The amp that didn't explode! Yet!

[Ivor]

So I finally get to hear this famous “It hasn’t exploded… yet!” amp. Well more than just hear it, the lads very kindly lent me an amp which I’ve now had in my system for the past five weeks or so…
As it happens the arrival of the “It hasn’t exploded… yet!” amp, or Unexploded Bomb, or UXB for short, coincided with my system being rearranged (through 90 degrees) and for a while I wasn’t sure if differences in the sound were due to the UXB or new speaker placement. It took a few weeks of speaker experimentation to get the sound “right” again but once that happened… well everything fell into place.
The UXB delivers micro detail effortlessly. You have a fair idea what gauge plectrum the guitarist is using… how the pianist is using the pedals and how tight the wire is through the snap of a snare drum. Often with that level of detail amps, even the highest of HiFi, can become harsh and cluttered. I tried to feed it lots of info at once but it barely noticed. If an amp could shrug nonchalantly it would have done so.

Bass was fine through my bass shy old Rogers speakers. It was clear and accurate which is far more important to me than deep deep subterranean bass. Stereo separation was superb adding to that sense of air and space. That space also contributes to the soundstage and imagery which was into the realms of 3D and among the best I’ve heard.

I’ll go straight into some of the tracks I played across vinyl, CD and those new fangled computer files.

Bettye Lavette – Political world (from Things have Changed, via PC 3199kbps)
Starts off with random percussion/guitar doodling and then morphs into a funky swagger typical of Bettye’s protest-light approach. Lots of high-hat and bluesy guitar with all instruments getting space to be heard. Nice unfussy production meant that the whole album had an almost live feel.

Public Service Broadcasting – People will always need Coal (from Every Valley PC 1521 kbps)
A really likeable and even addictive album from Public Service Broadcasting. I suppose I could get away with describing the music as “soundscapes” but it’s quietly political (as the track title implies) and musically it’s fairly straight up guitar bass and drums but with a lot of percussion and syth strings. Again, in a production that could be quite dense, every instrument finds it’s place. There’s never a sense of confusion or, God forbid, distortion.

Dinah Washington – Mad about the Boy PC 760kbps
So lets take an old track at a much lower resolution. This does undoubtedly sound much better on vinyl or CD but for academic reasons I put it on… yes it’s a bit tinny – that’s the resolution – but the trumpet intro was convincing and Dinah’s voice as good as it could be. Many amps fall over with low resolution files… this was more than listenable.

Emmylou Harris – Goodbye (Wrecking Ball CD)
This album has been a reference recording since its release in 1995. The complex production from Daniel Lanois means that the better the system the more you will hear. Simple. I don’t know if I heard anything new through the UXB but certainly that micro detail was easier to pick out… in fact it was just there. No picking required!
This Steve Earle standard has U2’s Larry Mullen Jr on “hand drums” (as well as a conventional kit) and you can clearly hear that the drums are not being played with sticks but with hands – hey U2! When the best musician in the band is the drummer you need to take a long hard look at yourselves!
Anyway.. I digress. The harmonies, the various guitars and the swirling percussion all come through effortlessly.

XTC – Complicated Game (from Drums & Wires CD)
Another track chosen for it’s familiarity. Starts of with almost whispered vocals and muted keyboards…. Then comes that bass and sharp snare drum - give it a bit of volume and that snare should hit you in the chest… with the UXB it does. Insert smiley face here.
2:30 minutes in and the calm descends into manic staccato guitar and anguished vocals. It’s a paranoid breakdown with added echo. It takes a good system to make sense of it and again, the UXB takes it in it’s stride.

Steve Earle & The Dukes – You’re the best lover I ever had (from Terraplane 180gm Vinyl)
Earle at his down and dirty best. Upright bass, guitar and drums with a touch of harmonica and fiddle thrown into for atmosphere. Sympathetic production gives this one life.
The track kicks off with picked guitar upfront and dirty distorted slide guitar behind it – bass and drums just do their job. All is delivered clear and clean but never sterile which, to these old valve fed ears, can be an issue with solid state amps. The dirty ‘live in the studio’ sound isn’t cleaned up either which would be a mortal sin and again something the highest of HiFi amps can be found guilty of.

Jim Callahan – Ride my Arrow (from Dream River Vinyl)
Another one of those ‘tester’ recordings… lots of absurd angular sounds and then this close mic’d deep voice of Callahan delivering almost stream of consciousness lyrics that, if delivered correctly, sound entirely plausible.
I noticed here that the bass was slightly floor shaking (floorboards) but still not distorted or boomy.


John Coltrane & Johnny Hartman – Lush Life (180gm Vinyl)
Begins with piano and Hartman’s deep voice and eases it’s way into Coltrane’s tenor sax, the subdued bass of Jimmy Garrison and the brushed snare of Elvin Jones. It’s when Hartman stops singing that the sax comes in hard and loud… presumably intentional! It’s like this on every recording of Lush Life I’ve heard (not many) so I assume it is meant to be this way. The track ends with the velvet baritone voice swaying with the sax… again it’s a simple production and the quartet and voice are allowed to shine with an impeccable soundstage. Lovely.


Junior Delgado - Away with you Fussing & Fighting (Augustus Pablo presents Rockers International 2. Vinyl)
A bit of dub reggae will always test a system! Recorded in King Tubby’s Kingstown studios this is far removed from the clean production we’re usually listening to. Does the amp make sense of and control the deep bass? The dub choppy guitar? The raw unprocessed vocals? Well yes. It doesn’t clean them up and process the shit out of the sound (it’s an industry term) it just delivers the source.
Just to be clear the production is fantastic… it’s just not “western”. It’s shanty town Jamaican and what’s coming out of the speakers is authentic.


So? A Verdict? Well it’s a giant killer alright. Certainly one of the best amps I’ve every heard in my limited experience. I keep coming back to that level of detail, those little things like the high hat, the touch on a guitar string or the pluck of a bass. The is piano correctly heard as a percussion instrument, the intake of breath just before a line is sung. All things any high end amp should deliver but very often falls short. I kept hearing about this “low noise floor” of the UXB but I honestly don’t know what people mean by that. I suspect different people mean different things. Is it that silence when the amp is idle? The silence when the music stops? Frankly I expect that of all amps. Any noise would be an intrusion.

Interestingly I found that the amp liked vinyl best of the three sources I threw at it. Just my own finding. I know people will say that’s because my system is set up that way but once you take the tube amp out of the equation it’s not a “for vinyl” system anymore is it? Yes my speakers favour vinyl but so does Quad, Eist and many other brands in use by this group. My speakers are quite at home with CD or computer files too. The amp handled everything thrown at it, regardless of source, with ease.

Thanks for the loan lads.

[tony]

I kept hearing about this “low noise floor” of the UXB but I honestly don’t know what people mean by that. I suspect different people mean different things on that

A shorter version! to describe the detail and clarity you are hearing. Never Going back Again by Fleetwood Mac is the best I have ever heard it. It can sound shrill but on this amp the guitar sounds so natural. Low noise I suppose means no clutter all instruments are clearly audible. Intricate stuff dare I mention Remain in Light! is dense pack full of multi instrumental riffs and fills and you can pick which ever one take your fancy and follow it till it ends.

Glad you enjoyed it

[nige2000]

I kept hearing about this “low noise floor” of the UXB but I honestly don’t know what people mean by that. I suspect different people mean different things. Is it that silence when the amp is idle? The silence when the music stops? Frankly I expect that of all amps. Any noise would be an intrusion.

my understanding of low noise floor is that
it as nothing to do with silence or how quiet its quite the opposite,
that noise cancels out low level detail
like a full fade out and reverberation
also that noise compresses dynamics something to do with intermodulation i think

to me low noise floor provides the detail,
in noiser amps the detail just seems to fall between the stools without much hint its supposed to be there

also would be interested in others perception of noise floor?

thanks for the feedback ivor

[Ivor]

Thanks for the explanation on low noise floor lads.

[Ivor]

I kept hearing about this “low noise floor” of the UXB but I honestly don’t know what people mean by that. I suspect different people mean different things on that

A shorter version! to describe the detail and clarity you are hearing. Never Going back Again by Fleetwood Mac is the best I have ever heard it. It can sound shrill but on this amp the guitar sounds so natural. Low noise I suppose means no clutter all instruments are clearly audible. Intricate stuff dare I mention Remain in Light! is dense pack full of multi instrumental riffs and fills and you can pick which ever one take your fancy and follow it till it ends.

Glad you enjoyed it

Well I have Remain in Light and absolutely no Fleetwood fucking Mac after Mick left. Rumours, regardless of its production is, to me, one of the worst albums ever foisted on the public. Contrived self absorbed "product". But don't mind me.

[nige2000]

yes clarity is a huge part of it too

[cybot]

An absorbing read Ivor!

This is my understanding of the lowering of the dreaded noise floor:

The principle effect of lowering the noise floor on music is to remove noise to allow you to hear the music that was being masked by it. Usual culprits are RFI, modems etc etc.
Fleetwood Mac without either Peter or Mick doesn't help either

[Ivor]

Fleetwood Mac without either Peter or Mick doesn't help either

You're quite right Dermot, I actually meant Peter. Before they turned into a pop band anyway.

[tony]

Guessed you meant Peter. I know were you are coming from. I missed Rumours when I was young so listening to it 30+ years later for the first time I could ignore the fact it was and still is played to death. Second Hand news,The Chain and Never Going back again are the three I like especially Never. The rest of it is pure pop.

[jkeny]

My take on the 'noise' is what I call 'dynamic noise' - in other words it's only present when the amp is playing & intermingles with the music, masking the detail that you are now perceiving. It's not a case of putting your ear to a speaker when no music is playing & declaring "there's no noise" - this would be "static noise" or what many people refer to as the "noise floor".

This "dynamic noise" results from the Power supply noise which in most amplifiers is varying with the power demands on it. These current demands are resulting from the amplifier handling/amplifying the dynamic music signal - so if heavy bass is being reproduced along with subtle snare drum brushing, normal PSes cause an interaction between these two concurrent sounds being reproduced - the noise of the PS current draw when reproducing the bass is intermingling with the reproduction of the subtle brush strokes on the snare.

When the PS is so stable that it can handle all current demands with aplomb & produce no noise fluctuation as a result we perceive it as Ivor & many others report - not as a perceived reduction in noise but as a change in the whole perception of the soundscape - a more realistic reproduction.

The same PS consideration applies to the source & one of the possible reasons why vinyl is often preferred to digital source - I'm convinced that most digital sources suffer from this 'dynamic noise' (it's been my focus with all my devices) but vinyl only suffers from a higher 'static noise' floor, not a fluctuating "dynamic noise". This may be the reason Ivor prefers his vinyl sources - when an amplifier doesn't suffer from this noise fluctuation it no longer masks this issue in the source.

What Nige has done is scale up the LiFePO4 batteries to meet the power/current requirements needed for this amplifier. These batteries make for such a stable, unfluctuating power source that is unflappable. It shows that most amplifier PSes are under specced & the ones that shine usually have way over specced PSes. It also shows that engineering greatly underestimates the dynamic requirements of the dynamic current draw in most amplifiers.

This also demonstrates some aspects of the workings of auditory perception - it can 'tune out' static noise to a large degree & 'hear through' it. Fluctuating noise however, intermingles with the reproduced notes & is perceived indirectly in various ways that we see posted here by Ivor.

Great review, ivor.