[stvnharr]

Thanks everyone for the carefully written observations on the LF's.  Hugh obviously has a great product on his hands.

It was mentioned that the amp David Ellis had just used attenuators with a digital source straight in, though doesn't say what it was.

I've become very hooked on the direct to amp mode, but my resident BEL 1001 amps have very low sensitivity (2v for full output when bridged).

With 860mv input sensitivity (+30.3db) for full output on the LF100, has anyone tried a Bolder modified Squeezebox (1.1v max) direct into one to see if it yields satisfying levels and sonics with reasonably efficient speakers (87-88db)?

Tom

Dave has my amp, and I believe he uses a modified Anthem cdp.
I have used my amp with a Sony C2000ES sacd player and have no issues with the setup.

My other system has a GK-1 in it, and I like that as well.

Steve

[fajimr]

It was mentioned that the amp David Ellis had just used attenuators with a digital source straight in, though doesn't say what it was.

Tom

I am running a CDP directly into my LF without any issues at all.  I use the same attenuators as Dave does -I heard of them from him and needed a solution at the time.  Since the amp makes such great music, I haven't been in too much of a hurry to build my Gk-1

check out http://mysite.verizon.net/vze4c5pt/ for the attenuators.

cheers
jim

[AKSA]

Hi TomS,

My apologies for not responding earlier, you wrote:

With 860mv input sensitivity (+30.3db) for full output on the LF100, has anyone tried a Bolder modified Squeezebox (1.1v max) direct into one to see if it yields satisfying levels and sonics with reasonably efficient speakers (87-88db)?

Two issues here, I believe.  One, the notion of direct to amp from the source, and two, the gain issue.

The gain of the Lifeforce amps - both of them - is 32.7, or 30.3dB.  For a power amp, this is in fact high, and the reason is that I was allowing for the use of shunt volume controls, which deliver better sonics.  This means that 1.1Vmax (which I presume is 1.1Vpeak, or 2.2Vpp) will deliver 71.94Vpp into 8R, which equates to precisely 80.9W, and around double that into 4R.  In practice, and in a domestic setting with even 85dB/watt/metre speakers, this would be VERY loud, loud enough in fact to cause ear damage.  So it should be fine on the basis of the calculations!!  (You will notice I try not to be too emphatic, someone always proves you wrong, and then I look a damn fool!   )

Second, the source direct issue.  This warrants a bit of philosophy, in fact.  There are two schools of thought on this - roughly divided into the SS camp and the tube camp, accuracy versus engagement as I see it.  SS is accurate, dry, surgical, even acerbic.  But lots of people like that - it is visceral, too, and delivers a thwack, particularly obvious on rock bass.  SS is quiet, usually quieter than tubes, and doesn't take forever to warm up after switch-on.  And on orchestral works, with tens of instruments and a big scale sound, this accuracy is very good as you can pick out individual instruments clearly, like the solo violinist, and still hear the pure, single notes above all the cacophony.  OTOH, tubes give a more organic sound, somehow more 'vox humana', a little bit warm, and, dare I say it, fuzzy.   aa  Huge numbers of people like this sound, too, because it seems somehow more engaging.  They find a tear rolls down the cheek more readily with tubes - the big one is female vocals, particularly blues, where tears appear de rigeur.  (Ever heard 'Strange Fruit', first sung at 'Cafe Society' in Greenwich Village by Billie Holiday in 1939?)  But there is a downside - there always is in the world of physics - and it's slightly loose bass, and some intermodulation, and a cloying sweetness which costs resolution.

So audio is forever doomed to compromise.  We have to choose!

I love tubes, but miss the detail.  I also like SS, but don't enjoy the surgery.  The best compromise, I've found, is a tube front end, the preamp, followed by a SS power amp.  This gives pretty much the best midway ground, and my GK1 and Swift were designed to complement the AKSA and Lifeforce power amps.  The tube in the preamp is used in a very benign, low distortion and quiet configuration, and there is dark chicanery in the circuit to fix the 'loose' bass I mentioned earlier.  To my ears (and remember I'm just one guy so YMMV, and likely does!) this is the best option, and it seems to win a few converts here and there.......

Hope this helps,

Cheers,

Hugh

[stvnharr]

It was mentioned that the amp David Ellis had just used attenuators with a digital source straight in, though doesn't say what it was.

Tom

I am running a CDP directly into my LF without any issues at all.  I use the same attenuators as Dave does -I heard of them from him and needed a solution at the time.  Since the amp makes such great music, I haven't been in too much of a hurry to build my Gk-1

check out http://mysite.verizon.net/vze4c5pt/ for the attenuators.

cheers
jim

Let me clear some things up here:
1.   The attenuators listed above are NOT the ones in my amp that Dave Ellis is using at the moment.  The attenuators in my amp are diy series attenuators that I got from Michael Percy.  They have 23 steps and the steps are 2 decibels each.  I believe the Endler attenuators to be a bit different, and the 12 step ones have much larger steps.

2.   Direct source input to amp vs. source to preamp to amp.
I have two systems and one is direct source in with the other having source in to a GK-1 and then amp.
Gain is not an issue.  With the direct source in I still have to attenuate the signal even on the lowest level recordings, though I do have a couple discs that only need a step or two of attenuation.
Sound: sound out of digital source is pretty dependent on the output stage of the player, most being full of opamps and such.  I just call it clean and clear while others use terms that are somewhat different and are not really like music terms, although clean and clear are not directly musical terms either.
GK-1 sound changes digital source sound ever so slightly with the tube output stage.  I've found that the teflon cap at the input to tube grid has cleaned up things while still preserving the wonders of the tube, and thus makes things about perfect.

I'm happy and pleased with both.  I like the simplicity of direct source in.  And I like the sound of the system with the GK-1.  Different flavors, same wonderful taste!!!

But as with all things audio, it's all just personal preference.


Steve

[AKSA]

Folks,

I've received a knockout review of the Lifeforce 55 as, would you believe, a POEM!!  It's from Alan Oldale, a NZ audiophile with a long background as an accomplished technician.  With Alan's kind permission, here it is:

The Lifeforce amplifier - what can I say
I can listen to the music night and day.
The highs, the middles and the lows,
For all of these the music flows.
Attack, sustain, release, decay
the Lifeforce superbly doth display.
You can safely bet your all
The Lifeforce is quite natural.
It plays music soft and sweet
and can also knock you off your seat.
I must say I'm truly astounded
when with music I'm surrounded.
Also with speakers electrostatic
I am simply left ecstatic.
Though this appears to be absurd
The Lifeforce is the amp I've never heard
So this must be my proclamation
there's no unwanted coloration.

Thank you Alan - I hope on your upcoming visit to Oz we can meet!!

Cheers,

Hugh

[Fredly]

Now that I’ve had the LF modules installed and running for approx 100 hours, I felt somewhat obliged to throw my two cents into this thread.

(Before I begin, let me just state that I’m more of a lurker on the Audio Circle forum (check what’s new every morning) but rarely contribute. However, this amplifier, and Hugh’s prompt and unwavering service & support, warranted me to getting off my lazy butt and write a few paragraphs.)

In a word, the LF modules are…..AMAZING!

IMHO they are in an entirely different league than my beloved N+ 55W.

They are quieter/blacker, more powerful, sustain notes longer, have absolutely “to-die-for” bass and reproduce the entire audio spectrum uncolored and effortlessly.

My modest setup is as follows;

A modded SB3 with DIY power supply.
A pimped-up AKSA TLP preamp
Paradigm Studio reference V2 80’s
and, of course, the AKSA 55W LF amp

This setup is “glued” together with Anti-cable speaker wire and mag wire for all internal hookups and interconnects.
 
My listening “den” in the basement is fairly insulated from any outside noise, allowing me the opportunity to hear subtle changes an upgrade may bring.

What I didn’t want to do in this review was wax poetically about a particular musical passage or how piano notes and acoustic guitars sounded with the LF. Rather, I thought I’d slant the review with a humorous anecdote that happened since moving to the Life Force.

Ever thought you heard the phone or doorbell ringing, or your wife calling you in the middle of a sing? You then quickly turn down the music, run for the nearest phone/door, or bellow up to your wife “Ya, wadda ya want!” Well…. this has happened a stupid amount of times since upgrading to the Life Force.

I’m hearing more phones ringing, wives calling, doors slamming, chairs squeaking and subsonic thumps in my music than every before.

This, of course, is due to the tremendous amount of low level information coming from the Life Force that, frankly, I rarely experienced with the N+ modules.

I’ve gotten somewhat used to it now, but initially, the situation was quite amusing (but not for my wife who was sure I was going mad hearing voices and bells in my head).

Needless to say, with this kind of sonic information coming forward, hearing my favorite cuts is like an entirely new experience. Everything is there. You are in the Studio. She is singing to you. The speakers are gone.

I think Hugh should be very proud of himself. He’s surpassed the N+ sonics, not by a little margin, but by a significant amount, and that my friends is unbelievable.

I’d like to close this review with a few simple statements.

For those of you out there that are considering buying into this solution…..don’t hesitate, I’m confident you’ll have a VERY difficult time finding a better amp, regardless of the price.  (Now that’s a pretty big statement, but one I’m prepared to stand behind).

Hugh, you da man! I’m a VERY thrifty audio consumer, saving for then sending the money took a HUGE leap of faith on my part. You didn’t steer me wrong and the amp is everything I could imagine and more, and for that I will be forever grateful.

Folks, hope you found this review useful, Fred in Canada.

[keithvv]

Well, I finally found the few hours at home with no
other pressing tasks and swapped out my 55N+ for the
newly arrived LF55. I've now had it running for about 30 hrs total.
I am simply stunned by the quality improvement!

I immediately had the impression of enormous bass
enhancement - then as I listened more, I found that
was an incorrect description; it wasn't the quantity
of the bass that changed, it was the "presence" of the
bass. It was absolutely clear that the string bass on
my jazz recordings was now in the room with me, not
just somewhere on the left side of the stage with the
piano and the drums on the right side.
The feeling of improved "presence" - call it the
perception that the instrument was "there, in the
room" applies across the board to all instruments and
vocals.
To me, this is where the LF excels. I found myself
sitting down on several isolated occasions during the
past few days to do "critical" listening so that I
could pass on my impressions to others (I.e.,
potential customers of yours). I found that impossible
to do. Why? Because I kept getting drawn into the
music and the musical performance and forgot that I
was suppposed to be criticising the darn thing!
Perhaps that statement says it all!

For the record, the "current system" consists of:
Meridian G98 source
Mobile Fidelity signature 21 DAC
GK-1 Preamp
Seas Thor Speakers

Before Hugh's amps entered the system, I had used a Proceed BPA-2 followed by a McCormack DNA 0.5 Rev A.

Cheers,
Keith

[AKSA]

Thanks Fred and Keith,

You've both nailed it;  resolution is the principle issue here.  If you improve resolution, the noise floor is lower and you hear more spatial information.  Therefore more of the venue and the instrument noises are exposed, introducing a new dimension you didn't realise was there.  This draws you in, and is different to the excessive detail one hears about which is virtual and electronic in nature, not actually on the recording.

I was very concerned about the loss of euphony when I stepped away from the AKSA, which part emulates the distortion profile of a tube amp.  I knew this would be missed, but realised it could be recovered with the GK1/Swift in the front end.  But I was very surprised at the increase in presence, 'being there' as I described it some time back, and then realised that much of the imaging and musical engagement of high end is, in fact, down to resolution, particularly across the 'dead zone' of a Class AB amplifier.

In this the LF excels, and I'm really grateful that people are listening carefully and hearing the same things!

My thanks to you both for your reviews, you've hit the mark!

Cheers,

Hugh

[PSP]

I have had two LF55s running now for about a month and--lacking time to write a substantive review--I want to at least take a few minutes to get my thoughts down.

By way of background, I'm building Orions (should have music in 2-3 weeks, maybe sooner) and I bought two LF55s to drive the Orion mids and highs.  After I converted my first 55N+ to LifeForce I put that amp in my bedroom system to break in (replacing an AKSA 100N+) while I worked to convert the second 55N+.

That evening I made a really serious mistake... I listened to the LF55 in the bedroom system (Luxman CDP --> TLP(N) --> LF55 --> GR Research Paradox 1 monitors) and fell in love.  In the first 30 seconds of listening to the LF55, with 2 hours of burn-in, I uttered a few silent curses at Hugh as I realized that I would never, never remove that amp from the bedroom system and that someday soon I was going to have to pony-up and buy another LF55 from that incredible Aussie amp-wizard, curse his hide! 

IMO, the LF55 is a discontinuity.  When I first listened to the AKSA 55, it sounded (to me) like an NAD 3020 on steroids... clear, musical, finesse with muscle.  N and N+ upgrades brought more transparency, sweet extended highs, and more authority in the bass.  The LF55 does not improve upon the N and N+, it doesn't seem like "more clarity" or "more transparent", rather it seems like "clarity and transparency in the absolute" while remaining polite and civilized (except of course when it's time to play nasty, then can be very nasty indeed).  Listening to solo cello, for example, I have often heard the growl of agressive bowing on the low notes, enjoyed listening for the bow on the strings.  The LF55 adds the clear woody-resonances of the cello body that I had never heard before.

For my bedroom system, the LF-55 is a total game-changer:  in the past (driven by a 100N+) I enjoyed the bedroom system, now I love it, look forward to listening to it.

In the main system (modded Philips 963SA--> modded GK-1R --> LF55 --> GR-Research Paradox 3) the LF55 is a significant step forward from the 100N+ I formerly used there.  The only caveat is that my main listening room is large and for complex orchestral works at high volume the LF55 can become conjested where the 100N+ would be unfazed.  Of course, I will soon have Orions in that room and there will be few if any power issues.

I am not in a position to compare the LF55 with a long line of high$$ amps because I started the serious phase of my audio journey with the AKSA 55.  All I can say is "I'm a very happy camper" and that the amps were more than worth every penny I paid.

Thanks Hugh, for your incredible design and for the generous trade-in opportunity.

Peter

[AKSA]

Hi Peter,

Thank you for your careful, measured, and precise critique!!  I was reminded of a review in Stereophile many years ago, Jonathan Scull I think, where he kept himself well in check for a couple of paragraphs and then waxed lyrical about the product (dammit, I've even forgotten what it was, a Krell of some sort I think!).  When you spoke of the '...clear, woody resonances of the cello body' you unerringly pinged the 'being there' thang really well, and that, I agree, is what the LF does best.  It draws you into the performance by bringing the performance to you.  Our love of music does the rest....  Managing to extract this performance from the LF after all those false starts (which began in earnest in 2003) has been a very great privilege, no question.  But I can't rest on my laurels because unless you have heard the LF the general trend amongst seasoned technocrats is to criticise it.  The next big challenge is sliding bias, getting a Class AB amp to do Class A tricks;  I've been working on this for five years so far and I reckon I'm about 20%, no more.  It's TOUGH, keeps you focussed.

The AKSA was an attempt to overcome the traditional weaknesses of SS amps by deliberately introducing some tube like distortion - in tiny quantities, I might suggest, around 0.045% at full power - but the Lifeforce is an attempt to produce an amp of such vanishingly low distortion that it completely disappears because it reveals ALL the low level information as well as the usual, high level fare.  This delivers realism.

BTW, I will signal this more clearly later, but the Transmission Line speaker, the VSonic, is almost there.  The speaker was developed in Australia and trialled in Britain - overseas the two developers were James Lewis, a 40 year speaker design consultant with a famous Brit company, now 86 and sadly very ill, and Soren Danner, a senior technician for 25 years with a driver manufacturer in Denmark, now living in the UK.  These two guys each built the speaker to our design and trialled them, and both have remarked it's the best transmission line they have ever heard.  Laurie Menogue has gone to hell and back on the design of the crossover, which has extraordinary performance - phase shift of just 0.01 degrees for the 300 Hz bandpass around the crossover.   He extensively used Xover Pro to assist during development.  Impedance variation, a pet peeve of mine, does not drop below 5.5 ohms, and efficiency is 89dB/watt/metre.  By making it very easy to drive, the sonics are improved!!  Drivers are the XT25G Vifa tweeter to which we add a new, CNC machined Al front plate with Aspen VSonic engraved upon it, and the new 830884 Peerless phase plug 8" Nomex mid-woofer.  And Laurie has just managed to pull the design back to 32 litres with no loss of bass and a significant improvement in image and focus;  the enclosure is just 72cms tall, so it is VERY high on WAF!!

Cheers,

Hugh

[AKSA]

Folks,

New LF55 review from Paolo Bizai in Italy.  Very nice review, thank you Paolo!

"Hi to everyone I'm an Italian Aksa fan, I bought an Aksa 55 some years ago, then I bought a GK1 preamplifier and upgraded my Aksa 55 to Nirvana plus.  I'm always satisfied with Aksa products and now I have bought a Lifeforce 55.

My first impression was:
"This is not an amplifier but a JEWELL", I never believed I would change my AKSA55 N+ but when I listened to the LF55 I changed my mind!

The LF55 is without any doubt the best amplifier I have ever heard, better than Mark Levinson, Audio Research, Audio Analogue (a famous Italian amp) and many others.

With the LF55 Hugh did a great job.

I use the LF55 with the GK1 and I find the sound of this gear very right, I love this sound with CDplayer and with Vinyl too.

When I turned on the LF55 for the first time immediately I exclaimed WOW!!!!

The bass was more extended and deep, mid frequencies were very clean and liquid, and I can listen to every nuance in the music.  But what I like about Aksa products is the live effect and the amazing soundstage - I can touch the musicians, the LF55 can do this so well.
 
Voices are real and natural, highs are very extended without harshness.  This means a lot of air and details.  This amplifier is very neutral, much more so than AKSA55 and I like it more with its perfect match with the GK1 preamplifier.

I can write many words but I cannot explain you how good this amplifier sounds.  I can only say "I'LL NEVER CHANGE MY LF55 FOR THE REST OF MY LIFE!!!!!!!!

.............. ........... ..............................until Hugh releases a new amplifier, anyway!


Ciao Paolo"

[Johnny]

Hugh,

I know I promised you “listening impressions” of the new Life Force 55 amplifier ages ago, but every time I get ready to sit down and write something, a new post comes along, like the last one from Italy, and I just say to myself “what he said!”. Well I'm finally sitting down to do it, so I can pester you about that new loudspeaker system in good conscience 

One thing I don't recall having been mentioned explicitly is that anyone owning a stock AKSA, as I did, just HAS to do this upgrade. N, N+, N+ non-plus-ultra owners seem unanimous in noting improved sonics from the LF. I can attest to the fact that for those of us with modest systems, the results are nothing short of Transformative!

I had a very nice vintage tube amp in my system for about 30 years which I upgraded and modified several times over that period. The rest of my system has remained largely stable for about the last 15 years- PS Audio 5.1 preamp which I run in “straight wire”, ie. passive mode, exclusively; Ruark Templar II speakers, that are remarkably similar to the Aksonics in appearance, driver compliment and I suspect, sonics; JVC XL-Z1050 used as transport to an AckDac! (the latter being the second most significant improvement to the system after the AKSA); analog sources are a homemade turntable (seen in my avitar) fitted with an SAEC tonearm from the 70's and Grado low output MM cartridge and preamp, and a Creek analog FM tuner (very sweet).

While the venerable old tuber was not without some shortcomings, I knew I couldn't live with anything I heard in the ss world, at almost any price- certainly nothing within reach. I went for the original ss AKSA in hopes of obtaining better efficiency (certainly), bass response and transparency, while retaining the best characteristics of my tube amp promised by AKSA. I wasn't disappointed- it was very easy to live with, and more than lived up to expectations. I thought about N upgrades off and on, but couldn't really justify the incremental cost and improvements in my case. When you rolled out the LF, I took a chance once again, with considerable confidence by now, and am absolutely thrilled with the results.

Did I say transformative? Over the years I've tried various diy tweaks on the cheap- cable, interconnects, contact cleaners, buffer amps, etc., etc. Any improvements were subtle at best.

The LF55 changed everything in the first five minutes of play, and of course improved with run in time. Here for the first time were sound stage, wide and deep; tuneful bass; detail without a hint of harshness; and most significant to me, a stunning rendition of musical timbre. I suspect it is the latter trait of the LF that brings the sonic experience of recorded acoustic instruments a quantum leap closer to the live experience.  From a personal point of view, it is especially gratifying to have these qualities finally present in my modest system 

Thank you!

[AKSA]

Hi Johnny,

I'm a little unsure of identity;  are you John N. from Harvard?  Most times I can figure it out, but this one has me beat!!

Thank you for your great review!  I appreciate the candour;  this is seminal stuff and I think you've nailed it.  Musical timbre is resolution;  the high resolution gives proper rendition of tiny signals otherwise lost in the noise floor or non-linearities, and this is traditionally a big problem with emitter follower Class AB amps.  The Lifeforce uses nested feedback, most from the output stage, but some from the voltage amplifier, the second stage, and this gives far superior control over fine detail, resulting in the extreme detail you hear.  What is interesting is that all loudspeakers, pretty much regardless of cost, will respond very favourably to this higher resolution.

The sensation of 'being there' relates directly to this fine detail, because it comes back to spatial details like instrument noises, foot shuffling, soft air movement and furniture noises.  These are all tiny signals, less than 3Vpp, and they define the acoustic space.  This is incredibly important, because it transmits the venue to the listener, and this does something to our perception of the performance.  We think people are in our room with us;  what is amazing is that so many of our CDs and DVDs have this detail on them - we often attribute poor sound to the CDs and this is often proved wrong.  I remember that JBL (??) ad where an audiophile is slumped in a chair, which his hair swept way back, an obvious huge volume pouring from his speakers......  this is a fetching metaphor, but it subtly indicates that true enjoyment is only possible with the volume set high, and in truth this hides the malaise that low volume usually wipes off lots of detail - another traditional amplifier problem.  This was an issue I went after in the LF design brief.

Thank you again, John, great review!

Cheers,

Hugh

[Johnny]

Yup that's me 

[sts9fan]

With reviews like this I am gonna have to give one of these a listen some time.

[LM]

Trouble is, listening starts you on the path to possession.  Most people seem to know within about 30 seconds that they are experiencing something special even if they are not audiophiles (whatever they exactly are).  At her first listen, I remember my wife looking at me and simply smiling – and she doesn’t know one technical term from another.

[AKSA]

......and then begins the drawn out process of delivery, which for modules is quick, granted, but for complete amps, slow.   

I've had people waiting too long, and to them I apologise profusely.  My problem is that I LOVE design with a passion, but am indifferent to construction, which I find tedious and slow, probably because I'm a perfectionist and I try to do it absolutely 100%, which often isn't possible.   

So, when you order, be mindful that the errant nerd is slow to deliver, but that once delivered, it will last you the rest of your days.   

Cheers,

Hugh

[fajimr]

With reviews like this I am gonna have to give one of these a listen some time.

sts9fan,

where are you located?  you know, us aksaphiles are a pretty friendly bunch.  i'm sure someone would let you in for a listen if they are in the vicinity.

jim

[sts9fan]

I live about 5 miles outside of Boston

[AKSA]

Johnny,

Would you be happy to give STS9 a listen - please?

Hugh