Hi all.
I recently built a 2 transistor RIAA preamp for my LP player.
The player uses what I believe a moving coil cartridge. It has 4 wires attached to it.
I got the circuit from an old electronics book. The curve is spot on and sounds to be correct. But, it is too soft when feeding it into my hifi systems AUX input.
Im getting a gain of around 23 at 1khz.
Does this sound right? Maybe my player is faulty.
I have attached the circuit and my build. Any help will be appreciated.
Sorry but im new to Phono stuff.
I recently built a 2 transistor RIAA preamp for my LP player.
The player uses what I believe a moving coil cartridge. It has 4 wires attached to it.
I got the circuit from an old electronics book. The curve is spot on and sounds to be correct. But, it is too soft when feeding it into my hifi systems AUX input.
Im getting a gain of around 23 at 1khz.
Does this sound right? Maybe my player is faulty.
I have attached the circuit and my build. Any help will be appreciated.
Sorry but im new to Phono stuff.
Attachments
It's designed for a midband gain of 15 (23.5 dB) at 1 kHz according to the book you copied: 60 mV out for 4 mV in. More usual values are around 100 (40 dB) at 1 kHz for moving magnet and for high-output moving coil and around 1000 (60 dB) at 1 kHz for normal moving coil cartridges. You can increase the gain to some extent by reducing the 680 ohm resistor, at the expense of accuracy and distortion, but not by tens of dB's.
Yes, it may be easiest to add a gain stage (after that circuit), with a gain of 3 or 4 times,
to give a more normal mm output level.
For a Moving-Coil needle, possibly 30-40.
And possibly not-so-much: that input stage will be hissy for MC impedance and signal levels, and you may not want to turn it up that much.
It is a cute simple build for common moving-magnet pickups, but with less gain than most systems want. I think for moving-coil pickups it might be best to start again.
In good ol' days, standard line input sensitivity was 100mV (along with DIN connector). That changed in 80s with arrival of CDPs when typical line level become >= 1V.
Anyway since you use an MC pickup, you need some MC preamp. I'm sure you can find several by searching this site.
Anyway since you use an MC pickup, you need some MC preamp. I'm sure you can find several by searching this site.
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Thread about a very simple, but well-designed moving-magnet RIAA amplifier with more gain than what you have now:
The high octane phono preamp
Amplifiers to get the moving coil level up to moving magnet levels: you can find several threads about that here, but I haven't looked into them much, so I have no circuit to recommend. I know there is a simple discrete circuit shown in this paper AES E-Library >> Ultra-Low-Noise Preamplifier for Moving-Coil Phono Cartridges , but obtaining the paper is expensive.
Are you sure the cartridge is a normal-output moving coil cartridge? Is there any type number or name to look up?
The high octane phono preamp
Amplifiers to get the moving coil level up to moving magnet levels: you can find several threads about that here, but I haven't looked into them much, so I have no circuit to recommend. I know there is a simple discrete circuit shown in this paper AES E-Library >> Ultra-Low-Noise Preamplifier for Moving-Coil Phono Cartridges , but obtaining the paper is expensive.
Are you sure the cartridge is a normal-output moving coil cartridge? Is there any type number or name to look up?
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