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Millett "Starving Student" hybrid amp

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  1. timmyGCSE
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    You're absolutely right, my apologies. Indeed it is R2 and R8 that need to be 390 Kohms.

    cheers!




    [​IMG]

    ...and...its all done [​IMG] it works perfectly too [​IMG] Koss Porta's sound amazing through them, so gonna sit down now and try my JH13's...ahhh [​IMG]

    I have some other jobs to do today but I will hopefully get around to posting some pictures later, its not too neat but hey whatever it works..in the words of vicki pollard..face..bovvered

    edit: wow..the 13's sound amazing with the SSMH!

    edit2: and here we go:

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    sorry there is no picture of the tube sockets themselves, I didn't have a camera to hand when I screwed the bottom plate on. I did take one on my phone, whether it came out good or not I don't know but I will have a look at that later. Following equalizer's revised pin mapping worked just peachy though.

    As you can see, tidy wires isn't my strong point. I'm not fussed at all..it works perfectly and yea its an open box design but pfft whatever I'm still proud that the damn thing works!!

    some notes:
    - For the wiring I used the wire from a CAT6 ethernet cable, both strands of each colour making up one wire. It worked quite well and is nice and still but I think it contributed to the messyness and my fingers hurt from stripping it! haha

    - the PSU is not a Cisco PSA-18, it is a Cisco EADP-18FB, its from what I can tell exactly from pdf specs exactly the same apart from the label colour and unit shape. The Cisco ADP-18PB is also the same/similar and will work which will make it even easier to find one on ebay, the PSA-18 on ebay UK was about £12, the one I got £4. The EADP-18FB and ADP-18PB both use 2.5mm sockets

    - the tubes are not 12Ax7 tubes..they are Philips 5963 tubes which are part of the same ECC82 family..this is what Jac Music says:
    Quote:

    Special Quality ECC82. Different in two points: 1)Longer Stand by function 2) balanced tube by default. * With those two points you have basically the same properties as the Telefunken ECC802S



    see here for other compatible tubes with this build:
    http://www.jacmusic.com/nos/ECC82.htm
    they cost me £5.50 each from ebay, and they are NOS tubes..imo a bargain

    - I used 2.2k resistors instead of 2k..whether this makes a difference or not I don't know but rapid electronics didn't have any 2k in stock and it sounds good regardless.

    so how does it sound? awsome.
    I haven't listened to it fully and properly yet but I had about 15 minutes and I was amazed. I tested with PortaPro's and they sounded fantastic then I listened to my JH13's and I was blown away, the sound is so much richer, fuller and soundstage is more airy. As an example I have a dubstep track that has an extra drum beat that is usually hidden behind the bassline, the only time I've heard this extra beat is using the foobar virtual 5.1 thingy on my RX700's, never just playing it standard even with the 13's. With the SSMH its clear as a bell [​IMG]
    The 5963 tubes sound brilliant..can't compare them to any others since this is the first tubes I've ever listened to..but I will probably pick some others up, 12A's or generic ECC82's to compare

    I would like to publically thank equalizer for the advice given on this build, and everyone who contributes knowledge because this is a great project...

    now all it needs is for someone get working on a proper schematic for SSMH v2 (i.e 12AU7)..lets not let the SSMH die out through lack of 19J6 tubes!
     
  2. hss3
    Hey, I'm currently drawing up a 12AU7 version PCB that was described in this thread earlier.

    I'm basically just redrawing the original circuit board that came inthe production run with the 12AU7 modifications

    Probably going to do a toner tranfer etch to make the PBC. I plan to actually etch both sides, then toner transfer on the markings for ease of assembly. I'll post pics when I'm done.

    I'm still checking over my circuitry at the moment, but I'll post up the .pdf if people are interested.
     
  3. hss3
  4. hss3
    gah! repost
     
  5. timmyGCSE
    ha just realised I've made a grave mistake! soldered only point 6 on the pot to ground and not point 3! well ok so its not really bad but the vol was acting as a fader not a volume control..sigh..out comes the iron..

    5 mins later done [​IMG] much better works now [​IMG]
     
  6. the_equalizer
    @timmyGCSE

    Cool! Another 12AU7 build ! [​IMG] I like the retro "1930s ham radio" look very much, the vintage military tubes add to the vibe.

    I'm glad it all worked great and that you're enjoying your amp. About tube rolling, you're not confined to ECC82/12AU7. I tried 12AT7 and 12AX7 and they all worked nicely; probably 12AY7 and 12AZ7 would work too. Still, if you'll be using IEMs with the amp I guess 12AU7 will work best, since the other options might have too much gain.

    Anyway, enjoy your music ! Again, just one suggestion in case you haven't read through the whole thread: do not turn the amp on or off with your headphones plugged in.

    cheers!
     
  7. the_equalizer
    Quote:

    Originally Posted by hss3 /img/forum/go_quote.gif
    Im actually going to run these as well.

    RK27112A-S20-C0-A104 ALPS Potentiometers

    I see nothing wrong with that? Enlighten me if i'm wrong.




    That certainly looks like a nice pot. While it'll certainly work with either a PCB or P2P build (even though it's 100K and the BOM usually specifies a 50K pot; just a minor point, really), I'm pretty sure it won't fit into the Beezar.com PCB Hammond case. Then again if that's not what you're aiming for, then it is not a problem!

    cheers!
     
  8. timmyGCSE
    Quote:

    Originally Posted by the_equalizer /img/forum/go_quote.gif
    @timmyGCSE

    Cool! Another 12AU7 build ! [​IMG] I like the retro "1930s ham radio" look very much, the vintage military tubes add to the vibe.

    I'm glad it all worked great and that you're enjoying your amp. About tube rolling, you're not confined to ECC82/12AU7. I tried 12AT7 and 12AX7 and they all worked nicely; probably 12AY7 and 12AZ7 would work too. Still, if you'll be using IEMs with the amp I guess 12AU7 will work best, since the other options might have too much gain.

    Anyway, enjoy your music ! Again, just one suggestion in case you haven't read through the whole thread: do not turn the amp on or off with your headphones plugged in.

    cheers!




    well thank you! without your help and original pinout work I wouldn't have this now. Cheers..I mean its not the nicest looking kid on the block but hey it does the job and sounds amazing. And I think I will roll a few tubes over time just to listen to the differences..but seriously these sound great - I let my mum and grandad listen with my RX700's and they haven't got a clue about audio in general and they were blown away. People say RX700's don't benefit from amping..I beg to differ

    and ah yea cheers I knew about turning on but not off so thankyou for that [​IMG]
     
  9. blitzpirate
    hey guys i just finished the assembly and i have a bit of a problem, the ssmh turns on and everything but when i hook it up to a dac i only get sound through the right channel then i turn the volume up on the Amp, after that i get sound on both channel however the right channel is stronger, and if turn the volume off i still get sound through my right ear.... and suggestions?
     
  10. the_equalizer
    Quote:

    Originally Posted by blitzpirate /img/forum/go_quote.gif
    hey guys i just finished the assembly and i have a bit of a problem, the ssmh turns on and everything but when i hook it up to a dac i only get sound through the right channel then i turn the volume up on the Amp, after that i get sound on both channel however the right channel is stronger, and if turn the volume off i still get sound through my right ear.... and suggestions?



    Sounds like the potentiometer pins that connect to the ground plane are not correctly soldered, particularly the pin corresponding to the right channel.

    Check those solder points. Getting the solder to really flow in those takes quite a bit of heat, you'll need to apply your soldering iron for some 2 or three minutes until the ground plane heats up and the solder flows.

    Problem is that you don't want to heat the pot pin as much, just the pad. So I'd suggest removing the solder, applying the iron to the pad long enough so that the solder flows, then apply the iron for some seconds to the pot pin too and then feed in the solder.

    cheers!
     
  11. timmyGCSE
    yea just to add to that, make sure pins 3 and 6 are soldered to ground, I had that and realised I'm not soldered pin 3!
     
  12. timmyGCSE
    Quote:

    Originally Posted by hss3 /img/forum/go_quote.gif
    Hey, I'm currently drawing up a 12AU7 version PCB that was described in this thread earlier.

    I'm basically just redrawing the original circuit board that came inthe production run with the 12AU7 modifications

    Probably going to do a toner tranfer etch to make the PBC. I plan to actually etch both sides, then toner transfer on the markings for ease of assembly. I'll post pics when I'm done.

    I'm still checking over my circuitry at the moment, but I'll post up the .pdf if people are interested.




    I'm going to give this a whirl too but with a twist, I aim to make it modular so that the tube sockets and MOSFETs sit on a different PCB and are connected via ribbon cable to the main PCB
     
  13. ezzieyguywuf
    Any chance of updating the first post or something with updates to this design. I'm guessing this 12AU7 is an alternative tube that can be used, with some modifications to the original design? I'm having a horrible time tracking down some 19J6's
     
  14. Juaquin
    Yes, the 12AU7 is the popular alternative with some modifications because of the scarcity of the 19J6.

    Chances are the original post will not be updated, considering it was written by Pete Millet himself and was the beginning of the SSMH. It's history. Perhaps someone (paging the_equalizer to the SMMH thread) could start a thread for the 12AU7 variant.
     
  15. tomb
    Quote:

    Originally Posted by Juaquin /img/forum/go_quote.gif
    Yes, the 12AU7 is the popular alternative with some modifications because of the scarcity of the 19J6.

    Chances are the original post will not be updated, considering it was written by Pete Millet himself and was the beginning of the SSMH. It's history. Perhaps someone (paging the_equalizer to the SMMH thread) could start a thread for the 12AU7 variant.




    If someone can provide me with a writeup, parts list/BOM, schematic, etc., on the variants (would want to include logistics' 12SR7 variant, too) - I can try to post it on the SSMH website. No guarantees as to when, though, it seems I'm staying pretty busy these days.[​IMG]
     
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