A story about the Sunn Orion series

[Kid Klash]

The Sunn Orion "series" was Sunn's first solid state amp; the "head" was actually only a preamp. The power amp was a new solid state design and was built into the bottom of the speaker cabinet. They built an amp for guitars and for bass, and the grill cloth had vertical stripes on it that got wider as you moved left to right. The cabinets themselves were wider and taller than the typical Sunn "C" cabinet.

While prototyping these amps, Sunn shipped 16 of them to the UK to The Who, so that they could "field test" them. The Who used them exclusively on their album "Magic Bus".

Only a few of them ever made it onto the market... the preamp section worked fine, but the early TO-3 transistors in the power amp were very fragile... if you bumped the amp/speaker cabinet around (as in doing a loadout) while the amps were still warm, the transistors would break.

Sunn shipped 40 or 50 amp modules to The Who during the recording of the Magic Bus album because they were so rough on the amps.  After the album was completed, they shipped all the amps back to Sunn (in Tulalatin Oregon at the time). About four weeks later, a carton of "Magic Bus" albums arrived at Sunn so all the employees (including their high school summer draftsman, me) could have a copy as a "thank you" gesture. Sunn threw away (!) all of the returned Orion amps... put them in their dumpster. Since most of us that worked at Sunn thought they were nuts for throwing them away, we went back at midnight and went dumpster diving.  I hauled away one Orion speaker cabinet (the amp had been removed and the grille cloth had been slashed), and a roll of Sunn Tolex.  After making a 3/4" thick panel to cover the opening where the amp used to be (covered with Sunn Tolex of course), I used it as a standard bass cabinet for many years.

I've still got this Orion 2x15" speaker cabinet; it's sitting in the corner of my basement.  

[Anonymous]

Does anybody have schematics for the Orion?

[JoeArthur]

The TO-3 transistors were fragile?  I find that hard to believe, by design the TO-3 is almost bulletproof.  A local Sunn dealer in my area at the time, told me they were discontinued due to overheating poweramp problems... and HEY, that was only a week after I received the advertisement from Sunn about the series.

Other amps that predated the Orion used TO-3's with no problem due to the case.  Thomas/Vox, Acoustic, and even the first solid-state series of Fender amps (this series had problems with construction - tube amp workers trying to flow solder circuit boards).

I'd love to see a schematic for the amp also!!  

[Kid Klash]

Hi Joe,

The problem wasn't with the TO-3 packaging (all metal cap attached to the thick metal base); it was the germanium guts inside that were fragile.  Cold, there was no problem, but when they were hot, they "broke" easily.  Same pricipal as an incondescent light bulb... cold, they're fairly rugged and can take the vibration and jarring that occurrs during shipment, but don't bang on a light bulb that's "on" and has a hot filament or you'll break it.  And, since the Orion power amps were located in the bottom of the cabinet (not even close to the bass reflex vent), they didn't get much air flow to cool them off, so they ran hotter than usual.  Take an extra hot light bulb and thump it with your finger, and 99% of the time the filament will break.  Same thing with the early TO-3 transistors used in the Orion series.  Dynaco used the same type and vintage power transistors in their first SS stereo amps with much success, but they had much better cooling (the heat sink fins were HUGE and were exposed), and they were never torn down and thrown around by 220 pound roadies when they were still "finger-burning" hot.  Hope this helps.

[jkruta]

I was drummer in a band that used 2 Orion cabs, one for guitar and one for organ. We loved them. Cool grill cloth too! The organist actually owned both and later had the amps installed in two Leslie  tone cabinets. They were louder than you would believe. The old bass player still has two cabs, in mint condition, without amp,s sitting in his living room. I wish he would sell them to me.
One last note... in the early seventies a Midwest band called the Guild was an opening act for the Who for a while. They wound up using four Orion cabs with amps for the bass cabs for their PA. They used 2 huge Altec horns for the highs and an early electronic crossover and an unknown amp for the highs. It was a hiant sound for the day, especially for  a somewhat local band.
Jim K.

[grimniggzy]

thought it was neat to see this on ebay
orion control amp
http://cgi.ebay.com/Vintage-Sunn-Orion-Control-Amp-EUC_W0QQitemZ350267692668QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518d94d67c

[george]

Bipolar transistors, either germanium or silicon, will self distruct when they are not connected to a heatsink and/or cooling system. The Orions like the Fender solidstate series amps (Taurus, etc) did not have proper thermal design and the transistors probably died of thermal "runaway". TO-3 transistors have survived the G-forces of space travel and are anything but fragile - the light bulb filament example is a flawed analog.

[loudthud]

The Orion power module used a huge heatsink extrusion as the chassis. It's bigger than the Coliseum heatsink. Granted, the fins are oriented the wrong way. On the example below the amp has been shoe horned into the back of an Orion preamp. The transistors have been changed to parts that came from a Phase Linear power amp. They are mounted rather close together which suggests that they started with four and doubled them to eight to try to improve reliability. In addition, there are two more driver transistors that are mounted to a bracket on the inside of the heatsink.

The story of the power transistors failing because of rough handling seems a little far fetched to me. But I know that in 1968 finding any silicon PNP transistor with over 100V breakdown was very difficult.