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Millett "Starving Student" hybrid amp

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  1. the_equalizer
    Quote:

    Originally Posted by quarzo /img/forum/go_quote.gif
    Yes, absolutely shure. They light but don't shine very much. Just a bit on the bottom and on the top



    Quote:

    Originally Posted by quarzo /img/forum/go_quote.gif
    By the way, I had the power source made so it's not bought from a dealer. I get 46v instead of 48 and I' starting to worry about the amper measure but i have no idea how to use the tester to get that value. I'm a beginner sorry



    Quote:

    Originally Posted by UKToecutter /img/forum/go_quote.gif
    You will only see a slight glow from the heaters.

    Most of the people here have put LED's underneath their valves, so don't be fooled by how bright they look.




    Actually most 19J6 give out a considerable amount of light. There are some, though, that have enclosed heaters and those will shine a bit on the bottom and on the top. They work just as well in the circuit.

    As to the power supply it's ok if it's a couple of volts off. My Cisco supply puts out 47 volts. The current that the supply puts out is a little bit more important; but I'm guessing if your amp turns on (meaning the tubes light up) your supply is quite probably coping with the current demand ok.

    cheers!
     
  2. tomb
    Quote:

    Originally Posted by drclaw /img/forum/go_quote.gif
    Here are some pics!
    [​IMG]

    With flash..
    [​IMG]
    [​IMG]




    Those are page links, not image links. Here's what they should look like:
    [​IMG]
    with flash -
    [​IMG]

    Good job![​IMG]

    P.S. I'm not sure, but it looks like you may have the bezels reversed, even though the endplate is on the correct side.[​IMG]
     
  3. the_equalizer
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    Those are page links, not image links. Here's what they should look like:
    <snip>

    Good job![​IMG]

    P.S. I'm not sure, but it looks like you may have the bezels reversed, even though the endplate is on the correct side.[​IMG]




    It certainly looks as if it were reversed in the first pic.

    cheers !
     
  4. getllamasfast
    Hey guys I'm having trouble with finishing my second 12AU7 ssmh. When the tubes aren't plugged in, the voltage at pin 4 on both sockets is ~16v, which is where it should be. When I put the tubes in, the voltage drops to ~.2V at both of them. With the_equalizer's help, I've managed to figure out that it is a miswiring, but I can't seem to find out where I've made my mistake.

    Does anyone know what could possibly be wired up wrong that would cause the big voltage drop?
     
  5. the_equalizer
    Quote:

    Originally Posted by getllamasfast /img/forum/go_quote.gif
    Hey guys I'm having trouble with finishing my second 12AU7 ssmh. When the tubes aren't plugged in, the voltage at pin 4 on both sockets is ~16v, which is where it should be. When I put the tubes in, the voltage drops to ~.2V at both of them. With the_equalizer's help, I've managed to figure out that it is a miswiring, but I can't seem to find out where I've made my mistake.

    Does anyone know what could possibly be wired up wrong that would cause the big voltage drop?




    Just to add a bit more info. The tubes are known good, since they work perfectly OK when plugged into a working SSMH.

    Thus, there has to be a miswiring in this other amp, causing a short and the supply to drop.

    As to where that short exactly resides, it is very difficult to say. Getllamasfast has already gone through the tube socket wiring and he tells me it is OK. So, it must be something in the protoboard layout.

    cheers!
     
  6. iPoodz
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    Get the 50K. We tried both in the prototypes and I couldn't tell a difference. However, it really just ends up being what input resistors you used. Since the input resistors that came with the kit were sized for the 50K pot, you should get that one.[​IMG]

    EDIT: Your LED's definitely are wired badly. You need to work on the connections to the PCB - that's why the other one is going out when you put pressure on the amber one. It's forcing one wire to connect and in turn, forcing the other wire to disconnect. That means shoddy connections on both, unfortunately - at the PCB. Those are pretty small holes on the PCB, so you have to be careful what wire size you use, etc. 22ga will fit, but you have to do everything just right. Maybe you could get some smaller wire - 24ga or even smaller. It's not going to hurt, the LEDs draw very little current.[​IMG]




    Thanks, Tom. I'll order that right away.

    I was on my way to make sure I turned the switch off and disconnected the power supply, when I tripped over the wire, and painfully found the answer to my question.

    I just checked, and both the tubes are getting hot, and I plugged in my headphones for a few seconds, and got sound in both ears [​IMG] {the right side might be a little lower, but I'll deal with that later!}

    I assume that because pretty much everything's working, using the MOFSETs without proper insulation for a few minutes wasn't a killer.

    Also, I cracked the ceramic on the R16 resistor. I had initially soldered the 100KOhm on, but realized that this was for low gain, and in the re-soldering, I cracked the ceramic part. I'm ordering two, from Mouser, but do I really need to replace it?

    Finally, what tool should I use to tighten the knob on the pot? I tried searching online, but I'm blanking on what it's called.
     
  7. the_equalizer
    Quote:

    Originally Posted by iPoodz /img/forum/go_quote.gif

    <snip>
    Finally, what tool should I use to tighten the knob on the pot? I tried searching online, but I'm blanking on what it's called.




    It's an Allen wrench or hex key.

    Hex key - Wikipedia, the free encyclopedia

    Unfortunately I can't tell you what size you need since I don't own a PCB version of the SSMH anymore.

    EDIT: OK, if my memory serves me well, I'd say it's the key labeled 3''/32 in my set.

    cheers!
     
  8. getllamasfast
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    Just to add a bit more info. The tubes are known good, since they work perfectly OK when plugged into a working SSMH.

    Thus, there has to be a miswiring in this other amp, causing a short and the supply to drop.

    As to where that short exactly resides, it is very difficult to say. Getllamasfast has already gone through the tube socket wiring and he tells me it is OK. So, it must be something in the protoboard layout.

    cheers!




    Actually I just figured it out!!! I feel so stupid now because the problem was so simple. It was that pin 2 of the mosfets was wired up after r13 when it should have been wired up right before it...

    I really need to take my time with these things.[​IMG]

    I'll post pics later. [​IMG]

    PS: I love you equalizer! : [​IMG]

    EDIT: well, upon testing the amp there is a buzzing noise that gets progressively louder as I turn up the pot. Also, there is this weird issue where the right channel is much louder than the left until I turn the pot about 3/4 it's full rotation. Any ideas?

    EDIT: EDIT: This is the pot I'm using: Digi-Key - P2S2503-ND (Manufacturer - EVJ-CC1F02368)
     
  9. the_equalizer
    Quote:

    Originally Posted by getllamasfast /img/forum/go_quote.gif
    Actually I just figured it out!!! I feel so stupid now because the problem was so simple. It was that pin 2 of the mosfets was wired up after r13 when it should have been wired up right before it...

    I really need to take my time with these things.[​IMG]

    I'll post pics later. [​IMG]

    PS: I love you equalizer! : [​IMG]

    EDIT: well, upon testing the amp there is a buzzing noise that gets progressively louder as I turn up the pot. Also, there is this weird issue where the right channel is much louder than the left until I turn the pot about 3/4 it's full rotation. Any ideas?

    EDIT: EDIT: This is the pot I'm using: Digi-Key - P2S2503-ND (Manufacturer - EVJ-CC1F02368)




    Good to hear you're making progress! Buzzing almost always means a grounding issue. That the buzzing varies with the volume pot would seem to indicate that your interconnects are bad or that the pot itself is bad, or that it is incorrectly wired (see next paragraph). If the pot's body is metallic, solder a wire from the pot's body to ground.

    About the channel imbalance I'm at a loss. Maybe you wired the pot in reverse ? Make sure it is the pot's wipers that are wired to the tubes.

    cheers!
     
  10. drclaw
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    Those are page links, not image links. Here's what they should look like:

    with flash -

    Good job![​IMG]

    P.S. I'm not sure, but it looks like you may have the bezels reversed, even though the endplate is on the correct side.[​IMG]




    Silly me, I guess that's what I get for being on a 2 AM[​IMG]

    Opps. They are. Easy fix though!

    It's a great little amp, and a great learning experience! It was my first project, and I couldn't be happier!
     
  11. Oberst Oswald
    My Beezar Starving Student is done. Couldn't ask for a better amp for the money and a real shame that this is the end of the kits & tubes. Some pictures...?
    [​IMG]

    [​IMG]
     
  12. iPoodz
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    It's an Allen wrench or hex key.

    Hex key - Wikipedia, the free encyclopedia

    Unfortunately I can't tell you what size you need since I don't own a PCB version of the SSMH anymore.

    EDIT: OK, if my memory serves me well, I'd say it's the key labeled 3''/32 in my set.

    cheers!




    Thanks so much, equalizer!
     
  13. Logos
    Firstly, thanks to Tom for the really great work that went into this kit. It showed down to the immaculate packaging!

    *Edit* Seem to have found a solution to my problem, was a mistake in the crimping of one of the fast-on connectors. Back to [​IMG]

    This amp is super awesome and seems to provide a lot of value for the money. It's almost surprising. I've grown quite fond of the little guy...
     
  14. tomb
    Quote:

    Originally Posted by Logos /img/forum/go_quote.gif
    Firstly, thanks to Tom for the really great work that went into this kit. It showed down to the immaculate packaging!

    *Edit* Seem to have found a solution to my problem, was a mistake in the crimping of one of the fast-on connectors. Back to [​IMG]

    This amp is super awesome and seems to provide a lot of value for the money. It's almost surprising. I've grown quite fond of the little guy...




    Well, whatever the symptoms - glad you found your problem and that you're enjoying the amp.[​IMG]

    EDIT: Great pics, Oberst!![​IMG]
     
  15. Kitarist
    I really need to build one of these to see whats all the hype about [​IMG] [​IMG]
     
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