tubes 4 hifi
 "the path of least resistance is through a vacuum"



assembled & tested, ready to plug & play

presenting our SP14 preamp as built by Don Sachs . . . .

complete assembled/tested/warranted preamp, built into custom chassis
allow 3-4 weeks build time, these are custom built to order, and there may be a waiting list . . .

For pricing, click here to link to Don's website

Here's what Don has to say about the preamp . . .

This is the finest preamp that I have ever heard!

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, 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.  
The preamp is based  on the SP14 board from Roy Mottram.  Here is a link to Roy?s SP14 page: 

I looked at Roy?s page and decided to build my version because his basic design is absolutely fantastic.   
This is essentially a $3000-$4000+ commercial preamp built for $1600-$1900.  It is a cost no object  design without 
all the ridiculous markup and hype of the high end industry.   I have spent numerous  hours experimenting with parts choices 
based on my many years of experience restoring vintage tube  gear.  I know what parts sound very good in various positions in the circuit.  
This preamp is incredibly  good for a number of reasons.  First, the audio circuit itself is a wonderful, but simple design that has 
a very short signal path and really only one coupling capacitor per channel at the output.  The tubes are  direct coupled.  
The 6SN7 is a fantastic audio tube as noted above.  If you are used to the sound of small tubes you are in for a treat, 
and you most likely will never go back.  Small tubes just aren?t going to cut it  for you! 
Second, the power supply is a fully dual-mono design.  Each channel has its own B+ (high  voltage) and filament supplies.  
This gives amazing stereo separation because each channel is independent.   The B+ power supplies are tube rectified 
(the BEST way to go in a tube preamp, none of that solid-state  hash) which gives a soft-start and simplifies the design 
compared to a solid-state design, and it also  sounds better! Then the B+ is fed to a separate voltage regulator for each channel 
that eliminates all  variation in the supply, and reduces the noise by at least 20db, making for a deep, totally dark background.   
The two filament supplies (one for each channel) use ultra-fast schottky diodes, and then the filament  voltage is regulated 
by a low-noise, low-impedance device that is completely isolated from the audio  signals by floating the 6 volt supply about 70 volts 
above ground so there is no hum whatsoever.  The 6  volt DC regulated filament supplies are driven by completely separate transformer windings 
for each  channel.  In fact there are separate filament and high voltage transformers.  The power supply and  filament supply design gives 
stunning channel separation and the blackest background that I have ever  heard in ANY preamp, tube or SS.
My version uses a wooden case with the tubes on top.  That helps it run very cool and it will be reliable for  many years.  
Plus you can easily swap tubes.  I use full aluminum front and rear panels to allow easy  mounting of controls and jacks, 
and also to keep the signal path parts well separated from the AC.  All  signal cable runs to the jacks are done with 
Teflon insulated mil-spec shielded silver-plated OFC copper  wire.  The front panel controls are wired with mil-spec solid OFC copper 
Teflon insulated wire.  The runs  from the board to the output jacks are done with the really nice Belden shielded OFC copper wire 
we use in  the Citation II amp inputs.  The B+ and filament runs are done with mil-spec stranded OFC copper Teflon  insulated wire.  
This preamp is very quiet and the wire will NEVER become brittle with age.  It is the same  wire I use in all of the Citation II amps.  
All the signal path resistors have been chosen for the best sound.   There are Takman REX carbon film resistors on the grids and cathodes 
and 1% metal film resistors on the  B+ and in the power supply.  It is dead quiet and incredibly dynamic.  
The first B+ filtering before the  regulators is done using film caps, not electrolytic capacitors.  
The few electrolytic caps in the filament supply are all very high quality Nichicon or Panasonic 10,000 hour 105 degree rated capacitors. 
The volume control is a 48 step Khozmo attenuator.  It is built with very low noise resistors and has hard gold plated contacts that the manufacturer
says are good for 50,000 cycles!  I  have used Gold Point attenuators and they sound very good.  The Khozmo sounds just as good, has 48 steps and a wonderful feel.  
I have heard the odd pop or click from a Gold Point  attenuator, and none whatsoever from the Khozmo.  
It is like a continuous volume pot, but  sounds infinitely better.  The individual channel level controls are 21 steps and use the same  
surface mount resistors found in the Gold Point level controls.  The combination allows for  infinite balancing of channels and also lets you 
dial the level of the whole preamp up or down  to match the output of your sources.  Then you use the main volume control.  
It works  beautifully and is sonically transparent compared to a conventional balance pot. The preamp has two sets of output jacks, 
each driven by their own pair of output capacitors.  

If you have a very revealing system and want to hear just how good this preamp can be then consider using a super quality  capacitor on one pair of output jacks.  
My personal favorite is the Mundorf Supreme Silver/Oil cap.  These add $150 to the basic cost.  They easily  make the preamp 10% better.  
I can also build it with a pair of Russian FT-3 teflon capacitors on one set of outputs.  These are very good.  Not  quite as good as the Silver/Oils, 
but they only add $25 to the cost.  However, these are only available in a 0.22 uF value so that pair of jacks will  only be able to drive a power amp 
with a 100K or higher input impedance.  Most every tube power amp around is 100K or higher.  Available are larger caps that will drive the standard IHF 10K load.  

I have sent two units out to customers and these are their comments:
Mark from Sacramento:

          Moment by moment, the sound of this preamp is revealing its magic with absolutely zero detractions.  Among its attributes, 
          I am stunned at the black background on silent passages in music.  It was no bother with the HK Citation 1, 
          but this starts and stops at a black wall of silence.  A SS preamp could not be more quiet. 
          I am connected with these cats in San Francisco:  They have monthly meetings, 
          with shoot-outs comparing cables and all manner of gear.  
          This is a decidedly moneyed-up crowd that might be very keen to hear your preamp and I can make that happen.  
          The task ahead of you is getting the word out and perhaps you can post on their forum you stellar preamp to whet their appetite.   
          I have been in marketing for 30 years and it is one thing to have a great product, but the key is to make folks aware of it.  
          No question, this is a stunning preamp as I hear it more.  I think that like fine preamps, it is ruthlessly revealing.   
          I hasten to add that it is  dead solid quiet!  Much more so than I remember the Citation-I being.  I sure can hear thru the music!  
          I heard the Count Basie Band last  night in a fab venue.  It was almost a life-changing event!  Two hours of incredible big band jazz! 

Bill from Anaheim: 

          It?s been running 24 / 7 mostly since I got back here on Tuesday.  I turned it off one night.  
          All other nights I just turned off the amp and let  the pre cook.  It continues to improve (or my ability to listen to it appropriately improves).  
          The improvement is not subtle. Overall, the system is now presenting with extraordinary fidelity ? breathtaking dynamics and transparency ? 
          combined with a rich and  colorful tone. So easy to listen to and so easy to be drawn into whatever performance is playing.   
          Currently listening to John Williams playing Rodrigo Guitar Concerto ? a 70?s recording well done and well transferred to CD ? 
          and my rip to  a HD and playing back through the Wavelength ? Wow! I?m really glad to have this pre-amp!

send Don email at:

return to SP14 kit page
return to VTA home page

 tubes 4 hifi
 "the path of least resistance is through a vacuum"