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Bertha, Ruby's Chunky Sister

Discussion in 'Shock Brother's DIY Amps' started by SerpentRuss, Apr 11, 2021.

  1. SerpentRuss

    SerpentRuss TDPRI Member Ad Free Member

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    It seems a lot of the folks on this forum have played with the Ruby circuit, so I thought it was something I should build so I'd have that shared experience. I had every intention of following the schematic exactly, so I ordered some SMD J201s and the adapters. I'm sorry, but I had no idea how delicate a job that would be. I didn't even try.

    I had a bunch of LND150 MOSFETs around so I messed around on LTSpice with the Ruby Circuit and came up with something that looked like the buffer portion would have about the same amount of gain as Ruby, pretty close to unity. I breadboarded the amp and trialed the circuit using a small 6.5-inch woofer but I wasn't very impressed. The components sat on the breadboard for over a month and I was going to take it apart when I tried it with an old Chrylser 6x9 speaker. It sounded much better so I decided to throw together a case from scrap wood, mainly for the reason of actually completing something I started.

    As everyone knows, the ruby controls are very interactive. This means that when you dial in a sound you like, the volume is going to be fixed at that point. In my mind, it could use one more amplification stage but then you'd lose the simplicity and the ability to run off a 9-volt battery. It would also be like making a silk purse out of a sow's ear. At any rate, it's finished and it works. The DC supply is built from a multi-tap air conditioning control transformer. There's a 10 Ohm power resister between the filter caps to drop it down to around 16. I'm not sure the LND150 buffer would work well in a circuit powered by much less.

    20210411_143049_LR.JPG 20210411_143101_LR.JPG 20210410_200744_LR.JPG RubyLND150.JPG
     
    2L man and Zepfan like this.
  2. Zepfan

    Zepfan Doctor of Teleocity Gold Supporter

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    I made my Ruby circuit and used the MFP102 JFET and the LM386N3 chip because the N1 chips didn't last long.
    I had a little Behringer 10watt practice amp that died, so I put it in that cab with the 6" original speaker and it's awesome. Run it with a walwart.

    Later I cobbled together my own circuit design with a dual 386 bridged amp. It had way to much distortion and I never got around to tweaking it.
     
  3. Zepfan

    Zepfan Doctor of Teleocity Gold Supporter

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    BTW Your cab looks great.
     
  4. SerpentRuss

    SerpentRuss TDPRI Member Ad Free Member

    Age:
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    Thanks,

    I had the idea of using some Transfast, a dry water-soluble tint, in water-based polyurethane. Normally the tint goes on first, before the finish, but I thought it might work OK and it did. I think I'll do it with another project. Cocking the 6x9 at an angle was just something I thought would look good. The perforated metal the controls are attached to is salvaged from work. I'm going to try and make chassis with the stuff at some point.
     
  5. jmp81sc

    jmp81sc Tele-Meister

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    Great looking build and cab.

    I've done 2 Ruby's and I think they are great through a good speaker.

    User Johnny Crash posted a great thread on an Ultimate Ruby that was very informative. I want to copy his ideas at some point and play with the design.
     
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