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Philips High-Q International STEREO 932 Circuit Schematic Diagram

Wharfedale EVO4.4 Speaker

anirban420

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Hello Vinyl Lovers,

HMV and PHILIPS made small record players containing Ceramic Cart and Germanium output stages were once popular-most budget segment models in 70s and 80s. But schematics of these types of players are rarely available on the internet. Previously I have posted the schematic diagram of HMV STEREO 666 in this thread. Herewith I am attaching the schematics of Philips High-Q International STEREO 932.

The player consists of the following block.

Ceramic Cart/Input Selector > Input Buffer > Passive tone control (James edition) > Volume > Amplifier.

In the amplifier section, the inclusion of CD2A diode in the VCC of BC107 (Collector) is very unusual in this design. Another point to note that the Ceramic cart of Philips probably has such a high gain that the input section does not use any gain stage. The Volume Control also incorporates "Loudness" function by using a centre-tapped potentiometer for volume slider, which is not mentioned anywhere in the outside of the player.


IMG_20200719_203941.jpg
Philips High-Q International STEREO 932 Top View


IMG_20200719_204026.jpg
Philips High-Q International STEREO 932 backside In/Outputs. The "TAPE" DIN port has LINE_OUT also, but it is not mentioned in the panel.


01 Power Section & Tone Control EDIT.jpg
Power Section and Input Stage


02 Amplifier EDIT.jpg
Amplifier Section

Hope it is useful.

Regards,
Anirban
 

reubensm

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Great job Anirban, again these schematics aren't available anywhere so could be very useful. Interesting to see the Balance control circuit, i never come across that design, before :) Also the AD161/162 output pair, lovely stuff.
 

anirban420

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One thing I want to mention that there is no existence of the RIAA network in the input circuitry of the player, but the feedback network of the amplifier (from the output up to the Base of BC107, consisting of 47 K resistor, 15 K resistor, 1 KpF capacitor and 0.1 uF capacitor) resembles RIAA. I don't know whether it is doing the RIAA job or not, but, if this is the RIAA network, then the position is very unusual.
 

Bhaskar Jyoti Talapatra

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Thanks again Anirban for your endeavour to draw the entire circuitry of Philips hi q international 932 record player. I own this record player and I like it very much. Sometimes, thought of collecting it's schematics but was oblivious of it. So your effort is praiseworthy. I think both the schematics of Philips and sonodyne , some other designs drawn by other knowledgeable FMs should be kept in the HFV ,if possible in a separate thread entitled schematics or circuitry for all the respected FMs. However, this is my personal opinion only.
Cheers
 

analogadikt

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One thing I want to mention that there is no existence of the RIAA network in the input circuitry of the player, but the feedback network of the amplifier (from the output up to the Base of BC107, consisting of 47 K resistor, 15 K resistor, 1 KpF capacitor and 0.1 uF capacitor) resembles RIAA. I don't know whether it is doing the RIAA job or not, but, if this is the RIAA network, then the position is very unusual.
Thank you Anirban.

This network is in the Poweramp section and thus it is common to all inputs, i. e. it is effective with the tuner and tape inputs also. This network is tuning the sound signature to suit the full range speakers that Philips bundled with their systems. Full range speakers have some very positive qualities, but many of them, even the high end ones that can cost quite a bit, suffer from a peak in the frequency response. This peak is usually in the upper mid, lower treble region. This is known as the full range shout or Lowther shout. This network is compensating for the uneven response of the driver to give a balanced and smooth presentation that is not harsh on the ears. If the speakers that came with this system are used with some other low power ss amp, the listener would most probably turn it off in a few minutes.
Off course IMO, YMMV strictly applies to the above.:)

On a sidenote, Cosmic also used the centertapped volume control for loudness without mentioning it anywhere.

Regards,

Anwesh
 
Last edited:

anirban420

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Thank you Anirban.

This network is in the Poweramp section and thus it is common to all inputs, i. e. it is effective with the tuner and tape inputs also. This network is tuning the sound signature to suit the full range speakers that Philips bundled with their systems. Full range speakers have some very positive qualities, but many of them, even the high end ones that can cost quite a bit, suffer from a peak in the frequency response. This peak is usually in the upper mid, lower treble region. This is known as the full range shout or Lowther shout. This network is compensating for the uneven response of the driver to give a balanced and smooth presentation that is not harsh on the ears. If the speakers that came with this system are used with some other low power ss amp, the listener would most probably turn it off in a few minutes.
Off course IMO, YMMV strictly applies to the above.:)

On a sidenote, Cosmic also used the centertapped volume control for loudness without mentioning it anywhere.

Regards,

Anwesh
Thanks for your input Anwesh. The network is an RC feedback network, and your right that it is tuning the frequency response of the amplifier. I have found a similar RC feedback network in the pre-amp section of my HMV STEREO 666 TT. You can find the schematics of that TT in post #67 in this thread. I have marked it as "RIAA Equalisation Network".

On the contrary, I did not found any such network in the "Ceramic Cartridge Buffer Stage" of Sonodyne SCR-2065 Ampli Deck. I have posted the schematics of the deck in this thread.

My question is, do ceramic cartridges even need any RIAA equalisation?
 

reubensm

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Based on the many experiments i have done with ceramic phonostages, i have observed that a simple high impedance input is the bare minimum for a ceramic cart. However i have also noted that the end determines the means in this case. A humble ceramic cart can be made to sound quite attractive if a full fledged phonostage is used (incorporating riaa eq).
 
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