Back to Vinyl

davidlzimmer · 18th July 2006, 11:37 PM

Well, after digging out my old turntable and getting a phono pre, I'm listening to my old LPs again. Man! The MAGIC!!! The dynamics!!!

But! To get this sound, instead of going directly into my "chipamp" I had to go through the line input of my PC and set the level at about 50%. I've heard that these amps need a pre or a buffer to sound their best but, I don't want to stay PC based. Can anyone suggest a simple circuit to boost the signal? (12 VDC power on the phono pre)

Also, I would very much appreciate if anyone could tell me how to set the tracking force on a Pioneer PL-S70.

Thanks,

phn · 19th July 2006, 12:20 AM

I don't know what the sensitivity of the chip amp is. I would guess it's not unlike most modern amps, which makes it ideal for CD players with about 2 Vrms.

Older phono headamps seem to have a gain of 40 db. That will only give a MM cart 0.25-0.4 V. Today's phono headamps have around 55 db. For MC you would need around 75 db.

So first you need to answer these questions: what kind of preamp and cart do you use?

Great DIY options: http://www.geocities.com/rjm003.geo/rjmaudio/diy.html

sreten · 20th July 2006, 10:11 AM

Hi,

By the sound of it you already have a phono stage, output ~ 200mV,
and you also have a chipamp suitable for CD, i.e. input ~ 2V.

The simplest solution is to add a switch to your chip amp. It controls
a gain setting resistor in the feedback loop, normal or x10. If you've
built a chip-amp it should be easy to work this out. Stability at x10
will be fine (actually much better) but you will get slightly increased
noise, offset and distortion.

/sreten.

18th July 2006, 11:37 PM	#1
davidlzimmer diyAudio Member Join Date: Jan 2006 Location: Fairmount, GA	Back to Vinyl Well, after digging out my old turntable and getting a phono pre, I'm listening to my old LPs again. Man! The MAGIC!!! The dynamics!!! But! To get this sound, instead of going directly into my "chipamp" I had to go through the line input of my PC and set the level at about 50%. I've heard that these amps need a pre or a buffer to sound their best but, I don't want to stay PC based. Can anyone suggest a simple circuit to boost the signal? (12 VDC power on the phono pre) Also, I would very much appreciate if anyone could tell me how to set the tracking force on a Pioneer PL-S70. Thanks, __________________ Poor stereo mix? Switch to mono! Perfect.

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19th July 2006, 12:20 AM	#2
phn diyAudio Member Join Date: Oct 2004	I don't know what the sensitivity of the chip amp is. I would guess it's not unlike most modern amps, which makes it ideal for CD players with about 2 Vrms. Older phono headamps seem to have a gain of 40 db. That will only give a MM cart 0.25-0.4 V. Today's phono headamps have around 55 db. For MC you would need around 75 db. So first you need to answer these questions: what kind of preamp and cart do you use? Great DIY options: http://www.geocities.com/rjm003.geo/rjmaudio/diy.html

20th July 2006, 10:11 AM	#3
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, By the sound of it you already have a phono stage, output ~ 200mV, and you also have a chipamp suitable for CD, i.e. input ~ 2V. The simplest solution is to add a switch to your chip amp. It controls a gain setting resistor in the feedback loop, normal or x10. If you've built a chip-amp it should be easy to work this out. Stability at x10 will be fine (actually much better) but you will get slightly increased noise, offset and distortion. /sreten.

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