I ran the service department of the largest Olson store in the US in 1971 and 1972. It was at the end of "frat house row" at the University of Miami where rich kids took a 4 year break on daddy's money. A good bit of that money was spent at Olson's. Our store pushed the Craig Pioneer brand of car stereo stuff over Olson's own brand. It was indeed better and far easier to fix.
Olson sold stuff under their own brand, and a few house brands like Concord. The home cassette deck was built by Nakamichi, but other Concord stuff could have been built by other vendors. Some, but not all of the Olson branded tube stereo stuff was indeed rebranded Sansui. Their "Mighty O" guitar amp was made by ElectroVoice and it did have an EV SRO-12 speaker in it. The amp sucked badly and it could be blown up with a sustained guitar feedback at a frequency somewhere in the 80 to 100 Hz range. the failure was always the same, blown output transistors. I guess the engineer did not understand SOA and the kick back of a speaker driven with a square wave at resonance. The price of that thing dropped every time a new catalog came out. Sometime after I had left Olson for my 41 year stint at Motorola, I went into the Olson store in Ft. Lauderdale and made a deal to buy all of the Mighty O's in the South Florida inventory. We stripped out the speakers and trashed the rest.
Olson sold stuff under their own brand, and a few house brands like Concord. The home cassette deck was built by Nakamichi, but other Concord stuff could have been built by other vendors. Some, but not all of the Olson branded tube stereo stuff was indeed rebranded Sansui. Their "Mighty O" guitar amp was made by ElectroVoice and it did have an EV SRO-12 speaker in it. The amp sucked badly and it could be blown up with a sustained guitar feedback at a frequency somewhere in the 80 to 100 Hz range. the failure was always the same, blown output transistors. I guess the engineer did not understand SOA and the kick back of a speaker driven with a square wave at resonance. The price of that thing dropped every time a new catalog came out. Sometime after I had left Olson for my 41 year stint at Motorola, I went into the Olson store in Ft. Lauderdale and made a deal to buy all of the Mighty O's in the South Florida inventory. We stripped out the speakers and trashed the rest.
Alright, I guess I can't resist. Back in the 70's I was working at Tektronix with a freshly-minted MSEE degree. I was designing phono preamps and power amps on the side (my money-paying job had me designing test fixtures for Tek parts). I had a large number of JFETs and BJTs to experiment with, including some very nice dual JFETs. Most are now long-obsolete. Listening tests with my friends (who were designing and building speakers) pretty much eliminated the BJTs, at least for the front end devices. About that time we learned that it wasn't a good idea to use high-K ceramic capacitors in the signal path. Mica and poly caps were the least objectionable. The preamp was a single-supply design so there was no alternative to using some kind of capacitor in the signal path.
All the designs were hand-wired and bench tested to see how they behaved. I was lucky because I had good signal sources and oscilloscopes available.
These days I use LTSpice to see if there are any egregious problems with circuits I design. PCBs from places like JLC are so cheap that I usually don't bother with breadboarding, unless it's a simple one-off sort of thing. The times they have changed.
All the designs were hand-wired and bench tested to see how they behaved. I was lucky because I had good signal sources and oscilloscopes available.
These days I use LTSpice to see if there are any egregious problems with circuits I design. PCBs from places like JLC are so cheap that I usually don't bother with breadboarding, unless it's a simple one-off sort of thing. The times they have changed.
My first DIY project was a pair of Electrovoice 12TRXB "Triaxial" speakers. Big and loud.
I also built a lot of SWTPC stuff. The stereo version of the Universal Tiger power amp, their FET preamp, the Five Forty power amp and a color organ.
The tiny 540 amp sounded a lot better then the bigger Universal Tiger. So a decade or so later I rebuilt the Tiger into the Edward Cherry designed NDFL amp. Huge improvement! The NDFL used the same chassis, heat sinks, output transistors and power supply as the Universal Tiger so it was just a main board swap.
The theory behind the Cherry NDFL is little understood. While Douglas Self mentions it in his book he doesn't explain any details of the design.
I also built a lot of SWTPC stuff. The stereo version of the Universal Tiger power amp, their FET preamp, the Five Forty power amp and a color organ.
The tiny 540 amp sounded a lot better then the bigger Universal Tiger. So a decade or so later I rebuilt the Tiger into the Edward Cherry designed NDFL amp. Huge improvement! The NDFL used the same chassis, heat sinks, output transistors and power supply as the Universal Tiger so it was just a main board swap.
The theory behind the Cherry NDFL is little understood. While Douglas Self mentions it in his book he doesn't explain any details of the design.
The question was what i built 50 years ago.
49 years ago i (Ted & I) built (the ones i remeber):
Radford S90 clone with Philips drivers & XO.
Triangualted TL MTM with clear poly 8" spares (Spendor?) and Philips tweeter
Jordan Watts wall mounted TL
Lowther Acousta with PM6A
The last 2 had drivers we ordered from Wilmslow. There were a bunch of others. We would have built something for eveery drivers. Poorman’s Linn (brand escapes me) with SME3009 and a Grado.
Dyanco PAT-4 and SQA-80. 2 years before HK Citation 12s and matching pre-amp, those were still kicking around.
Speaker build material was ¾” K3 particle board. Cabinets were not really that good..
And the electronics: The Acousta showed us how bad the Dynacos were.
dave
49 years ago i (Ted & I) built (the ones i remeber):
Radford S90 clone with Philips drivers & XO.
Triangualted TL MTM with clear poly 8" spares (Spendor?) and Philips tweeter
Jordan Watts wall mounted TL
Lowther Acousta with PM6A
The last 2 had drivers we ordered from Wilmslow. There were a bunch of others. We would have built something for eveery drivers. Poorman’s Linn (brand escapes me) with SME3009 and a Grado.
Dyanco PAT-4 and SQA-80. 2 years before HK Citation 12s and matching pre-amp, those were still kicking around.
Speaker build material was ¾” K3 particle board. Cabinets were not really that good..
And the electronics: The Acousta showed us how bad the Dynacos were.
dave
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I think my first project was replacing the tube amp in our stromberg-carlson console(1970?) with a lafayette bare bones tiny amp that the pcb was just in the cabinet screwed down so you could turn the knobs. I think I had to add a transformer too. Then on to a heathkit 15 watt amp that replaced the lafayette. Then a dynaco sca-80 for one brother, another PAT-5/ST-80 for another brother, a hafler DH-101 for another and then for myself a EICO tuner, hafler 101, ST-120 and DH200. Also built a pair of single channel mic preamps using that 5534A and some 9V batteries in those small alum project boxes. I remember taking apart a fan and using the wire to string up some of those cheap RS 1or 2" speakers in the basement. Did some "open box" speakers using 6x9's on a piece of free panel sample dad got. I even recall putting a 8 or 10" speaker in a toy chest and another RS 12" coax in a bass reflex I built based on RS's design. That large basement made everything sound better than it should have. Good times 6th thru college. Audio on a shoestring or less. Those hafler's were dear to me at the time. A few hundred dollars was an enormous sum to me then. I still have everything I built for myself except the tuner, which was crappy. The hafler stuff is still in use although modified now.
About 1973 I was listening for hours at a time thru my folks giant Packard Bell console, the pictured unit here is exact, but had the "modern" woodwork & the tape machine was a Sony TC200.
The first speaker I fabricated was an old Jensen minus the mids & tweeters, I crafted a baffle & mounted a Realistic horn & that five-inch midrange, some beefy steel mesh grill & black Krylon spray-paint....At that time I was buying & selling receivers right and left. Those reworked Jensens got the STA-2000 to make it go....circa 1977.
-----------------------------------------------------------------------------------------------------------------------------Rick...
The first speaker I fabricated was an old Jensen minus the mids & tweeters, I crafted a baffle & mounted a Realistic horn & that five-inch midrange, some beefy steel mesh grill & black Krylon spray-paint....At that time I was buying & selling receivers right and left. Those reworked Jensens got the STA-2000 to make it go....circa 1977.
-----------------------------------------------------------------------------------------------------------------------------Rick...
Attachments
Silvertone with fold downturntable. 1966.
I disassembled it, putting the speakers in double walled boxes i built with wood from the madarin orange boxes and nails. Even had grill cloth, orange burlap.
Much, much later the amp became this:
https://www.t-linespeakers.org/tubes/SEP_50EH5.html
dave
My first Hifi began in the 80ies so I can only tell that my father had bought some nice equipment at a store in Germany called"PX" usually only accessible to american soldiers:
KLH boxes I miss much now and even more a great amplifier Fisher Studio standard and 3 head tape deck. Later gave all that away because I considered the sound of a NAD3130 better and had Celestion DL4 as first speakers
KLH boxes had a 12 inch driver with blue cone and paper cones for mids and highs but we're the size like the boxes in this picture.
Also there was a Panasonic all in one amplifier with integrated 8track recorder.
KLH boxes I miss much now and even more a great amplifier Fisher Studio standard and 3 head tape deck. Later gave all that away because I considered the sound of a NAD3130 better and had Celestion DL4 as first speakers
KLH boxes had a 12 inch driver with blue cone and paper cones for mids and highs but we're the size like the boxes in this picture.
Also there was a Panasonic all in one amplifier with integrated 8track recorder.
Mine looks identical ! Bought late '70's Bennett's Bookshop Palmerston North New Zealand.
Was a mine of information then and used it to build some TL using Kef BD139 drivers. Tight, big! (nearly to the ceiling as not folded lol) but a bit slow
hum.. fifty years ago...i and my brother built a "yelp oscillator" circuit in a gutted transistor radio case, annoyed the heck outta my mom and siblings then we made our first "frankenspeaker" out of 2 dozen old TV speakers, we where sorta hoping the SWEET SIXTEEN principle would magically make for good sound but midrange chaos said differently, we chose to blame our shoddy woodworking!
at "74" and my case - lots of physical pain that doesn't fully let up. I'd go to ER for current (tendon ?) pain in arms/shoulders - but last visit was charged $7000 and only received one shot and no diagnosis. From my POV, "Geezer" in audio also attaches to one who knows McGee Radio catalogs ;^)