I love the 70s
No, I’m not referring to the CD compilation of hit songs from the 1970s. This piece, in part, is about how the analog renaissance has placed tube audio gadgets on a pedestal to be virtually worshipped as the “holy grail” of listening pleasure, and the rave created by GM70 vacuum tubes among DIYers worldwide.
Sound amplification using vacuum tubes may be a “geriatric” approach in this day and age where everything can be had at the push of a button. But discerning audio designers — prompted by increasing demand from “re-born” audiophiles — have belatedly discovered that they had barely scraped the surface of a technology whose first practical application was made possible by John Ambrose Fleming in 1904 (known then as the “Fleming Valve”).
After the technology’s glory years in the 1950s to 1970s and at the advent of solid state sound gadgets, only a handful of tube factories were left to cater to “audiophile snobs” who refused to acknowledge the changing landscape of high-fidelity audio. But thanks to these “hard-headed” guys who had banded together, an underground movement which became the driving force of the so-called analog renaissance was formed. Together, they pushed some dedicated audio designers to take a second look at the technology. True enough; new topologies soon began spouting, making full use of the tubes’ previously untapped potential: more power with less distortion.
Today, the once “lowly” tubes enjoy rock-star status. Ironically, the older among those produced during their heyday (new old stock of NOS) command hefty dollar prices, with some outrageously priced at more than $1,000 a piece. In my book, some excellently produced ones did not actually age at all. Once put into good use, I can personally attest that they bring out that same seductively beautiful sonic in music.
The GM70 are super triode tubes which have been around and used by refutable audio companies such as Lamm Industries, deHavilland Electric Amplifier Technology in their respective amplifier products. They are Russian-made transmitter tubes similar to the likes of the pricey 845s, 211s and 811A made by the pedigreed brands from the West, among them, General Electric, Western Electric, Mullard and Philips. The difference, according to DIYers, is that the relatively cheap GM70 has a fairly large heater requirement of 60 watts 20 volts at three amperes. Just turn on the heater, and the whole tube glows hotter than the standard. Never mind the technical gobbledygook; what this means is that GM70 is much easier to drive than an 845, thus making it easier to pair with any driver tubes. The result is dynamic yet soulful sonic presentation with the quietest of operations when properly designed.
Amps currently in production using these tubes are like the flea next to mid-power mould with amplification capability ranging from 18 to a maximum of 50 watts. The first to break this norm is the country’s Trodt Audio. Rodrigo Tiope or “Mang Rod” to audiophiles — one of the country’s foremost audio designers whose Trodt product lines have become legendary — recently came up with a GM70 monoblock amplifier (single-ended parallel) design carrying a punchy 70 watts per channel. The amplifiers have components of two GM70 output, two 6S4A driver and one 12au7 input tubes per channel. They each have a separate monstrous power supply weighing no less than 40 pounds each. Not surprisingly, Mang Rod is keeping most of the technical details close to his chest. His latest creation is, after all, an original masterpiece — a design which took him weeks of sleepless nights to conceive and months of soldering to concretize.
You can just imagine what these 70-watt behemoths are sonically capable of. If a GM70 18 watt amp could have ample power to drive even low-efficiency speakers (which are hard to drive) such as electrostatic and full-range speakers, what more with an amplifier four times its power?
Trodt GM70 is heaven-sent to audiophiles who have hard-to-drive speakers. The amp would preserve the soothing sonic of SET, while adding muscle in reproducing lifelike dynamics swings in some passages of your favorite music. Since the tubes’ character is similar to that of an 845, one can consequently expect a detailed presentation with a sense of fluidity and splendor. Some high power and expensive amps, from where I sit, get low marks when it comes to music presentation. Mang Rod definitely outdid himself in this new product offering. Trodt GM70 is definitely musically abundant and never mechanical in interpreting music.
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For comments or questions, please e-mail me at audioglow@yahoo.com or at vphl@hotmail.com. You can also visit www.wiredstate.com or you can tweet audiofiler at www.twitter.com for quick answers to your audio concerns.
