"Ben Duncan "
I think you mean Ben Poehland.
I have both his two-part article, and Walt Jung's brief review.
The amps in question were a basket case as received, some of the wiring harness actually had been on fire. Remarks made during de-construction indicate the units had severe problems as originally built.
Ben did what was IMO a less than perfect job, and mixed different brands and even used different part numbers for outputs.
The author had a bit of a problem after re-build as he was driving 40Khz at full power and mentioned that it put out 363W (it's rated at 250W).
The author also admits to accidentally shorting the output to ground, and then trying to drive it to full power. The Pecor outputs blew up, the Motorolas did not.
The author continues driving into clipping at 20Khz~40Khz and observes commom-mode conduction (I wonder why), and even drives it as high as 90Khz at high power.
The author concludes "The Beasts performed like docile workhorses, really belting out the power without harm either to themselves or to the rest of my system components"
"As regards noise, Tigersaurus is the quietest amp I've ever owned."
"Bass response is deep, tight, and controlled to almost a
Spartan degree, without the low-end "bloom"....Tigersaurus comes across as the warmer, sweeter amp. Tigersaurus posses the leaner bass response but still delivers more warmth and overall musicality."
"I can summarize my listening evaluation simply: Tigersaurus is the overall best-sounding amp I've ever owned. I have hear other amps that do sound better, but not by much, and at prices I can't afford."
The author in conclusion states "Tigersaurus should never have been sold as a kit."
Despite having built various SWTPC products for people I know (and getting paid the princely sum of $5 per Tiger for doing so) and always having them work, I might have to agree with him as it seems everyone else has too many problems with SWTPC product in general.
I think you mean Ben Poehland.
I have both his two-part article, and Walt Jung's brief review.
The amps in question were a basket case as received, some of the wiring harness actually had been on fire. Remarks made during de-construction indicate the units had severe problems as originally built.
Ben did what was IMO a less than perfect job, and mixed different brands and even used different part numbers for outputs.
The author had a bit of a problem after re-build as he was driving 40Khz at full power and mentioned that it put out 363W (it's rated at 250W).
The author also admits to accidentally shorting the output to ground, and then trying to drive it to full power. The Pecor outputs blew up, the Motorolas did not.
The author continues driving into clipping at 20Khz~40Khz and observes commom-mode conduction (I wonder why), and even drives it as high as 90Khz at high power.
The author concludes "The Beasts performed like docile workhorses, really belting out the power without harm either to themselves or to the rest of my system components"
"As regards noise, Tigersaurus is the quietest amp I've ever owned."
"Bass response is deep, tight, and controlled to almost a
Spartan degree, without the low-end "bloom"....Tigersaurus comes across as the warmer, sweeter amp. Tigersaurus posses the leaner bass response but still delivers more warmth and overall musicality."
"I can summarize my listening evaluation simply: Tigersaurus is the overall best-sounding amp I've ever owned. I have hear other amps that do sound better, but not by much, and at prices I can't afford."
The author in conclusion states "Tigersaurus should never have been sold as a kit."
Despite having built various SWTPC products for people I know (and getting paid the princely sum of $5 per Tiger for doing so) and always having them work, I might have to agree with him as it seems everyone else has too many problems with SWTPC product in general.
Tiger vs T-Saurus
My recollection is that the SWTPC stuff was offered both as a kit and as assembled versions, depending on model, and what year it was.
Dan Meyer was way ahead in terms of applying these circuits to consumer audio - there are those who say that industry/military applications of this full complementary type of solid state circuit predate the Tiger and others by a decade or more. I can't say, I don't know.
Since I never had hands on a Tigersaurus, I don't know if it was stable or not. The others were not at all. Some of them seemingly refused to be tamed. The articles in Audio Amateur, imho did not offer means to prevent the "magic smoke" from coming out of the amps...
I have both a Tiger and Tiger 01 here - both have let the magic smoke out, despite some efforts to tame the instability. I think the inherent layout & ground scheme is one issue - short of ripping everything out and making a new amp, that's hard to change.
I think I now have the glint of an idea on how to prevent the thang from frying so quickly - but until I find the extra time to try it on the actual circuit, it's just an idea for now...
Back in the day, these amps were very exciting since they offered incredible power for not much money, and back then they looked huge!
He also offered preamp boards, and a preamp based on the same basic topology... I still have mine back in the storage area...
_-_-bear
My recollection is that the SWTPC stuff was offered both as a kit and as assembled versions, depending on model, and what year it was.
Dan Meyer was way ahead in terms of applying these circuits to consumer audio - there are those who say that industry/military applications of this full complementary type of solid state circuit predate the Tiger and others by a decade or more. I can't say, I don't know.
Since I never had hands on a Tigersaurus, I don't know if it was stable or not. The others were not at all. Some of them seemingly refused to be tamed. The articles in Audio Amateur, imho did not offer means to prevent the "magic smoke" from coming out of the amps...
I have both a Tiger and Tiger 01 here - both have let the magic smoke out, despite some efforts to tame the instability. I think the inherent layout & ground scheme is one issue - short of ripping everything out and making a new amp, that's hard to change.
I think I now have the glint of an idea on how to prevent the thang from frying so quickly - but until I find the extra time to try it on the actual circuit, it's just an idea for now...
Back in the day, these amps were very exciting since they offered incredible power for not much money, and back then they looked huge!
He also offered preamp boards, and a preamp based on the same basic topology... I still have mine back in the storage area...
_-_-bear
I only spoke to Dan Meyer once, in 1974, but I did read his articles. He did say at the time, that he gave JB the comp differential input stage and JB ran off with it. I had the same problem in 1972, when I gave BS in England the circuit on a napkin, after seeing that Dan had let the idea out in TAA in an ad in early '72, and BS tried to patent it within the next year.
Dan was a very smart guy, but his 'execution' suffered a bit. I think that he tried to do too much himself, such as layout, etc. I would have suffered the same criticisms at the time, if I tried to make and sell kits.
Bear is right, I have heard of very early secret designs made with comp diff, but no proof. I do know that both Jon Iverson and I preceded Dan Meyer by several years, but we kept it at company confidential, and we did not dare publish.
Dan was a very smart guy, but his 'execution' suffered a bit. I think that he tried to do too much himself, such as layout, etc. I would have suffered the same criticisms at the time, if I tried to make and sell kits.
Bear is right, I have heard of very early secret designs made with comp diff, but no proof. I do know that both Jon Iverson and I preceded Dan Meyer by several years, but we kept it at company confidential, and we did not dare publish.
Here's a Tigersaurus that I built from scratch: I was 16 when I did the mechanical layout, to fit the parts that I had purchased surplus. Didn't worry about how it looked or the size, that is a Hafler 500 on top of it. I upsized many of the resistors, and substituted higher power driver transistors. The series output stage design helped reduce the voltage across the output devices and stay in a better area of the SOA curve. This amp was highly stable in use, unlike my experiences with the Universal Tiger. I did carefully consider the grounding issues:
Pete B.
An externally hosted image should be here but it was not working when we last tested it.
Pete B.
anyone finding this thread should do a search, I seem to recall another thread on the Tigers that covered some specific circuit details that are not in the TAA articles, etc...
They are scary unstable in stock form.
All of the ones I've ever seen or owned have been unstable.
You never want to plug and unplug the RCAs while they are on! <poof>
I haven't cured mine yet, no time, but I think I know how now...finally.
_-_-bear
They are scary unstable in stock form.
All of the ones I've ever seen or owned have been unstable.
You never want to plug and unplug the RCAs while they are on! <poof>
I haven't cured mine yet, no time, but I think I know how now...finally.
_-_-bear
You never want to plug or unplug RCA's on any amplifier while the amplifier is on.
Not only would the Tigersaurus amplifiers blow up but also the famed GAS and SAE from the great JB. Unfortunately this downfall is shared by many amplifiers. The DJ's and roadies unfortunately can not understand the concept of turning the amplifier off first before making connections. Another thing that is great for taking out amplifiers is the thumb test on the old RCA jack. Works wonders.
Tigersaurus information I have somewhere in my garage. I have the build manual information and the schematics.
I will look this weekend.
Oh, I still have my two Tigersaurus amplifiers and they still work.
If memory is correct DJK has/had a great cure and fix for hot swapping the SAE.GAS, and other amplifiers that were unstable in this area. Maybe he will share if he reads this.
here is the other tiger thread I remember. It might answer a few more questions.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=41926
http://www.diyaudio.com/forums/showthread.php?s=&threadid=41926
Tigeraurus
I built two of these babies in 1978 and coupled them to external cap banks (300,000 mfd each) via short umbilical cords. I used them to power KEF B139 based subwoofers to match a pair of stacked Quad ESL 57's, a pair of Sequerra T-1 tweeters and a pair of Dennessen DM-4 toob amps. I used a Dahlquist DQ-LP1 crossover, and the system sounded awesome - kind of like a poor man's HQD system.
In each Tigersaurus, I used an air conditioner relay and a big Dale resistor to limit turn-on surge. My amp.s had all Motorola output transistors, but a variety of other parts, which I replaced with better stuff where warranted, (ie. 1% metal resistors vs. the 5% carbon junk they came with, better connectors, etc.) They worked well right out of the box and had HUGE power, (over 300 watts each). They were perfect subwoofer amps.
They never failed until the guy I sold them too had the misfortune of spilling water in one of them while listening to The Doors....I heard it put out one hell of a bang that took out all the outputs, (which can't be replaced). These amps were a challenge to build RIGHT, but were a fundamentally good DESIGN. Also, like the Ford F-150 pick-up truck, I'd bet most of the ones that didn't go up in smoke in the first week are operable.
I built two of these babies in 1978 and coupled them to external cap banks (300,000 mfd each) via short umbilical cords. I used them to power KEF B139 based subwoofers to match a pair of stacked Quad ESL 57's, a pair of Sequerra T-1 tweeters and a pair of Dennessen DM-4 toob amps. I used a Dahlquist DQ-LP1 crossover, and the system sounded awesome - kind of like a poor man's HQD system.
In each Tigersaurus, I used an air conditioner relay and a big Dale resistor to limit turn-on surge. My amp.s had all Motorola output transistors, but a variety of other parts, which I replaced with better stuff where warranted, (ie. 1% metal resistors vs. the 5% carbon junk they came with, better connectors, etc.) They worked well right out of the box and had HUGE power, (over 300 watts each). They were perfect subwoofer amps.
They never failed until the guy I sold them too had the misfortune of spilling water in one of them while listening to The Doors....I heard it put out one hell of a bang that took out all the outputs, (which can't be replaced). These amps were a challenge to build RIGHT, but were a fundamentally good DESIGN. Also, like the Ford F-150 pick-up truck, I'd bet most of the ones that didn't go up in smoke in the first week are operable.
No, it shouldn't cause the destruction on amplifiers.
No, its shear stupidity to make any connections on ANY amplifier regardless of its stability when the power is turned on to the amplifier.
Those of us that do this for a living have learned to power down any equipment prior to making connections. Its a heck of a lot easier all around to practice safe connection procedures than to bitch about a particular amplifiers stability problems.
Way back in the day I successfully built a Tigersaurus for a friend, who used it and another in a band; he said they were reliable. I also built a Tiger .01 which is what I'm listening to at the moment along with an eBay-ed unit that only needed a solder short removed to function.
Were I to get my hands on one now, I'd certainly use better quality parts; the only original parts that would be difficult to replace would be the RCA 40409/10 driver transistors which were welded to their own solderable heatsinks. But there are better driver parts anyway, they'll just need their own heatsinks.
I'd replace the output transistors with MJ21193/94 or 95/96. The totem pole output stage certainly had a lot to do with the amplifier's ability to put out so much power by keeping individual devices within their SOA. More rugged transistors today make a simpler parallel array practical, though I suspect the totem pole is still used in commercial amps.
I've forgotten; did the Tigersaurus also use a CFB configuration? Those can be tricky to stabilize and I'd like to think a review of the design might reveal some worthwhile tweaks and adjustments.
Were I to get my hands on one now, I'd certainly use better quality parts; the only original parts that would be difficult to replace would be the RCA 40409/10 driver transistors which were welded to their own solderable heatsinks. But there are better driver parts anyway, they'll just need their own heatsinks.
I'd replace the output transistors with MJ21193/94 or 95/96. The totem pole output stage certainly had a lot to do with the amplifier's ability to put out so much power by keeping individual devices within their SOA. More rugged transistors today make a simpler parallel array practical, though I suspect the totem pole is still used in commercial amps.
I've forgotten; did the Tigersaurus also use a CFB configuration? Those can be tricky to stabilize and I'd like to think a review of the design might reveal some worthwhile tweaks and adjustments.
I built a whole bunch of kits (Dynaco,etc ) before I built any SWTPC stuff:
At 1st the smaller kits - Theremin, Class A headphone amp, etc. Eventually a couple of Tigers; I liked the small 1/4 rack modularity and separate PS and meters.
John Curls statement :
The Tigers were most definitely sensitive to the differing loads I placed on them, during the years I used them.
Still I kept them functional and retired them ( to storage somewhere? ) when I got a Hafler 220.
At 1st the smaller kits - Theremin, Class A headphone amp, etc. Eventually a couple of Tigers; I liked the small 1/4 rack modularity and separate PS and meters.
John Curls statement :
Reflects my experience. The kits were pretty much a piece of paper and a bag of parts.
The Tigers were most definitely sensitive to the differing loads I placed on them, during the years I used them.
Still I kept them functional and retired them ( to storage somewhere? ) when I got a Hafler 220.
Tigersaurus Power transformer
I built a pair of Tigersaurus amplifiers for a former employer about 35years ago. They were used in conjunction with an audio oscillator to generate simulated 50 Hz and 400 Hz power supplies for testing silicon rectifier firing devices. There were no operating problems with either piece. I tried them out in my stereo system at the time, but the equipment I used with them probably wasn't good enough to properly evaluate their performance. They sounded good to me. I am surprised that no one has mentioned one of the Achilles heels of the Tigersaurus, namely the inadequate power transformer. I noticed that the transformers ran uncomfortably hot, but thought nothing of it at the time, as it did not cause any limitations in power output. Later on, I purchased one of the Tigersaurus power transformers from SWTPC for use with an Ampzilla module that I owned. I again noticed the high operating temperature of the transformer and this time investigated the cause. First, I discovered that the transformer overheated even when the secondary was completely disconnected. It was pulling about 60 watts when unloaded. Then I put an incandescent lamp in series with the primary and observed that the lamp (60 watt) lit brightly. I placed a low resistance in series with the primary and looked across it with an oscilloscope. What was happening was that the transformer core was saturating on peaks (due to inadequate steel in the core stack) at any line voltage over 90 v.a.c.. I reported this to SWTPC and suggested that they verify my findings with another sample from stock, which they did, with the same result. I'm sure nothing was done about it which is understandable as it did not affect performance, but it sure as hell wasted energy. After all, the transformer cost only $37, which was a bargain at the time. I still have it, but I will never put it into a piece of equipment that I care about. I found a cool running substitute for it for use with the Ampzilla module, which I still have and use daily in one of my systems.
2chanman
I built a pair of Tigersaurus amplifiers for a former employer about 35years ago. They were used in conjunction with an audio oscillator to generate simulated 50 Hz and 400 Hz power supplies for testing silicon rectifier firing devices. There were no operating problems with either piece. I tried them out in my stereo system at the time, but the equipment I used with them probably wasn't good enough to properly evaluate their performance. They sounded good to me. I am surprised that no one has mentioned one of the Achilles heels of the Tigersaurus, namely the inadequate power transformer. I noticed that the transformers ran uncomfortably hot, but thought nothing of it at the time, as it did not cause any limitations in power output. Later on, I purchased one of the Tigersaurus power transformers from SWTPC for use with an Ampzilla module that I owned. I again noticed the high operating temperature of the transformer and this time investigated the cause. First, I discovered that the transformer overheated even when the secondary was completely disconnected. It was pulling about 60 watts when unloaded. Then I put an incandescent lamp in series with the primary and observed that the lamp (60 watt) lit brightly. I placed a low resistance in series with the primary and looked across it with an oscilloscope. What was happening was that the transformer core was saturating on peaks (due to inadequate steel in the core stack) at any line voltage over 90 v.a.c.. I reported this to SWTPC and suggested that they verify my findings with another sample from stock, which they did, with the same result. I'm sure nothing was done about it which is understandable as it did not affect performance, but it sure as hell wasted energy. After all, the transformer cost only $37, which was a bargain at the time. I still have it, but I will never put it into a piece of equipment that I care about. I found a cool running substitute for it for use with the Ampzilla module, which I still have and use daily in one of my systems.
2chanman
I would blow power supply caps in my 275 and now wonder if it was due to undersized transformer iron. I didn't think so. I assumed it was undersized caps. I just kept a fan on the amp if I wanted to use it at a party.
I'm using 10,000uF/75v caps now with no problems. They don't fit in the chassis but work much better.
I'm using 10,000uF/75v caps now with no problems. They don't fit in the chassis but work much better.
Tigersaurus transformer
rickl:
The heat radiated from the transformer was probably the cause of your capacitor failures, as electrolytics don't like heat. I never experienced any capacitor failures in the two Tigersaurus that I built, but they didn't get much sustained use and the company I built them for relocated, so I don't know how they fared later on. Except for the inadequate power transformer, they were a remarkable bargain IMO.
rickl:
The heat radiated from the transformer was probably the cause of your capacitor failures, as electrolytics don't like heat. I never experienced any capacitor failures in the two Tigersaurus that I built, but they didn't get much sustained use and the company I built them for relocated, so I don't know how they fared later on. Except for the inadequate power transformer, they were a remarkable bargain IMO.
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