I'm glad to say that I've come into possession of a set of these SWTP Tigersaurus monoblocks, the infamous "Frying Tigers."
They're actually pretty good amplifiers that are real sleepers thanks to the fear built around these. Near as I can figure, the Tigers were a bit difficult to build properly and set. Perhaps the legend came about from too many amateurs kit building these units and declaring it a design flaw when they launched into destructive oscillation? I know that two of my Tigers were competently built and had seen over three decades of regular, hard use (on a pair of very inefficient speakers) sitting idle only for about a year before I got them. Even now, they're working great, dead silent but very powerful Maybe my definition is wrong, but that seems pretty reliable to me.
A few weekends back when my neighbors were gone and I had friends over, I made good use of a pair of these monoblocks driving a set of rather inefficient Magnepan Tympani bass panels. It was punishing playback including Telarc canons, yet the Tigers loafed the whole time. Unfortunately, the same could not be said for the amp on my more (~8-9dB more) efficient ribbons -- it became so hot trying to keep up that plastic plugs inside melted before it irreparably died. Wish it were as reliable as the Tigers.
As to the issue of these units catching fire, that is true. Poehland's "Odysey" article looks into this issue when he rebuilds a unit that became a "Tyger burning in the forests of the night." Evidently, the problem is due to a couple of resistors that were undersized in the original circuit (one run twice its ratings) that unsurprisingly have a tendency to toast. Combine this with a bank of bias resistors (putting out a couple dozen watts of heat dissipation) set on the board up tight to other components and things could catch on fire. Granted, he did encounter some issues with burning up transistors, but in Part II he acknowledged that was due to his using inexpensive replacements -- the original type worked just fine. With just the minor upgrades of larger resistors and moving the bias resistors up off the board and these become very good, very underrated amps.
The Tigersaurus is just such an unassuming (ie plain and/or ugly) looking amplifier that doesn't declare its power in big, bold white print on the front or relied on big flashy ads and claims. Yet, when measured by Benjamin Poehland, this 200 watt at 8 ohms, 250 watts at 4 ohms, rated amplifier was putting out 270 watts before clipping with THD+N at 0.04% and exceeded the measuring equipments range at 360 watts at 4 ohms.
Now here's something interesting: Poehland hinted at in his article that some of the 'inventions in circuit topology' of the GAS Ampzilla that came afterwards may have been copied from the Tigersaurus. Here's an excerpt from the Ampzilla website:
Ampzilla was created by world famous designer, James Bongiorno in 1974. At the time, James was the director of engineering at SAE. ... While at SAE, James conceived the concept of the full dual differential full complementary amplifier topology which has since, for the last 27 years, become the defacto world standard road map for virtually all high end power amplifiers made today. Ampzilla was originally designed as a construction project for Popular Electronics Magazine. However, the response was so overwhelming, after the rave reviews, that James left SAE to found "The Great American Sound Co. Inc." (GAS CO.). The rest was history.
I kind of have to wonder when I consider that Dan Meyer's original design and construction article on the Tigersaurus using a full dual differential full complementary amplifier topology was published by
Radio-Electronics in the December 1973 issue and the kit made available then. The Tigersaurus then was just an upsized version of the Tiger .01 (numbered for its 0.01% distortion rating which evidently was a first and lower than the ability of most test equipment then to measure) using a full dual differential full complementary amplifier topology that he had described in the March 1973 issue. Any thoughts on that one? Granted, if true it would not be the first time in audio someone has claimed and gained fame for inventing some design that they ripped off from someone else. I do wonder.
At any rate, it is definitely an amp worth looking into. The Tigersaurus is probably one of the first true high current, low distortion designs to come about and uses a circuit topology that is found in TOTL units today with just a bit of refinement.
Pictures shortly soon as I reduce them in size (forgot about the limitations).
- JP
Edit:
How about some pictures? The transformers are a modest 29lbs, which I suppose is sufficient to have two in a stereo pair of modestly rated monoblocks from the early '70s.
