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Bottlehead Amplifier Discussion / Comparison Thread: Crack, SEX & Mainline

Discussion in 'Headphone Amps (full-size)' started by loquah, Sep 24, 2013.
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  1. adydula
    Send the pix to the guys at BH on their forum, I would think they would be the experts to help u out.
  2. deserat
    Looks like my SEX 2.0. With the old iron. ( Chokes and Output Transformers ). You can upgrade the Iron, but the c4s upgrade isn't sold anymore. So having c4s is a plus.
  3. FunyunBreath
    Getting ready to wire this thing up :) Can't wait to hear how it sounds!

    Last edited: Feb 22, 2018
  4. Loquah
    The plate and case look gorgeous! Nice work!
  5. JamieMcC
    Looks great the corner details on the enclosure are a classy touch. You want to be 100% sure your paint finish has cured fully this might take several days if its not been heat cured, if not there is a risk of wrinkling and tearing the paint in areas surrounding fixings as they tightened up even though the paint surface might feel dry to the touch.
    Last edited: Feb 22, 2018
    slankoe likes this.
  6. FunyunBreath
    Thanks! I figured I'd spice up the stock alder with some Granadillo splines to match the black top plate. I did a 6-coat hand rubbed oil finish (tung oil, BLO, varnish mixture) and I'm really happy with the way it turned out. :)

    I did about 4 coats on the top plate to get the hammered texture I was looking for. I let each coat cure for at least a week before adding another coat, so I think it should be cured enough to screw the components in without damage.

    I do know it's not fully cured yet though (I can still smell a bit of the fumes). On my last bottlehead build I did the same hammertone paint job on and it took at least 2 months before the plate was fully cured.

    I've heard of some people baking parts in the oven at around 200 degrees for an hour or so to cure hammertone paint, has anyone tried this and had any success?
  7. NightFlight
    We used to do this for rushed tests in a paint factory I worked in. In my case it was acrylic paints, but all paints should respond to this treatment more or less the same way. I'd be careful on the temp. I would assume 200F not C.

    I am not a chemist, YMMV
  8. Doc B.
    We've had a couple of cases where the paint got brittle and cracked some time after it was baked. However that was baking with a heat lamp, which may have gotten the paint too hot. An oven's even heat will probably be safe enough. Definitely don't go over 200 F, and I'd suggest keeping it under 20 minutes of baking time. Or just let it sit for three weeks.
    Loquah likes this.
  9. adydula
    Just got the ship email!

    Yahoo...Be here next week, Tue the 20th....soldering iron is heating up!

    deserat likes this.
  10. slankoe
    Bottlehead S.E.X. (Single-Ended eXperimenter) Amplifier Mini-review

    I purchased this product myself for personal enjoyment in July 2017. It is a fantastic amplifier that I have truly enjoyed listening to music with. At the time of purchase, I opted for the C4S upgrade, which is an optional component that stabilizes the electric current coming from the power circuit. This upgrade carries multiple benefits over the base product including lower distortion and noise as well as improved bass. In this review, I will compare this product mostly with Mjolnir 2 from Schiit Audio, although Mjolnir is priced slightly higher, at $849 for the base model.

    Perhaps the most interesting thing about S.E.X., besides the sound signature, is that assembly is required when purchased directly from the manufacturer. Construction of the amp is a slightly more complicated than building the Bottlehead Crack amp (the lower-tier product from the same manufacturer). However, it remains a manageable challenge, given that this was my first kit after all. The total build time was approximately 10 hours, spread over two evenings.

    Priced at $540 ($450 when it goes on special), S.E.X. is difficult to beat in terms of price/performance ratio.

    The tonal balance is great. Not too hot or too cool – imagine a perfect bowl of porridge that goes down smoothly leaving you wanting more. The overall sound signature is detailed with slightly accentuated but well-extended bass. The high end is transparent to the source without a perceptible treble boost. Although the upper range does not extend as linearly as a solid-state amp, it is nonetheless impressive for a build-your-own tube amp.

    The mids are buttery, yet not recessed compared to other OTL tube amps or push-pull types.

    The bass region is neither as tight nor as deep as Mjolnir 2, but it is still decent. The whole spectrum of sound is remarkably well-represented with a slight, even downward slope in frequency response.

    While the sound signature of S.E.X. is detailed, it is also quite gentle. Rather than coming across the eardrums with blunt force, S.E.X. subtly unfolds the soundscape in front of listeners sublimely when compared to the less-subtle, punchier Mjolnir 2.

    In addition to the aforementioned, S.E.X.’s dynamic range is simply fantastic. From the subbass to the brilliance, the dynamism of S.E.X. is truly a delight. While certain solid-state amps may nonetheless outshine it in this regard, S.E.X. keeps up the pace remarkably.

    The noise floor is low with the C4S upgrade, which reduces interference inside the unit. During testing, when cranked to full volume, I could hear a hiss in the background. However, for my own listening safety, I have never been compelled to listen to music above 10 o'clock on the volume knob (with the Sennheiser HD650).

    The sound stage is wide, well-defined, and holographic. Unfortunately, the depth isn’t as satisfying as I have had hoped, but some listeners may still find it satisfactory and acceptable. This is one place where the Mjolnir matches the S.E.X. in sound stage reproduction ability.
    S.E.X. has more than enough power and headroom for both planar magnetic drives and dynamic ones alike. Below are my notes on different sets of headphones, listened to at around 80 dbs:

    ● The rather-demanding AKG K340 (now an uncommon vintage set of headphones from a bygone era) were powered well and sounded punchy through this amp. It is also one of the few power-hungry headphones with which the volume pot needs to be cranked above 12 o’clock.
    ● With more mainstream headphones like HD650, I could get the volume turned to about 10 o'clock before it becomes a health hazard. In particular, S.E.X. pairs well with HD 650, giving the already-good sound stage a pinch more dynamism while bringing out the liveliness of the music gracefully and effortlessly. It also does wonderful things to the low end, bringing low-frequency details I didn’t know was there before.
    ● The Focal Clear had a highly addictive sound when paired with S.E.X. and its tasteful bump in the bass frequencies blended well with the amplifier's tonality. This combination made the analytical Focal Clear a lot more engaging than it would otherwise be coming out of lower level amplifiers - a clear cut above the entry-level Schiit Vali 2 hybrid tube amp (which performs incredibly well in its price range).
    ● When it comes to Hifiman’s HE-560, the synergy between this particular amp and the headphones is unmatched by all other pairings I’ve tried. Unlike some other amps that I have tested the HE-560 on, the HE-560 sounds rich and full of life with the ample power that S.E.X. supplies.

    Finally, I paired S.E.X. with different DACs. Among the different DACs I have tried (Gungnir Multibit, Modi 2 Multibit, Chord Hugo), I preferred Gungnir the best, followed by the Modi 2. While Chord Hugo sounded neutral with SEX, some may find the treble region too bright. That being said, the differences between the various DACs are so minute that they are difficult to detect without extended testing. After listening to all of the DACs on S.E.X., I am confident to conclude that most well-made DACs will not disappoint when paired with S.E.X.

    Overall, I praise SEX for its low harmonic distortion, wonderfully balanced tone, dynamism, versatility, and the ample power it provides. TL;DR: It is a superb all-rounder at this price range.

    29366304_835883373250026_3579148019016138752_n.png 29389484_836348336536863_8616502662692601856_n.jpg 29495956_836349733203390_2337267438082588672_n.jpg
    Last edited: Mar 21, 2018
    pure5152, deserat, attmci and 2 others like this.
  11. JamieMcC
    Nice review
    slankoe likes this.
  12. adydula
    Well, we started the Mainline build today...got the kit yesterday and took inventory, was missing two 49.9 ohn resistors and one #6 fiber shoulder washer for the smaller transformers. Waiting on BH to ship me these.

    But lots to do in the meantime, populated the 4 circuit boards andgot most of the stuff mechanically mounted on the main mounting plate.

    Glued the base, sanded down and got a first coat of Tung Oil on it.

    Painted the Power Transformer Bell Housing a nice gloss black and its drying overning and will install tomorrow.

    Will recheck the 4 boards tomorrow for correctness...and start wiring up stuff....

    Probably will not get this to totally power up until late next week I think...stay tuned
    slankoe likes this.
  13. adydula
    First power on test of the power supply passed!!...6.3VAC and 390 VDC....working on the wiring now!
  14. adydula
    11.jpg 44.jpg Progress...
    Last edited: Mar 23, 2018
    slankoe and vaibhavp like this.
  15. adydula
    44.jpg 55.jpg More Progress:

    Last edited: Mar 23, 2018
    slankoe, JamieMcC and vaibhavp like this.
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