Cosmic LAB-3000 Stereomaster Amplifier Schematic

[SIDEWINDER18X]

Dear Sidewinder,
Does SA5000/6000 have VU meters?
I really would like to see how SA5000/6000 looks like !

SA 5000 & SA 6000 both had this LED bargraph for both Left & Right Channels.
Unfortunately there is no pictures available over the net.

 

[Danieljohn]

Dear All !
What's soo Distinctive about BC157A 24K Glod lead Transistors?
I was told this sounds superior to BC547A .

 

[reubensm]

nice to see these old silicon transistors, used loads of them, 147A/B, 148A/B/C, 149A/B/C

whether they sounded better than BC5xx series, well I could not find any difference

but yes, the 107, 108 and 109 were much better in my opinion

 

[Danieljohn]

I'm confused !
You mean BC157A by mentioning 107, 108 and 109 ?

 

[reubensm]

no, the BC157A and its peers were not the same as the metal body 107, 8 and 9. The 10x series were far better transistors in my opinion especially on the noise front.

The transistors that you mentioned the BC 14x and 15x series were used in general audio circuit designs, from portable radios and cassette recorders to amplifiers. I still remember these used to cost Rs.2 back in those times

 

[deepakkadam]

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 !

Please try with EFY

 

[rupy]

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 !

No.It was not the philips circuit mentioned by you.

 

[Danieljohn]

Wher can I get 10-Pin 500K×2 Log Type Volume Control for Cosmic LAB-MK-II Amplifiers?

 

[SIDEWINDER18X]

Try with ....

Potentiometers

Alps Potentiometer India

theaudiocrafts.com

 

[Bhupinder Singh]

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.

Lab 3000 circuitry is quite similar to Sonodyne's SA5000 & SA6000 amplifiers.

@SIDEWINDER18X kindly let me know what is the per channel power output of cosmic lab 3000 amp.?

 

[veekm]

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.

Lab 3000 circuitry is quite similar to Sonodyne's SA5000 & SA6000 amplifiers.

Thank you - just got my paws on a Cosmic LAB 5k MK2 with one channel AWOL (faint audio) and I was wondering about the Class and such. Would you be able to identify some of the components - I am unfamiliar with some of them.

Are you sure the Cosmic LAB5kMK2 is Direct Coupled.. it has 2x2 power transistors with each set driving one set of speakers and I have a problem with one speaker/power-transistor-channel-thingy..

 

[SIDEWINDER18X]

Thank you - just got my paws on a Cosmic LAB 5k MK2 with one channel AWOL (faint audio) and I was wondering about the Class and such. Would you be able to identify some of the components - I am unfamiliar with some of them.

Are you sure the Cosmic LAB5kMK2 is Direct Coupled.. it has 2x2 power transistors with each set driving one set of speakers and I have a problem with one speaker/power-transistor-channel-thingy..

I am 100% sure. It is direct coupled.

 

[veekm]

I am 100% sure. It is direct coupled.

okay so it uses a BC147A+HL100 and the power transistors (4 of them) to drive 2 spkrs (left spkr and right spkr) in 'A+B' mode.. The two power transistors are direct coupled? BC147+SL100 for voltage amp - to get the signal strength up? Any idea what the part number is.. mine is blackened.. (2N3055?)

Also, what's the purpose of the other two ports - recollect there are 4 ports so if 2 ports are being driven by the 4 power transistors.. then what drives Port 1,3?

 

[SIDEWINDER18X]

All outputs were 2N3055

 

[SIDEWINDER18X]

You should upgrade all the small and big transistor with next generation types for improvement in overall performance.
BC 147, BC 148 - BC550C
BC 157 , BC 158 - BC560C
SL100 - BD139
SK100 - BD140
You can also replace the power output transistor with the Japanese Shaken make 2SC2580 or 2SC2581. Though it's a TO218 plastic package but can be fitted in the same heat sink with slight orientation.

 

[SIDEWINDER18X]

After doing all this don't forget to monitor the quiescent and adjust it between 50- 80mA and measure the offset voltage at the speaker output for near +/- 0V DC. This can be obtained by using matching the input diffential transistor for same HFE at the power amp input stage.
Use a HFE meter to select the matching input transistors.
And at the end .... re-capping can be the icing on the cake.

 

[Danieljohn]

Thank you - just got my paws on a Cosmic LAB 5k MK2 with one channel AWOL (faint audio) and I was wondering about the Class and such. Would you be able to identify some of the components - I am unfamiliar with some of them.

Are you sure the Cosmic LAB5kMK2 is Direct Coupled.. it has 2x2 power transistors with each set driving one set of speakers and I have a problem with one speaker/power-transistor-channel-thingy..

Share Pictures is it black or silver ?
If Silver then Output Transistors would be 2n3773
if Black then 2n3055.

 

[veekm]

Share Pictures is it black or silver ?
If Silver then Output Transistors would be 2n3773
if Black then 2n3055.

hi, the front plate with all the dials is silver - pics are here:

https://www.reddit.com/r/diyaudio/comments/jftvrw

(thanks for telling me)

 

[Deepak c]

You should upgrade all the small and big transistor with next generation types for improvement in overall performance.
BC 147, BC 148 - BC550C
BC 157 , BC 158 - BC560C
SL100 - BD139
SK100 - BD140
You can also replace the power output transistor with the Japanese Shaken make 2SC2580 or 2SC2581. Though it's a TO218 plastic package but can be fitted in the same heat sink with slight orientation.

Hi sidewinder
I want to change all transistor in my cosmic lab 6×1000
Which no transistor is good for this cosmic lab 6×1000 my no is 9004008003

 

[ronthedon]

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.

BTW 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.

Log pots are no longer available. You can instead use a 6pin linear pot and convert it to a log pot with 2 simple resistors in between its pins.