A member asked for this schematic, so here it is:
http://baselaudiolabs.googlepages.com/TIGER-01-207B.pdf
Hope it helps to repair the amp, I've never worked on one myself.
Pete B.
http://baselaudiolabs.googlepages.com/TIGER-01-207B.pdf
Hope it helps to repair the amp, I've never worked on one myself.
Pete B.
Here it is online, wish I had found this before I scanned it, LOL.
I think this is the A version and the one I scanned is the B, not sure of the differences:
http://www.swtpc.com/mholley/RadioElectronics/Mar1973/RE_Mar1973.htm
I think this is the A version and the one I scanned is the B, not sure of the differences:
http://www.swtpc.com/mholley/RadioElectronics/Mar1973/RE_Mar1973.htm
Very good! I've got a couple of 207s here which I'll try updating. I also have a blank board which I'll stuff as a repair/experiment unit--possibly the last ever 207 to be assembled?
I installed MJ21193/4s in one and think I see a reduction in high-order distortion products. I can measure as low as .005% distortion at a one watt level, but of course it rises with power and tends exhibit significant high-order products above 5 or so watts. Careful adjustment of bias while monitoring the Tek AA501's output on a 'scope can help to minimize this problem; I'm curious to see what the change in the feedback network may have on this issue?
Anyone tried modifications to SWTPC amps, especially the 207 and Tigersaurus?
I installed MJ21193/4s in one and think I see a reduction in high-order distortion products. I can measure as low as .005% distortion at a one watt level, but of course it rises with power and tends exhibit significant high-order products above 5 or so watts. Careful adjustment of bias while monitoring the Tek AA501's output on a 'scope can help to minimize this problem; I'm curious to see what the change in the feedback network may have on this issue?
Anyone tried modifications to SWTPC amps, especially the 207 and Tigersaurus?
I scratch built several of the Tiger amps years ago as a kid and always wondered why many of them blew up. I've not looked carefully at the real hardware for probably more than 30 years now but I do plan to take a look, perhaps when I retire, LOL! Something that I always noticed was that the output signal would go very close to the rail, which means deep into saturation. This is because the driver has more voltage (Vce) to work with than say a typical EF type of configuration. This is good for using all the voltage available from the rail, good for efficiency lets say. However, BJTs become VERY slow when deep in saturation and I'm fairly certain that this leads to severe cross conduction and they might even become unstable due to the slow down. I've often seen the capacitors melt in the output stage. I've seen cross conduction peaks in simulation of 2 amps or so. These amps are dangerous for this reason and I would not use them unless you could be sure to protect your speakers in some way. Perhaps reduce the fuse sizes. I considered clamping the drivers/outputs to avoid saturation but was unable to come up with a simple, low parts count solution. A thought just came to me, perhaps reduce the output BE resistor from 100 ohms down to 22 or even 10 ohms, then use something like the MJE15032/33 as drivers that can provide the current to drive that low R. The low resistance might turn them off fast enough, but it would take some analysis/experimentation.
You're probably aware that most poweramps with BJT outputs are not intended to provide full power into clipping for extended periods of time at HF due to this very reason, certainly not above 20 KHz. This is because the cross conduction duration becomes a significant length of time as compared to the period of the waveform.
My experience has mainly been with the Universal Tiger and Tigersaurus both of which I built from scratch, I also built the kit version of the Universal and repaired it probably 3 or 4 times after it blew up.
I had a lot of hope for these amps over the years, but now after seeing the cross conduction I'm not so sure.
You're probably aware that most poweramps with BJT outputs are not intended to provide full power into clipping for extended periods of time at HF due to this very reason, certainly not above 20 KHz. This is because the cross conduction duration becomes a significant length of time as compared to the period of the waveform.
My experience has mainly been with the Universal Tiger and Tigersaurus both of which I built from scratch, I also built the kit version of the Universal and repaired it probably 3 or 4 times after it blew up.
I had a lot of hope for these amps over the years, but now after seeing the cross conduction I'm not so sure.
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Yes our kit built version of the Universal Tiger also blew up on the bench but we were not driving it hard, just sitting there with a signal generator connected. It also blew up under music conditions when driven hard a bit into clipping. This same amp did not blow up again for 20 years or so when used in light duty probably never seeing more than 20W out. This was the stereo version with less heat sink and no thermal cutout. My scratch built versions never blew up, but both ran on slightly lower supply voltages so perhaps that is part of it also. I also had figured out by then that the 100 ohm resistors needed to be 1-2W. And I did not try to use them as bench amps, that is for sure.
It certainly is not a bench amp, LOL! But there is something seriously wrong with it given all the reports of blow ups.
People also talk of them blowing up when they plug or unplug the input forgetting to turn it off. I've seen one with a note on top to that effect, LOL!
Damon, did you notice this thread: http://www.diyaudio.com/forums/solid-state/41926-universal-tiger.html
Some of the SPICE work that I did can be downloaded here: http://www.diyaudio.com/forums/solid-state/93637-swtpc-universal-tiger-improved-simulation-2.html
I would include Bob Cordell's spice model file and replace all of the bad models with his.
It certainly is not a bench amp, LOL! But there is something seriously wrong with it given all the reports of blow ups.
People also talk of them blowing up when they plug or unplug the input forgetting to turn it off. I've seen one with a note on top to that effect, LOL!
Damon, did you notice this thread: http://www.diyaudio.com/forums/solid-state/41926-universal-tiger.html
Some of the SPICE work that I did can be downloaded here: http://www.diyaudio.com/forums/solid-state/93637-swtpc-universal-tiger-improved-simulation-2.html
I would include Bob Cordell's spice model file and replace all of the bad models with his.
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I just added a new LtSpice simulation file at that link that includes Bob Cordell's models. I the old simulation to include reasonable selections from Bob's file. The sim shows 3A cross conduction peaks when clipping at 20 KHz. The zip file includes everything that's needed to run the sim under a standard LtSpice install.
this is old in a way .... but here is what i ve seen
if you look at the original application notes or built info original as was for the tiger 01 it seems that the way is made especially regarding ground distribution , pcb , and wiring between transistors is a complete nightmare .
I am pretty sure that any amplifier constructed like this will have serious stability /oscillation problems .
It could be very interesting to look at the simulation results see if there is any trouble there and then clone the amp with modern devices proper compensation and a new pcb without all these problems .
since i don't run simulators PB2 here you jump in !!!!
Again i think that at the time nobody was cloning Tiger 0.1 or one may copy it as was so mistakes made where simply repeated so also here is how these amplifiers have a failure history ...
I rebuilt one of them as we speak but i am also trying to correct the building mess I will try to keep everything original except the building /ground / distribution errors
kind regards
sakis
if you look at the original application notes or built info original as was for the tiger 01 it seems that the way is made especially regarding ground distribution , pcb , and wiring between transistors is a complete nightmare .
I am pretty sure that any amplifier constructed like this will have serious stability /oscillation problems .
It could be very interesting to look at the simulation results see if there is any trouble there and then clone the amp with modern devices proper compensation and a new pcb without all these problems .
since i don't run simulators PB2 here you jump in !!!!
Again i think that at the time nobody was cloning Tiger 0.1 or one may copy it as was so mistakes made where simply repeated so also here is how these amplifiers have a failure history ...
I rebuilt one of them as we speak but i am also trying to correct the building mess I will try to keep everything original except the building /ground / distribution errors
kind regards
sakis
Hello All,
This thread still active?
New to this site. Was just Googling “swtpc tiger 01”. Found this Thread, so I joined so I could post. I purchased (4) Tiger 01’s in 1976 (Quad Era, lol), Built the kits myself, and beyond a bad Clamp Transistor Q17, (# SS1123) in one Amp, new from the Factory, I have never had an issue with these amps. I’ve never even had to open them up (be curious to see how well my soldering actually looks , lol). I originally set the bias using an Intermodulation Distortion Meter.
These have been the Power for my "Stereo” System now for 37 years. Still Kicks. Not debating that these amps may have issues. I just haven’t ever experienced that. Best Audio Investment I EVER made (OK, getting rid of my turntable & going with CD’s / MP3 player was the best fidelity advancement, but that COST a lot more).
Piping in here because, as I have these, I’m interested in other's experiences with them. Not a lot about these posted anywhere, beyond the occasional ebay listings.
As “Rock & Roll” Implies, I CRANK ‘em.
Welcome the Comments.
This thread still active?
New to this site. Was just Googling “swtpc tiger 01”. Found this Thread, so I joined so I could post. I purchased (4) Tiger 01’s in 1976 (Quad Era, lol), Built the kits myself, and beyond a bad Clamp Transistor Q17, (# SS1123) in one Amp, new from the Factory, I have never had an issue with these amps. I’ve never even had to open them up (be curious to see how well my soldering actually looks , lol). I originally set the bias using an Intermodulation Distortion Meter.
These have been the Power for my "Stereo” System now for 37 years. Still Kicks. Not debating that these amps may have issues. I just haven’t ever experienced that. Best Audio Investment I EVER made (OK, getting rid of my turntable & going with CD’s / MP3 player was the best fidelity advancement, but that COST a lot more).
Piping in here because, as I have these, I’m interested in other's experiences with them. Not a lot about these posted anywhere, beyond the occasional ebay listings.
As “Rock & Roll” Implies, I CRANK ‘em.
Welcome the Comments.
I don't think this Forum gives awards for "Thread Necromancy" - I've seen some much larger gaps between posts on some threads.
Those designs were real popular in the late 1960's and 70's. I have stumbled across the Popular Electronics articles from time to time on the 'net, and I'm sure you can get microfilm copies from a decent public library.
I recall building the "Lil Tiger" circa 1968, used it to boost some pocket-sized transistor radios to decent volume, then started some experiments and modifications to try understanding how it worked until it didn't work any more. About 1971 used one of the "Tiger" series as the modulation amplifier for a college dorm AM radio station. I think we had to add a few capacitors to keep the RF from upsetting the biasing. Shortly after, I tried building one of the higher power Tiger amps but it was plagued with instability and gave up after going through 3 or 4 sets of output transistors.
Dale
More Tigers:
http://www.updatemydynaco.com/HistoricDocuments/UniversalTiger.pdf
A scan of the original Universal Tiger Article from Popular Electronics.
http://www.updatemydynaco.com/HistoricDocuments/UniversalTiger.pdf
A scan of the original Universal Tiger Article from Popular Electronics.
IMO the grounding and bypassing on these is critical to whether they survive. Another trick is sizing the output inductor correctly. Everybody seems to want it too small and that's a sure ticket to fuzzy oscillation on the waveform peaks during operation. Messes up the sound. The cap value across the feedback is also important and changed several times in the published schematics. I tried reducing it and using a miller cap but sound quality suffered and I immediately changed it back. Not sure why as I didn't look into it further. Still, I'd willingly build another one today, but probably change the input circuitry to reflect the views of Self and get the THD down.
Wow - what a blast from the past!
Back in the 70s I was playing in a rock & roll band and we used two Tigers for stage monitor drivers.
I built them from kits and never did any modifications. We never had any problems with them. I fused the speakers "just in case".
I was cleaning up the basement yesterday and found them. I had mounted the two Tigers into one homemade cabinet and added output meter (from Radio Shack if I recall). I decided to do a google search and found this thread.
The last time I used them was in the '80s as a keyboard amp. I may have to plug them in and see if they still work.
Back in the 70s I was playing in a rock & roll band and we used two Tigers for stage monitor drivers.
I built them from kits and never did any modifications. We never had any problems with them. I fused the speakers "just in case".
I was cleaning up the basement yesterday and found them. I had mounted the two Tigers into one homemade cabinet and added output meter (from Radio Shack if I recall). I decided to do a google search and found this thread.
The last time I used them was in the '80s as a keyboard amp. I may have to plug them in and see if they still work.
I built a pair of them in the early 70's and have fond memories of their great sound.
I recently acquired 3 of them and have rebuilt 2 of them and put them in a custom case to make a stereo tiger. Still sound great.
If anyone knows of any dead or alive for sale, please let me know. I'd like to buy some more. Also, don't forget to check out this great site......
EDIT: Broken link removed by moderation.
I recently acquired 3 of them and have rebuilt 2 of them and put them in a custom case to make a stereo tiger. Still sound great.
If anyone knows of any dead or alive for sale, please let me know. I'd like to buy some more. Also, don't forget to check out this great site......
EDIT: Broken link removed by moderation.
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Presently using my Tiger .01s while repairing/updating/modifying my various Leach amplifiers. I beefed up the power supplies with Philips 22000 uF @50V caps and 3 amp rectifiers, and will eventually change all carbon film resistors to metal film. I think the sound lacks a little depth and imaging compared to the Leachs, but within their power range sound quite good for such old units. One unit is using MJ21193/94 output transistors, faster and more linear than the original Motorola MJ802/4502s.
The design is very symmetrical, like the Leach Low TIM amplifier, but uses CFP output (with an extra emitter follower/Darlington-style driver) which is what originally interested me. Wondering if the input differentials could stand more emitter degeneration and a better VAS design.
The power supply rails don't have much local decoupling, but I haven't had obvious stability issues to date. I need some long-lead axial electrolytics to go from the driver board to the power supply star ground, to help with the rather long wiring (inductance) from the power supply board to the fuses and back to the driver boards. That might help stability.
The design is very symmetrical, like the Leach Low TIM amplifier, but uses CFP output (with an extra emitter follower/Darlington-style driver) which is what originally interested me. Wondering if the input differentials could stand more emitter degeneration and a better VAS design.
The power supply rails don't have much local decoupling, but I haven't had obvious stability issues to date. I need some long-lead axial electrolytics to go from the driver board to the power supply star ground, to help with the rather long wiring (inductance) from the power supply board to the fuses and back to the driver boards. That might help stability.
Tiger .01 power supply
I wanted to add that my Tiger .01, after many years of use, has recently had failures in the power supply capacitor. The cPacitors become leaky and if measuring the voltage using a DVM it will show a low voltage on one side of the PS. This is easily remedied with replacement capacitors available on eBay, 10,000uF/64 V, 105'. The OD of the relacements might require some tape to make the 5mm difference. Great, informative website, thanks.
I wanted to add that my Tiger .01, after many years of use, has recently had failures in the power supply capacitor. The cPacitors become leaky and if measuring the voltage using a DVM it will show a low voltage on one side of the PS. This is easily remedied with replacement capacitors available on eBay, 10,000uF/64 V, 105'. The OD of the relacements might require some tape to make the 5mm difference. Great, informative website, thanks.
My New Tigers
I just picked up a pair of 207/A amps at an estate sale ($5.00 each).
I don't know anything about them except what I have read online over the last few days. I dabble with a soldering gun, but l'm no electrical engineer. So I'm looking for advice.
I powered up my amps (with dim bulb) and was thrilled when they came to life. After a while, I noticed they did not have much power - certainly not 60 watts. I also noticed they never got very warm.
Is it possible for these to play through the first stage of amplification and not the power transistors?
If so, where do look for the problem?
Thanks!
Joe Y
I just picked up a pair of 207/A amps at an estate sale ($5.00 each).
I don't know anything about them except what I have read online over the last few days. I dabble with a soldering gun, but l'm no electrical engineer. So I'm looking for advice.
I powered up my amps (with dim bulb) and was thrilled when they came to life. After a while, I noticed they did not have much power - certainly not 60 watts. I also noticed they never got very warm.
Is it possible for these to play through the first stage of amplification and not the power transistors?
If so, where do look for the problem?
Thanks!
Joe Y
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