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Record deck connection problems
Jasper - 11/2/08 at 04:28 PM

My father-in-law has a good quality Yamaha home cinema system. He wants to connect up his record player as he doesn't have a regular HiFi amp any more, but whatever input connections he uses on the back it doesn't work (CD/MP3/DVD etc).

I seem to remember that record decks need a specific input to work. As on one of the amps inputs you can here the music but it's very low volume and tinny ....

It has standard red and white phono leads and a third cable with what looks like an earth terminal on the end....

Any help????

iank - 11/2/08 at 04:36 PM

You are correct he probably needs one of these (or similar)
http://www.richersounds.com/showproduct.php?cda=showproduct&pid=VIVA-PA111-PREA

[Edited on 11/2/08 by iank]

stuart_g - 11/2/08 at 04:38 PM

Turn tables need to be pre-amplified and therefore need to go into a specific input. If there is no input for a turntable then a seperate pre amplifier will be needed.

JeffHs - 11/2/08 at 04:39 PM

You need a phono input stage. The output from a cartridge is a few mv and your aux inputs are expecting about 1volt. Note also that there are two standards of cartridge - moving magnet (MM) and moving coil (MC) with different output power and characteristics , so the phono stage has to match the cartridge - most are switchable. I think Richer Sounds sells a cheapish phono stage that will do the job, or get hold of an old amp with a built-in phono stage - all of the 70s & most 80s amps had them as standard.

Jeff

02GF74 - 11/2/08 at 04:43 PM

there is a little more to it than that.

there are two main types of phono cartidge - moving coil MC and moving magnet MM.

The former are of better quality but much lower output voltage.

Both need a pre-amp stage. Due to the limitation of the vinyl recording medium and play back, the amplifiaction varies according to the frequency (think lower ones are boosted more the HF?) according to the RIAA curve.

In layman's terms it means you cannot just take any amplifier and turn it up to 11 but need one with the correct frequency/gain response.

Jasper - 11/2/08 at 04:47 PM

He got the amp in Richer Sounds, so i'll get him to take the turntable in and get the right bit.... thanks guys...

02GF74 - 11/2/08 at 05:21 PM

^^^ good point - or it may be a needle and wax cylinder

ChrisW - 12/2/08 at 01:27 AM

quote:
Originally posted by 02GF74
Due to the limitation of the vinyl recording medium and play back, the amplifiaction varies according to the frequency (think lower ones are boosted more the HF?) according to the RIAA curve.


LF needs to be boosted. Lower frequencies have less cycles per second (obviously!) so need more 'movement' per cycle to create the same perceived audio volume. On a record, if the groove got too wide, it would overlap the neighbouring groove, so RIAA specifies that low frequencies are rolled off to keep the peak movement of the groove within acceptable limits so this doesn't occur.

Same principal as FM radio, only the opposite way around. HF is increased at the transmission stage and then reduced in the reciever, to overcome noise in the transmission stage. This is why a lot of pirate stations, who tend to use very simple pre-emphasis circuits, sound tinny.

Chris

[Edited on 2/12/2008 by ChrisW]

Jasper - 12/2/08 at 10:03 AM

Chris mate - I would LOVE to know what you're talking about