somebody had to do it, might as well be me!
introducing the super performance SP14 preamplifier . . .
January 10, 2012
I am very proud to present my best ever preamp, the SP14
photos and more info posted here
Let me start with an introduction to this product. This is a major upgrade with many refinements to my previous best SP12 preamp.
This preamp is NOT intended for the casual listener. This preamp is for those who are NOT satisfied with a $3000 preamplifier.
This preamp IS intended for those DIY builders who may have already experienced my SP12, or who want the best preamplifier kit available at any price.
This preamp IS intended for those who want a $6000 preamp but who can't afford that. This preamp built as a kit will total under $1000,
or I can supply it custom built and ready to use.
Strong statements? YES! Do I stand behind them? YES!
I have been building, testing, evaluating, and designing tube preamps for nearly 25 years. Up until last year, my products were aimed at the DIY builder on a budget.
But my customers have been graduating from budget projects, and my better products have been attracting the attention of non-builders who want a super preamp at a super price.
So I decided it was finally time to design a cost-no-object preamp. As a lifelong audiophile and electronic design engineer, I have listened to and evaluated MANY high-end products,
and I can tell you from the inside view that a typical $3000 preamp has about $300 worth of parts inside a $300 chassis. The rest is all mark-up and profit, to pay for expensive
manufacturing engineers and production lines, massive marketing and advertising expenses, reserves for spare parts, and reserves for warranty work.
Let's get to a description of what makes this a great sounding product. First, start with a great but simple circuit design that has been proven (my SP12 product).
Now let's graduate to the bigger octal tubes, that were popular at the peak of tube audio back in the 1950s and 60s. The small common 12AU7 tube used in the SP12
was derived from the 6SN7 octal tube. Tube fanatics that have been around for more than 10 years, or even better, the ones who were around in the 1950s, know that the
6SN7 is a much better sounding tube than the 12AU7. And because they are no longer as popular as they were 30-40 years ago, their prices are very reasonable for the higher quality tubes.
Next, the basic power supply of the SP12 is replaced with a fully dual-mono design. Each channel has it's own B+ and it's own filament supply. This gives better separation between channels
and lessens the load and interdependence. The B+ power supplies are tube rectified (the ONLY 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 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.
Finally, since we aren't worried about high-priced parts, the important signal output coupling caps are chosen by the user.
On this first build I've added a pair of Russian military surplus K40Y PIO capacitors, which are relatively inexpensive for their performance,
along with my standard issue SoniCaps, similar to AuriCaps.
Another capacitor for the next comparison will be Mundorf Silver-Oil PIO capacitors.
OK class, let's get on with it!!
The build is here
pay attention, take notes, and do it right. No questions please until this build is finished!
Last edited by tubes4hifi on Sun Jan 22, 2012 12:59 am; edited 1 time in total