RSA F-35 The Lightning Review
Jul 17, 2013 at 5:21 PM Thread Starter Post #1 of 40
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What’s that?  You’d like a review of the smallest fully balanced portable amp in the world?  Why I’d be happy to, here you are my friend.
 
 

 
 
But before the write up, I must offer special thanks to Ray Samuals for asking me to review his latest amp.   Ray has been a strong leader, supporter, and innovator in the world of portable headphone amps, and his latest entry pushes yet another envelope.
 
So…  Why another balanced amp you might say?  Doesn’t Ray already make two other balanced amps?  Yes he does, but this one is different, and is aimed at a specific listener, with specific headphones.  more on this later.
 
The Amp:
The F-35 Lightning is indeed the smallest fully balanced portable amp in the world to this date, to this writers knowledge.  It measures about 4.5cm wide, 2cm deep, and 9.5cm long (volume knob included).  I honestly don’t see how an amp like this could get any smaller.  Every inch of real estate is used for the plugs and switches. 
 
 

 

 
 
The amp has the typical rock solid construction and feel of all RSA amps.  All casing is metal including the volume control, and all switches feel solid.  4 screws on each end hold everything together and are nicely flush with the rest of the case.  As with all RSA amps, the power swich is backlit with a red LED when it is on.  When the battery starts to lose power, you can see the power switch fade as well.  I don’t know why, but I like that.  There have been times when I hear the sound breaking up on my RSA hornet and think to myself “damn this recording sucks”.  I then look down at the amp, and the power switch is a pale red, showing me that my recording doesn’t suck, but I am in dire need of a charge.  Anyway, moving on. 
 
On the back of the amp you have the DC input (used to charge the rechargeable battery), a balanced input plug, single end input plug, and an input selector switch.  As on Rays other balanced amps, you have the option of inputting the signal with a balanced or single ended plug.  This means that you can use a portable player with a simple LOD, or your $25K balanced cd source, both signals will be delivered to the headphones fully balanced.  In Ray’s words, “The lightning, has phase split circuitry that converts a single input signal, fed to the SE input, to a balanced signal”.
 
 

 
 

 
On the front of the amp you find the volume control, power switch, balanced output plug, and separate gain controls for the left and right channels. The power switch can not be easily toggled while the headphone plug is in.  You must unplug your phones to turn on/off the amp.  So did you notice anything?  What is missing here?  That’s right, there is NO single ended 3.5 output.  You either go balanced, or go home.  This amp is for those people who run their cans balanced, and want nothing to do with the inferior single ended world. 
 
 

 
 

 
Usability:
I made mention of using specific cans.  I spoke a great deal with Ray while I was testing the amp in different scenarios.  As this amp is a prototype, there were no instructions or specs to refer to.  I had very little idea what kind of power I was looking at, or what I could expect as far as drivability.  After some experimentation and consultation with Ray, I have confirmed the following. This amp is designed for low impedance headphones like the LCD 2, LCD 3, HE-500s, Grados, Denons, most IEMs, etc. The Lightning is not however designed to drive the HE-6.  If you want a portable amp for that beast, look to the RSA Intruder.  The Lightening can drive the higher impedance cans like the HD600/650/800 to respectable volume levels, but as it is not designed for that, it is not the best match.  I do wish I would have had some balanced IEMs, Denons, or Grados to try with the amp, as I am curious as to how they would perform.  Maybe I will be able to update with that info at a later date.  The majority of my listening was with the LCD-3 and HE-500’s. 
 
Gain:
The gain switch has 3 levels.  As per his website, the gain is 3, 6, and 21.  The low gain is used for sensitive IEM’s.  The middle gain is used when a strong signal is fed to the amp.  A good example of this would be the balanced out of a CD player or other full powered source.  The high gain is used when a lower power source like an iPod is feeding the amp.  Helpful if you are driving something like the HE-500.  This is all relative of course because it has a lot to do with how loud you listen to your music.  I found the middle gain fine when using my ipod as a source.  I just needed to turn up the volume pot a bit more.
 
And now the most important thing…
 
Sound/Performance:
For anyone not familiar with RSA portable amps, they consistently deliver full and powerful sound, with a ridiculously small footprint.  The lightening does not disappoint here.  The sound is rich and full throughout the spectrum.  Bass is delivered with authority, and the mids and highs are clear and smooth.  When listening to the LCD 3, well known for its bass performance, I got the sense that not only was the bass quantity and quality excellent, but that it was well supported.  Sometimes you hear an amp that has great attack on the bass notes, but seem to lose steam on the sustained portion.  Not so with the Lightening.  Bass notes ring the way they should.  Not emphasized, just delivered.
 
Highs and mids are equally represented with effortless support.  Listening to a nice acoustic guitar/vocal recording reveals a beautifully smooth grain and honk free tone, with a nice sense of space.  Soundstage is quite good.  Recordings that put some effort into creating a sense of air and distance around the listener come across with good multi layer presentation.  I believe the headphones to be the only limit on air and space here.  The amp will deliver what you feed it.
 
Source:
The quality of your listening experience is defined by the quality of your source.  The better your source, the better the sound.  It really is as simple as that.  People often ask where they should put the bulk of their money when building a system.  Your source should always be the answer to that question.  As such, the Lightening will of course sound better with your $25K balanced cd player then your gen1 ipod.  But then again, you can’t take your cd player on the train.  But there are those who might choose to use their portable amps for everything, so it is important to experiment with all sources.
 
I did spend a lot of time using the lightening with two different balanced cd players (listed below).  Besides the difference in sound signatures, both did an excellent job and delivered superior sound.  I could be very happy running the Lightening as my home amp.  Are there desktop HP amps that would sound better?  Very likely; But that would be another investment, and a fairly major one to surpass what the Lightening can deliver.
 
But the Lightening is a portable amp.  It wants to be taken outside, to be part of the world, to let the sun shine upon its face.  So that leaves us with portable sources, and while there are many, most people use either an Apple or Microsoft product.  My listening was done with the 160gb ipod classic with lossless files.
 
So how did it perform?  I did indeed need to turn up the volume a bit more to make up for the lower power input signal, but I’ll tell you, it sounds great.  The technology involved in converting the single ended signal to balanced works like a charm.  In comparison to the balanced cd players, there is a lot less difference then you would expect.  You have to consider of course the superiority of the DAC’s in the cd players, but that little ipod is representing quite nicely.  As a further test, I hooked up my ipod to my Pure i-20, and ran that into the Lightening.  Much better sound as expected by the nicer DAC.  So, long story short, Lightening performance with an ipod is very good at delivering a solid balanced sound.  About as good as you can expect from an ipod.  This is a pairing I foresee using a lot.
 
Final thoughts:
As the latest edition to the RSA portable lineup, the Lightening holds its spot firmly as another great performer.   In an industry where the advantages of balanced configurations are becoming more evident and popular, Ray leads the way with the smallest one on the market.  It performs extremely well with a portable source, and exceedingly well with a high quality desktop cd player or DAC.  I’m not sure how much more you could want.
 
If balanced is your game, the Lightening should be on your short list. 
 
 
Equipment used:
Audeze LCD-3 – Stock cable fitted with balance connector
Hifiman HE-500 – Moon Audio Silver Dragon balanced cable
Sennheiser HD-600 – Equinox HD600/580 balanced cable
 
Meridian 508 CD player balanced out
Emotiva ERC2 CD player balanced out
160gb Ipod Classic lossless files – Whiplash Audio LOD
 
SE Comparison amps:
Bottlehead Crack
RSA Hornet
Grant Fidelity TubeDac-11
 
Jul 18, 2013 at 11:03 AM Post #3 of 40
Quote:
Great review mate. I have a question though, I am kinda newbie on these things. So is there a difference in sound when you use the SE input or Balanced input?

Maybe a newbie, but that is an excellent question, and one that I was struggling with as well.  I struggled, because to test this properly, I needed to have the same quality cable going from the source outputs, which I did not.  I was using an xlr to balanced plug made by Ray, and all I had was a cheap stereo out to 3.5 plug to use as the single ended input.  The other problem was that the balanced out on the source is much more powerful then the rca, so there was a marked difference in volume when switching back and fourth.
 
having said all that, I will say that I preferred the balanced input in comparison.  I thought the sound had a bit more definition and separation by a margin.  But, I must repeat that the cable I used as the single end input was crap.  I will speak with Ray and see if he can offer any other insight.  I have to call him anyway.
 
Jul 18, 2013 at 11:50 AM Post #4 of 40
Okay mate, I take your answer like, even if used with SE input, it will sound excellent, maybe slightly lower than excellent.
 
So, this little item is def. in my list. Gotta check it later on when I save up some money again.
 
Jul 18, 2013 at 1:16 PM Post #6 of 40
Well, I am just about to purchase a high end ciem (if my ears are big enough to build it), so anyway I have a lot of time in front of me to save for it. I hope The Lightning won't be a wallet crusher.
 
Jul 19, 2013 at 5:06 PM Post #7 of 40
....want nothing to do with the inferior single ended world.....
 
Great review except for the line above.  IMO, that's a little harsh and exaggerated according to my long time background/experience in pro audio equipment and recording.
Balanced signals are always good and tend to be cleaner if you're affected by unclean power source and other types of interference... A well-designed amp should not have any problem terminating in SE and still have stellar performance, thus many high end HP amps still only have SE output.  Just my opinion.
 
Jul 19, 2013 at 6:12 PM Post #8 of 40
Quote:
....want nothing to do with the inferior single ended world.....
 
Great review except for the line above.  IMO, that's a little harsh and exaggerated according to my long time background/experience in pro audio equipment and recording.
Balanced signals are always good and tend to be cleaner if you're affected by unclean power source and other types of interference... A well-designed amp should not have any problem terminating in SE and still have stellar performance, thus many high end HP amps still only have SE output.  Just my opinion.

well, that line was mostly an attempt at irony and humor.  if you include the beginning of the sentence, you see that I am talking about the thoughts of this imagined individual who is committed to balanced cables.  But, having said that, I do not disagree with you.  I love my SE amps, and agree that they can, and do produce exceptional sound.  No disagreement there.  But I do believe that given two setups, where the only difference is balanced vs SE, the balanced configuration should sound better if care was taken in its implementation.  All IMHO of course.  most of my amps are single ended and wonderful.
 
I do wonder though what my bottle head crack would sound like if it was set up in a balanced configuration.  lol.. but thats crazy.
 
Jul 19, 2013 at 6:35 PM Post #9 of 40
Quote:
well, that line was mostly an attempt at irony and humor.  if you include the beginning of the sentence, you see that I am talking about the thoughts of this imagined individual who is committed to balanced cables.  But, having said that, I do not disagree with you.  I love my SE amps, and agree that they can, and do produce exceptional sound.  No disagreement there.  But I do believe that given two setups, where the only difference is balanced vs SE, the balanced configuration should sound better if care was taken in its implementation.  All IMHO of course.  most of my amps are single ended and wonderful.
 
I do wonder though what my bottle head crack would sound like if it was set up in a balanced configuration.  lol.. but thats crazy.


agree +100.
 
Jul 20, 2013 at 7:48 AM Post #12 of 40
intruder is the usual amp but powerfull, this one seems to be more current oriented than voltage. so ideal for low impedance, current hungry cans/iem.
 
at least that's what i understand from the different feedbacks, and i would love Ray himself to give us some intels.
 
 
Jul 20, 2013 at 9:19 AM Post #13 of 40
I also think this could be more ideal for lower impedance cans. But it seems also capable of driving heavyweight too. My intruder is definitely a power monster though.
 

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