tubecube 7 upgrade?

Discussion in 'Tube Audio' started by lostrockets, Jun 8, 2018.

  1. lostrockets

    lostrockets New Member

    Messages:
    16
    i just got a tube cube earlier this week and setup a new system for my home office, small room 10x10ft.
    using with a klipsch premiere 150s and a 12" SVS sealed sub. it has plenty of volume and power and exceeds my expectations in terms of sound.

    given its my first tube amp not sure how its supposed to sound or how much better other more expensive amps would sound.

    i did order a mullard 12ax7 and sovtek el84s and despite trying different combinations can't tell a major difference between the different arrangements! it's also only been used for about 7 hours so far so maybe the tubes need to burn in...

    since my ears cant tell the difference rolling the tubes (at least not yet), is it even worth considering more expensive and powerful tube amps? my budget was to stay under $1k for the amp.

    i was originally looking at a kingko amp, but was concerned about resale value and also lack of reviews. so as i was about to get a primaluna prologue 4 i came across the tubecube and bought it.

    now that i've been doing more research people seem to also be happy with the olchen amp.

    for those whove used the tubecube as well as other larger tube amps what are your thoughts?

    i guess my main question is will i notice an obvious difference in sound quality upgrading the tube amp.
     
    Last edited: Jun 8, 2018

     

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  2. birchoak

    birchoak Hi-Fi Nut Subscriber

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    Location:
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    lostrockets, I had a TubeCube 7. I sent it to a friend who was going through a bad time. I replaced it with a Harman Kardon A300 tube amp (15 watts per channel, stereo). To be honest, that little TubeCube sounded better to my ears--much, much quieter. The build quality on the TubeCube is also killer--extremely well made. I was excited about the A300 as this particular one had been extensively restored/upgraded, but the reality is I still have a amp with some very, very old parts (a chain is only as strong as its weakest link, right?) and there is audible hiss at low listening volumes. I don't remember the TubeCube having any hiss whatsoever. The TC7 has automatic tube biasing as well, I believe, so that's one more headache off your head. I suppose you could get the bigger amp and A/B sound test them side by side; it depends on your application. After putting a new amp, through its paces, some of us then revert to "normal listening" characterized by moderate volume. Just 1 watt is quite loud for day in, day out listening. Best of all, the TubeCube is brand new, with absolutely no irritating, mysterious issues that can kill the joy of listening to tube gear.
     
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  3. mnmmt

    mnmmt AK Subscriber Subscriber

    Messages:
    146
    Location:
    Minnesota
    My experience has been that audio components need time to burn in, especially capacitors. One amp I reworked with new elna capacitors took probably 50 hours of playing until the sound became what it is now.

    Rolling tubes is worthwhile in the tc7. Mine came with the Chinese 12ax7 and jj el84. One jj went bad quick, so I used some old Soviet 6p14p, which were an improvement. I now have vintage rca oval plate 6bq5 with a ge 12ax7, and the sound is excellent. I have found that Rolling tubes results in small changes, but they are noticeable.

    My advice is to listen to out for a while and get used to it. It is a different sound from solid state--it takes me a while to get used to my tube amp when I swap it in. Softer bass, but smooth mids and highs.
     
  4. lostrockets

    lostrockets New Member

    Messages:
    16
    thank you birchoak and mnmnt. i think i'm going to sit tight for another week or so and see if i can notice a difference with the tubes and the sound.

    my main system is a pioneer rack system (SS) that i got more than 20 years ago and i can definitely hear the difference in tube vs SS, (which is the whole reason i got the tubecube - for the tube sound!!)

    after doing a lot more reading and research, here's what i've been considering both before i got the tubecube and now - (in no particular order)

    1. the vta st70 1 x GZ34, 3 x 12AT7, 4 x KT88 ----$1320 shipped wired
    + rectifier tube (better/different sound??)
    + 2 modes- triode/pentode
    - not autobiasing
    - not integrated
    - lots of tubes

    2. the elekit 8200 2 x 12AU7, 2 x 6L6GC ---$700 shipped as kit
    + autobiasing
    + headphone jack ( i dont listen to headphones often, but nice to have)
    + 3 types of amplifier modes (Ultra-linear, Triode, or Pentode)
    + 2 inputs
    - no rectifier
    - not integrated
    - need to spend at least a day to assemble

    3. primaluna prologue 4- 4 x EL34, 2 x 12AX7, 2 x 12 AU7 --- $980 shipped
    + point to point wiring
    + autobiasing
    - not integrated
    - lots of tubes
    - single mode (not sure which one? )

    5. kingko ka 101 - 4 x EL84 , 1 x 5AR4 , 2 x 12AU7 , 1 x 12AX7 ----$840 shipped
    + integrated
    + rectifier tube (better/different sound??)
    + el84 tubes which are cheaper/more durable
    + multiple inputs, VU meter
    + headphone jack ( i dont listen to headphones often, but nice to have)
    - lots of tubes
    - unknown resale value, not many users
    - single mode (not sure which one? )

    4. oldchen luxury 1 x 5U4G, 2 x 6H9C, 2 x EL34 -----$265 shipped
    + rectifier tube
    - one mode - ultralinear OR triode

    5. MP 301. 2 x 6J8P, 2 x EL34 -----$420 shipped
    + headphone jack ( i dont listen to headphones often, but nice to have)
    + 2 inputs
    + integrated
    + small footprint
    - single mode (not sure which one? )
    - not sure it will sound much different from the TC7??


    let me know if i missed anything significant in the pros and cons of each above... i may just stick with the TC7 unless someone can persuade me that i'm really missing out on something. i'll update in couple weeks re the sound!
     
    Last edited: Jun 9, 2018
  5. Robie

    Robie Live it or live with it. Subscriber

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    Location:
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    I've replaced the stock tubes with Tung Sols (upon the advice of the Tube Cube website) and love the way it sounds. More open, focused and bigger.

    I've used this amp as my desk driver driving everything from Indignias to Kef F-15s to Pioneer SP-BS22-LRs.

    Sources are my lil' Sony XDR-F1HD tuner or internet via my computer sound card via a GigaLab Moon DAC Mark II.

    I'll never get rid of this lil' thing.
     
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  6. lostrockets

    lostrockets New Member

    Messages:
    16
    for the tung sols, you replaced both preamp and power?


    im finding with the tubes i bought, i like the mullard 12ax7 with the stock power tubes vs the sovtek el84s i bought.

    i'll need to give the sovteks another good listen though to be sure, they are a lot brighter and seem to have more treble and definition at the highs.
     

     

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  7. DavidTT

    DavidTT AK Subscriber Subscriber

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    I'm not sure if my experience is helpful, but I have compared two tube amps in a desk top home office set up recently, powering Klipsch R-15Ms and receiving signal from a U-Turn Orbit turntable. I own a Gemtune X-1 8WPC EL34 amp and an APPJ mini2013 at 3WPC. The Gemtune is noticeably fuller and "rounder" in sound with better bass. The APPJ is really great and only cost $99 through MassDrop, and is physically tiny. I could happily live with it long term and will find an application for it, perhaps for a very small office set up with some very small desk top speakers. However, it produces a drier, perhaps thinner overall sound than the Gemtune.

    Again, not sure if any of that is helpful, but I certainly hear a difference in these two little ChiFi gems.
     
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  8. lostrockets

    lostrockets New Member

    Messages:
    16
    yes it is helpful. appreciate the feedback!

    have you found different tubes sound better with the gemtune?

    i may give one of the EL34 amps a try in a few months to see for myself! will update when i get around to it.
     
  9. Robie

    Robie Live it or live with it. Subscriber

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    Location:
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    Yes, I changed both the pre and power tubes with Tung Sols.
     
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  10. DavidTT

    DavidTT AK Subscriber Subscriber

    Messages:
    545
    I bought Tung Sols for the Gemtune but found that the PSVanes that it came with were as good, perhaps warmer than the Tung Sols, so the spec tubes are in the amp with the Tung Sols serving back up duty. To each their own, and maybe I'll splurge some day on a more elaborate tube amp and set up, but for my purposes and for the $$ spent, the Gemtune turned out to be a revelation.

     
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  11. Wildcat

    Wildcat Audio Sommelier

    Messages:
    4,784
    Location:
    MI, US
    Got a TubeCube|7 here myself. Not impressed. It is very rolled off in the highs, just like one online review measured--it is OK for nearfield listening (where "dull" is passable), but it sounded terrible in my main system, and woefully underpowered. Putting in new issue Mullards helped somewhat from the no-name glass it shipped with, but it's still lacking. I'm not kidding myself this is anywhere near a "high end" component. So @lostrockets, don't let this sour you on tube amps--this is not a high quality item. There are so many good things out there, new and vintage, I'd hold out for something better.

    And now, over the past few days, it won't turn on. I have to fiddle with the power switch a few times before the tubes start lighting up. Two years old and it's failing already. :rolleyes:
     

     

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  12. triode17

    triode17 Super Member

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    1,173
    I do hope you know that these are two different amp types, Push-Pull (4 output tubes) and Single Ended (2 output tubes). They produce different sound. Plus, in your OP, you said, "...it has plenty of volume and power and exceeds my expectations in terms of sound." So why not just stop there? You are jumping ahead too fast. Give your amp. 20 hrs. or so to break-in, then decide if you want a change. But for a small office, I think you made the right choice with the TC7. There is a symmetry between the tubes and supporting parts. Both affect the sound. Don't expect much change from rolling, its generally subtle.
     
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  13. lostrockets

    lostrockets New Member

    Messages:
    16
    yes agree, i've definitely had over 20 hours with it already and will be sitting tight for at least a few more weeks!
     
  14. lostrockets

    lostrockets New Member

    Messages:
    16
    so it's been a few weeks and my tube cube actually seems to have broken. i've had the same set of tubes in for about 3 weeks and today it wouldnt turn on. i can see the powerlight is on in the back but no sound. i tried switching out the pre and power amp tubes and it still doesnt work.
    the power tubes usually have a little glow and get warm, same with the pre but there is now no glow and they dont get warm... the tubecube itself does feel quite warm however...

    i did try switching the fuses (there was an extra) in the back but that didnt change anything.

    any ideas how i can troubleshoot?
     
  15. mnmmt

    mnmmt AK Subscriber Subscriber

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    Location:
    Minnesota
    Are the filaments in the tubes glowing when it is on?
     
  16. lostrockets

    lostrockets New Member

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    16
    none. they always did when it was working
     

     

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  17. Wildcat

    Wildcat Audio Sommelier

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    Still haven't gotten mine working either--if I let it sit all day, it might turn on. No idea what's up.

    Popping off the cover, it's full of cheap parts. Capacitors by a company named Chong...inductors in black plastic with no markings, can't tell who made the switching IC for the power supply or the other TO-220 semiconductors since the print is so damned small, and a lot of surface mount parts. I am betting, though, that one of those caps is what went bad. The soldering isn't terrible, but it's not perfect like what I would do. No cold solder joints though. I have a bill of materials to replace all of the electrolytics with Nichicon, and the film coupling caps with a WIMA equivalent. But it's a moot point if something else has gone bad. Fuse is fine, power switch is good, so...who knows? I won't have time to start troubleshooting it until after mid October. I may just find something that's not Chi-fi (new or used) that is similarly small but hopefully a lot more reliable. Even if I found a good small class A transistor power amp, I would go that route.
     

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