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Spectro Acoustics

Started by onanparts, February 07, 2012, 07:59:46 PM

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Robin

The 217R has a rack mount face plate. That is the only difference.
Robin Gudgel

olddude55

How about the headphone jack?  Judging by the pictures, not all 217s have the headphone jack.
Which is the biggest surprise of all.  The 217 is an outstanding headphone amp if nothing else.  Can't believe how much better my headphones sound over the DB amp I've been using for the last ten years or so.

Robin

I forgot about the headphone jack.
It is just in parallel with the output.
When Brian Morrison designed the 217, it was the first all integrated circuit preamp. We did not do this because of technology. I believe it was just the easiest way to do it. IC's that were capable of this application were very new so we took advantage of it.
None of the Spectro engineers had any formal schooling in electronics. We were just all passionate about electronics.
Robin Gudgel

boB

I don't think that MY 217R has a headphone jack ?   Did I get a raw deal ?

Happy new year-ish !
K7IQ 🌛  He/She/Me

onanparts

Quote from: boB on December 30, 2018, 02:06:35 PM
I don't think that MY 217R has a headphone jack ?   Did I get a raw deal ?

Happy new year-ish !

boB, I think you had some connections at SA.... Got a deal on an early model?  :) My #009 has no jack, but #440 does.

I got the deluxe kit, it had a solar cell and a meter.

Midnite B17-10. 50kW Cont. 150kW Surge... Me/Myself/And/I

Kryten42

#170
Hi all ;D Name is Paul (I've used Kryten42 online for years & most people who know me use that). Live in Australia (Victoria).

Don't know if this thread is still active, but I had to reply! This was a memory overload for me. Awesome!

I saved for almost three years to build my dream Super Hi-Fi system. I got almost every Audiophile mag published! I was an apprentice Studio Engineer & session drummer in the late 70's, went back to College then Uni & became an Industrial Design Engineer (retired now).

I was excited when a new large Audiophile store opened in a Melbourne suburb called Richmond (I forget it's name now) around 1978. I spent as much time there as I could until 1980/1 when I had enough $ (with a nice discount & a bonus from the studio) to buy my dream. They asked if I could get them some time in the studio sound lounge as they wanted to set up their own for testing & customer listening without annoying the whole suburb! They offered me and the studio a nice discount & the boss agreed. We all got a lot out of that & the studio bought a lot of gear from them. I got a phone call one day to tell me that had some new US gear I'd be interested in. I sure was! Because of that, the studio & I bought what might have been the first Spectro Acoustic's gear & EV D's in AU.

My system ended up being:

Rega Planar 3 Turntable with Rega-Acos R200/Ortofon MC 20 MK II (originally), SME Series III/Ortofon Concorde 30 later.
Technics SL-10 Linear Turntable, later with Ortofon OMP30 T4P MC Cartridge
(I couldn't decide! I have broad music tastes & some sounded bettor on one or the other).

Spectro Acoustics 217R Preamp
Spectro Acoustics 210R Equalizer
Spectro Acoustics 500R Power Amplifier
Spectro Acoustics 220R Tuner

ElectroVoice Interface D Speakers

AKG K340 Headphones

Some time after I got that, the store called to say they had a Valve Amp I'd be interested in (I was looking for a decent one to play with). They'd found a Fisher (The Fisher) A-202-B in perfect condition. I grabbed it! They threw in some Polk Cobra Cable (they weren't actually manufactured by Polk, just marketed. I think they were made in Japan if memory serves) & said they'd probably work best with The Fisher. I read some horror stories about these cables & ran a lot of tests with some Tektronix test gear I had at the studio & found that the stories were mostly garbage. They worked fine on both systems for years & neither amp exploded!

I was such a geek back then! Still am to be honest. ;) :D

I loved that system for years. Thanks for the memories.  ;D
Born a geek... I'll die a geek! ;) :D

boB


Kryten, than you so much for the story !    That's great !

Do you have some old HiFi magazines from back then that might have any of our ads ?

I can't remember much about which magazines we advertised in ?  I remember one ad, which I ~think~ was a full page ad was of Eddie Money standing next to a fancy expensive car and also one of our racks of gear  (which was his payment for the ad)
The title was "It's Only Money"
K7IQ 🌛  He/She/Me

Kryten42

Hi boB  :D Thanks for replying. It was a good time & worth the memories.

You know... I think I do remember that ad! I did keep most of the mag's & I had complete series of Electronics mag's that became collectors items. Sadly, I lost the majority in 2009 in a flash flood. I'd moved to a town in Central Victoria & we'd had a long drought. One day, late in 2009 not long after I'd moved, the skies opened and we had a torrential downpour lasting more than a day. Most of my boxes of mag's, books, documents & some gear I'd kept (Rega P3 & Fisher Amp & some other bits) were kept in the garage as the house had a decent carport where we kept the car, so we thought the garage would be good for temporary storage until we got around to sorting things. We were near the bottom of a hill & the driveway had about a 15deg slope. It flooded quickly & the water had nowhere to go. Almost everything was destroyed. Lost several photo albums... It was a bad time honestly. But the past is the past & I still have some good memories.

With my job as an Engineer & eventually Project Manager & Consulting Engineer, I got to travel around the World a lot. I worked in the USA for GD on a joint US/AU project for over a year. Saw a lot of the USA... Well, a lot of airports, hotel's, motels, GD facilities & USAF bases!  ::) :-\

I really missed working as a studio engineer (and roadie on some big gig's, Kiss Concert in 1980 was the last one, I was busy with College again. Biggest open-air concert in our history I believe). It was a lot simpler & I had time to enjoy things, you know? I miss that system too. I spent about 2 years planning and dreaming! 8) :D Oh! I think I saw an ad for SA in Radio-Electronics, maybe? One of those mag's like that.

Anyway, now I am retired, I have time on my hands! So who knows... Maybe I'll build a new *dream*! ;) :)
Born a geek... I'll die a geek! ;) :D

boB


That's too bad about the flooding, Kryten...

I spend many years in audio working at various companies around the northwest.  Mainly pro-audio stuff.

Mixers and compressors and all sorts of stuff.  Always had some kind of basement or living room studio to play in !

boB
K7IQ 🌛  He/She/Me

Beauregard

#174
Hi,

I'm servicing a Spectro Acoustic model 202 amplifier (no opamp) and it works ok but stays too cold to my taste. I varied the bias trim pot and it does not seems to change anything. Without any signal, I measure 0v the 0.33ohm (edited) emitter resistors. Any help would be appreciated.

Thank you.

boB

Quote from: Beauregard on December 21, 2019, 11:21:22 PM
Hi,

I'm servicing a Spectro Acoustic model 202 amplifier (no opamp) and it works ok but stays too cold to my taste. I varied the bias trim pot and it does not seems to change anything. Without any signal, I measure 0v the 33 ohm emitter resistors. Any help would be appreciated.

Thank you.


Is it working otherwise ?  Maybe the bias circuit is somehow kaput and not allowing the bases of the top and bottom output transistors to separate in voltage from each other  ?

Do you have a schematic of the 202 module ?  I'm going off of memory but I think there might be a fixed resistor across the trim-pot ?  Maybe it needs to be taken out of circuit or raised in value ?

Zero volts across the emitter resistors is not right of course.  Can't remember what should be measured there ?  Maybe 5 millivolts or so ?







K7IQ 🌛  He/She/Me

Beauregard

Hi boB, thanks to chime in!

It works but I think the distorsion could be less. The emitter resistor is 0,33ohm, my bad. I'd  be happy to measure 5mv but last time I checked it was really 0mv with my fluke 87. After two hours being on (no signal), both heatsink don't have any heat.
The schematic I have has the opamp and maybe a few other differences with the actual circuit. I'll take a look when I'm at the shop.

Have a good night.

boB


The only difference between the amplifier with and without the op-amp is that the one with the op-amp in the front end adds a gain of around 3X and then the amplifier feedback resistor changed from like, 27K Ohms to 8.2 K Ohms I think.

The bias circuit should be exactly the same in both and if the bias is working, should give you SOMETHING across the 0.33 Ohm resistor and/OR maybe make the main power transistors heat up a little bit without putting out any power.

Merry Christmas !
K7IQ 🌛  He/She/Me

onanparts

Quote from: onanparts on January 17, 2015, 04:02:02 PM
Now for the first time ever seen....as far as I know by anyone outside of Spectro Acoustics.

THE ROCK! The 600R Prototype Spectro Amp that unfortunately never saw the light of day until now.  :o

This was going to be the 500R's big brother. Massive heat sinks! It was very close to being completed when Robin and boB moved onto other projects. Maybe someday boB will have the time to bring this beast to life, but Midnite has his undivided attention with their numerous projects so it may be awhile, if ever. But I will try twisting his arm now and then about it.  :)

Well....Christmas came early for me a few weeks ago. Stopped in at Midnite for a Holiday visit. Didn't get much of a chance to snoop around and get any pics of the current Inverter program, B17, Rosie etc. as Robin thought I would have more fun helping him play musical chairs with his T-Bird collection....:)

Dead batteries and a few mechanical issues required relocating the birds using the push and pull method...all by hand..!

It wasn't all hard labor and I did get to see most but not all of the new much bigger facilities they have moved into. By the end of the day it was time for dinner, but Robin had a big sack for me, about 45 Lbs worth of sack to be exact! It was a nice sack even though I had to pick it up and haul it out to my car.....:)

So what was in Santa's sack? Well......Here is the lowdown....


After nagging both boB and Robin about bringing the "Rock" /600R to life the past few years, it appears I nagged Robin one time too many. Well, it has been gathering dust since about 1979........

Robin asked me if I wanted it? Hmmm..let me think about that for a microsecond...Sure! 🙂 Now it's on my bench with plans to get some voltage on the rails! No circuit boards were ever made for it but Robin has offered to help me design the boards from scratch for the Rock. I'm looking forward to getting the Rock out of mothballs and bring it to life sometime this year.

Thanks again to Robin for the "not available in stores" Christmas Present!  8) 8)

First look under the cover.




I got the deluxe kit, it had a solar cell and a meter.

Midnite B17-10. 50kW Cont. 150kW Surge... Me/Myself/And/I

onanparts

When I pulled the cover off and turned it upside down a couple outputs fell out.....:) NEC D746's surrounding a few Sanken 2SC2774's and 2SA1170's.

I got the deluxe kit, it had a solar cell and a meter.

Midnite B17-10. 50kW Cont. 150kW Surge... Me/Myself/And/I