SP14 Preamp Listening Impressions
Quite simply the finest preamp I have ever heard!
Warning. This is not an unbiased review! I have started building my version of Roy Mottram’s SP14 preamp for sale because I was so impressed by the first one I built.
I first discovered the SP14 when looking at Roy’s site for parts to restore a vintage Dynaco preamp for a customer. He eventually decided to abandon the project,
but I was intrigued by the design of the SP14 board. I finally decided to build one for myself because I really wanted to hear one. Good move on my part!
This is the first preamp I have ever heard that I thought was every bit as good a piece of gear as a fully restored Citation II amplifier.
Really, like the Citation II, this preamp is so good that it is scary. It is based on the 6SN7 tube, which has always been one of my favorites.
The bigger octal tubes like the 6SN7 have a much more relaxed, fuller, and richer sound than the smaller tubes like the 12AX7, 12AU7 or 12AT7 tubes
used in many other preamps. You get all of the detail with no brightness. I have now built four of them and have spent three months tweaking the parts choices
used in construction. The first one that I built was very good and easily the best preamp I had ever heard, and I am a pretty tough crowd.
I have spent the last 6 years restoring vintage tube gear for a major portion of my living. I am Jim McShane’s authorized tech/installer for all of the
Harman Kardon Citation upgrade and restoration kits. I also restore a lot of other tube gear by Scott, Fisher, Sherwood, Mac, Eico, you name it.
I have heard a lot of preamps. I have completely rebuilt Citation I and Mac C20 preamps with very good parts and Gold Point stepped attenuators.
I have worked on a number of more modern preamps, many of which I thought were very good. All of these are good enough that if you had any of them
in your system you could live happily ever after. The SP14 will absolutely embarrass any of them. Really. I am not easily impressed.
While I don’t have a super expensive system, it is very revealing. The speakers are Joseph Audio RM25XL, the power amp is a completely rebuilt
Harman Kardon Citation II with every McShane kit and a number or experimental tweaks. The source is a Schiit Gungnir DAC with balanced and single ended outputs,
fed by my Windows laptop and JRiver Music Center. I play full resolution red book cd files and some hi-res files. This is not a $50,000 system, but each of these
components is of very high quality. The speakers are very neutral and revealing, and the Citation II is the finest amplifier I have ever heard.
There are other great amplifiers in the world as well, but few are better. The Schiit Gungnir will run with DACs costing two or three times it’s $849 price.
I added a pair of XLR inputs to the SP14 using Cinemag line transformers for the conversion to single ended inside the preamp so that I could use the XLR outputs
on the DAC.
So how does the SP14 sound in this system..? I have listened to the SP14 for a few months and I build them with very good parts.
I use a Khozmo 48 step attenuator, Takman carbon film resistors on grids and cathodes, really good metal film resistors on the plates and the output caps are excellent.
I use a large film cap for the first power supply filter after the rectifier tube and very good quality electrolytic caps elsewhere.
I have spent the most time listening to the Russian FT-3 teflon capacitors and most recently to the absolutely stunning Mundorf Supreme Silver Oil caps as the output capacitors. I have never heard a stock SP14 built with the standard kit parts, but I am sure it is really good. The one I am listening to has 32 uF of film caps
as the first power supply filter cap, the silver oil caps on the outputs and all of the other parts listed above. It also has a very good 10 gauge power cord.
So it is not the stock SP14 and I have never heard one built with “normal parts”. I can say that if you build one – or I build you one with the really top notch parts,
you will be stunned by how it sounds within the first 10 minutes before the tubes even warm up fully. I have spent quite a bit of time listening to a fully restored
Citation I preamp with a Gold Point attenuator and Russian KBG oil caps on the main line stage tubes in the same system. Also a SpaceTech Labs 6SN7-based
custom tube preamp with a full tube power supply. Both of these are fine units. I have used a couple of completely rebuilt Mac C20 preamps that I was running in
before returning them to customers. The Citation I is more ruthlessly accurate, the SpaceTech a bit sweeter, the Mac is in the middle, but all three deliver
amazing musicality and detail, and are completely involving.
When I replace them with the SP14 I hear considerably more detail without any hint of brightness. With any of these preamps it is the kind of detail where
if the recording engineer in the control room dropped his pencil you hear it. Except with the SP14 you can tell which side of the chair it fell on, and that it was
a #2 pencil, and the eraser hit the floor first. Seriously, the differences you hear are not subtle. Where before you could tell that there was a little triangle in
the percussion section over on the right, with the SP14 you know that triangle is waist high and you can more fully hear the decay as it fades away.
When you listen to a stand-up bass you can really hear the slap of the fingers on the strings. It is easy to listen to different sections of the orchestra.
Of course the individual vocalists in a choir or a group of background singers are easily discerned, much more so with the SP14.
Try listening to the old CSNY recording of “Helplessly Hoping” on your stereo. You can sort of hear where all of them are in the sound stage.
With the SP14 I can tell exactly where they are and how far away each one is. I am currently listening to Glen Gould’s second recording of the Bach Goldberg Variations.
This is a very fine piano recording to say the least. I have listened to it for years and am very familiar with it. I am sitting 30 feet away from the speakers in the kitchen
as I type this. I have never been able to focus on the left and right hand parts so easily, even from this distance. Gould was a fantastic pianist, but as most of you know,
he was quite the eccentric genius. He drove the recording engineers crazy because he hummed when he played certain parts. With every other preamp I could hear
the faint humming in the background. With my version of the SP14 I can hear the humming more distinctly, even from 30 feet away. It is not unpleasant.
Sort of like a third part along with the two hands. The sound of the piano is astonishingly real.
To sum up, I guess the thing that is most striking about the SP14 is the level of detail and the realism of the voices and instruments. If you need rock and roll slam
it can easily do that. If want subtlety with jazz brush strokes on the cymbals, no problem. You want to hear the resonance in an acoustic instrument? Easy.
With other great preamps there is just a bit of haze around everything. I never realized that until I heard this preamp. With my tweaked SP14 all of the voices
and instruments are more clearly and distinctly presented, but they are not bright at all. It is incredibly musical. I keep coming back to the Citation II comparison
because that is the hallmark of that amplifier. You hear everything in amazing clarity, but with no trace of brightness. The dynamic range of this system is astonishing,
with the blackest background I have ever heard in all my years of restoring, building and tweaking tube equipment. I once read a review where the author stated that
he was listening to a Diana Krall recording and the system was so good that he could imagine that she was smiling when she sang a certain lyric.
I thought that was nonsense when I read it. With the SP14 in the system I think I know what he meant now. Vocals are just stunningly clear.
It certainly makes me smile whenever I listen to this system
link to Don Sachs consulting website . . . http://www.dsachsconsulting.com/sp14%20review.html
another link to Don Sachs website . . . . http://www.dsachsconsulting.com/custom%20line%20stage.html