Pete Millet "Butte"

Discussion in 'DIY' started by JK47, Feb 11, 2016.

  1. JK47

    JK47 Guest

    I finally got the "Butte" from Pete Millet together and sorted out. I had a problem with the right channel not playing music, just a pulsing/throbbing noise. After messaging back and forth with Pete (quick to reply, and very helpful), he helped me trouble shoot and narrow it down to a short in (actually underneath) one of the surface mount FET's.

    This turned out to be a really nice little desktop amp, and I won't be missing the Liquid Carbon I sold last week at all. The only weakness would be the volume pot, at certain positions there is some distortion, and one has to fiddle in those areas to find the sweet spot. Maybe things will smooth out with more use. It has a ton of gain and can nicely drive HD650's with room to spare. @Hands posted a solution if you don't need that much gain in the comments on Tyll's Innerfidelity review of the "Butte."

    http://www.innerfidelity.com/content/diy-beauty-pete-milletts-butte-headphone-amp

    All in all, a fun build with the only real challenge being the two surface mount FET's which don't need to be installed. I ended up re-installing them after I fixed the small short.

    DSC_0150.JPG
    DSC_0155.JPG
    DSC_0190.JPG
     
  2. Cspirou

    Cspirou They call me Sparky

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    8,200
    Trophy Points:
    113
    Location:
    Northwest France
    Nice! Did you have to supply the components yourself or did it come as a kit? What is the total cost? It seems similar to the O2, how does it compare?
     
  3. JK47

    JK47 Guest

    Pete has a BOM link to Mouser that has all the parts in the basket, apprx $60 shipped.

    https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=6f16d25474

    The chassis and board are on his ebay store, apprx $65 shipped

    http://stores.ebay.com/pmillett

    And an excellent set of instructions for assembly and testing

    http://www.pmillett.com/file_downloads/Butte_assy.pdf

    Here's his "Butte" page with all the above links, plus schematic and more links, also his home page with a bunch of DIY stuff.

    http://www.pmillett.com/butte.htm

    http://www.pmillett.com/index.html

    You're looking at roughly $130 for everything shipped with supplies like solder, etc. I have never listened to an O2, so I can't compare the two. A fella on Innerfidelity did in the comments for the review of the "Butte" and said it was a step up from the O2, YMMV.

    It does play nicely with the HD650 (full sound with body), much nicer than the Liquid Carbon to my ears (the LC makes the HD650 sound lean and thin, even in balanced). The "Butte" is fairly well balance across the frequency range wth a slight tilt towards warm. I like the fact, treble has no glare, but is still present without being rolled off.
     
  4. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Pete provides the case and PCB on his eBay store. He has a convenient BOM that loads up all the necessary parts on Mouser for you. His instructions are dead simple and very idiot friendly.

    I am running discrete voltage regulators in mine from Sparkos Labs. I did have to add a heatsink to them, and they are angled at about 45 degrees to fit in the case. No idea how they sound vs. stock regulators. That pumped up the cost by about $80.

    One could also consider getting a higher quality 12VAC PSU. That might improve the sound over the stock wall-wart.

    If you don't mind using a different case, the first thing I'd change is the volume pot. It has pretty poor channel balance, and with the stock high gain, you're more or less limited to hard-to-drive headphones. Otherwise on more sensitive headphones, you have low volume + bad channel balance OR really, really loud, ow-my-ears volume.

    I suppose you could also swap out some of the caps and resistors for nicer parts. Most of the parts are picked with the idea of this being a budget build and simply get the job done.

    I do recommend installing the CCS parts (SMD). They're a pain, and I think I messed mine up a bit, because channel balance got a tiny bit worse after somehow, but they do lower the noise floor and improve the sound primarily by removing a bit of grain.

    You can tweak the sound with different opamps, though the OPA552 is picked for having high current output, I believe (yes, no?). If you drop the gain below 5, you need to switch to the OPA551, which is stable down to a gain of 1. These opamps already sound pretty good. The Sparkos discrete opamps brought some improvements to the table but sound a bit rough and slightly bright with this amp...part of that might be the fact I'm running my Butte around a gain of 1, and part of me thinks they'd work better if I swapped out some of the caps, resistors, and pot for warmer, smoother sounding components (thinking Elna Silmic II for caps). He was kind enough to send me discrete opamps with higher current output, however, so it's worth considering.

    Looks like JK47 sniped my post and already answered some things as I typed this.
     
  5. gibtg

    gibtg New

    Joined:
    Oct 23, 2015
    Likes Received:
    3
    Trophy Points:
    8
    Location:
    United States
    'Hands' could you please recommend a pot upgrade for this unit? Would the pot resistance remain the same at a gain of 5.7 with OPA552? I contacted Andrew at Sparkos and he didn't recommend I use discrete opamps due to their limited current, did you have the same situation? I have also considered upgrading the caps, anything recommendations you could give on components would be great! Thanks,
     
  6. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Havent tried a new pot myself, just something Pete recommended if the stock pot has poor channel balance. Sparkos guy sent me custom opamps with higher current output but am not sure if he'd do that for others.
     
  7. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    I am also interested in building this. Is there a recommended list of opamps that can be used apart from the OPA552 and OPA551? That gain seems way to high for my easy to drive IEMs and headphones, so will defiantly have to get the gain down to one.
    This seems to be a bit more expensive to do than the Objective 2 and impressions seems to few and far in between. How have you liked it so far @Hands or @JK47 ?
     
  8. JK47

    JK47 Guest

    It would best to ask Pete himself if there are other opamps that are compatible, he can be contacted through his ebay store or his own website, both links are posted above.

    I really enjoy the "Butte", it takes turns with my Vali2 coming along on my 3 week work stints. I enjoy the extra gain the Butte has when I play my non-compressed own vinyl rips (I don't rip them at crazy clipping levels, to save the dynamics).

    On another note, the volume pot has smoothed out and I no longer encounter distortion in the former trouble spots.
     
  9. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    I still use mine from time to time, when I need a decent SS amp. I'd recommend starting with the OPA551 and going to a gain of one if using IEMs. The volume pot I got is pretty poorly matched, so you may want to consider an alternative enclosure with a better pot.
     
  10. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    Thank you guys. I am looking to use it with my 32 ohm headphones FIdelio X2 and HD650. Possibly better to build the smaller battery powered Objective 2 for the IEMS when time and funds allow as I know that is pretty silent with IEMs. I will make contact with Pete and see what he suggests. Then probably next step is some DIY tubes. Out of curiosity, how does the Butte compare with the Schiits? Would it be worth the effort to build compared to something as inexpensive as the Vali/Modi 2?
     
  11. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    I decided it is more fun and Pete was very helpful and had some extra suggestions. For now I will be using OPA551 and gain of 2. @Hands mentioned an improved PSU, what kind do you mean?
     
  12. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    I dunno, some random 12vac PSUs from China I found on eBay that didn't look like the standard wall wart stuff. Might suck for all I know. Have not tried it yet.
     
  13. dubiousmike

    dubiousmike Friend

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    269
    Trophy Points:
    63
    Location:
    Los Angeles
    Please report back on how it sounds! Butte remains on my short list of future diy projects. Any chance you could share the BOM recommended by Pete for a gain of 2?
     
  14. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    .
    It will take a while to get here to Europe from the States. Sure I will post some thoughts. I do not have a BOM, but Pete said the following in the email: "
    The OPA551 connected in unity gain (a gain of 1) would work well. To do this, just do not install R7 and R10. You also do not need C1 and C8.
    The HD650 needs more gain than the others you mentioned. The OPA551 is fine, but you probably want more than 1x gain. Again, it depends on how loud you listen.

    To use the amp with both, I would start with a gain of about 2 and see if it gets loud enough on the 650. For a a gain of 2 you can make R7 and R10 1k. You might need to experiment to see what’s best – you want the gain as low as possible but still drive the 650 adequately."
     
  15. dubiousmike

    dubiousmike Friend

    Pyrate
    Joined:
    Sep 27, 2015
    Likes Received:
    269
    Trophy Points:
    63
    Location:
    Los Angeles
    Thanks @Eugene du Toit! This sounds like an interesting option for my bedside rig - on which I mostly listen to th-x00's but also use Westone 4's. Unity is perfect for both. I'm currently using an agdr booster board (http://www.agdraudio.com/o2 booster board.html ) modded O2 and working on Wire SE SE build, but I think I'll do a Butte next.
     
  16. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    It actually came very fast. Excellent speed from both Pete and Mauser. I finished the build already yesterday, thanks to the very detailed building instructions. I used the OPA551 and a gain of one and still it has plenty of volume. No volume pot problems so far, but can imagine the original gain be too much for my setups. Will have to test later with HD650 and see if there is enough gain for those. Have to contact Pete and ask about the slight thump when powering on. None the less, first impressions are of clean, full,(not lean)' refined sounding amp with no grainy/grit at all in the treble.
     
    Last edited: May 1, 2016
  17. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Thump could be from DC couple.
     
  18. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    It's put out some DC. Investigating build...

    Edit: Pete replied that it's normal for the Butte too make a thump, as the is no muting circuit.
    It's harmless, but best practise is too unplug it before turn on. I really like this amp...now have to find a nice dac for it.
     
    Last edited: May 1, 2016
  19. Poleepkwa

    Poleepkwa Friend

    Pyrate BWC
    Joined:
    Oct 1, 2015
    Likes Received:
    1,557
    Trophy Points:
    93
    Location:
    Finland
    Browsing around on the internet I saw a Pete Millet "Butte" for sale and the seller talks about and "optional Class A biasing". I checked the install instructions and Pete mentions "An optional CCS circuit can be used to draw current from the opamp output to the negative supply, essentially biasing it into class A for very small signals." Has any one here implemented this?
     
  20. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Pyrate MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    12,285
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Yeah, I just two SMD parts. A bitch to solder. Actually had a measurable affect on cleaning up the noise floor.
     

Share This Page