Stereo cartrige for mono

eds65gto · 17th April 2005, 07:17 PM

Has anyone hooked a stereo cartrige up to play mono records?
I know a stereo cart. has a higher compliance than a mono cart.
There was an article a looonnngggg time ago about how to wire the stereo cart. but I cannot find it. This would make the cartrige respond only to the lateral stylus motion and not the vert. motion.
Anyone???

sek · 17th April 2005, 10:03 PM

Hi,

the RIAA standards for cutting/pressing records are actually ensuring mono compatibility for stereo systems (or so I thought).

You have L+R 'encoded' in the one, L-R in the other direction. Thus, if an L-R cut is missing in the groove, your system's L and R channel both should play the mono signal.

An issue is noise in the vertical plane, but can't you simply mix your L and R signals together to get a true mono signal?

Sebastian.

AndrewT · 18th April 2005, 07:03 PM

Hi,
the horizontal wiggles are the mono signal, just as you suggested.
The vertical wiggles are the out of phase information that the stereo cartridge uses to generate the L & R.
If you sum the 2 outputs from a stereo cartridge into an inverting summing stage you have mono, but it's even easier - just switch the 2 signals together and both channels of the following amps will play a double mono signal. The stereo cartridge does have a vertical compliance to allow it to follow the stereo info. Whereas a mono cartridge has a low vertical compliance that would damage a stereo record.
ps I would put the switch in after the phono preamp. That's the way a mono switch works on all the amps that are switchable.

Frank Berry · 18th April 2005, 07:23 PM

Andrew T is correct.

In the past, you merely connected the L+ to the R+ and the L- to the R- of the phono cartridridge.
It's far better to sum them after the preamp so as to maintain the proper loading on the cartridge and minimize the vertical (L-R) information.

sek · 18th April 2005, 08:32 PM

Cool,

I was just unsure about the loading effect, that's why I've choosen the tern 'mix' (hinting to a low source impedance).

Actually it's rather unimportant wether you mix them properly (with a summing amplifier input) or just tie them together (using a mono switch) as long as you do it after an appropriate gain stage (or impedance transformer).

Cheers,
Sebastian.

17th April 2005, 07:17 PM	#1
eds65gto diyAudio Member Join Date: Dec 2004 Location: Mt Pleasant Sc	Stereo cartrige for mono Has anyone hooked a stereo cartrige up to play mono records? I know a stereo cart. has a higher compliance than a mono cart. There was an article a looonnngggg time ago about how to wire the stereo cart. but I cannot find it. This would make the cartrige respond only to the lateral stylus motion and not the vert. motion. Anyone???

18th April 2005, 07:03 PM	#3
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the horizontal wiggles are the mono signal, just as you suggested. The vertical wiggles are the out of phase information that the stereo cartridge uses to generate the L & R. If you sum the 2 outputs from a stereo cartridge into an inverting summing stage you have mono, but it's even easier - just switch the 2 signals together and both channels of the following amps will play a double mono signal. The stereo cartridge does have a vertical compliance to allow it to follow the stereo info. Whereas a mono cartridge has a low vertical compliance that would damage a stereo record. ps I would put the switch in after the phono preamp. That's the way a mono switch works on all the amps that are switchable. __________________ regards Andrew T.

18th April 2005, 07:23 PM	#4
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	Andrew T is correct. In the past, you merely connected the L+ to the R+ and the L- to the R- of the phono cartridridge. It's far better to sum them after the preamp so as to maintain the proper loading on the cartridge and minimize the vertical (L-R) information. __________________ Frank

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17th April 2005, 10:03 PM	#2
sek diyAudio Member Join Date: May 2003 Location: Berlin	Hi, the RIAA standards for cutting/pressing records are actually ensuring mono compatibility for stereo systems (or so I thought). You have L+R 'encoded' in the one, L-R in the other direction. Thus, if an L-R cut is missing in the groove, your system's L and R channel both should play the mono signal. An issue is noise in the vertical plane, but can't you simply mix your L and R signals together to get a true mono signal? Sebastian.

18th April 2005, 08:32 PM	#5
sek diyAudio Member Join Date: May 2003 Location: Berlin	Cool, I was just unsure about the loading effect, that's why I've choosen the tern 'mix' (hinting to a low source impedance). Actually it's rather unimportant wether you mix them properly (with a summing amplifier input) or just tie them together (using a mono switch) as long as you do it after an appropriate gain stage (or impedance transformer). Cheers, Sebastian.

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