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MJW Amps -- New Build for Thorpy FX. BUILD PICS!

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  • If I remember correctly from my A levels toroidal transformers are more efficient compared to a standard laminate type. As the coils surround the core (as opposed to not fully surrounding the core) there is less stray (wasted) magnetic field which would also reduce the amount of hum/unwanted noise from the amplifier I would have thought. Also they can be smaller (though not always) and most of the time lighter than their nom toroidal counterparts.
    But they are more expensive to manufacture, hence why they aren't used as much.

    Bear in mind transformers were my least favourite part of my A level so take it with a pinch of salt so feel free to correct me if I have gone wrong anywhere!
    I'm not a McDonalds burger. It is MkJackary, not Mc'Jackary... It's Em Kay Jackary. Mkay?
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  • martinwmartinw Frets: 2149
    tFB Trader
    That's about the size of it. :)
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  • martinwmartinw Frets: 2149
    tFB Trader

    A pic of the completed chassis wiring:

    image

    The next stage is to finish the design and drawings for the turret boards and layout, and then get those built and fitted.

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  • BigMonkaBigMonka Frets: 1763
    The twisting of the black&red wires is immaculate!
    Always be yourself! Unless you can be Batman, in which case always be Batman.
    My boss told me "dress for the job you want, not the job you have"... now I'm sat in a disciplinary meeting dressed as Batman.
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  • ThorpyFXThorpyFX Frets: 6090
    edited November 2015 tFB Trader
    I really do love gutshots of amps, especially when they start off so well!
    Adrian Thorpe MBE | Owner of ThorpyFx Ltd | Email: thorpy@thorpyfx.com | Twitter: @ThorpyFx | Facebook: ThorpyFx Ltd | Website: www.thorpyfx.com
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  • martinwmartinw Frets: 2149
    tFB Trader

    These are the turret boards for the amp, awaiting populating with components. I'm using 'perf' board on this one, as opposed to the blank board I use on some amps. I'm coming over to use this more these days, as although it costs a lot more, it save a fair bit of time drilling the plain board to a template.

    The clean channel board is on the left, and the overdrive and power amp are on the right.

    image

    The boards are then populated and are shown here offered up on to their stand-offs. Also, you can see the relays for channel and boost switching, and the SDM Zero Loss loop PCB attached to check clearance.

    image



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  • ThorpyFXThorpyFX Frets: 6090
    tFB Trader
    That is looking bloody neat, and...... Some great quality components there too.
    Adrian Thorpe MBE | Owner of ThorpyFx Ltd | Email: thorpy@thorpyfx.com | Twitter: @ThorpyFx | Facebook: ThorpyFx Ltd | Website: www.thorpyfx.com
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  • martinwmartinw Frets: 2149
    tFB Trader
    ThorpyFX said:
    That is looking bloody neat, and...... Some great quality components there too.
    Thank you! Nothing but the best :)
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  • jpfampsjpfamps Frets: 2723
    re toroidals, the price has come down due to advances in winding machines.

    Toroids are the transformer of choice in virtually all consumer electronics that doesn't use a switch mode power supply, and this has also driven down prices; in fact the use of EI transformer would be deemed risible in most applications.

    Winding output transformers on toroidal cores is difficult as for best results you need to interleave the windings, ie divide up the primary and secondary into sections, which will also require additional insulation. As a result of this it gets harder to wind as the hole in the middle of the toroid soon fills with the additional windings and insulation.

    There are a few companies making toroidal output transformer, but these are mainly marketed to the valve "hi-fi" brigade.

    I've not tried a toroidal OT in a guitar amp, so can't comment on their sonic properties, however I can see why they would be better or worse than an EI transformer.

    One other issues with toroidal transformers is that they are very prone to saturation due to DC on the primary. Thus in an OT the two halves of the push pull pair would need to be very well balanced to avoid problems with saturation. 

    DC on the mains, which will cause buzzing, can also be a problem in some territories, eg Japan. Although I've had no issues with this in the UK.

    Toroidal PTs can experience very large in rush currents on power up, so for more power amps some form of in rush current limiting is recommended.

    I think most manufacturers don't employ toroids for a number reasons. 

    Historically they were more expensive than an EI transformer, however that is not so much the case now if at all. Companies will often employ the same transformer manufacturer for their PT, OT and chokes (the later 2 need to be EI), and many manufacturers are not set up to make both toroids and EI transformers, especially though au fait with valve OTs. Many smaller (and even some quite large manufacturers) use off-the-shelf parts and there aren't so many toroidal options. Also many manufacturers are more or less copying existing designs, so a toroidal PT would be seen as not authentic.

    For what it's worth, we use always used toroidal PTs in our amps, and these are custom made for us in the UK by Tiger Toroids in Norfolk.
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  • martinwmartinw Frets: 2149
    tFB Trader

    The amp is working now and being tested, and the cabinet build is underway. Hoping to complete it for delivery early next week. :)image

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  • CabicularCabicular Frets: 2214
    loving that!
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  • martinwmartinw Frets: 2149
    tFB Trader
    Cabicular said:
    loving that!
    Thanks! You should hear it! :)
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  • ThorpyFXThorpyFX Frets: 6090
    tFB Trader
    I do feel like Christmas is going to come early this year
    Adrian Thorpe MBE | Owner of ThorpyFx Ltd | Email: thorpy@thorpyfx.com | Twitter: @ThorpyFx | Facebook: ThorpyFx Ltd | Website: www.thorpyfx.com
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  • equalsqlequalsql Frets: 6084
    :-O
    (pronounced: equal-sequel)   "I suffered for my art.. now it's your turn"
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  • drwiddlydrwiddly Frets: 911
    ThorpyFX said:
    I do feel like Christmas is going to come early this year


    You've clearly been a very good boy indeed! :)
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  • markslade07markslade07 Frets: 833
    edited December 2015
    @thorpyfx I reckon I'll be able to hear you try it out for the first time from here (I'm just down the road in Chippenham!)
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  • ThorpyFXThorpyFX Frets: 6090
    tFB Trader
    @thorpyfx I reckon I'll be able to hear you try it out for the first time from here (I'm just down the road in Chippenham!)
    listen out on friday!!!
    Adrian Thorpe MBE | Owner of ThorpyFx Ltd | Email: thorpy@thorpyfx.com | Twitter: @ThorpyFx | Facebook: ThorpyFx Ltd | Website: www.thorpyfx.com
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  • :D
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  • martinwmartinw Frets: 2149
    edited December 2015 tFB Trader

    Nearly finished now. I did some tweaking to the boost function, and have added a second relay to switch some additional functions to improve the sound in the unboosted mode. I'd hoped to do it with one DPDT relay, but tonally it wasn't up to my expectations. With 2 relays, the boosted mode is pure SLO, and unboosted is 2203/JCM800 in tone, and has better access to lower gain crunches.

    On with the cab then. Here's a pic of the woodwork. High quality 18mm Baltic Birch ply, butt jointed, stapled and glued with Titebond. Well, it's enough to hold the neck on a Gibson! A very strong construction method, ask any Matamp owner.

    image

    Here's a snap of the parts required to complete the amp, including the footswitch and cable. Just noticed that I forgot to include the corners, ah well. Note the steel bar handles. The footswitch has now had the switches replaced with DPDT and LEDs added. It has a 5-pin DIN socket on the rear, meaning you can replace the cable more easily, or use different/shorter/longer ones.

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  • ThorpyFXThorpyFX Frets: 6090
    tFB Trader
    Thats a big ole heatsink over the power scaling mosfets!! i assume they get very hot?

    Adrian Thorpe MBE | Owner of ThorpyFx Ltd | Email: thorpy@thorpyfx.com | Twitter: @ThorpyFx | Facebook: ThorpyFx Ltd | Website: www.thorpyfx.com
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