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Cosmic LAB-3000 Stereomaster Amplifier Schematic

Danieljohn

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Good Evening Dear fellow forum Members !

I'm Searching for 1970's-80's Cosmic LAB-3000 Stereomaster Amplifier's Schematic.
I Request all Senior forum members to help me find the above mentioned Schematic.

Thanks in Advance !

Regards
IRONICAL
 
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Danieljohn

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I was told by a Amplifier builder that Cosmic LAB-3000 was basically a Philips 40+40 watts amplifier circuit from 1970's-80's but with 2N3055 output Transistors. If anyone happen to be having Philips Amplifier Schematic kindly let me know. I tried online but didn't found it.

Thanks in Advance !
 

Danieljohn

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Daniel, for what purpose are you looking for the schematic, is to build a clone or service an existing amplifier?
Hahaha hahaha am I that Smart to make a Clone?
Just my uncle needed it what would I do with Schematic I don't understand a thing in it.
btw Can we use Complimentary Transistors in this Circuit?
If so it would be Great I believe.
btw Thanks soo much for drawing attention to this Thread as well Dear Reuben Sir. :)
 

reubensm

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Not sure. The only experience I have working with complimentary pairs is when I got a chance to repair some high power amplifiers that featured push-pull parallel configured complementary power output transistors
 

SIDEWINDER18X

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I was told by a Amplifier builder that Cosmic LAB-3000 was basically a Philips 40+40 watts amplifier circuit from 1970's-80's but with 2N3055 output Transistors. If anyone happen to be having Philips Amplifier Schematic kindly let me know. I tried online but didn't found it.
Thanks in Advance !
This is not true. Cosmic Lab 3000 was a direct coupled amplifier powered by dual rail power supply. And so was Lab 5000 & Lab 6×1000.
All the CO series were powered by single supply rail.
And were capacitor coupled to the speaker load .

Each and every Philips amplifier manufactured in India had a circuitry powered by a single rail power supply capacitor coupled to output load or speaker.

Sonodyne amplifiers were similar to the Cosmic Lab series .... powered by dual symmetrical power supply coupled directly to the speaker load.

I had repaired several Cosmic, Sonodyne and Philips amplifiers in those days which were quite popular and common among audio lovers in the late 80 - 90s.
 

Danieljohn

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Dear Sidewinder,
When you mentioned dual rail power supply,
Does it mean two transformers?

Thanks soo much for your Support & Valuable Inputs.
 

SIDEWINDER18X

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Ok so having this kind of power supply is Good? or Prone to problems?
If you happen to have Cosmic LAB-3000 Stereomaster Amplifier Schematic kindly let me know Dear Sidewinder.

Thanks !
Capacitor coupled single ended power supply amplifiers are an age old approach towards audio
amplification. This design is no more in use in hi quality amplifiers.
The direct coupled symmetrical powed amplifiers are the best sounding amplifier.
The advance design in this direction is the full DC coupled amplifiers .... straight from the input to the output. This was quite popular in Sansui, Pioneer, Technics and many other top line amplifiers in the
80-90s. They were clean sounding and low distortion amplifiers with very higher slew rate.
The only disadvantage of such design is the probability of D.C offset or D.C volt at the output stage in case of instability or faulty situation....
which can damage the speakers if not protected by a D.C detection with speaker disconnecting circuitry.
 

Danieljohn

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1.Then Cosmic LAB-3000 Stereomaster Amplifier is DC Coupled !
2.Bcuz it damaged not just speaker but VU meter as well as bias was getting adjusted.
3.Kindly have a look at the attachment & let me know whether this Philips 40 + 40 watts amplifier circuit diagram is single or dual rail power supply.IMG-20181118-WA0001.jpg
 

SIDEWINDER18X

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1.Then Cosmic LAB-3000 Stereomaster Amplifier is DC Coupled !
2.Bcuz it damaged not just speaker but VU meter as well as bias was getting adjusted.
3.Kindly have a look at the attachment & let me know whether this Philips 40 + 40 watts amplifier circuit diagram is single or dual rail power supply.View attachment 31750
This is powered by single +60V supply and is capacitor coupled to the speaker via a 2500uf 63v capacitor marked as C12 in the diagram.
 

Danieljohn

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Do you find any resemblence between the above schematic & Cosmic LAB 3000 Stereomaster Amplifier ?
 

Danieljohn

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Dear Sidewinder & All !
Which Potentiometers/Controls are appropriate for Cosmic Amplifiers bcuz they used NOBEL Pots which I was told were custom made for Cosmic & these were never available outside Cosmic circle which includes dealer's technicians & service centers.
I require 100K×2 Log type 6 leg pot.
 

Danieljohn

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Dear Sidewinder you said Cosmic & Sonodyne Amplifiers are alike but all Cosmic Amplifiers without exception rated their Amplifier's power at 4 ohms. I believe ther is no amplifier made in india did this soo far.
 

SIDEWINDER18X

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If you have an oversized power transformer with adequate power filteration and good heat sink for the output transistors 4 ohms operations are not an issue.
Sonodyne amplifiers also had 4 ohms capabilities at speaker A+B modes. It's that they might have not mentioned their ratings for 4 ohms in their spec sheet.
 
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