Shortest Way 51 (SW51+) Amp Impressions (Only)

I've only heard this amp through demos and short passing snippets. It had a special quality that is reserved for expensive amps... and it left me with the impression that it was highly engaging, possessing an "it" factor that allowed it to pull away from similarly priced mid-tier tube amps like the Liquid Platinum and Lyr 3. Now owning it and having had some time to digest its qualities, I feel like I can better articulate what this thing is doing.

I should say first off, I did not care for the stock tubes. They are fine, and very resolving, but had this overly crystalline purity that was a little too much and did not seem to impart enough tonally dense instrumental timbre that I'm used to with high quality tube amps. I guess we could say the stock tubes move it closer to solid state. This is not a bad thing, just depends on your priorities.

The Mullards were better in this regard, but boring... gave the impression the amp was dragging its feet through mud, to use an exaggerated term. The RFT EF184 tubes were the sweet spot, a revelation actually... it took the amp closer to TOTL territory IMO, imparting it with even more lively presence... and instruments now had the tone density and timbre I was after. Really these are the best tubes for this amp for my preferences and I feel no need to tube roll (which I loathe doing).

None of the above tubes change the basic nature of the amp though, which is a bit hard to describe. And it is a quality I have not quite heard in any other amp, not to this extent anyway. It has this kind of relentless momentum, like the music is unfolding in real time, locked into sync with reality. As a result, voices feel like they are hovering right in front of you. Instruments feel like they are not being stymied at all. There is an effortless grace and agility to the unfolding of supreme musicality. I've heard some of these qualities in other TOTL amps, but not quite to this extent... or maybe they just had a different take on the same idea. But the idea here is extremely compelling in how it presents the musical landscape. Resolution, microdynamics, micro detail are all decidedly above mid-tier amps.

That said, not everything is perfect. The sound, while extremely resolving, is a bit simplified compared to the best amps. Or rather, this purity and effortless grace maybe creates the impression that the amp is going a little too fast and not gathering the last bits of information needed to really bring you in 100% sync with the recorded moment. It is very very close, but with TOTL gear you are talking about the final 5%- 10%... so the fact that the SW51+ gets you so close is quite a shock, but also a very very good thing for the increasingly overpriced and overhyped hobby we find ourselves a part of.

Slam also leaves a little to be desired.... again, it as if the amp is so "go go go!" that it forgets to do certain things like create the necessary impact that gives the musical moment proper weight when called for... related to this is the amp's slight lack of overall body. It is has body to be sure, and of course we are talking small degrees here, but compared to the best amps, it falls a bit short here. Part of it is how strikingly linear it is from top to bottom, so it's both a plus and a minus in a sense.

Imaging is also very good, but still leaves something to be desired. It is not as focused as you get with certain amps, even the Schiit mid-tier stuff (I've always felt Schiit's amps have some of the best imaging capabilities). This becomes more obvious with classical music, where the stage starts to sound a bit more diffuse and lacking ultimate accuracy compared to the best of the best. But there is still enough there to satisfy for those focused more on the music. And it's very much a "music" first amp.

But what the amp does well, it does extremely well and paired with the right DAC, is easy endgame material for any discerning but sane audiophile. The Yggdrasil LIM for instance opens up the amps decidedly small-ish stage, and combined with that DACs supreme liquidity and similarly spooky realistic renderings, the pairing is a match made in heaven.

I'd be lying if I said I'm not drooling at thought of what @ZampotechNA could cook up for a bit higher cost/better materials. A TOTL version of this amp would be a scary-good proposition.

 

I can attest to this as well. I think the RFT EF184 tubes are the best tubes for the SW51+ I’ve tried as well. I like the stock tubes as well, but the RFTs are just a bit better overall. I haven’t taken them out of the amp for over a year at this point. As I recall, they were really cheap as well. Definitely recommend trying to source these tubes if you haven’t tried them yet.

I have experienced this synergy as well with my Yggdrasil A2. I used an OG BF2 for years with the SW51+, and it sounded pretty good with my Auteur. That being said, I always preferred my Quicksilver amp.

After selling the Quicksilver, I picked up a Yggdrasil A2, and the improvements it has brought to my chain have surprised me to say the least. Now the SW51+ sounds like it has been unleashed to show what it can really do. It even sounds good with my one set of planars, the Meze Elite. With the BF2, I never found the SW51+ to be a good match with the Elite. The addition of the Yggdrasil has changed my opinion. Now I find myself alternating between the Cayin iHA-6 and SW51+ almost equally. DAC choice seems to make a disproportionately large difference with this little tube amp.

 

^^^This

 

I'll need to revisit the RFT tubes now that i have my SW51+ set up properly again.

Funny this thread got bumped, last night was the first time in about a year I had the SW51+ properly going, as I think you need something like a Bifrost 2 to get the most out of it. Had the Bifrost 2 64/2 properly warmed up and the first song I heard was like Ah yep, this sound is what I was so enchanted with.

 

Swapping in the Bifrost 2 yields interesting results.

The increase in plankton/grit becomes obvious over the Yggdrasil LIM and seems to better match the more linear nature of the amp. Or rather, complements what could come off sometimes as excessive neutrality. BF2 has a thicker more organic sound as it were, and the pairing becomes like peanut butter and jelly. Diametrically opposed but complimentary.

I do feel the BF2 better suits the amp on an overall basis and would guess the organic Yggdrasil A2 would suit even better still. And the Yggdrasil models are just livelier and more "exciting" in general, which increases "engagement".

 

I should post a WTB, but does anyone have a spare pair of RFT EF184s they want to sell?

Are these them?
https://www.ebay.com/itm/284715067350

Where else would people recommend buying them from?

 

This looks it.

The RFT used to be everywhere but now are harder to find.

 

I just bought a matched pair from the same seller, they'll be here Tuesday
I'll let you know what I hear later in the week

 

Tubes arrived today: packaging is kinda skimpy (one thin layer of bubble wrap inside a small business envelope) given they're glass, but no problems

Really quick listening test:
Volumio Primo/Spotify > Bifrost 2 > SW51+ > HD6XX or HD600 (both made in Ireland)
Some blues, some rock; mainly focused on vocals & guitars
Stock tubes > HD6XX is a really great pairing, everything bar a complete production disaster
sounds at least very good if not better
RFT EF184 > HD6XX is a bit more clear/detailed
this is mostly a good thing; especially on some older blues tracks, voices & guitars sound
more real to me
things got a little more edgy on Bonnie Raitt/Walking Blues & Dr John/Cold Cold Cold but
I think I'll live with that for the engagement elsewhere
RFT EF184 > HD600 definitely were too edgy on those tracks and some BritPop stuff
some of the old blues stuff really came to life, but I don't ever listen with the idea that some
songs are off limits
Didn't try stock tubes > HD600 in this comparison, but I have several times & I think I would still prefer HD6XX with either tube set
HD600 might pair better with an original Torpedo I have; need to give that a fair shake

 

So I've given the Mullards another shot and am glad I did. The biggest difference for me is the stage... first, everything feels alot more positionally accurate, laid out in a more coherent manner, whereas the other tubes (stock and RFT) feel messier. This is a plus since stage real-estate on this amp is limited. The increase in plankton/microdetail (which is a noticeable step up from the other tubes) adds to this... everything is more laser focused without any etch or treble weirdness. The BF2's already cramped/cluttered stage gains tremendously from this, making everything seem more "neat" and "organized". The Mullard's organic grittiness also provides a nice contrast to the "clean" nature of the amp, moving it closer to a traditional tube sound.