will only be around 60w per channel driving the Pearless 10" XLS drivers, as compared to the 150w currently, but SL is adamant this is plenty when they are driven directly with no intervening crossover, and that it avoids any dangers of bottoming at high volume. So I'm going to give it a try. I can always go for some bridging/paralleling if it seems like they need more.

    So... any thoughts, suggestions or cautions? (Not a whole different approach though please.)

    And... I'm thinking about going the whole hog and making some aluminium enclosures from scratch, so does anyone know where I can get some suitable heatsinks? Or alternatively any suggestions for where to get waffy but reasonably priced boxes?

    Cheers

    Gordon
     
    Hamilton, Jan 8, 2009
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  2. Hamilton

    robM

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    are you going to be using the 3886s in parallel mode or just using a single chip for the amp?

    I'm not convinced at all on the sound of the LM3886 amp clones. I know that Jeff Rowland uses parallel versions on some of his models but those amps just don't sound as good as a well designed discrete bipolar amp. The 47lab units sound like toys to me....even the lowly Naim variants 'sound' a lot better and these circuits can be found on the web also.

    I have heard the Orion as I have a friend in the states that uses them. You need a big roon but they do sound good. He uses a set of older/ modified Musical Fidelity amps. I do believe that there is nothing like large discrete transistors for current handling and you'll need it if you have a large room.
     
    robM, Jan 8, 2009
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  3. Hamilton

    Hamilton

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    Well after a bit more thought and some input from Tenson (thanks) I'm thinking single 3886's for the treble and mid where the demands will be relatively benign, and an LM4780 per woofer in bridged or parallel mode. My (admitedly limited) experience of chipamps suggests that it is a lot about the implementation, and I've heard them sound very good indeed with the right power supply etc. The active nature of the Orions should make them less amp-dependant for their sound than most. SL himself seems to be an advocate of the chips, and very conservative about the needs of the speakers... Also the room they're in isn't that big, certainly by US standards, so...

    This won't be a costly experiment. Should be able to start soon building the top end (treble and mid), without worrying about fancy enclosures for now, keeping the current Alesis on the woofers, and see how it sounds.
     
    Hamilton, Jan 9, 2009
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  4. Hamilton

    robM

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    mmmm

    I think because they are active, the demands on the amplifier quality will be paramount. Chip amps are quite limited in my experience of them.. If you haven't heard one...listen first before the plunge. SL is Ok with them but does prefer discrete amps for absolute audio quality!
     
    robM, Jan 9, 2009
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