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SWTPC Tigersaurus 250W Amp Simulation
SWTPC Tigersaurus 250W Amp Simulation
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Old 31st May 2011, 04:10 AM   #1
PB2 is offline PB2  United States
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Default SWTPC Tigersaurus 250W Amp Simulation

Here's the LtSpice simulation .zip file for the SWTPC Tigersaurus using Bob's SPICE models, substituted semis but trying to be as close as possible to the original. I did not do the series output stage because the MJLs will take the voltage and I was too lazy. Others are welcome to do it if needed. I also just used zeners that were in the library. Run the sim to see the reverse Vbe issue on the drivers - good reason not to build this as is.
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File Type: zip TIGERSAURUS_AMP_MJL.zip (7.8 KB, 343 views)
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Old 31st May 2011, 05:24 AM   #2
davada is offline davada  Canada
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Hi Pete,

Indeed the same problems.

I seem to remember that it was only the outputs that would blow with the Tigersaurus kit.
I know you say your scratch build didn't have this problem.
Funny that the amp would work for a few months then not.

Some friends and I back in 79 rented a pair of JBL 4560 loaded with 2225 and some horns for a party driven by the Tigersaurus. Not only did it sound bad but the Tigers couldn't controls those 15" drivers. I've never seen excursion like that since then.

Maybe we should just get the Tiger UN working first.

David.
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Old 31st May 2011, 05:44 AM   #3
digits is offline digits
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1971 Plastic Tiger

remember these?
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Old 31st May 2011, 05:48 AM   #4
davada is offline davada  Canada
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Mine ran on slightly lower supplies of +/-65 and I upsized the drivers to MJE243/253 with large heat sinks, other than that it was the same. I never really pushed this amp that hard, well I say that then there were all the parties that it got dragged to. I think I was careful knowing how the UT fried so easily and not wanting to have to replace all those outputs.
Perhaps the drivers were being damaged over all those months and then finally gave up. The reverse voltage causes a shift in the parameters, lower beta, more noise and I believe final death. But interesting that you say they didn't fail, when I looked at the design I was worried that they would fail and so the substitution.

Here's a page with the original article in case anyone is interested:
Tigersaurus | TigersThatRoar

I agree David, I have no plans to do much with this other than to point out the problems.

Quote:
Originally Posted by digits View Post
1971 Plastic Tiger

remember these?
It is a lower voltage/power version of the UT and will have all the same problems.

Quote:
Originally Posted by davada View Post
Hi Pete,
Some friends and I back in 79 rented a pair of JBL 4560 loaded with 2225 and some horns for a party driven by the Tigersaurus. Not only did it sound bad but the Tigers couldn't controls those 15" drivers. I've never seen excursion like that since then.

David.
I have a theory regarding the excursion that you saw, note that the protection just essentially turns off the transistor with excessive current and does not pull the output to zero. So, the output hits max current and then the output turns off allowing it to slam back to zero or the other rail if the other side turns on. I think a more traditional protection that clamps the VAS output would be better.

Hi Pete,

I think you're referring to Q14 and Q15?

It's funny where the ground is place on the emitter of Q10. I would think between R28 and R29 would make more sense intuitively. Is this a mistake in the drawing of the schematic?

I'm looking at the original promotional write up on the Tigersaurus.

http://www.tigersthatroar.com/wp-con...-Article-2.jpg

David.

Hi Pete,

I was considering suggesting a current limit approach like this in the Tigersuarus for the Tiger un except rather than limit at the base of the output TR, connect the collectors of the limiter TR to the bases of the VAS TR and current sink TR respectively.

I saw this done in a similar way in an old Motorola power amp app note in the 70s. I think they called it robbing the current from the VAS.

David.
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Old 3rd June 2011, 07:39 PM   #5
Michael Chua is offline Michael Chua  United States
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Quote:
Originally Posted by davada View Post

It's funny where the ground is place on the emitter of Q10. I would think between R28 and R29 would make more sense intuitively. Is this a mistake in the drawing of the schematic?

I'm looking at the original promotional write up on the Tigersaurus.

http://www.tigersthatroar.com/wp-con...-Article-2.jpg
It's a drawing error. Ground should be between R28 and R29.
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Old 3rd June 2011, 09:19 PM   #6
PB2 is offline PB2  United States
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Yes it is a drawing error and several component values are wrong right at the output, see the parts list for the correct values.
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Old 3rd June 2011, 09:58 PM   #7
Burnedfingers is offline Burnedfingers  United States
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quote:
Some friends and I back in 79 rented a pair of JBL 4560 loaded with 2225 and some horns for a party driven by the Tigersaurus. Not only did it sound bad but the Tigers couldn't controls those 15" drivers. I've never seen excursion like that since then.


Hey, thanks for the laugh.

I have a pair of these sitting on my shelf out in the garage. I used to beat the hell out of them and never had problem one. I always thought they sounded good. They haven't had any problems running any JBL, Klipsch, or EV speakers that I have. I cannot help but think that possibly yours did have a problem. My experience with them is if they were put together correctly they ran without problems. Now if we want to talk problems they maybe the discussion should be about the Ampzilla. Its funny that James came up with the ampzilla after the Tigersaurus was out.
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Old 3rd June 2011, 10:05 PM   #8
PB2 is offline PB2  United States
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Yes, mine worked well and my theory about the protection would only apply if it actually tripped, if the set point is high enough, say mainly to protect against shorts then it should not have the problem that I described. I don't recall if I built mine with or without protection. I also got a laugh out of the comment!

Does anyone know who designed the UT, was it Dan Meyer himself? And are we sure Bongiorno designed the Tigersaurus, it has more of a UT feel/style than anything like Ampzilla.

Last edited by PB2; 3rd June 2011 at 10:12 PM.
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Old 4th June 2011, 12:34 AM   #9
davada is offline davada  Canada
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I think it more likely we got the bottom of the rental pile and the speakers probably were beaten to death before we got them. The Tigersaurus sounded fine on everything else and never had a problem other than blowing outputs every few months. But then they were not mine and I don't know what the guy was doing with them. Could have been a user problem.

David.
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Old 4th June 2011, 10:49 AM   #10
Burnedfingers is offline Burnedfingers  United States
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Quoteoes anyone know who designed the UT, was it Dan Meyer himself? And are we sure Bongiorno designed the Tigersaurus,

Meyer designed the Tigersaurus. Bongiorno designed the Ampzilla after a conversation with Meyer. Bongiorno admitted the conversation with Meyer on another site. Meyer had the Quad diff circuit and complimentary design first. Check the article dates on the Tigersaurus and the Ampzilla. Bongiorno did his own twist on things and then let his ego do the rest.

When we talk simulation in my mind the only correct way would be to wire up the output stage the same as the Tigersaurus was wired. Maybe this design is considered fatal by todays standards but like anything else it could be improved on using todays semiconductors. It its day the output stage was massive with the outputs available. It beat the hell out of the Ampzilla and about anything else out there on the market. I would not hesitate to put it up against some of the top brands today in a blind listening test. The amplifier sounded great and still does. In the years I have owned the Tigersaurus amplifiers I have had little maintenance issues with them. I replaced some driver transistors and some Quad diff transistors. The output stage still continues to hold its original transistors. Granted some day I will go back into the amplifiers and replace the outputs with some perforated emitter outputs like the 21193's and 4's I believe. The only thing I would do to this amplifier would be to design a protection circuit with a relay to disconnect the speakers if a failure were to happen.

I get a kick out of the people here trying to compare the Tiger to the Tigersaurus. If one takes the time to examine the schematics it is clearly visible that they aren't the same. Comparing the Flame Linear to anything is a laugh. They sounded horrible as did the Crown DC150 and DC300. Not too much back then sounded great and not too much stayed together either.

I have had virtually hundreds of amplifiers over the years. I done comparisons of the Ampzilla verses the Tigersaurus with blind listening tests. Have run them both up on the test bench the Ampzillas go boom the tigersaurus keeps running. I will however give Bongiorno credit for the bias circuit on the Ampzilla however the bias circuit on the SAE2400 was better. Would have liked more heat sinking on the Tigersaurus. The Ampzilla's tunnel design was better. Never did have the Tigersaurus go thermal and shut down.

The Tigersaurus was ugly and so is the Ampzilla. The Ampzilla was better looking and less like a hurriedly put together kit. I've modded the hell out of Ampzilla's with matched parts, bypass caps on the electrolytic, and by pass caps in the power supply. The Tigersaurus still comes out ahead 95% of the time in a blind listening tests.

Probably the stupidest thing I have done with respect to the South West Tech Kits was to let go of the preamp kit that was available back then also. There were several kits one was fully complimentary and the other wasn't. The fully complimentary kit when used with the Tigersaurus was aw some sounding. Its amazing that some of the so called authorities here haven't touched base on these or should I say slammed these kits.

Would be interesting to design an amplifier with the best parts of both the Ampzilla and the Tigersaurus.

From another thread


14th May 2008, 06:40 AM #1
JAW
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Join Date: May 2008 Tigersaurus





7th July 2008, 11:42 AM #25
john curl
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Location: berkeley ca 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.

Quote does anyone know who designed the UT

The "ut" meaning universal Tiger?

Meyer did.
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