New DIY Altoids Tin Amp - The Pocket Class A "Wintergreen Handwarmer" by xrk971

  1. xrk971
    The EBL's don't have a step up - I think they use maybe 3 internal cells. It has dropping voltage with time so no DC step up.

    The OK's don't have it and if you can't hear it it is fine to not use CRC filter with the other DC step up. I only added it because I could measured a broad -90dB noise hump from 1k down with the DC switcher step up. 2200uF RCRCRC actually fits in tin with 3000mAHr LiPo and charger an step up.
  2. stellarelephant
    Great info. I really need to get set up to make measurements with my sound card. For now, I just bought some Duracells to compare audible hiss from the amp with them vs. OKCells. In the long run I hope to copy your 3K mAh setup. How many hours of runtime do you get out of it?
    Last edited: Jul 18, 2017
  3. stellarelephant
    Can any Nichicon capacitor dethrone the Panasonic FR as my current favorite in the PCA?
    Here are my listening impressions:

    25V 1000uF KW
    Reasonably pleasant, but the treble is quite dulled. Nicely engaging, slightly grainy mids. Bass extends low but is a little uncontrolled and surprisingly quiet for a 1000uF cap. Subpar detail and dynamics.

    25V 1000uF FW
    Brighter than KW. More balanced mids sit on par with the rest of the spectrum. Clearer treble, with some sparkle, but still lacking air up top--stuffy. Good presence in mids, with just the right amount of bite. Bass quantity is better than KW but a bit distorted.

    16V 470uF FG
    A small step closer to KZ sound in resolution and overall engagement. Smoother than KW or FW, with a balanced frequency response. Deep, punchy and controlled bass. Still a bit "closed in" vs. Panasonic. A bit short on high treble. Can sound strained in louder passages.

    25V 330uF FG
    A hair smoother than the 16V, with a little more treble. Just enough bite in the mids to make vocals "in your face" without being gritty. Surprisingly good bass, though theoretically less quantity than the other FG. Again, the soundstage is small and stuffy. Where is the high treble, Nichicon? In the KZ only, I guess. Sheesh.

    25V 1000uF KA
    I've already auditioned the KA a lot, but mostly the 470uF. The KA actually stands out from the typical Nichicon "house sound" IMO. It has a slightly mid-centric signature with enough treble to sparkle some, though the treble is a tad hot. Midrange and vocals come forward in the mix nicely, but without grain--they are the smoother than even the FG. Bass has decent weight and control. Somehow I find the KA more natural in timbre than all the others--the sound is clearer, though not particularly airy or exciting.


    25V 1000uF Panasonic FR
    FAR more neutral and revealing than all of these Nichicons. Maybe its the ultra low ESR…it just gets out of the way and lets the music come through. It gives the cleanest and most spacious presentation, with excellent detail and real air on top for a beautifully open soundstage. The bass is awesomely powerful with deeper extension than any of the Nichicons, and tight control. Blackest background. Fastest transients. Need I say more? If I had to nitpick, I'd wish for a touch more warmth and presence in the mids, but I suppose that might just be a coloration that suits my taste. These caps simply sound REALISTIC.

    With the Pannys in place, I played the amp today for my buddy who has a degree in audio engineering. He kept repeating the words "unbelievable!" and "crisp!" He also commented on the superb instrument separation and his jaw dropped when he heard the bass drop =).

    I am awaiting a package of Elna Silmic, Elna Cerafine, and Nichicon KZ in the mail…KZ is too big for this build, but I want to hear it anyway. I'll be impressed indeed if any of them sound better than my current setup!

    All the caps tested are 10x20mm, but have different voltages and capacities. For reference, here's the predicted bass response of each cap value I tried in this test paired with my 50 Ohm cans in parallel with the 1K resistor load.
    Last edited: Jul 18, 2017
    xrk971 likes this.
  4. xrk971
    Did you compare to 1000uF 16v SEPF OSCON?
  5. xrk971
    3000mAhr at 3.6v step up to 16.5v gives about 650mAhr, so same as EBL's - about 4.5hrs.
  6. stellarelephant
    I have indeed auditioned that OSCON, in both my builds now. I found it to be extremely well balanced thorough the frequency range, with excellent bass weight and particularly great bass control, with a full, creamy, sound signature. But it has a soft/dull one-dimensionality to my ears, and fails to engage me. It seems short on detail compared to the other caps I have tried.

    More cap tests to come, with some of the best-regarded audio caps this round...but I think the Panny FR may still reign supreme.
  7. xrk971
    What's the part number for the FR cap on Mouser or Digikey? Is there a 3300uF 35v version? I could use for the HyQu MP.
  8. stellarelephant
    The one I'm using is manufacturer part number EEU-FR1E102. I found out that there is also a longer 10x25mm 25V that would fit just as easily in the PCA, which gets you a smidgen more capacity...1200uF. That's part number EEU-FR1E122L. I haven't heard it but I would assume it sounds the same, and ought to crank out bass even with 30 ohm cans. 1000uF is perfect for me though. On my third build I will probably audition the bigger one just for grins, and possibly omit the battery connector socket to accommodate 12.5x25mm 25V 1800uF FR rail caps, theoretically improving stereo separation a tiny bit over my current 1500uF, right? I think at that point I will have the board completely stuffed edge to edge with FR :)

    There are definitely 35V FR caps also!
  9. xrk971
    Thanks for the info. I will order some for the PCA and for the new HyQu amp.
  10. gwompki

    Good write up on the caps!

    Stupid question...are you using those as the rail caps? Or one of the other positions?
  11. Sodacose
    done top view open smaller.png
    Pic of my build with stock values!

    And here's a guest post review I wrote up after building this amp:

    All-in-all, it's a great amplifier! Sound is excellent and it pairs really well with what I assume to be the typical companion gear (smartphone, streaming services, mid to high impedance headphones).

    Well done, XRK!
    Last edited: Jul 28, 2017
    xrk971 likes this.
  12. xrk971
    Thanks so much for the review Sodacose! I am looking forward to building your hybrid tube amp as well. Never had a tube amp before so that will be cool.
    Sodacose likes this.
  13. Sodacose
    My pleasure, seriously. It is really interesting to compare the two amps: lots in common between them. I'd say 'great minds think alike' but I'm not so sure about my own :beerchug:
  14. stellarelephant
    Yeah, great review Sodacose. It reads as very balanced, and full of useful descriptions and comparisons. Glad you agree that this amp rocks. Why isn't the link working anymore?

    I do have 1500uF FR soldered in on the rails too, but all the comparisons I have been doing are for output caps, including the 1000uF FR.
    Last edited: Jul 28, 2017
  15. stellarelephant
    Output Caps, Final Round:
    BEST OF THE BEST electrolytic capacitors duke it out for a place in my no-holds-barred PCA. :)

    The majority of my listening tests for this round were performed through ATH-M50 headphones, which I have found to be invaluable for giving an honest rendering of sonic differences. These findings were confirmed through further comparisons using my HD598 and also feeding my Tripath->Aurasound system. Sources were a wide variety of FLAC files played both from my XDuoo X3 or my Mac's ECHO soundcard. This test was intended to compare caps of similar size that will fit into the available space on my PCB for this particular build. Voltage and capacitance ratings thus vary across caps tested, but all caps are 10x20mm unless marked with an asterisk, which means they are 12.5x25mm.


    Elna Cerafine
    values tested: 16V 330uF, 25V 220uF, 25V 470uF*
    I can see why a few people like these more than Silmics. They have more midrange forwardness and bite to them, and at first blush seem to offer a more engaging sound. However, their treble can be a little harsh after a while, and the response is rather poorly extended on both extremes of the frequency spectrum, resulting in a less detailed, somewhat boomy and congested sound, with noticeably less bass control than the Silmic. Not my cup of tea.

    Elna Silmic II
    value tested: 16V 220uF
    Bass has rather flawless texture, speed, and extension, even with a marginally undersized 220uF cap. A polite, soft midrange and treble makes you want to crank the volume, and the overall sound is nice and full. It hides the flaws of harsh recordings, but also seems to push vocals farther away and hide some harmonic texture, resulting in an odd hollowness in midrange timbre. I'd say these sound spacious due to decent extension and a somewhat exaggerated treble sparkle, but the high treble is missing. I particularly dislike the way these do metal percussion. Cymbals and hi-hats do not sound realistically metallic. Other than that, these sound great, if slightly veiled in parts of the spectrum.

    Nichicon Muse KZ
    value tested: 25V 330uF*
    Nice. These are quite detailed, with a beautiful, jangly midrange and sparkly treble that gives an incisive "electric" sound to the upper ranges. Vocals really jump out and grab my attention so that song lyrics have excellent intelligibility. The overall presentation is ever so slightly on the hot/forward side of neutral, with a hint of upper mid harshness, but the overall timbre is natural, with enough treble to give an open soundstage. Metal strings and percussion sound right. This size gives impactful, fast, and detailed bass with my 50R cans. With these, I never feel like I'm missing any detail whatsoever, and I wouldn't say the soundstage is huge, but certainly bigger than either Elna. They're lightning fast, and darn revealing.

    Panasonic FR
    value tested: 25V 1000uF
    I've described these before, but I'll compare them here to the others in this lineup.

    - They're really just better than the Cerafine in every respect.

    - Compared to Silmic, they have a strikingly similar smoothness in the mids, but this time the effect isn't exaggerated by a contrived treble sparkle, maintaining a more natural timbre overall. FR has much more clarity and extension than the Silmic in the high treble, for a wider soundstage with real air. I chalk this up to less distortion. Switching from Silmic to FR is like lifting a thin veil. Chimes and cymbals are simultaneously less fatiguing and more realistic. Bass is powerful and full, with effortless extension from the 1000uF size, but a little less textured than the sweet Silmic bass. In fact, I'd say the entire presentation is a little "slower" than the Silmic, which has a bit snappier attack. Most importantly, these FR are even less fatiguing than the already smooth Silmic. There, I said it.

    - Compared to the Muse, this FR sounds a lot smoother, with much less of that addictive Muse midrange texture, and a slower transient attack speed. FR has a cooler presentation, with more extension up high, and slightly less distortion throughout the spectrum. Bass isn't quite as punchy nor textured in the midbass region as what the Muse puts out, but upon listening back and forth, I feel the FR bass is more neutral, with deeper extension due to more capacitance. FR has a better soundstage due to its superior treble transparency, and sounds less fatiguing. I'd say the two are evenly matched for detail, with the KZ giving more speed and midrange zing and overall a fuller body, but the FR letting more micro details come through the mix by virtue of clearer imaging and a more neutral signature.



    FR is the only electrolytic I have heard that actually gives this amp an expansive soundstage, with real air, even with a closed headphone. Silmic and Muse, while both great in their own ways, always sound "on my ears" while with the FR, music seems to come from slightly "beyond my ears". The FR sound has a certain magic to me because it sounds less dense than the other electros, highlighting the silence between notes and giving instruments a good amount of breathing room. The subtle but delicious consequence of this effect is that "space" is better represented through a delicate rendering of reverb tails and other subtleties of the recording. I can listen to the PCA more comfortably at higher volumes with the FR than with any other cap--it never grates me in the least. Most importantly, its neutral signature encourages me to just kick back and enjoy the music instead of analyzing the sound and wishing for improvements--something that can be quite hard for me with other caps. Silmic and Muse sound great, and each have subtle tonal colorations which may certainly appeal more to personal tastes or give great synergy with certain equipment. But I feel that if measured, the Panny would show significantly less distortion than either of the others. That's how it sounds to me, anyway. YMMV. Try them and see!
    Last edited: Jul 28, 2017

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