How to put fixed attenuation between preamp and amp. Lpad or just resistor in series?

PUCK · 18th November 2003, 05:58 PM

I have a Parasound preamp hooked into my McCormack amp, and although I love the sound, I have a need to put some fixed attenuation between the two. The reasons aren't that important, but the McCormack doesn't have variable gain on it, and I would like to get somewhere around 6-10db attenuation.

According to the specs online, the preamp has an output impedance of 60 ohms, and the amp has an input impedance of 100k ohms.

With the goal of attenuating and yet keeping the sound quality as unaffected as possible, how should I accomplish this? Resisitor in series with signal? Lpad? Something more complicated?

Any help is appreciated

richie00boy · 19th November 2003, 03:59 PM

Fortunately you are blessed with an amp with high input impedance. Make an potential divider using 5k1 on o/p of source connected via 5k1 to ground. Take wanted signal from junction on resistors. This gives 1/2 original signal level, or -6dB.

Use 7k5 and 3k3 for approx -10dB.

18th November 2003, 05:58 PM	#1
PUCK diyAudio Member Join Date: Jun 2003 Location: SF Bay Area	How to put fixed attenuation between preamp and amp. Lpad or just resistor in series? I have a Parasound preamp hooked into my McCormack amp, and although I love the sound, I have a need to put some fixed attenuation between the two. The reasons aren't that important, but the McCormack doesn't have variable gain on it, and I would like to get somewhere around 6-10db attenuation. According to the specs online, the preamp has an output impedance of 60 ohms, and the amp has an input impedance of 100k ohms. With the goal of attenuating and yet keeping the sound quality as unaffected as possible, how should I accomplish this? Resisitor in series with signal? Lpad? Something more complicated? Any help is appreciated

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19th November 2003, 03:59 PM	#2
richie00boy Did it Himself diyAudio Member Join Date: Nov 2003 Location: Gloucestershire, England, UK	Fortunately you are blessed with an amp with high input impedance. Make an potential divider using 5k1 on o/p of source connected via 5k1 to ground. Take wanted signal from junction on resistors. This gives 1/2 original signal level, or -6dB. Use 7k5 and 3k3 for approx -10dB.

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