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Millett "Starving Student" hybrid amp

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  1. the_equalizer
    Quote:

    Originally Posted by ezzieyguywuf /img/forum/go_quote.gif
    I think I'll have to attribute my channel imbalance to a bad pot. I've checked the resistances manually and they are never equal, throughout the whole sweep of the wipers. I mean, I payed $2.53 for it. I dunno if that's a lot for a pot or not, but I was seriously trying to keep this thing cheap. And (as I've mentioned twice) I'm already over budget, so I new pot will have to wait. Probably for a while... *sigh*.

    the_equalizer, thanks for all your help. I'm rather certain that its wired up properly. I did all the checks that dsavitsk talks about in post #3861 on page 258 and everything actually measures pretty good. The thing is, though, that my AC Voltmeter doesn't have super high resolution, so even with the pot maxed and the input maxed, the voltages at grid and output are still in the 0.0 to 0.3 range. And I noly get the one decimal, so yea on that. Oh, and I had to use a 70Hz tone, though I'm sure that made no difference...oh gawd, did my headphones just blow up? :p

    Anywho, I had lots of fun building this thing, but can't really listen to it as it stands now. I'll have to wait till later in the summer, or maybe closer to august to give a new pot a shot.

    It does sound good though :-D




    I agree, your pot does seem to be correctly wired. Maybe it got damaged while soldering? Difficult to say but in any case, I use the same 'phones you do (Grado SR-60i) with my 12AU7 SSMH and the pot sits at 9 o'clock for my normal listening (and I like listening at low levels).

    Well, the pots I use for prototypes are $2.73 at Mouser, part number RV24BF-10-15R1-A50K. Not a "blue velvet" but robust and functional.

    cheers!
     
  2. ezzieyguywuf
    Quote:

    Originally Posted by nullstring /img/forum/go_quote.gif
    did you add the 330k resistors?

    if the pot balances out as it gets louder, then this would be a quick fix..
    It wouldn't be able to get as loud.. but at least it'd be usable right?




    I did add the resistors. :-/ No help really (surprisingly)


    Quote:

    Maybe it got damaged while soldering?



    Could be. I ended up soldering on it like 3 times. *sigh*. It's not real easy to justify paying shipping from mouser or digi-key for just a pot. I wonder if I could get a decent one at radiowhack?

    Both the pot you listed and mine have a tolerance of 20%. Thats rather large if you ask me, but far be it for my ears to distinguish a difference where yours can't. This is most likely probably potentially without a shred of a little bit of what might possibly be doubt a damaged pot.

    +1 to headfi for helping me figure that out though! And assuming thats the only problem, I'm pretty satisfied that everything else is good. I even sorta like the cardboard enclosure :p
     
  3. nullstring
    Digi-Key - P2R1503-ND (Manufacturer - EVJ-C51F02B54)
    I'd use this pot if I were going from digikey.
    It's the 50k variant of the pot that tangent suggests for the CMOY.

    if you choose USPS first class shipping, the shipping will work out to only ~$2.50

    I am sure a radioshack pot will end up being over $5..
     
  4. alphaphoenix
    Sorry folks if this is already dressed, but search didn't come up to confirm. I have an interested buyer from Australia who is interested in my MSSH, which uses the 48V Cisco power adapter rated input 100-240V. My question is, "can the mate use the amp in Australia as is and only needs to have a power plug converter?" I just want to make sure the amp itself doesn't need any changes with resistors and such for use in the land of down under.

    Thanks.
     
  5. Fred_fred2004 Contributor
    I made a MSSH in Australia its bog standard and uses the 48V Cisco adapter, works fine, I also made one for another Aussie and he had no problems

    cheers
    FRED
     
  6. alphaphoenix
    Thanks Fred. BTW: Nice work on the CMOY amps.
     
  7. hellomoto
    Hello,

    First, sorry for my poor english. I come from France.

    I discovered the Millet Starving Student Hybrid a week ago, and I would like to build one. It's the first amp I build. I would like to drive Grado headphones, and I only listen to Rock Music

    The main problem is the tube. I looked a lot for a 19J6, I found website who could sell them 20$ each, is it worth the price? It's really high, in comparison with Millet's Bill of Material! Is there a replacement for what I need? I tried to look on the board but my English comprehension is poor, so if someone could give me some simple answers. The problem is that I think I'll have to change lot of parts to adjust to the new tube.

    I also would like to have a model of alimentation I could use in France. I couldn't find "Cisco PSA-18".

    I have also seen on "Beezer" that they were plate to soldier on the materials. Is it still possible to buy them?

    Thanks you very much for your attention and your answer, sorry for my bad English!

    Antoine
     
  8. tomb
    Quote:

    Originally Posted by hellomoto /img/forum/go_quote.gif
    Hello,

    First, sorry for my poor english. I come from France.

    I discovered the Millet Starving Student Hybrid a week ago, and I would like to build one. It's the first amp I build. I would like to drive Grado headphones, and I only listen to Rock Music

    The main problem is the tube. I looked a lot for a 19J6, I found website who could sell them 20$ each, is it worth the price? It's really high, in comparison with Millet's Bill of Material! Is there a replacement for what I need? I tried to look on the board but my English comprehension is poor, so if someone could give me some simple answers. The problem is that I think I'll have to change lot of parts to adjust to the new tube.




    The tubes started out at $2 and went up as the scarcity increased. I believe $10-$15 should be the normal going rate from the few tube dealers who still have them. $20 sounds too high.

    Quote:

    I also would like to have a model of alimentation I could use in France. I couldn't find "Cisco PSA-18".



    Search for "Cisco PSA18U" on ebay - you'll get almost a couple of dozen hits. The power supply is good for either 110V or 220V wall supplies. Quote:


    I have also seen on "Beezer" that they were plate to soldier on the materials. Is it still possible to buy them?



    The PCB's are gone. Unfortunately, there's no economic justification to order another manufacturing run when there are so few tubes left. Quote:


    Thanks you very much for your attention and your answer, sorry for my bad English!

    Antoine



     
  9. Juaquin
    Don't forget you can also build the 12AU7 and other versions, if those tubes are easier for you to find.
     
  10. hellomoto
    @tomb: Thank you very much for your answer! Is there some part from the original Bill Of Material that I should change?
    I've seen that the original film capacitors (150104K100AA Cornell Dubilier Polyester Film Capacitors) were discontinued, I think I can replace them with these one (150104K100BB Cornell Dubilier Polyester Film Capacitors) Am I right?

    @Juaquin: Thanks! Will I have to modify some things if I take 12AU7 tubes or will it be the same?

    Thank you very much! It's really hard to find informations on French forums, Head-Fi is like a Gold Mine!!!


    THanks!

    Antoine
     
  11. Juaquin
    Quote:

    Originally Posted by hellomoto /img/forum/go_quote.gif
    @Juaquin: Thanks! Will I have to modify some things if I take 12AU7 tubes or will it be the same?



    Yes, here is a schematic and some notes on the variant versions: SSMH Variations
     
  12. baka1969 Contributor
    I'm purchasing a MSSH from a fellow Head-Fi'er. Sent out payment on Tuesday. I hope that because I didn't build it myself that I can still ask questions. [​IMG] This is also my first tube amp. It should be interesting to compare/contrast it with my GLite. I only have another 300 pages to read. LoL

    Pece,
     
  13. timmyGCSE
    Quote:

    Originally Posted by tomb /img/forum/go_quote.gif
    Search for "Cisco PSA18U" on ebay



    they are rare in Europe (well...in the Uk certainly, and they are quite expensive when they do pop up, ~£20/$30
    Cisco ADP-18PB and EADP-18FB-B both are from what I can tell exactly the same (perhaps an EU model? :-/ ) both are 48v, 0.38A and use a standard 2.5mm jack. I'm using this one:
    Cisco power supply EADP-18FB-B 48V 0.38A on eBay (end time 06-Mar-10 19:39:48 GMT)

    with my build and it works like a charm

    which as you can see is only £6/$9
     
  14. Ryuichi
    Double post, sorry.
     
  15. Ryuichi
    I bought a starving student amp a while back, and it does something a bit strange. Sometimes with a fairly low level input, I hear humming that grows in volume until it pops (sounds like an arc) and the humming goes away. It will also 'pop' when I tap the amp with my finger and the humming goes away.

    Any idea what is happening? I don't know much about tube amplifiers.
     
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