Marantz CD5001OSE Headphone Amplifier Improvement - diyAudio
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Old 13th August 2013, 11:57 AM   #1
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Location: Collingwood, Victoria
Default Marantz CD5001OSE Headphone Amplifier Improvement

I realise that this may be a few years too late but I've only recently obtained the schematic to the 5001 OSE. What's troubled me all this time is the signal from the headphone amp - lack of bass and a treble that seems to have been forced through the eye of a needle. Curiously, all the 'presence' (e.g. the reverb from an organ in a large church) was sucked out leaving an exemplary clean but un-involving sound.

This mod couldn't be simpler. Short out the two 10uF electrolytics that couple the amp to the socket. Ultimately, I'd like to remove those muting transistors but my eyesight is sorely tested trying to see all those SMDs.

Pretty easy to do as you can see from the pic. (The pic shows just the tacks I used to test this out.) There are two solder points with a capacitor symbol drawn between. Solder a wire across them. Job done.

You get bass, that lovely smooth treble everyone loves and a decent soundstage that feels more relaxing to the ears.

Phones are AKG 601s and Grado SR-80s.
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File Type: jpg headamp.jpg (247.1 KB, 26 views)

Last edited by marcaemus; 14th August 2013 at 05:18 AM.
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Old 13th August 2013, 09:19 PM   #2
dfy is offline dfy
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Have you measured DC offset at the headphone jack after shorting the caps?
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Old 13th August 2013, 10:15 PM   #3
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Yes, its within 2mV of 0 which is the limit of accuracy of my DMM. Also, there are no audible clicks when plugging in even low impedance 'phones.
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