Any Southwest Technical Products Builders/ Owners Out There?

I followed all those Popular Electronics/SWTPC construction articles, too. I finally saved up enough to build a pair of the Tiger .01 kits back in the mid-70's, along with the matching stereo preamp. Couldn't beat the price, only 90 cents a watt for the amps and the specs were excellent.

The amps worked great, more power than I'd ever experienced! I was always blowing fuses or outputs and other parts, mostly due to just doing dumb things like moving the speaker wires while the amp was cranked and shorting it out. After getting tired of buying outputs at $10 each, I tried a 2N3055 and it's complement (MJE2955?) which you could buy 10 for a dollar in surplus and they worked great. I learned a lot about fixing amps dealing with the Tigers. While it was more often operator failure rather than a weak design, there was a lot of current on tap and not much in the way of circuit protection. One little mistake and pow!

I always had problems with the push-button inputs on the preamp. The bass/treble buttons worked fine, though. I simply used the tape monitor to switch between TT and tape deck and pretty much avoided the other inputs. My unit also had some oscillation problems when pressing input buttons, but I can't recall if that ever was loud enough to blow anything. I usually kept the master levels on the amps turned down to where it didn't distort too badly if someone got on the loud pedal too hard, maybe that saved my bacon a couple times. I always thought the preamp's wallwart power supply was a bit chintzy, but I guess it did help remove a hum source.

I used them to drive a large pair of homebuilt speakers and it was probably the most powerful setup in my town for many years. Sold it after about 10 years, even making a small profit. I always sorta regretted selling it, but there was simply not enough room for those monster speakers and my new wife and I needed the money.

Last fall a friend gave me a Tigersaurus he was working on. A couple of those oddball heat-sinked driver transistors were shorted, and maybe some other stuff. He'd bought the parts but hadn't installed them yet. He even found the manual and dropped that off just a week or two ago. It's waiting in my shed till I'm ready to tackle the project, got a home remodel to complete first. I've thought about adding a second driver board and trying to make a stereo amp out of it with half the per-channel output.

Peter,
If that guitar preamp was featured in Popular Electronics (most all of SWTPC's kits were), I probably have that issue.

-Ed
 
I have a couple of Tiger Bs that actually work and run cool, nice sounding amps. I haven't studied them internally, but they seem pretty good.
 
SWTP - Many fond memories

Ok guys, I am new to AK and just saw this thread, but you really brought back some memories! In the late 60's & early 70's I built many of their products and sold most to friends who could not afford real stereos.

But my first kit in high school was a shocker. No parts list, no instructions, just a schematic. I thought what is up with this company? I thought I should get a real amp for $39 or whatever! But since I had never built a Heathkit or Dynaco or anything, I was not spoiled yet. I stuck to it and was amazed when the little preamp worked perfectly. Learned a lot and went on to build Plastic Tiger, Universal Tiger, Tiger .01, the later preamp (model?), light organ, accelerometer, and I forget what else.

I blew the outputs on the Plastic Tiger several times before putting in truly massive heat sinks, and then - no problem. I must have built 4 or 5 sets of Universal Tigers and found them quite reliable. Ugly maybe, but back then it was cool for some poor college kids to have that much power and at those prices, you can't complain. I still have some Tiger .01's, so will have to fire them up now. I recall being puzzled by the DC/AC inputs and was surprised to find extended bass response with the DC inputs.

Anyway, that company was the source of no end of amusement and got me started on a nice career in electronics, so hopefully there are some analogous companies for the young people of today.

Yes, I have "real" amps now,
Jeff
 
Tigersaurus Memories...

Wow..this brings back memories! I built two Tigersaurus 250's and two Tiger 01's back in 1975...or so. Also had a 198/a preamp. I used the bigger amps with a pair of Altec Lansing 1215/1225 speakers and played records for school dances and parties. The amps blew a couple of times, and one of the 1215's burned out once...but Altec replaced the driver for free...it had an unconditional warranty. The sound was fantastic! I ended up selling the whole system around 1980.
 
One of the most interesting parts of this discussion is the number of people who began their careers (or were inspired to careers) in electronics because of the SWTP stuff.
The same mostly holds true for me.
Since my last post in this thread - a year ago at least- I have taken the .01s out of storage, tested them A-B against all sorts of other units, and have incorporated them into my main electrostatic based system. They sound amazing.

DH
 
The Universal Tiger runs the speaker load off the output transistor collectors, not the emitters, against the "norm". mcIntosh did this too. It sets up voltage gain in the output stage, and places a heavy burden on the drivers. Many of these blew the 40409+40410 RCA drivers...now considered unobtanium. If the amps sounded great it was the hefty power supply!
 
I built a pair of the tigersaurus amplifiers for test use where I worked back in the late 1960's. Neither gave any trouble that I was aware of. I later bought one of the power transformers from the tigersaurus to use with an Ampzilla amplifier module that I still have. Unfortunately, that transformer was designed with insufficient core material and ran hot even when powered with no secondary load. The transformer core was saturating on normal line voltage peaks. I called up SWTPC and told them about the problem, which they confirmed. I still have that transformer but no longer use it. I also have 3 of their function generators and I built a tiger .01 amplifier and a stereo preamplifier. There stuff was a bit crude but was unbeatable for the money. I'm sorry they folded.
 
Count me as another SWTPC builder back in the 70s. I _think_ I built the Tiger 01s but purchased only the board kits and built my own power supply. In my case, I built 2 separate monoblocks with some rack-mounted chassis that I found at the local metal recycler.

Looking back, I now realize that I used Ampex 351 record/play amps, gutting them, pulling the tubes and all that other 'old' stuff in order to mount the 'new' solid state amps. Doh!

They were stolen in a break in less than a year later.

I also built one of their little preamps for a friend with the circuit boards that mated with Molex connectors and those push-button switched functions. I was a bit weird but worked ok.

I got into computers by about 1977 or so but never dinked around with their digital stuff.

Cheers,

David
 
I remember bringing them into a McIntosh audio clinic and the tech running them up past full power and still not being able to measure any distortion at all. A crowd gathered and one guy asked me if they were lab instrument amps used in an R&D environment. He was most amazed that they amplified clear down to zero DC and that they only cost around $60.

The flustered Mac tech finally pointed to the scope trace of the sine wave output and noted a little bit of a 60 HZ signal being imposed on it from the over-driven power supply. That, he said, proved they were not as good as the Macs.

I still own the distortion graph from that encounter. The distortion line is flat - straight across the bottom from 20 to 20KHZ - exactly identical to the "ideal" example given in the literature supplied with the test graph to help with interpretation.

Note: for the past few years I've used them to power a pair of electrostatic speakers.

DH

Nakdoc said:
The Universal Tiger runs the speaker load off the output transistor collectors, not the emitters, against the "norm". mcIntosh did this too. It sets up voltage gain in the output stage, and places a heavy burden on the drivers. Many of these blew the 40409+40410 RCA drivers...now considered unobtanium. If the amps sounded great it was the hefty power supply!
Click to expand...
 
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I was playing in a show band in the D.C. area around 1971-1973. In search of a decent p.a. to replace the Shure VocalMashers we were unsing, we ended up with a very nice home-made pa consisting of a swtp power amp driving 2 cabinets, each loaded with 2 Altec 12" drivers on bottom, and an Altec horn on top. I forget the make of preamp / mixer, but that little swtp amp had no problem driving those Altecs to un-real volume levels!
Thanks for the memories!
 
was doing a bit of SWTP cruising and refound this thread.

What do people think of the Universal Tiger, also known as the Tiger "B" or the Tiger 275? It sounded like a simplfied earlier version of the .01 but reading up on the pages where there were later catalogs, there were the later Tiger "B"/275 models which had the full complementary symmetry driver section added to it and put in the .01 type chassis.

I've found a few locally and a Tigersaurus on the east coast, wondering whether worth looking into (never owned them personally) but intrigued by the comments in this thread.

Bart

EDIT: sorry, rereading again gives some flavor for the UT/B/275, however, wanted to see if there was a comparison between the .01 sound and the 275.
 
I have a pair of 275s. I haven't listened to them in some time, but if memory serves me correctly, they are nice sounding amplifiers.
 
Bart,
Did you ever get your Tiger "B" amps?

A thread got re-started over on DIYaudio and while googling I found this post.

I have two Tiger B's with very few problems since the mid 70's. I'm more into tubes these days but recall they sounded fine.

If you have questions check out the posts over on DIYaudio/solid state.

rick
 
Hi Rick,

No, I decided not to venture into the SWTP world. I've probably got too many flavors of amps so couldn't justify starting with them. The only new thing is trying out a Leach LNF-1A commercial version of the Leach amplifier. I'm still looking for an LSR&D later version. This will complement a Leach amp I have had since the 80's that I built (sort of) DIY.

Bart
 
They even made it to Europe

Happen to have a stereo Brute-70 amplifier as described in Popular Electronics, February 1967 with two 40411s in the output stage. Boards come from DEMCO, as SWTPC was then still called. Assembled in a Belgian factory, as stated on the cover.

This 2 x 70W RMS amp sounds much like... a solid-state amp from the late 60s, but the bass punch is still remarkably good, even with the "vintage" power supply caps.

brute70-2.jpg


For the schematic, the article gives credit to RCA Data Bulletin ATC-408 -- anyone able to find that back? I'm not. Any pointers appreciated.

Cheers,
 
I built the tiger .01, two of the Tigersaurus, 3 of the function generators, the 198a preamp, and one of the digital l.e.d. IC troubleshooters. They all worked well and represented excellent value. The only problem I found was that the Tigersaurus power transformers contained insufficient iron which caused them to saturate on line voltage peaks and run excessively hot. In fact, you could disconnect all the transformer secondaries and the transformer STILL overheated. Charivari: try it and see.
I still have and use two of the function generators.
 
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Tigers, M/M/Ms, and Theremins

I could not determine how to start a new post, so I am "replying" to the last post, sort of. Bear with me.

I built the SWTPC M/M/M guitar 60 watt amplifier many years ago. It has two channels, but four inputs. Channel two contains tremolo, fuzz, and reverb. I also beefed up the output and power supply capacitors. I use it on a regular basis today in 2009. It sounds great with a tight bottom and clear highs. Two brothers also built single channel versions of the M/M/M amp.

Shortly after the M/M/M, I built a pair of Tiger .01s and the matching 198/A preamp. I also use them today. The pushbutton switches on the 198/A have gotten a bit scratchy, but if you work them a bit, its not a problem. My speakers are an efficient folded horn design, so the meters never move too much to fill a room with sound.

I started my SWTPC kit work in high school by building the SWTPC theremin, which was fun. I also did a phono preamp or two for friends. Fortunately, I kept a few of the SWTPC catalogs as a reminder of their stuff.
 
I have built 18 of the tigersaurus 210A's. I currently have 16 in my possession. 14 are working, one has a non functioning power transformer, and the other has other problems that I never fixed. I converted a couple of the working units from carbon resistors to metal film resistors. These amps are very clean sounding.

Anyone else here still using these amps today?
 
Hi, I just joined this forum and wondered if anyone is still watching this thread. I have a SWTP amplifier Tiger B/275 that I built back in the 70's and really never used much, but it worked perfectly and still does. Anyway, I of course misplaced the original documentation, so I was wondering if anyone out there might have one of these and still have the schematic. I realize this is VERY unlikely but I thought I'd try anyway. It's not that I need to repair it (as I said it works great) but I would just like to have it. Thanks!
 
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