Need help hooking up a basic turntable to an ampw w/o phono input


New member
Username: Andrey

Post Number: 1
Registered: Dec-04
I was wondering if anyone could give me a suggestion to what seems as infantile problem. I have a small amp, that has two line in audio inputs but no Phono and ground inputs. when i hook up my turntable into one of the lines in, the signal is low and terrible. Is there a converter for this type of situation or any other solutions? Thanks for the help in advance!


Silver Member
Username: Frank_abela

Berkshire UK

Post Number: 238
Registered: Sep-04
Welcome to the forum Andrey,

You need what is known as a phono stage or phono preamp. The phono stage takes the very small signal supplied by the cartridge and amplifies it to something more like line level. It will still be lower volume than a CD player, but it will not be that low and distorted.

The output of a cartridge is either around 2 - 4mV or 0.2 - 0.6mV depending on whether it's moving magnet or moving coil (different operating principle). The output of the typical CD player is 2V - 1000 or 10000 times more than a cartridge.

Since the output of the cartridge is so low, it can be difficult to magnify that signal without magnifying a lot of circuit noise with it. Therefore the output of the typical phono stage is not as high as you'd get from a CD player, simply to keep the Signal to Noise Ratio (S/N) as good as possible.

The process of magnification through the phono stage also puts the signal through an inverse RIAA curve. The grooves on a record are about the same width all the way through the record. However, bass frequencies are much larger than treble frequencies. This means that a bass note of (say) 50hz has a wavelength several feet long, whereas a treble frequency such as 19khz has a wavelength less than an inch long. The RIAA curve squashes all the wavelengths so they fit into the width of a groove - this is done in production. The phono stage does the opposite process - whch also accounts for a lot of noise amplification in a badly designed phono stage...! This accounts for the terrible sound you're getting since you're hearing the 'squashed' version of the signal, rather than the properly readjusted thing!

The best inexpensive phono stage I prefer is the Project PhonoBox which retails for around £45 in the UK. You'll need an interconnect to go between it and the amp. The only other inexpensive one I can think of is the NAD PP2 which retails for similar money but does not need an interconnect.


New member
Username: Andrey

Post Number: 2
Registered: Dec-04
frank, thanks very much. this helps quite a bit.
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