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Little Dot I+ Tube Rolling

Discussion in 'Headphone Amps (full-size)' started by mapstec, Sep 16, 2008.
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  1. signet02
    Hello, all... I'm a novice to headphone amps, and I am looking for a little clarity on an issue with the Little Dot 1+ I just ordered... Delivery is still a few weeks out at most, but I've been looking at different tube sets for this amp... My issue follows:
    A few days ago, after ordering the Little Dot 1+ from Amazon.com through a Chinese vendor, I put this question to the vendor, who is listed as SHENZHENAUDIO… My question:
    Hello: One more question, if I may: If I decide to use the WE 408 A tubes in the Little Dot 1+, do I have to change the jumpers or pin-out or anything else like that?... Also, do you have a favorite op-amp change for these tubes?... I listen to mainly classical music, and I like a lot of airyness and definition... Not really a bass freak... ???... Thank you, and best regards, Mark.
    Answer from seller:
    Dear Mark: You mean use WE 408A in the Little Dot 6J1 version? If so, please don't do that. I used to change the tubes. But it smells bad for the amp. Please kindly check that. If you have anything, please contact me freely. Thanks and best regards, Tina.
    Now, since I’m a novice at all this, this has me worried… Are there different versions of the Little Dot 1+ other than just what tubes it comes with?... I thought one of the main features of this unit was that you can roll different tubes into it, with the caveat that you may have to change internal jumpers, which are supposed to come with the unit… So, I guess I’m asking for a little clarity here… Thanks in advance, and best regards, Mark.
  2. gibosi
    It would seem that Tina is very misinformed...  The LD1+ is specifically designed to accommodate 408A tubes. And yes, all you have to do is change a jumper. EF91, EF92 and EF95 tubes require a cathode heater voltage of 6.3 volts, whereas, 408A tubes require a voltage of 20 volts, and the jumper allows you to easily make this change.
    Op amps... I would say LME49990 and MUSES 01 are somewhat dry and airy and OPA627AP and MUSES 02 are somewhat wet and dark. 
  3. signet02
    Thanks, gibosi... I thought something was fishy with her reply... I've been reading this thread avidly... I do have other tube gear [Decware Triode]; however, this is my first foray into tube-based headphone amps... I didn't want to spend too much until I decided I liked using headphones... And it seems as if this is the 'go-to' unit in this price-range...
  4. MunkyOne

    Gibosi's answer is spot-on, so you can change your tubes with confidence :)  
    What headphones are you using with the LD?  It may influence your choices of tubes and op-amps.  There is an excellent starter guide http://www.head-fi.org/t/563884/little-dot-tube-amps-vacuum-tube-rolling-guide that describes some of the various tube sound characteristics.
    Be warned; tube rolling can become addictive :)
  5. signet02
    Hello, Munky: Right now, all I have on hand is a pair of Sennheiser HD 380 Pro headphones that I use for my Yamaha digital piano... They are very good, but designed for low impedance, low level sources, such as recording consoles and such...
    I also have a pair of HD 280 Pros I use for the same purpose... I do plan, however, to get myself a good pair of Hi-Fi headphones soon... What to get?... I'm going to do my homework here...
    I do have a fair amount of knowledge regarding tube rolling into audio gear such as integrated amps, but headphone amps, not very much knowledge... It seems like this is the place to get that...
    I sold audio way back in the 70's in NYC, and met Joe Grado... He's a great guy, and has always offered a lot of bang for the buck... Maybe I'll get a pair of Grados... Any suggestions for listening to classical music?... Let's say, in the $300.00 range?...
  6. MunkyOne
    Yes, this is definitely the place to be, for headphone-related things; I gained a fair chunk of my knowledge from Head-Fi members, and have thoroughly enjoyed the journey thus far.
    As a relatively new convert to headphone listening, my experience of headphones is limited to Grado, and only a few of those.  For classical litening I like my SR325i, which is in your price range.  For everything else, I like my modded SR80i.  Both of these sound excellent when paired with the LD1+
    My usual sources are FiiO X3, or laptop using X3 as DAC, or my E07K as DAC.
    I purchased the LD1+ with 6CQ6 tubes, which are a pretty good jack of all trades, very smooth - somewhat taming the Grado edginess in the treble.  They are warm, but not too much, and very engaging and musical to listen to.   From this point, I changed the op-amp, as the stock one is known to be mediocre wrt SQ.  I chose a Burr-Brown OPA2107AP, which was a quick and easy mod.  This opened the sound up more and seems to offer slightly more gain, with more attack and energy.  Bass also feels a bit tighter.  I was quite surprised how much I noticed it.
    Recently, after some more listening, I decided to roll the tubes, and found a matched pair of Mullard M8161 NOS on ebay.  I have only about 10 hours on these tubes, so they are still settling-in, but I have to say, these immediately sounded more spacious, with a touch more bass and more detail in all frequencies.  So far, with my Grado's and my two sources, I am happy with how it all sounds.
    I have no way to know how it would be with other makes of headphone.  I suspect that with each headphone choice, the process of tube and op-amp rolling might start again :)
    As I said, my experience is limited, but there are many here who will have more experience of this little amp and of different headphones.
    I wish you a great adventure :)
  7. signet02
    I would guess that because you have the transducers right up to your ear, any hum at all would be a problem...
    So, I guess that would be my first criteria, and after that tuning the sound to my taste...
    By contrast, a little hum through my speakers is not really a problem, as even a foot or two away, the hum can not be heard... Some of my favorite tubes for my main amp have some hum...
    Like the Amperex Bugle Boy 6DJ 8 with 'D' getter... My favorite input / driver tube... At any rate, I'm going to keep on reading the posts on this thread, as they are very helpful... It seems like all the trials and tribulations have already been experienced here...
    And now comes the long wait for the amp... Time goes by fast when you're listening and enjoying, but very, very slow while you're waiting for gear to arrive!...
    Also, thanks for the recommendations...
  8. MunkyOne

    Yes, hum through headphones could be quite distracting, even annoying.  However, I have yet to hear any noticeable hum from my Ld1+.  It sits on my desk alongside a laptop and monitor, with a power cable crossing the souce interconnect.  If there is any hum at all, it is probably masked by ambient noise, which is minimal in my study.  
    Hope your amp arrives very soon :)
  9. i luvmusic 2
    Anyone thought about drilling a hole under the LD 1 so no need to undo the bottom part each time you want to change jumpers(similar to the bottom of LD MK III)?
    If i drill a hole or make a cut-out under does it affect some kind of RF shielding?
  10. SJWorne
    Funnily enough, I was just thinkning about taking the LD apart again... the screws are quite delicate and i'm scared of stripping the heads.
    Was thinking of replacing the screws with allen bolts or even torx bolts.
    It would give it a cool look in my opinion... as well as relieving the worry of damaging anything!
  11. MunkyOne

    I was thinking about making a small hinged door underneath from a cut-out in the base, with a single retaining screw.  Since there is so much tube rolling ahead, I figure this would be a suitable mod.
  12. gibosi
    I like the idea of using better hardware, such as allen head or torx screws. However, when I replace the screws, I just make them snug, not tight. So I never have to worry about stripping the heads of the screws when I remove them. After all, since the amp will work perfectly fine without the bottom, I figure there is no good reason to make the screws really tight.
  13. SJWorne
    I see your point!
    However I guess i'm a little ocd when it comes to the screws... they're supposed to be flush with the rest of the chassis, and for me, they MUST be flush :p lol
    Good idea!
  14. i luvmusic 2
    The thing with cutting a door underneath is the  J1 is actualy just past the front left foot of the unit so you need to cut flush to the edge of the front foot not a bad idea though.
    To me it's not the head of the screws being stripped it's the thread but if you can find a screws that have a rough thread it's better and if you look at the bottom piece you dont have much room for a bigger screws.To do it properly you need to drill a slightly smaller hole than the screws you are using then you need to TAP it and you need to counter sink the face plate or you can use a self tapping screws or you can use a wood screw/sheet metal screw without drilling and tapping that should work but finding a small screws that will fit in that spot is not that easy.
  15. i luvmusic 2
    You are right when i put back the bottom plate i usually turned the screws just barely tight but it anoyed me by taking off 4 screws everytime i want to open it up.
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