Hi guys!
in this site, but in an other thread, I'm asking some tips about a vintage amplifier based on two TCA940 ic (from the'70s).
The TCA940 provides about 8+8 watt at 0,5% of THD.
Now, I am choosing if I've to use a pre-phono based on the TBA231 (powered by 18volt stabilized) with a shure ED75 type2...or if I've to use a simple well sounding ceramic cartridge like the BSR SC-12 H (about 177 mV of output).
My purpose is to get more gain on the volume of the small amplifier.
Below you can see the schematic of the pre phono RIIA based on the TBA231..and at the following link you can see the TBA231 technical features:
http://www.bg-electronics.de/datenblaetter/Schaltkreise/TBA231.pdf
Please guys, could you give me this tip...I need your precious support!
Thank for the patience and best regards!
in this site, but in an other thread, I'm asking some tips about a vintage amplifier based on two TCA940 ic (from the'70s).
The TCA940 provides about 8+8 watt at 0,5% of THD.
Now, I am choosing if I've to use a pre-phono based on the TBA231 (powered by 18volt stabilized) with a shure ED75 type2...or if I've to use a simple well sounding ceramic cartridge like the BSR SC-12 H (about 177 mV of output).
My purpose is to get more gain on the volume of the small amplifier.
Below you can see the schematic of the pre phono RIIA based on the TBA231..and at the following link you can see the TBA231 technical features:
http://www.bg-electronics.de/datenblaetter/Schaltkreise/TBA231.pdf
Please guys, could you give me this tip...I need your precious support!
Thank for the patience and best regards!
Attachments
The RIAA gain is around 40dB, so there should be plenty of output from the Shure.
Thank you Rayma!
What a wonderful new!...I was almost certain that a ceramic with 170 mV of output could sound louder than a magnetic one.
Please forgive my ignorance, I'm a newbie but I like to learn new things of this beautiful hobby!
Best regards from Italy
Thank you Rayma!
What a wonderful new!...I was almost certain that a ceramic with 170 mV of output
could sound louder than a magnetic one.
Let us know how this works out for you.
The ceramic may very well have a little more output, than the Shure with phono stage,
but either should be enough.
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Hi Kay, thank you for your reply, it helps me so much.
However I've used both cartridges...obviously the wonderful sound of the Shure M75 wins...but (believe me) also the BSR SC-12 sound very well, moreover it tracks fine just at 2,5 grams.
One of the finest ceramic cartridges!...but if I can increase the gain, I'll use my Shure M75
Thank you once again, Kay!
Regrads
OOOOPSSSSSS what a bad news, dear Mooly!
I've just controlled the pre phono board and you are absolutely right: there're three cables for the power supply.
In this case my only option is to use the BSR ceramic cartridge...what a shame
Thank you and best regards from Italy, Mooly
The diagram is not real clear, but there are split supplies. One is shown on each half.
TBA231A, SN76131 and the original Fairchild µA739C are equivalents. The Fairchild datasheet shows a single supply RIAA equalization preamplifier at page 4-53.
German hifi manufacturer WEGA copied this application in their 3120 and 3121 tuner-amplifiers as well as in their 3220 console (bottom right hand corner).
In about 1975 German electronics magazine Elektor also issued a true copy of this Fairchild application, along with a suitable PCB layout.
Note that the inputs aren't set at half the supply voltage!
Best regards!
Edit: About two years ago I bought a used Shure M75ED Type II cartridge in good condition for little money. I'm running it on a Dual 1226 turntable that is sitting in my Grundig Studio 2000 console and that I had modified wit both the arm and the synchronous motor of a 1228. It sounds amazingly, believe me! Electrically and sonically it is the same as a Shure M91ED.
German hifi manufacturer WEGA copied this application in their 3120 and 3121 tuner-amplifiers as well as in their 3220 console (bottom right hand corner).
In about 1975 German electronics magazine Elektor also issued a true copy of this Fairchild application, along with a suitable PCB layout.
Note that the inputs aren't set at half the supply voltage!
Best regards!
Edit: About two years ago I bought a used Shure M75ED Type II cartridge in good condition for little money. I'm running it on a Dual 1226 turntable that is sitting in my Grundig Studio 2000 console and that I had modified wit both the arm and the synchronous motor of a 1228. It sounds amazingly, believe me! Electrically and sonically it is the same as a Shure M91ED.
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The split rail supply is not necessarily an insurmountable problem. The opamp draws little current and so a simple method of obtaining a negative from the power supply could be an option.
If the mains transformer has a single secondary winding to generate the positive rail then the addition of a cap and a diode will generate an equal and opposite polarity rail. All you would then need would be either a negative regulator or a simpler resistor/zener shunt.
Ceramic cartridges can be very good indeed but most fail in having a poorly designed preamp that is far to low in input impedance, the result of which is inaccurate response and a curtailed LF response.
If the mains transformer has a single secondary winding to generate the positive rail then the addition of a cap and a diode will generate an equal and opposite polarity rail. All you would then need would be either a negative regulator or a simpler resistor/zener shunt.
Ceramic cartridges can be very good indeed but most fail in having a poorly designed preamp that is far to low in input impedance, the result of which is inaccurate response and a curtailed LF response.
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