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  1. mcentee2

    Bleeder resistor calculation and questions: current, watts, time

    Yep, totally get that :) Serendipity, always good to get a free bonus :) I built my Supa Deluxe and Black Flag amps recently with raised heater CT off a split bleed from HT to ground as was suggested in an earlier post, all good!
  2. mcentee2

    Bleeder resistor calculation and questions: current, watts, time

    Looking at the Hiwatt and similar power supplies, they have those 200k resistors across the 2x200uF caps to regulate the voltage across each. Looks like a designed in bleed to me :) might take a while though....
  3. mcentee2

    Another Hiwatt DR103 Build

    Really nice - I love using cable ties too to keep those pesky leads together where they should be before their bend points! I've finally finished a BoM list for my DR504, the circuit parts are always the easy bit, it seems it's the usual haberdashery of chassis bits and pieces causes the...
  4. mcentee2

    Hiwatt DR103 Bias Mod - Layout check before implementation

    Looks good to me! Radial caps would poss look uglier I think, sticking up at whatever angle, the leads might also need spreading just as awkwardly?
  5. mcentee2

    Useful Plexi mod: switchable bright cap on volume pot, or switchable treble peaking cap on 470k mixer resistor?

    I would say switchable bright cap too. Not messed with the mixer cap but have read it kills both channels if clipped :) Bright cap for me is 100pF for strats and clean end of the dial. 600pF is good for Les Paul at the clean/bteakip end, but tbh 100pF is ok too. 4800pF for anything above 6...
  6. mcentee2

    Hiwatt DR103 Bias Mod - Layout check before implementation

    Both my Supa and Black Flag bias circuits are fed from the main PT wind, one side of the AC feed before the rectifier, rather than a dedicated bias PT wind, so the DR504 is just the same :) it does seem a lot easier to get in the ballpark
  7. mcentee2

    Hiwatt DR103 Bias Mod - Layout check before implementation

    Good stuff! I saw there were 6 tags used on the Hoff layouts and saw you needed 7, but was thinking I had misread it. For my DR504 I'll beat these bias circuit s in mind re fitment, I was going to just do the simple single link replaced with a trimmer. In my Supa Deluxe I added a fixed bias...
  8. mcentee2

    Hiwatt DR103 Bias Mod - Layout check before implementation

    Hi - didn't spot this earlier post/thread on your DR103! Layout looks ok to me (not an expert though!) - just the last bias out feed from the pot wiper not shown. Which 7 tags is this going on, as am matching this up against the Mark Huss layouts. Did you put this in as I can't see it on your...
  9. mcentee2

    Another Hiwatt DR103 Build

    As above a DR504 is next on my list. Same preamps as the DR104 but bolted on to 2xel34 power amp :) Make sure you get that OT impedance right if you do take 2 tubes out of the DR103. Even though the volume isn't much less so might stick with that 100w, you might find there are more and...
  10. mcentee2

    Another Hiwatt DR103 Build

    Yep, it's Mark Huss site preamp info site that I have been looking at. I wanna build them all of course, but one will have to do in practice. Am more tempted by the linked versions, but then again you can do that with the 4 hole ones as well as keep the low inputs. I am torn between that...
  11. mcentee2

    Another Hiwatt DR103 Build

    Looking good,and so glad there is a Hiwatt thread going on! Since I built my Modulus Supa and then a Black Flag I feel able to have a go at one of these and a DR504 is next on the list but am having a long break and taking my time with it whilst working through all the various choices that can...
  12. mcentee2

    Lightbulb Limiter Wattage

    Many thanks, that's what I was looking for :) much appreciated. Pretty sure eBay can provide incandescent bulbs still, especially high wattage ones.
  13. mcentee2

    Lightbulb Limiter Wattage

    Ah ok, didn't realise it worked like that , thankyou :) Question still stands though re what is a good ballpark wattage bulb to use ? Ta
  14. mcentee2

    Lightbulb Limiter Wattage

    Not sure I follow?
  15. mcentee2

    Lightbulb Limiter Wattage

    Watts is watts, but is also Volts X Amps, so if Volts is twice as much, the current limiting max is half what is over in the US for the same wattage bulb.
  16. mcentee2

    Lightbulb Limiter Wattage

    Yep, understood. I was trying to work out what "non-catastrophic" would be, IE about 100mA, and then work out what wattage bulb would give the best all round indicator of catastrophic Vs that.
  17. mcentee2

    Lightbulb Limiter Wattage

    Any clues as to what wattage bulb to use here ? Am building a JTM50, 2xel34, 3x 12ax7, gz34 rectified (or SS), so idle bias current should be about 100mA, a bit less maybe. So, a 25W bulb would be effectively on all the time (24W=240V X 100mA). A 100W bulb would probably be dim/off all the...
  18. mcentee2

    How Do We Like this?

    Apologies, I learned to use "ground" years ago but am slowly switching to use 0v and forgot this time.
  19. mcentee2

    How Do We Like this?

    Here is another angel for you folks...... In the layouts above, for the high gain jcm and the earlier JTM, we have cap cans being used. In the high gain amp the first cap can is joined together to act as a single cap with its ground node, the second can is split to screen and PI but they share...
  20. mcentee2

    How Do We Like this?

    Ah, ok! I hadn't spotted the star for the speaker was at the PI node, dual cap cans always confuse me :) I am building a Modulus jtm50 (with a single point ground scheme like the jtm45 layout below) where the speaker ground comes all the way across to join the presence pot ground wire at the...
  21. mcentee2

    How Do We Like this?

    I notice you moved the speaker 0v/ground from to directly connected to cap can point A, and away from its board turret which is connected A anyway. What's the reason for this move, as there no other ground destined connections made on that wire between A and the turret board where the speaker...
  22. mcentee2

    How Do We Like this?

    Could you point me to where I can find more info on the heater elevation voltage divider set up please - this is new to me and looks interesting, as I am starting a JTM50 build! :) Edit: DOH! Of course, here it is...
  23. mcentee2

    Shielded wire I can’t be liking this

    That's a good example I wouldn't have thought of. I suppose it's a case of where the signal is most susceptible to noise, like the input is essentially a very small signal so the s/r ratio can easily get disrupted. Same with the NFB wire.
  24. mcentee2

    Shielded wire I can’t be liking this

    Just extended this topic.. Apart from the input to a faint preamp first stage, where else can shielded best add value? I have seen it on NFB back from the speaker output to wherever it connects to the PI or easier stave cathodes. Anywhere else? Where is it overkill and just not needed at all?
  25. mcentee2

    To twist or not to twist

    Poss me being thick (again!), but when you say "a single wire", just the one?




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