Author Topic: Supersonic One-Eleven  (Read 572 times)

Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Supersonic One-Eleven
« on: May 19, 2018, 06:54:06 PM »
While visiting my dad today he asked me to see if i could sort out his old receiver - I remember us getting it when I was a little kid. It is a Supersonic One-Eleven. I haven't found many references to it on the internet - I suspect that it was badge engineered and assembled in South Africa.



I hooked it up, and it sort of works a bit, but lots of hum, noise, scratching of pots and I think maybe motorboating - certainly some sort of low-frequency oscillation any way.

Opened up:



Surprisingly clean inside! So I cleaned it up cosmetically - will see if I get round to the electronics at some point, and sand & varnish the cabinet. Cleaned up:



There was a turntable that came with it but he's not sure where it is. It is a Garrard AP75. The plinth was wood, and it had a lid with clear blue plastic.







Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Re: Supersonic One-Eleven
« Reply #1 on: May 19, 2018, 07:02:22 PM »
Looking at its design, there are some interesting features. The supply appears unregulated - just rectified and smoothed (unless there is regulation on the other boards but it doesn't look like it). Each amp is a completely independent board. They are not push-pull but SET (single-ended transistor  :o ;D):

Offline Family_Dog

  • Administrator
  • Trade Count: (+23)
  • *****
  • Posts: 8,199
  • STEEL & GLASS - Everlasting Beauty!
    • Repcom 2-way Radios
Re: Supersonic One-Eleven
« Reply #2 on: May 19, 2018, 07:29:11 PM »
Supersonic were originally made in Southern Rhodeisa and were known for excellent consumer products at the time.

Motor-boating and hum would be caused by a kaput filter cap - that big green one standing vertically in the power supply section. Cannot see for sure, but it seems the PSU is fitted with a selenium rectifier (might be wrong here), that being so, change it as well with a suitably rated bridge rectifier (or loose diodes, 4 x 1N4001 should do it).

If the RF section uses germanium transistors (AF117 etc), they have probably also have seen better days.

It is worthy of restoration!


-F_D



-Eric

That Guy in South Africa...
*************************************
http://groups.yahoo.com/group/vintage_tube/
*************************************

Offline Steerpike

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 4,594
    • Toybox
Re: Supersonic One-Eleven
« Reply #3 on: May 20, 2018, 01:03:59 AM »
They are not push-pull but SET (single-ended transistor  :o ;D):

Are you SURE?
That would require an air-gapped output transformer.
But I'm also not seeing an output capacitor big enough to make sense as a push-pull design from a single-ended supply.
Unless it is really low power, like 1W per channel.

Anything out of sight underneath the PCB ?

As FB said, Supersonic had a factory in Bulawayo. Some nice products!
Definitely some AF114s in there!
« Last Edit: May 20, 2018, 01:07:35 AM by Steerpike »

Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Re: Supersonic One-Eleven
« Reply #4 on: May 20, 2018, 08:37:15 AM »
Are you SURE?
That would require an air-gapped output transformer.
But I'm also not seeing an output capacitor big enough to make sense as a push-pull design from a single-ended supply.
Unless it is really low power, like 1W per channel.

Anything out of sight underneath the PCB ?

As FB said, Supersonic had a factory in Bulawayo. Some nice products!
Definitely some AF114s in there!

No Iím not sure, but I only see one power transistor on each module. But I havenít given the electronics anything more than a superficial look. Would it necessarily need a transformer?

Offline Steerpike

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 4,594
    • Toybox
Re: Supersonic One-Eleven
« Reply #5 on: May 20, 2018, 11:20:31 AM »
No Iím not sure, but I only see one power transistor on each module. But I havenít given the electronics anything more than a superficial look. Would it necessarily need a transformer?

A single ended output stage (one transistor) would almost always use an output transformer with an air gap in the core, to keep DC from the loudspeaker.
Even a push-pull arrangement - when powered from a single-ended supply, as you have there (only one supply voltage, not a symmetrical negative-zero-positive supply) needs a large capacitor (1000uF to 2200uF) on the output to keep DC off the loudspeaker.

I see a trimmer potentiometer, so that also suggests a push-pull design; single ended would not need an idle current adjustment.
A single large power transistor output is just such an illogical design, it would make much more sense to use two smaller transistors in push-pull.

Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Re: Supersonic One-Eleven
« Reply #6 on: May 20, 2018, 12:10:06 PM »
Like I said, superficial examination. Lo and behold there is the other output transistor. Anyway, the duplication of many components on the pub suggests push-pull

Offline Steerpike

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 4,594
    • Toybox
Re: Supersonic One-Eleven
« Reply #7 on: May 20, 2018, 01:33:25 PM »
Lo and behold there is the other output transistor.

and the output capacitor!
It ought to be replaced, as it is likely to be dry. For best bass performance you can install a higher-than-original capacitance.

Offline marantz123

  • Trade Count: (0)
  • AVForums Veteran
  • ***
  • Posts: 226
Re: Supersonic One-Eleven
« Reply #8 on: May 20, 2018, 08:08:08 PM »
Also couldnt find much info on the set. Apparently the wood/veneer is Rhodesian teak. The set was sold with the AP75 turntable and a "Supersonic" 3way 10"  16ohm /8ohm speakers... hope that ur dad still has those as they are the  Isophon "prepared baffle" set and they sound good, solid, well built with brass screws etc. The amp is loaded with ROE capacitors.  The Hunts  "safety" wax capacitors should be changed for safety reasons with fresh x/y capacitors. According to the Garrard catalogue the turntable is transcription quality, has the same motor as the  301 and is loaded with features...its a gem! Lots of Din connectors and old speaker connectors. Would love more information on the set...please keep it coming. Is it truly a class A design?

Offline ron g

  • Trade Count: (+19)
  • AVForums Veteran
  • *****
  • Posts: 2,745
Re: Supersonic One-Eleven
« Reply #9 on: May 20, 2018, 08:53:44 PM »


i'm finding this really fascinating.

i always had the impression that supersonic were inferior products designed to be sold through furniture shops.

seems i was wrong. or did they perhaps have different ranges?
if millennials were faced with a zombie invasion, there would be zombie rights activists.

Offline Steerpike

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 4,594
    • Toybox
Re: Supersonic One-Eleven
« Reply #10 on: May 20, 2018, 11:37:55 PM »
i always had the impression that supersonic were inferior products designed to be sold through furniture shops.

They WERE sold through furniture shops, but that is not a reflection on quality. The OK/Hyperama sold Yamaha NS1000s for a time!

Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Re: Supersonic One-Eleven
« Reply #11 on: May 26, 2018, 03:32:13 PM »
Also couldnt find much info on the set. Apparently the wood/veneer is Rhodesian teak. The set was sold with the AP75 turntable and a "Supersonic" 3way 10"  16ohm /8ohm speakers... hope that ur dad still has those as they are the  Isophon "prepared baffle" set and they sound good, solid, well built with brass screws etc. The amp is loaded with ROE capacitors.  The Hunts  "safety" wax capacitors should be changed for safety reasons with fresh x/y capacitors. According to the Garrard catalogue the turntable is transcription quality, has the same motor as the  301 and is loaded with features...its a gem! Lots of Din connectors and old speaker connectors. Would love more information on the set...please keep it coming. Is it truly a class A design?

The Supersonic speakers are long gone it would seem (replaced by some seriously shite 80s Technics), and one of my brothers may have the Garrard - I hope so! I am the proud owner of a Beomaster 1000 so have plenty of din signal and speaker connecots.

Re the Hunts caps, I assume you're talking about these? (only now that you mentioned hunts did I realise that's what it says on them)


Can't even see what value they are. There are also those small ones across the mains in and DC out - RF suppression?

Another curiosity - the back panel calls for 15Ω speakers. I noticed 15Ω resistors across the speaker terminals. Would this be because the amp modules were designed for 8Ω, but the speakers are 15Ω? Seems unecessary to waste half the amp's power?





« Last Edit: May 26, 2018, 03:34:41 PM by El Sid »

Offline Steerpike

  • Forum Moderator
  • Trade Count: (+6)
  • *****
  • Posts: 4,594
    • Toybox
Re: Supersonic One-Eleven
« Reply #12 on: May 26, 2018, 04:41:43 PM »
so have plenty of din signal and speaker connecots.

DIN audio connectors are videly available new from many component suppliers.

Quote
Another curiosity - the back panel calls for 15Ω speakers. I noticed 15Ω resistors across the speaker terminals. Would this be because the amp modules were designed for 8Ω, but the speakers are 15Ω? Seems unecessary to waste half the amp's power?

The DIN speaker plugs have internal switches: if nothing is plugged in, the 15R resistor acts as a load for the amplifier. When you push a plug in, the resistor disconnects. Certain amplifier designs  - usually early transistor, but ALL valve amplifiers - can be damaged by operating them with no load.

Small capacitors across the DC out of the rectifier, or across each diode in the rectifier, suppress diode switching noise which is problematic in shortwave & medium wave radios - the diode noise is in the AM band.

Offline El Sid

  • Trade Count: (+10)
  • AVForums Veteran
  • ***
  • Posts: 977
Re: Supersonic One-Eleven
« Reply #13 on: May 26, 2018, 05:49:03 PM »
DIN audio connectors are videly available new from many component suppliers.

The DIN speaker plugs have internal switches: if nothing is plugged in, the 15R resistor acts as a load for the amplifier. When you push a plug in, the resistor disconnects. Certain amplifier designs  - usually early transistor, but ALL valve amplifiers - can be damaged by operating them with no load.

Small capacitors across the DC out of the rectifier, or across each diode in the rectifier, suppress diode switching noise which is problematic in shortwave & medium wave radios - the diode noise is in the AM band.

I got a whole lot of DIN connectors when restoring the B&O except I see the "gramophone" needs a 3-pin din

Ah! I wondered why the speaker sockets had 3 terminals - when I measured the two were connected together so I just thought it was a convenience thing. That's quite a clever thing.

The small (10nF I think) caps go from each AC line to ground (Y caps?). Of the Hunts caps (some ĶFs I'd guess based on size), one is across the AC in (X cap?) and the other across the DC out. Not entirely sure what it's for since it's in parallel with the whopping 5000ĶF reservoir cap.

Offline marantz123

  • Trade Count: (0)
  • AVForums Veteran
  • ***
  • Posts: 226
Re: Supersonic One-Eleven
« Reply #14 on: May 26, 2018, 09:30:46 PM »
Found my notes on this. The Hunts capacitors are 100nF (0.1uF) 400v rating, and correct...its one across the secondary AC and the other across the rectified DC, in parallel with the 5000uF 55v Elko/ROE cap ( Elko RAU 2A).  The lamps in the display are 6v ,1watt festoon-type, 30mm length x 7mm diameter.  Trailer lamps fit here perfectly, just have to check the voltage...never got to do this fix though. Some useless info.....Serial no. of the unit I had was 2412. Model TRS111M. The speakers were labelled as "TL111L Supersonic 15 Ohm".  Transistor line-up...BC143/ 142/ 145/ 116, metal can types (TO3/5) and then  BC148A / 149B/ 149C. The power output transistors 2x BD116 TO3 packages, and 2 others I couldnt see. On the tuner board, possibly Germainiums here...AF178/ 124 /125. 3x 8A130 diodes. The bandspread control on my unit wasnt connected to anythng.

Hopefully ur unit just needs a recap and the general cleanup. Be very careful.....the painted text on the tuner display is very flaky and comes off easily.