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Millett "Starving Student" hybrid amp

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  1. FallenAngel Contributor
    That's backwards [​IMG] Tip is left, ring is right.
     
  2. Sganzerla
    Thanks, will go back again... [​IMG]

    So everything I said about sound stronger on left channel... invert. It will be at the right side, and when fading, it slowly begins to imbalance to the left channel. Back to the first description... [​IMG]
     
  3. ezzieyguywuf
    Quote:

    Originally Posted by nullstring /img/forum/go_quote.gif
    What pot do you have?



    I have this pot. I'll add all those resistors, though I'm loathe to as the easiest way will be to splice all my cables, and the just sucks [​IMG] .

    What research are you talking about? You mean I shoulda looked up why to do the mods?
     
  4. nullstring
    yeah, you shoulda looked up why those were put there.

    Resistors are way too cheap to skimp on >_>

    Anyway, I attached my resistors right to the pot. Just unsolder the wire from the pot and put the resistor in between the pot and the wire.
     
  5. netsky3
    Wich one is the base version of this amp?
    I hope to build one of this in the future, how much is the cost of the pcb and all the components necessary? (without case and other stuff)
    [​IMG]
     
  6. tomb
    Quote:

    Originally Posted by netsky3 /img/forum/go_quote.gif
    Wich one is the base version of this amp?
    I hope to build one of this in the future, how much is the cost of the pcb and all the components necessary? (without case and other stuff)
    [​IMG]




    Do some reading in this thread and on the SSMH website - Starving Student Millett Hybrid

    I keep getting inquiries, but the PCB's are gone. If someone tells me where I can buy a hundred or more 19J6's, we'll do another PCB production run - but other than that, no.
     
  7. the_equalizer
    Quote:

    Originally Posted by ezzieyguywuf /img/forum/go_quote.gif
    <snip>

    Finally, with my source set at 0dB volume, I can barely touch the pot on the amp before it is too loud to do anything with. Its like off-off-offf-off-SUPER LOUD. The only reason I mention this is that on my CMOY, I can use the same source at the same volume and have a fair bit of play with the volume knob.

    </snip>




    Quote:

    Originally Posted by ezzieyguywuf /img/forum/go_quote.gif
    </snip>
    I did not use an R16/R17 as they are marked "optional". Decided to go with the simplest build possible. (already over budget ya know). I do have some spare resistors though, so what would you suggest?




    Quote:

    Originally Posted by nullstring /img/forum/go_quote.gif
    lol, you shoulda done a bit more research.
    Anything from 33k to 150k or so should work fine... just make sure they match.
    [EDIT: you should probably add R14/R15 as well if you have any spare resistors in the 1K area.]

    What pot do you have?



    It won't actually fix the mismatch.. you just won't be using the pot at the very low end anymore.





    R14, R15, R16 and R17 are optional. I can even use my very sensitive ER-6i IEMs with my SSMH (without the input resistors) and strong sources. Your problem sounds exactly like what a miswired pot does. Make sure it's the pot's wipers that are connected to the tube's grids. Then one end to ground and the other end to the RCA's

    cheers!
     
  8. the_equalizer
    Quote:

    Originally Posted by Sganzerla /img/forum/go_quote.gif
    Well, let me first thank you both for your time and attention.
    Here are the links for the 4 images I made:

    LINK1
    LINK2
    LINK3
    LINK4



    Yes, they do. Looks like they fade a little from the intensity they are at start, but they continue lit up.



    I have problems with terminology of these components, could you point wich value (or the color) are the power caps and the output caps? It is easier for me to understand.

    Thanks again!




    Well, after reviewing your pics, I just can't find any obvious mistake. I just have a suggestion: when soldering to a terminal strip, you want it to look like this

    [​IMG]

    That is, the solder blob is covering the whole terminal, this insures a solid mechanical and electrical connection and you don't even need to wrap component leads around the terminal as that will make them very difficult to remove if the need ever arises.

    The connections to the leftmost terminal on both terminal strips in this pic look a bit suspicious.


    On other things... the components you used look all so very familiar, I'm betting you bought them as a kit on ebay; my first SSHM I built from that very same kit [​IMG]

    cheers!
     
  9. ezzieyguywuf
    Is it pretty? No. Is it messy? Not really actually? Does it work? Sometimes (working on it!). Does it sound good? Actually, I'm holding off on that judgement until I get it working 100%. From what I've heard I think I'll be pleased though. Yes, that is a digi-key box that I put it in. As I've stated earlier in this thread, I've gone over budget on this already and just couldn't justify paying for a case at this point, plastic or otherwise. This enclosure is definitely temporary, and hopefully this summer I'll be able to enclose it properly. The problem I'm having is that I get only some sound on one of the channels (left I think, I haven't bothered to label them yet). I've traced it to what I believe is pin4 on one of my tubes, as when I move it, I get some popping in my earphone. I'm hoping to get around to re-soldering that connection tomorrow. I went and re-did all of the pins on both tubes after tracing a problem to pin 1, but I guess that one didn't take. Yea, and after taking a second look, I'm almost certain it's this pin4 connection. This goes to the output cap (don't know the technical terms, sorry), so I'm fairly confident that when I resolder the connection, it will fix it. Everything was actually working great until I closed up the bottom of the box and moved it to on top of my Compass, so a loose connection seems to make sense. If I sound repetetive, it's cuz I reaaaly hope thats the only problem.

    I did add R16/R17 and R14/R15. We'll see how that helps.

    Oh, and my ground is this huge copper plate thing I found in the plumbing section of Lowe's. Worked out great cuz I was able to bend it to fit in my box, and it already had holes so I didn't have to sodder anything to it, I just bolted it down. Soldering to something that big seemed impossible, as it effectively acts as a heat sink, so the copper never gets hot enough to hold the solder.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  10. Juaquin
    At least with cardboard, you don't have to worry about the MOSFET isolation!
     
  11. m11a1
    Darn it, I'm so frustrated. I had a problem with volume imbalance on my SSMH. Originally, I had actually thought that the problem was because one of the MOSFETS but after getting new MOSFETS, the problem still exist....arg!

    Now that it isn't the MOSFETS, I have no idea what is causing the volume imbalance anymore....

    [​IMG]
     
  12. tomb
    Quote:

    Originally Posted by m11a1 /img/forum/go_quote.gif
    Darn it, I'm so frustrated. I had a problem with volume imbalance on my SSMH. Originally, I had actually thought that the problem was because one of the MOSFETS but after getting new MOSFETS, the problem still exist....arg!

    Now that it isn't the MOSFETS, I have no idea what is causing the volume imbalance anymore....

    [​IMG]




    Sorry about that. I didn't think the MOSFETs could cause a channel imbalance, but it was easier to send them to you rather than argue the point.[​IMG]

    There are potentially three things that can cause the channel imbalance:
    1. Mis-matched tubes,
    2. imprecise volume pot tracking, or
    3. mis-matched resistors somewhere in the signal path.

    Of those three, the tubes and pot have the greatest chance of causing the imbalance (unless you mistakenly used different-sized input resistors, as in one at 100K and the other at 200K). If the volume difference is consistent across the range of volume travel, then most likely it's the tubes. Swapping the tubes is an easy check. If the volume difference is inconsistent and changes with the volume travel, then it's the pot. What you can do there is adjust the input resistors to get the volume range you like within the most consistent portion of the volume pot travel.

    As for the resistors, it would take a huge difference to cause a volume mis-match between channels - something like the example given above - as in incorrect values, period, in one channel.

    Hope that helps.[​IMG]
     
  13. ezzieyguywuf
    Wow great post tomb. I'll be checking those things if my bad solder joint doesn't turn out to be the culprit.
     
  14. nullstring
    Quote:

    Originally Posted by ezzieyguywuf /img/forum/go_quote.gif
    Wow great post tomb. I'll be checking those things if my bad solder joint doesn't turn out to be the culprit.



    did the addition of those resistors and removable the alligator clips not help?
     
  15. ezzieyguywuf
    Quote:

    did the addition of those resistors and removable the alligator clips not help?



    Ah, yea it fixed the hum. There is a very silent "swooooooosh" like a very very distant waterfall, but only when no music is being played. The problem that I'm having now is channel imbalance, and like I said I think I've found the culprit.

    <edit> Turn out it wasn't a bad solder joint. One of the pins fell out of my tube socket at one point, and I couldn't get it to stay in there, so I (stupidly) tried making the hole bigger, i.e. the metal thing the tube pin sits in. I apparently had made it so big that there was minimal contact when the tube was installed. This is fixed now! The only imbalance I have is when my pot is at a low setting.

    The resistors don't seem to help. When I feed the SSMH an analog signal out of my Compass' DAC, which I can't attenuate with the volume knob, I can't turn the pot past the "imbalance point" without bleeding ear syndrome (this is on my Grado SR60s). If I plug in my DAP, I can cut the volume down to where I'm forced to turn the pot on the SSMH past the "imbalance point". So whats the next step, bigger resistors? I'm at 100k for R16/R17 and 1k for R14/R15. My next step up is 330K for what I got laying around.
     
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