"Shortest Way" Amp Impressions (Simple SET Amp)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Hands, Jul 12, 2019.

  1. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    This is in reference to the amp mentioned in the following FS thread, courtesy of @Zampotech.

    If SBAF members are interested, @Zampotech said he can make a limited batch to sell here. I think he's shooting for somewhere around $250 + shipping, if I understood correctly.


    I've spent a fair amount of time with this "Shortest Way" amp. I still have some comparison testing to do, especially with the ZDT Jr. but have enough thoughts to get started.

    So, what is this thing?

    - Single-ended, Triode, using 6Z51P tubes
    - Output transformers (two types of steel to improve performance at a smaller size, would have to use regular, larger transformers if more are produced)
    - Class A
    - No capacitors in signal path. Really just a pot and a few resistors, that I can see, plus tubes and OPTs.
    - "No feedback except natural communication through the cathode resistor"
    - Short signal path

    It's a really simple design with nicely picked components (given the originally targeted small size of the amp). In a sense, these bullet points strongly remind me of the same design goals in the DNA Sonett 2. Now, I haven't heard the DNA amps, so I am NOT suggesting any similarities or trying to guess any other relative performance metrics. But I do have to assume there is definitely some appeal for purist type amps.

    How does it sound?

    Whatever tubes you use will have a noticeable impact on the sound, but I'll mostly cover what I've found using the GE 6EJ7s and Mullard EF184s.

    The first thing that stood out to me was how hard it was to put a finger on the sound characteristics. Not because anything was immediately blowing me away or seriously amiss, but because most everything just sounded...pure? Which sounds like a lame term to use given I just mentioned a "purist" design, but, on the other hand, I suppose I'd hope a purist design would sound pure. Anyway, I'll get back to that.

    Nitpicks and Misses

    I'll get some limitations out of the way. There is a bit of roll-off in the lowest octaves. It's slight, but it's there. It's a tiny bit light on its feet, but not what I'd call wimpy sounding. Maybe a little lean, but only just? For example, the Valhalla 2 I think had a leaner sound than this, but it's evident that, say, the Magni 3 has a bit more robust and better extended bass. I don't have a Vali 2 on hand, but maybe the Shortest Way most closely equates to that? Or somewhere in between Valhalla 2 and Vali 2?

    It's also just a tiny bit rolled on the top end as well, with a little sweetness thrown into the mix. Or, perhaps it's more accurate to say there's absolutely nothing akin to solid-state-like sheen, glare, over forwardness, or over-sharpening on the amp. Could be a matter of perspective.

    The stage size itself is on the smaller end of the spectrum. But it has some real upsides I'll get to later.

    Lastly, it isn't the hardest hitting amp around. Again, doesn't quite suffer like the Valhalla 2, but it's a tick behind the Magni 3 with macro-dynamics. It won't make your music sound sleepy and dull, but it won't smack you upside the head either.

    Positive Traits

    As for the good stuff...Not sure where to start, so I'll just move through things somewhat at random.

    The amp has a really normal, clean, and, as I already mentioned, pure sound. And I don't mean "clean" in the sort of way where you just obliterate all nuances, up the contrast, and run the sound through a simultaneous noise reduction, smoothing, and sharpening filter. Clean as in a totally non-processed sound.

    It has a really smooth, liquid sort of sound, but other than sharpest transient peaks, doesn't sound soft or gooey. It actually seems pretty quick and tight overall, though I think it's same to assume some level of tube bloom (mostly in bass and lower mids, but is very minimal, and tighter sounding than Magni 3). No grain, no glare, no etch, no strain, but also not slow or dull. If you've seen running water from a faucet hit that perfect equilibrium, where it hits that perfect state and appears to be stopped in time, that's the sort of clear, liquid, but defined sound you get.

    In that regard, the timbre is almost spot on ideal, at least in the mids and treble

    Though the Magni 3 is generally sharper and more incisive sounding, just a tiny bit, it doesn't manage clarity like this at all.

    The stage is somewhat small, as touched on, but sits at a moderate distance, has nice layering, and actually sounds 3D. Unlike the Magni 3, and many other Schiit amps, which sounds forward, a bit wide, but like a flat wall of sound, the Shortest Way maximizes what stage it offers up. It doesn't have huge feet, so to speak, but it fills the shoes perfectly.

    (Note that if more amps are made, the chassis can be made larger to space transformers apart, to reduce inter-channel interference, and hopefully expand the stage somewhat.)

    The overall tone, as you might have guessed, is neutral but very slightly leans towards mid-centric. But that's not quite the best way to describe it, because it's really just the last octave or two that are a hair reduced. Really aggressive or bright music may sound slighter brighter than usual due to the slight bass roll-off. Still, it's not a bright sounding amp at all. I just want to reiterate this is not a bombastic sounding amp.

    It is not quite as tubey sounding as you'd expect, i.e. probably being more akin tonally to the Magni 3 if you were to give it the sensation of tightening up and leaning out the bass bloat a bit. (Just talking tone here specifically.)

    Though the amp won't knock you over with huge dynamic swings, it excels at micro-dynamics. Again, it never sounds dull on a macro sense, but it's a tiny tick behind the Magni 3 here. But when it comes to keeping the beat of the music alive, it's very good. This sort of clean groove and overall nuance is generally pretty hard to find in most amps unless you're shelling out the big bucks.

    Best of all, there's just a lot of resolution to be had with the amp. I mean, I was using this to compare DACs and found it very easy to tell them apart. Sure, the amp's limitations made for similar limitations when comparing DACs, but otherwise it seemed more like the sky was the limit for how much the Shortest Way amp could scale.

    With the excellent timbre, clear overall sound, small-but-3D staging, and good micro-dynamic abilities, ambient effects in music provide that sort of spooky-real feel to them. Low-level information, especially tiny percussive elements like piano pedals being pressed quietly in the mix, have the sort of audible and tangible feel you expect from high performing amps. Live music in particular, while not necessarily grand or huge sounding, actually captures that live feeling.

    And that's what I have to say for now. Will try to get the ZDT Jr out to play soon, since that's probably a more interesting comparison. But I didn't have to get it out to hear that the Shortest Way amp was quite good in many ways.

    Headphone Pairing Notes

    Seems to work great with dynamic headphones, at least high impedance ones. Still have yet to try low impedance dynamics. What planars I have on hand seem only so-so with the amp, but I'll look into that more.

    The HD650 pairs decently with the amp's slight low-end roll-off. It doesn't sound veiled or slow necessarily either, so as a whole seems to work well with the amp. The HD600 seems OK as well, providing an overall fairly neutral sound, but won't be the best pairing if you try to use amps to flesh out the HD600. Somehow the amp helps take some edge off the HD600 without screwing up the HD650's treble.

    Tube Notes

    The Russian 6Z51P tubes it came with were fairly lean sounding. Definitely lacked dynamics, but sounded sharp and clean.

    The GE 6EJ7s make the Shortest Way sound more akin to a Magni 3, filling out the low end, but still a little dialed back from the Magni 3 in that regard. Gets fairly close with macro-dynamics and treble sharpness but keeps all the better traits. A little bloomy when cold.

    Mullard EF184 is more akin to the GE. It's a little less forward sounding, a bit more space and air, and a little tighter, a bit less thick sounding overall (maybe). However, it's also a little more rolled sounding up top and slightly less dynamic overall.

    TL;DR

    - Really natural, effortless, pure sound.
    - Very mild bass roll-off, slightly warm treble (or at least no nasties at all), but mostly neutral.
    - Excellent timbre, almost perfectly balanced, being liquid but clear and defined.
    - Somewhat small stage, but good layering. 3D sounding.
    - Not explosive sounding, but not lean or dull. Decent macro-dynamics, very good micro-dynamics. Your music will keep you engaged and happy.
    - Nuanced and graceful, but not shy or aloof
    - Very good resolution
    - Definitely worth checking out if you like, or are interested in hearing, tube amps, tube + OPT amps, really simple/pure designs
     
    Last edited: Jul 12, 2019
  2. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Some comparison notes against the ZDT Jr:

    - ZDT Jr sounds very thick and bassy in comparison. More rounded and tubby sounding on the low end. However, it does have a good sense of power in the lower octaves, and it is pretty well extended in comparison to the Shortest Way. It also has a very slight uptick in treble relative to the Shortest Way. (Summary: ZDT Jr more of a dark slope down with some flair, Shortest Way more mid-centric.)

    - When you switch to the Shortest Way, it doesn't sound lush or rich like the ZDT Jr, but rather quite neutral with a slight bass roll-off. This also means that you can't rely on the Shortest Way to deliver a sense of dynamics as much via bass.

    - Bass on the Shortest Way at least sounds faster, tighter, and has better pitch differentiation. While, say, bass guitar might not be at quite the level you want in the mix, it is generally easier to hear and follow. ZDT Jr leans towards kind of mixing anything in the lower octaves together into a soup.

    - ZDT Jr has the slightest amount of tizz in the treble and doesn't sound as tonally balanced in the mids and treble overall. You'd probably never notice this outside of a direct comparison given how slight it is.

    - I still favor the Shortest Way overall for timbre, given the incredibly smooth but defined nature. Nothing about it sounds forced, underdone, or overdone. ZDT Jr is really quite good but just a hair less coherent. Both find their tone and timbre weaknesses mostly in the bass, at sort of opposing ends of the spectrum.

    - ZDT Jr, while generally decent with staging and layering (not mind blowing, but captures more good stuff than you might initially notice), sounds relatively flat, stuffy, and overly forward compared to the Shortest Way. Shortest Way takes a slight steps back, and narrows in the stage width, but provides more depth and better layering.

    - ZDT Jr definitely hits harder on a macro level, I'm sure largely due to the more filled out low end, but the Shortest Way is more nimble and has faster attacks overall. In a sense, the ZDT Jr has better macro dynamics, but it's complicated. Anything relying on the low end will hit harder, but the Shortest Way just seems to pop more overall, especially in the mids and treble. The Shortest Way settles faster and can more quickly respond to smaller dynamic swings as such.

    (The above point applies to the Magni 3 comparisons as well, on second thought. It can be hard to fully judge dynamic qualities with what appear to be subjective frequency response differences in the bass.)

    - Everything on the Shortest Way seems to sort of appear out of nothing. ZDT Jr doesn't really do this, like it has a lower contrast.

    - Resolution is similar between the two amps. The Shortest Way certainly sounds clearer and deeper across the board and of a higher resolution for that. I'm listening to the Shortest Way now and can hear into mixes with total ease. Nonetheless, close examination shows they are more equivalent than not with micro details. But you do have to listen through the soupier bass on the ZDT Jr to hear the smaller stuff.

    - In fact, it generally it seems other amps seem a bit soupy compared to the Shortest Way...Or, if another amp isn't soupy, it risks sounding flat, sterile, bright, brittle, etc. The Shortest Way doesn't really seem to do any of that.


    Given all this, the ZDT Jr is more akin to a baby Eddie Current Super 7 (w/ bassier tubes). It's a bit forward, pretty thick and powerful sounding, somewhat tubby, but technically very capable with lots of great tube + OPT magic. I think many have underestimated how capable the ZDT Jr can really be, possibly unable to look past its coloration and the like. The Super 7 is like a refined version of that.

    The Shortest Way is more like what I wish the Valhalla 2 was. I think were the stage wider on the Shortest Way (may be possible if OPTs are separated from each other), it's the closest equivalent we'd have to capturing the Valhalla 2's staging and layering. I think it certainly matches it in speed and clarity, but without any of the sandy nasties and a slightly less lean, slightly more lush sound overall. (This is all based on memory.)


    With the HD600, I definitely do enjoy the extra low-end oomph I get from amps like the ZDT Jr or Super 7 (Mk2). But neither of these quite match the effortless clarity, smooth definition, layering and depth, and grace of the Shortest Way. This little amp just has a ton of magic going on in the mids and treble, that while tonally not what I'd call lush, makes for a really entrancing sort of listen.


    Summary Highlights of Shortest Way, Revisited and Reiterated

    - Great layering, depth, despite narrow stage width, and resolution.
    - Mostly neutral. Slightly mid-centric, mostly due to mild bass roll-off.
    - Possibly near perfect timbre? Smooth but defined.
    - Fast, tight, clear, clean.
    - Sounds appear from nothing, and fast dynamic shifts are handled with ease.
    - Easy to hear everything in the music mix.

    Nitpicks

    - Mild bass roll-off.
    - Narrow stage (possible fixable by moving transformers further apart if anyone wants to buy a newly produced unit)


    3117087B-6A92-4535-9D89-AE511789D37E.jpeg
     
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  3. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    As mentioned, @Zampotech would be able to produce more of these for SBAF if there's enough interest. Would have bigger transformers and have them separated more, so won't be quite as petite of an amp overall.

    If a few senior members would be interested in checking it out, I may be able to arrange a limited loaner. By that, I mean the sort of folks with plenty of related experience under their belts (OTL, OPT, and especially purist sort of SET or similar amps) or the generally tenured, trusted guys.

    If not, then this will remain an interesting part of my collection. :)
     
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  4. Zampotech

    Zampotech Friend

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    First of all, I want to say a big thank you to @Hands for a detailed and scrupulous study of this amplifier.

    I would like to add post technical details

    About tubes
    Tubes 6EJ7, EF184 and Soviet analogue 6Z51P were developed in the heyday of the vacuum era and are perfect tubes.
    For tube 6Z51P life expectancy is over 3000 hours. I do not know the life expectancy of the tubes 6EJ7, EF184, but I'm sure it is close to 3000 hours. Or more
    If translated into human language, a pair of tubes will last my life, and will go to my grandchildren.
    It is also nice that these tubes are available and not expensive.

    About the shortcomings of the amplifier
    All said @Hands taken into account and technical solutions to eliminate or reduce deficiencies will be found.
    The bass and the width of the stage can be improved.

    If suddenly this amplifier will be interested in a respected community SBAF, it is necessary to solve the main issue. The name ( unfortunately I can't think of the names, the imagination is paralyzed). This should probably be discussed collectively.
    I will be glad to hear the suggestions of the forum participants.
    Also (in the case of interest) it is necessary to ask the forum administration permission to display the logo SBAF
    IMHO it is logical, if the amplifier will be distributed only among the members of SBAF

    About the amplifier design.
    The most optimal design will be similar to NBM (ZDT-Jr), of course, in other scales and proportions.

    A little later I will provide rendering of this amplifier.
     
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  5. Biodegraded

    Biodegraded Friend

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    ZAmp0. A play on the manufacturer's name, a reference to the similarity of design & nature to ZDT Jr, and a reference to zero capacitors in the signal path (or if you prefer, replace the zero with an O for reference to OPTs).
     
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  6. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    @Zampotech What would it take to improve the bass? On mine, is it the transformers that might roll off there?

    I haven't measured to see if there's an actual roll off. It just sounds like there might be.
     
  7. e.schell

    e.schell Friend

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    If we get some changes made that help alleviate Hands nitpicks (even if it increases price a bit) I would be in!
     
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  8. FlySweep

    FlySweep Friend

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    This looks really interesting. I'm absolutely in if Hands' issues w/ the amp were resolved. A "souped up Val2" <$400 is a terrific proposition.. I would prefer an XLR headphone connection (even if the amp is single ended), if possible, but hey, i can always get an adapter.
     
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  9. Biodegraded

    Biodegraded Friend

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    On second thought, maybe that's a bit too Parasound-ing. How about ZHA-0 (Zampotech's Headphone Amp-zero caps) instead.
     
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  10. zonto

    zonto Friend

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    Why not just Shortest Way?

    @Hands, how do you think this would pair with Utopia/Clear?
     
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  11. Walderstorn

    Walderstorn Friend

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    I don't get it, what is wrong with "shortest way"? I think it's catchy.
     
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  12. james444

    james444 Mad IEM modding wizard level 99

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  13. Zampotech

    Zampotech Friend

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    The amplifier can be made to work with bass, if you change the parameters of the transformer. It's not technically difficult.
     
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  14. Zampotech

    Zampotech Friend

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    You have a good sense of allegory. Thank you!
     
  15. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    Yeah, I don't really see why the name would need to change.

    It's possible! The output impedance is low enough, but not too low. And it might just help with the metallic timbre a tiny bit. But I know that sometimes the Focals like a bit of extra bass from an amp, whether it be the amp's tone or higher OI, and this amp wouldn't necessarily deliver as-is in that regard.

    Would if affect any other sound areas?
     
  16. Zampotech

    Zampotech Friend

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    If you apply a good transformer steel reputable manufacturers, and competently design the transformer, the nature of the amplifier will not change. Usually a good transformer is obtained after the second-fourth attempts.
    It will be necessary to work a little head and hands
     
  17. e.schell

    e.schell Friend

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    Upgrading the transformers is one place I would imagine like myself most people would be more than willing to shell out a few extra bucks. This is starting to get exciting.
     
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  18. gixxerwimp

    gixxerwimp Professional tricycle rider

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    The "Way" in "Shortest Way" has an awkward feel to me. "Shortest Path" sounds better, or how about "Direct Path". I tend to be very literal and direct. These are boring options.
     
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  19. Lyer25

    Lyer25 Too sensitive for SBAF

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    KwikSET/QuickSET? I've been on a 1950s hype train lately, but it'd fit the amp's aesthetic, apparent sound, and history.

    Bullshit naming aside "Shortest Way" is great, has a nice zen feel to it. Seems like it's exactly what I wanted the ZDT Jr. to be based on @Hands's impressions, so I'm hoping Zampo maybe considers limited runs in the future too (even at added cost for small runs).
     
  20. Walderstorn

    Walderstorn Friend

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    Maybe a vote will be the way to get somewhere because "direct path" sounds over complicated, like trying to hard to be technical and boring to me, for example. I think a 3-5 names vote will be ideal, if the project moves forward.

    Edit: like shortest path as an alternative to shortest way.
     
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