WARNING: Any audiophile who has no self-control over his or her audio spending (unless you’re very wealthy) should not read this review!
“A Really, really (really!) High End Company”
As you can guess from the opening sentence of this review, Ypsilon components are expensive - $36,000 for the PST 100 MK2, the subject of this review. As you can also guess from that paragraph, they are really, really good. How good, and how does it compare? So good that I won’t be spending a lot of time splitting hairs. The Ypsilon PST 100’s strengths are so obvious that I can get right to the point and hope my editor doesn’t think that I need to make this review more detailed. (We’ll see. –Ed.)
The maker of this fantabulous (fantastic + fabulous) preamp is a Greek company named Ypsilon. I’ll need to ask them how and why they chose that name. Perhaps it’s linguistic. Wikipedia indicates that upsilon (uppercase Υ, lowercase υ; Greek: Ύψιλον) is the 20th letter of the Greek alphabet. In addition, in the system of Greek numerals it has a value of 400. In early Greek, it was pronounced like oo. In Classical Greek, it was pronounced like French u or German ü — a sound that is not found in most dialects of English. In Modern Greek it is pronounced like continental i or English ee.
On the other hand, maybe it’s scientific. Also according to Wikipedia, the Upsilon meson
(ϒ) is a flavorless meson formed from a bottom quark and its antiparticle. It was discovered by the E288 collaboration, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered because it is the lightest that can be produced without additional massive particles. It has a lifetime of 1.21×10−20 seconds and a mass about 10 GeV. I knew you’d want to know.
What I do know is that Ypsilon has built quite a reputation in other parts of the world and has retained Brian Ackerman’s Aaudio Imports as its US distributor. Brian has done an amazing job in finding fabulous audiophile gear and bringing it to the US, so when he said he had found a great preamp, I love to listen. In our July Issue, Constantine Soo reviewed the Ypsilon SET 100
monoblock amps, and this month I have the privilege of writing about the matching,Ypsilon PST-100 MK2 preamp.
The Design
I almost said “who cares?” to this section. The Ypsilon PST 100 MK2’s design defies categorization. Oh yes – it seems simple. It’s a tube preamp using two Siemens C3m triode tubes. However, the preamplifier requires that you forget most of what you know about how preamps sound. As Ypsilon’s website states:
“Conventional wisdom suggests that the most critical part of a preamplifier is the active circuit design. Ypsilon, however, believe that the means of signal attenuation (the volume control) is the most critical to the overall sound of a preamplifier.”
Ypsilon believes that even the best resistor-based volume controls are too noisy to achieve the best sound, which they define as the sound of live performances. They prefer transformer-based volume controls:
“In a transformer, however, the magnetic circuit can be ultra linear when the very best core materials are used. The sound of such materials is much more musical and detailed compared with the best resistors. So Ypsilon produced, in-house, a special transformer attenuator with 31 taps.” The following is table of the volume attenuation levels in both active and passive modes:
for passive mode
up to " 5 " 3db
up to "10" 2db
up to "28" 1.5db
up to "31" 1db
for active mode
up to "11" 3db
up to "16" 2db
up to "34" 1.5db
up to "37" 1db
Ypsilon also believes very strongly in single-ended design, and has incorporated such design in its power products.
“The active gain stage is a no–feedback S.E. triode, transformer coupled. The power supply uses valve rectification and choke regulation. Wiring is made with custom made pure silver wire. The transformer attenuator is placed after the valve stage, preserving the purity and micro details of the signal.”
The use of a single-ended design is interesting not only from a design standpoint, but also from a “feature” standpoint. As you will note from the picture at the beginning of this article, the PST 100 MK2 sports one XLR input and one XLR output in addition to its single-ended inputs and one single-ended output. These XLR connections are not balanced. If you want balanced operation you need to get Ypsilon’s BC1 Transformers for the output. Fully balanced operation with the BC1’s adds $3600 per pair, not to mention the cost of another pair of cables. BC1’s are great products in their own right, adding isolation which results in lowering the noise floor and letting through even more natural-sounding detail. I hope to do a separate review in the next few weeks.
The tubes used in the PST 100 MK2 are Siemens C3m, obtainable for $20 each. Ypsilon claims that the PST 100’s tubes should be good for up to 15 years or 10,000 hours of operation. This is totally contrary to my prior but admittedly dated experience with tube preamps, where expensive tubes were necessary to get the best sound, and where I seemed to be replacing a tube every several months. Maybe I’m exaggerating a bit, but it sure felt that way when a tube went bad during a Saturday listening session and I had no replacement on hand. In my book, this ability to operate on the same set of tubes for an extended time is a substantial benefit.
