kustom defender 5h many pics

Discussion in 'The Squawk Box' started by TWANG, Jun 29, 2010.

  1. tinman402

    tinman402 Senior Member

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    I may have fried it... :(

    I am going to get to testing tomorrow.. I get glowing tubes, power light, but zero sound. Not a pop, a crackle, or a snap... lol

    I must have a loose connection or open end somewhere.. If I can't get it figured out.. Twang you may need to quote me a price on one of your VJ frankenamps.. ;)
     
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  2. Syrus

    Syrus Senior Member

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    As long as you don't fry yourself lol

    That's the fun part, debugging.

    BTW
    Have any of you ever seen this?
    Might be a interesting mod for a KD5H

    Tube-Town Online-Store - Bausatz Adapter EL90 - EL84 - ABGEKNDIGT kit-el84-90

    Too bad it is discontinued.

    A EL90 is almost the same as a 6V6, only in a smaller package.
     
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  3. TWANG

    TWANG Senior Member

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    Boy I know the drill on that one tinman..

    last night. I stupidly plugged an 8ohm cab into the 16ohm tap of my new build.
    What a moron! I not only built the amp, I wired the cabs!
    So I'm standing there for half an hour playing and saying to myself

    why does my great sounding new amp sound so crappy?

    then, to be even more stupid
    I stuck my head in the speaker to try to identify the noise.

    Am I lucky I didn't blow the OT. or worse?

    There's a natural symbiosis between stupidity and luck we should all appreciate.
    Because we're all gonna need it!

    hang in. they're tough amps! You can find it.
     
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  4. TWANG

    TWANG Senior Member

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    Syrus. that's interesting. I'm gonna look up that tube
     
  5. Syrus

    Syrus Senior Member

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    Yeah, it is also very compact.

    Makes me wonder why no amp companies use these instead of the 6V6.
    It is still available, but I see only NOS.
     
  6. OwlOfBlues

    OwlOfBlues Junior Member

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    by the way, with the adaptor it would never fit into that amp chassis... so either building a new one/ modifying it or somehow mounting it sidewards... interesting though...

    @Syrus
    wasnt me asking the other day...

    anyone has an idea of the max. peak power output? just wondering because of the speakers... i have finished my red 1x10" cab some while ago :) and loaded it with a celestion tube 10 ( G10E-30) but i think i want to replace it... (any suggestions?)

    EDIT:
    Let me share with you my tumblr, where i just uploaded pictures of my cab ;) (+ there's other guitar stuff)
    http://owlofblues.tumblr.com/
     
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  7. OwlOfBlues

    OwlOfBlues Junior Member

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    dear Twang, i just read your message on tumblr, thank you! and i got you some pictures of the grill.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    i must admit the other one ( larger, 2x10") looks a little better. all you need is a frame that is slightly smaller than your inside of the amp, take the cloth into consideration. then you cut that cloth roughly to size, lay it on a large flat surface and stretch it a little. then you wrap it around, see that it fits and start to staple one side. then stretch it (helping hand is useful, but you can do it alone), staple opposite side and so forth. cut the cloth on the backside, maybe trim it on the edges so it is not too thick (depends on how deep you need to go with your grill into the amp) and then dilute some wood glue with a little bit of water. take a brush and apply it to the cloth so it wont start tearing apart... thats pretty much it :) not too hard. anyway i have a nice cloth, cotton, all soft, not the usual hard stuff you get, but i love the color (+ the red cab <3 ) and the close mesh
     
  8. TWANG

    TWANG Senior Member

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    excellent. I imagined that was it.. and there it is.. !
    I'll get something working pretty soon.. got a cab I hate the grill on!
    many thanks!
     
  9. tinman402

    tinman402 Senior Member

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    My defender is still being defensive..lol

    Gonna go at it again after a time out..
     
  10. Syrus

    Syrus Senior Member

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    Max. output of any EL84 is around 12-14W.
    But the Defender won't even come close to that power, as the bias isn't around the required 400VDC, on the KD5H it is 280VAC before rectification according to the schematic.

    This means it'll put out clean around the 5W RMS but when driven maybe 7,5W or something, but the answer is yes, your speakers will be safe.

    I run this amp with a 15W 10 inch 16 Ohm ceramic speaker and it's fine.


    TWANG correct me if I got anything wrong :)
     
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  11. TWANG

    TWANG Senior Member

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    I thought 5W was pretty much the top end..but more watts, maybe 6 or 7
    when pushed really hard. I think you get about half that when clean.
    but

    6BQ5 / EL84 / CV2975 DATA & RATINGS
    Heater voltage: 6.3V
    Heater current: 760mA
    Max anode voltage (B+): 550V
    Max anode voltage: 300V
    Max anode dissipation: 12W
    Max screen voltage (Ig2=0): 550V
    Max screen voltage: 300V
    Max screen dissipation: 2W

    But I have to say. modded vjs blackhearts kustom et al. sure seem louder.

    and

    Comparative Tube Ratings
    Vh Ih VaMax Vg2Max PaMax Pg2Max Notes
    EL84
    6.3 0.76 300 300 12 2.0 12 watts max plate dissipation with
    300V max plate volts.
    7189
    6.3 0.76 400 300 12 2.0 12 watts max plate dissipation with
    400V max plate volts.
    7189A
    6.3 0.76 440 400 13.2 2.2 13.2 watts max plate dissipation with 440V max plate volts.
    E84L
    6.3 0.76 450 300 13.5 2.4 13.5 watts max plate dissipation with 450V max plate volts.
     
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  12. tinman402

    tinman402 Senior Member

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    Alright I got a technical question...

    I have inspected the board and tested some.. I went ahead and put the original value back in r8 (220k) and 68k back in r17, also put the .022 capacitor back in c2..

    Here is what I get, a slight buzz like you would normally hear with a amp on.. Just that slight hum of a transformer.. What I don't get is sound..

    Looking at the bottom of the board the traces right where D5 KBP02 (check the schematic around the 5 pin header) looks black. Maybe I shorted it there or D5 is bad.. It flows to pin 4 and 5 on the power tube..

    Any ideas?
     
  13. tinman402

    tinman402 Senior Member

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    The rectifier, that is the word I am looking for.. I am on the way to radio shack to look for one..
     
  14. TWANG

    TWANG Senior Member

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    why? it doesn't do anything but make the amp quit.
    pull it, toss it, forget it.
    I think I remember the D5 designation. .one diode all by itself.
    It's useless and trouble.
     
  15. tinman402

    tinman402 Senior Member

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    so remove it all together... This has 4 pins, pin one is a positive side from pin 4 of the power tube, then pin 2 runs to pin 4 the 5 pin header. pin 3 runs to pin 5 of the 5 pin header, and pin 4 is ground.. 4 and 5 on the 5 pin header seem to be the 6.3vac - 1.1a from the power transfomer on the other side.. That should be the heater circuit right..

    Do I need to jumper any of those connections?
     
  16. tinman402

    tinman402 Senior Member

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    Scratch that.. I think I might have found the issue.. I may have a bad spot on a bus I am repairing it now and will see if that fixes the issue
     
  17. tinman402

    tinman402 Senior Member

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    FIXED IT... LOL

    It was the bus. Alright now I have put it back to stock and will attempt this mod again Saturday... :)

    I am going to add the tone stack and Master volume like you showed in your post twang.. Now what are all the components that can just be removed or discarded...

    I bought a Black-heart Killer Ant, brand new un-opened in the box, for a hundred... I may wait till I pick it up this weekend before I take this one offline again.. Mods in it's future too.. ;)
     
  18. OwlOfBlues

    OwlOfBlues Junior Member

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    I messaged Kustom about speakers & wattage a while ago and they kindly replied, i thought I'd share the correspondance with you:
    "Hello!
    I'd just like to inquire about the peak power rating of the Defender 5H amplifier. While you provide 5W as RMS in the specifications, I would like to know about the peak power in order to precisely match my speakers to it, so I won't ruin them.
    Thank you very much in advance.
    Kind regards"

    Kustom's reply:
    "Please see the reply from one of our engineers below:


    The "peak" power is 2X the "RMS" power so it would be 10 Watts.

    However, that is not what will blow a speaker. If the amplifier is played very loud, to the point where the output is a square wave, that is what will blow a speaker. This is because the square wave is nothing more than DC that changes polarity at the fundamental frequency. What happens is the signal is pushed to the "rail" voltage and stays there; at this point there is no more acoustic output, only heat in the speaker.

    What does that mean? It means that you heat up the speaker's voice coil during which time there is no more sound produced. The speakers cone is as if a battery has been placed across the terminals.

    It is quite easy to blow up a high powered speaker under this condition even with a modest amplifier.

    Fortunately the 5H is very low power so a reasonably good 30W (or more) speaker will probably handle it. But you should still be careful since over time the speaker may get damaged if routinely played at that level."
     
  19. Syrus

    Syrus Senior Member

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    Crank it? Don't crank it?

    If I interpret this correct, this guys says to not play it loud or what?

    I mean, that's the magic of small tube amps.
     
  20. TWANG

    TWANG Senior Member

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    There's a diode in there that does nothing. I think you pulled that already?
    on RevD of the amp it's not even there.

    Remember. these amps do NOT have a bleeder resistor. The caps can easily stay charged. That can kill you.
    Do not touch the board until you've bled those caps.
    and check them all .. more than one person has reported voltage on one and none on the others.



    See the jumper that runs off Pin 9 of the El84? jp7.
    pull that and put in an SGR (screen grid resistor). 1K 1W.
    that's good for it not for tone but so that if the tube goes bad in a bad way, it doesn't
    fry the rest of the circuit. Just a 10 cent resistor.

    R17 can be pulled.. I like an 8.2K to 20K resistor, 1W, connected to a 50K pot.
    for a tone control. use sheilded wire and keep the pot above the filter caps as far as you can.


    the smaller bypass caps will help tighten up the low frequencies. For single coils especially for cleaner tones the 2.2uf would probably be fine, for humbuckers and especially for higher gain tones I'd try 0.68 to 1 uf.

    R9 be 270 ohm with a Shuguang EL84 and 220 ohm with a Sovtek (or JJ etc)EL84.

    If you're using the stock Output Transformer,the only cure for the string noise.. when you slide up the strings with your hand.. is a conjuntive filter.

    If you use a Classic Tone OT, you probably wont have to. And that gooses the amp up considerably for tone.
    MPS OT10SE is also a good upgrade and less money.


    get the plate maybe 300 to 310 and the screen 290 - 300 or so. EL84 plate is pin 7, the screen is pin 9 and the cathode is pin 3. You use the plate voltage, the cathode voltage and the value of the cathode resistor give you the dissipation.
    10W diss. I think. someone correct me I'm stupid when I'm hungry.

    I did another the other day but I've been in the shop all day and my heads spinning.
    I'll get some pics up, later.
    I did this one as cheap as I could without using junky stuff at all.. no new OT for instance
    and it really sounds pretty dang good!
     

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