Vrms & Phono Cables

[Hut6]

Hello to all. I have no electronics knowledge, but am unsure where to turn, to try and get my query answered, I wish to connect a turntable to a Ruark Audio R3 system. I know I need a phono cable to connect to the Ruark, via a Stereo RCA input, with a maximum input value of 2.3 Vrms.
My question is, how can I measure or confirm that no more than 2.3 Vrms is going into the Ruark from the phono cable used. My understanding is that some phono cables are specifically designed for turntables and are of higher specification, whereas other cables are not. I do not wish to cause damage to the input on the Ruark by using an unsuitable phono cable, because I assume, it may allow a higher Vrms? However I do not know how I can check that any particular phono cable I use to connect, meets the specification re max Vrms input value?

Please accept my apologies if this post is not suitable.
May I thank you in advance for any assistance you feel able to give.

Steve H - UK

 

[Nigel Goodwin]

You're worrying completely without cause.

Cables don't limit the input voltage in any way, and the maximum input voltage of your amplifier isn't 2.3Vrms, and you can't damage it by applying even considerably more than that (that's not what the spec. means).

Any phono cable will be perfectly fine, and you don't need special ones for turntables - don't be scammed into paying for a special cable, or indeed anything other than a cheap cable.

The only thing of 'concern' is a phono preamplifier - it looks like your amplifier doesn't have phono inputs (which would be specced at only a few mV) - so you need either a separate phono preamp, or a turntable with one built-in (some have a switchable preamp built-in, in which case you simply need to turn it ON).

The Ruark input is simply a 'line level input', and a phono preamp simply amplifies the weak phono signal to suit it (and also corrects the frequency response from the pickup).

 

[rjenkinsgb]

As Nigel says.

Just be aware that if the turntable does not have a built-in preamp, you will need a "phono" or "RIAA" preamp specifically intended for whatever type of pickup cartridge the turntable has.

It could a ceramic cartridge (with a turn-over stylus) or a moving magnet cartridge, with the stylus in a push-in unit.

 

[crutschow]

It could a ceramic cartridge (with a turn-over stylus) or a moving magnet cartridge, with the stylus in a push-in unit.

As implied, ceramic cartridges have a different frequency response and higher output voltage than a magnetic cartridge (either moving coil or moving magnet) so may not require a preamp.
Most HiFi cartridges are moving magnet.

 

[rjenkinsgb]

As implied, ceramic cartridges have a different frequency response and higher output voltage than a magnetic cartridge (either moving coil or moving magnet) so may not require a preamp.

A ceramic cartridge may not need much equalisation, but it cannot feed a normal "AUX" input, it must be a high impedance one, 1M or more.

Amps typically have inputs with impedances of 10K - 100K, so a suitable buffer amp is likely to be needed to give proper frequency response without overloading the cartridge.

 

[Nigel Goodwin]

I'd 'like' to think that anyone silly enough to jump on the current band wagon for antique lower quality audio, would invest in a decent turntable and cartridge - rather than ruining their new incredibly expensive records.

Ceramic cartridges? - they NEED a preamp, both to give a high input impedance, and to give gain as well - their output is too low for a line input. If you were using a PA system (as you might for discos) a simple FET buffer is all that's needed, as the PA has plenty of gain.

However, if you connect a ceramic cartridge to a moving magnet input (or preamp), then it works remarkably well - as the vastly higher gain compensates for the low input impedance, and the RIAA correction compensates for the lack of bass. Not perfect, but works surprisingly well.

 

[Hut6]

May I just pass on my sincerest 'thanks' to Mr Nigel Goodwin and all contributors, in relation to my question. Your help, guidance and time is very much appreciated and of great assistance.

Thank you again.
Steve Hughes