Jcm800 2204 Build

Discussion in 'Building the Classics' started by coolidge56, Mar 22, 2019.

  1. Exojam

    Exojam Well-Known Member

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    Well that sucks but at least your health is there.

    What truck do you have a Raptor?
     
  2. coolidge56

    coolidge56 Well-Known Member

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    No my health has taken a nose dive also (censored). You know damn Ford, a 6 cylinder Raptor...REALLY?? Total turn off. I drove one, talk about gutless off the line. I'm driving a 6.7 diesel super duty...wait for it...440hp and 925lbs torque. It will do a burn off at 40mph LMAO!
     
  3. Matthews Guitars

    Matthews Guitars Well-Known Member

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    It is a fact that there are factors in play where the relative position of components affects performance. There is a somewhat obscure subset of electronics knowledge called "circuit constants" and by adjusting relative component locations you can change the character of the amp. Capacitors and other components close together do exhibit mutual capacitance and mutual inductance as well. You have to be careful with wire dress and routing. Manage wire lengths and how they are routed.

    I've worked on equipment where wire dress was critical to the unit simply OPERATING. You might say that if it was that critical, then the design itself was suspect, but when the wire dress was right, the unit operated to designed specifications reliably and without issue.

    Randall Smith tells tales of spending many hours adjusting component locations and wire dress in prototype amps in order to achieve a certain sound, and when it's achieved, freeze the PC board design so that those distributed capacitances and inductances are reliably replicated in prodution amplifiers.

    If you disagree with the notion that electronic components interact with each other due to their relative positions, then you DON'T know electronics. Inductive and capacitive coupling is very real. And it becomes ever more important as frequencies get higher. At microwave frequencies, it DOMINATES circuit layout.
     
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  4. coolidge56

    coolidge56 Well-Known Member

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    My last 100 watt Plexi build was so quiet with the volume on 5 I thought it was broken. True story. :eek:
     
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  5. coolidge56

    coolidge56 Well-Known Member

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    All this talk of amp building...while my work schedule is insane I could finish the CAD for the chassis and have it made. :hmm: You know, after the tow truck driver gets here and hauls the Ford to the dealership and I get a loaner, come home and hose all the coolant off my driveway.
     
  6. ibmorjamn

    ibmorjamn Well-Known Member

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    How much would the that cost ? I have some software that does PCs schematics and will build a board but I’m not well versed in using it.
     
  7. coolidge56

    coolidge56 Well-Known Member

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    Okay lets empower you guys to craft your own boards. First up I use DesignSpark PCB. Its a free download and easy to use. Lets walk through a few important steps.

    1. Here I have clicked Output/Manufacturing Plots to open this Output Manufacturing Plots popup window. This will generate several files that you need to send to the PCB manufacture so they can manufacture your boards. On the left you see the plot layers I selected for the boards. Everything except the copper paste. To the right on the Output tab note I selected Gerber.

    [​IMG]

    2. Here is the Layers tab. Note that I selected Board Outline and Top Silkscreen. The board outline will be used to route the boards, just what it sounds like they use a router to separate the individual boards more on that below.

    [​IMG]

    3. On the Position tab you see the size of the board 25.35 x 3.5 inches. It adds a .0025 buffer. So one giant board with a bunch of individual boards defined by the board outlines for each.

    [​IMG]

    4. Here I zoomed in so you can see what's going on. The green border is the board outline. This will be the outside edge of each board after routing. The red lines are the paths for the router bit. There is .100 inch between all boards, that's the waste material the router bit will remove. So .050 inch spacing either side of the center red lines. The white boarders are part of the white silk screen layer. Technically they are not required on these small boards since its just a printed white boarder but turns out they look pretty cool.

    [​IMG]

    Its MUCH less expensive to design a single large board with all these multiple boards on it, routed to separate the boards from one another vs having individual boards made say one for the preamp and a 2nd for the power supply.

    GET CREATIVE - I added some additional length to the board and added a bunch of small boards. One for the two guitar input jacks for example, an idea I borrowed from my Marshall Studio SC20H. I used PCB mount cliff jacks. These jacks still attach to the chassis with the classic Marshall chrome nuts so they are chassis mount. But I'm tying the jacks together on a brute .125 inch thick PCB mini board on the back side which makes them even stronger. Plus I have a place to solder the 470k/470pf and 1M components into brute plated through hole PCB locations with plated through holes for the connecting wires. NOTE: You need to design the input jack board so the face of the jack sticks out a bit farther than the edge of the board so the jacks mount flush/flat against the chassis.

    The rest of these little turret boards are for various chassis locations, holding up one end of resistors, those double/triple turret boards I'm mounting near each preamp and power tubes for the heater wires.

    Here's my quote for these boards. As you can see price per board varies by quantity of boards ordered and days. I opted for 10 boards, 5 day manufacturing, price $1,029.50 or $102.95 per board. If I was willing to wait 20 days I could have saved $183.80.

    Note I opted for a number of upgrades. These boards are quite thick, .125 inch. Lets define that, the thickness of the board plus the thickness of the copper pad plus the thickness of the plating = .125 inch. Just the thickness of the board is about .120 inch.

    Its a 2 layer board copper top and bottom. Plated through holes. So you have a pad on the top, bottom, and the hole through the board is also plated creating a very stout soldering point. Most of the board holes are sized for turrets so I'll never had to re-solder them but for the few that are solder pads for components you could re-solder them multiple times. Note I also used plated through holes for all the screw locations that mount the boards to the chassis.

    Tab Routing - Here you have to tell the PCB manufacture you want the boards FULLY ROUTED. Tab routing typically leaves tabs of board material connecting all the individual boards. V scoring by the way is more expensive, e.g. where they score the boards with a V and you snap them apart. You won't be snapping boards this thick apart because V scoring still leaves a LOT of material in the middle. So opt for tab routing with no tabs.

    Note I opted for LEAD plating. This is the least expensive, but then its not RoHS compliant. I don't care I'm not selling amps. There are however multiple other plating options, including RoHS compliant. The more exotic plating options are more for computer motherboard type boards.

    2 OUNCE COPPER - This means 1oz copper on top and 1oz copper on the bottom = 2oz copper total. They literally take 1oz of copper and smash it flat over a board that's where this oz copper stuff comes from. Now I got all chest puffed and ordered 4oz copper once thinking if 2oz was good 4oz would be even more brutish. But it was so thick the manufacture contacted me as the etching process was eating in/under the solder pads so we backed off to 2oz. Just saying.

    Note the board material is FR-4 pretty standard fire retardant board material. It is quite strong especially in this thickness. True story, I ordered boards once and they forgot to separate the preamp and power amp boards. I cut them apart with a scroll saw...half way across the 4 inch wide board all the teeth on the scroll saw blade had worn off lol.

    Note BLACK solder mask color because black boards are badass! White is a great silkscreen color on the black. But there are other colors. I opted for a blue once, man it was a puke blue/green I didn't care for it. But RED boards with a white silk screen looks pretty good. I almost opted for that on this order.

    [​IMG]

    HOLE SIZE & TOOLING - Try to use standard sized holes and nothing too small or you may have additional charges for odd tooling or tiny holes. Here are all the pad/hole sizes I'm using on the boards. The smallest hole size is .030 but you can likely get away with .020 inch.

    PLATED THROUGH HOLES - You need to leave some wiggle room for the plating. Also hole sizes are not accurate to a micron. So for turret holes for example leave a few thousandths of an inch wiggle room for manufacturing variance don't cut it too close. PCB Prime has some how-to info and guidance on this on their website.

    [​IMG]
     
    Last edited: Sep 28, 2019
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  8. coolidge56

    coolidge56 Well-Known Member

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    INCH or METRIC...here comes a face palm. So originally I decided to convert to Metric figuring this would be easier than working in inches which is true. But it turns out for PCB boards everything is in mills e.g. inches so they convert back. I don't remember the issues I ran into using metric but I remember doing a giant face palm and starting over on the boards in inches.
     
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  9. coolidge56

    coolidge56 Well-Known Member

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    COMPONENT LEAD LENGTH - If you opt for boards this thick you can run into issues where the lead lengths on components, caps, turrets are too short and not long enough to extend through the opposite side of the board. So keep an eye on this when ordering components.

    KEYSTONE TURRETS - I'm using 2 different sized turrets, the 1540-4 and 1509-4. Note the .172 inch length of the shank, this is so there's enough of the turret shank sticking out the bottom of the .125 inch thick board for staking. ALSO Keystone is smoking crack the TL-5 staking tool does not work on the 1540-4 turret use the TL-8 staking tool. I stake the turrets into the plated through holes, then solder the bottom of the turrets to the board for added BRUTE!

    [​IMG]
     
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  10. Exojam

    Exojam Well-Known Member

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    Well the health part sucks. Trust me, I am still not completely healed up and I have been dealing with possible life ending stuff for over a couple of years now. I am hoping it will be over (for now) in a few more weeks.

    I actually just picked up a Ford F-150 sport,4*4 limited edition. The part that killed was getting it setup so the drivers seat would rotate out and down so I can transfer from my wheelchair, and the the hoist to take my wheelchair and put it in the bed. I am loving the truck.

    Watch your health man!!!!!
     
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  11. coolidge56

    coolidge56 Well-Known Member

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    Exojam I see Fedex is slow as molasses, ETA your location next Monday.
     
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  12. Exojam

    Exojam Well-Known Member

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    No problem it may be a slow build anyway.

    Thank you very much again for sending them over.
     
  13. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    "It is a fact that there are factors in play where the relative position of components affects performance."

    Now here is a guy who is using his smarts. It's a major difference in sound. (and thank you for recognizing the fact)
     
  14. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!

    Did anybody actually build this board and listen to it?
    Did it turn out as sounding good?
     
  15. Exojam

    Exojam Well-Known Member

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    No one has made one yet.
     
  16. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    Hell yeah Bro!!!!
     
  17. MarshallDog

    MarshallDog Well-Known Member Premium Member

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    Love those F0RD diesels...nice!
     
  18. Exojam

    Exojam Well-Known Member

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    And we were waiting for you to let us know if the capacitor spacing was correct:duel:
     
  19. ampmadscientist

    ampmadscientist Well-Known Member

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    Capacitor spacing has to be tested.
    It will either work good or it will sound like ass.
    Put it together and test it.

    But I will give you this advice:
    if 2 caps are located side by side, one will radiate into the other and vice versa.
    That could be a good thing or a bad thing.
     
  20. Exojam

    Exojam Well-Known Member

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    I am pretty sure we understand that Amp, you have seen the layout so I gather you would be able to let us know if the cap spacing looks good-bad or what ever.

    Is there no formula that can be used taking into account the construction of the cap, the spacing being used etc, that would provide the needed data? How do top shelf amp manufacturers determine this? I do not disagree with the first statement you first made but I think it to much of a blanket one.
     
    Last edited: Oct 4, 2019

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