I'm about to build a power amp and I'm currently looking at Peter Daniels (www.audiosector.com) LM3875 based amp.
I would like to know if it is possible to drive such an amp directly from my DVD player (a Marantz DV4500) only using a passive pot for volume control? I understand that the LM3875 amp has a 22K input impedance, unfortunately the output imp of my source is unknown to me. Can someone please eleborate on the pros and cons of this approach? Also, what would an input buffer do for me when driving the amp directly from the DVD?
I have tried to search the forum for answers to my questions, but so far without any luck. Please let me know if there are threads handling my questions already.
M.A.
I would like to know if it is possible to drive such an amp directly from my DVD player (a Marantz DV4500) only using a passive pot for volume control? I understand that the LM3875 amp has a 22K input impedance, unfortunately the output imp of my source is unknown to me. Can someone please eleborate on the pros and cons of this approach? Also, what would an input buffer do for me when driving the amp directly from the DVD?
I have tried to search the forum for answers to my questions, but so far without any luck. Please let me know if there are threads handling my questions already.
M.A.
Hi mac-attack,
I've built the 3875 kit and have used it with a Meridian206/Pioneer DV535 and a passive pot with no problems at all.
Although i believe driven by a pre-amp it will sound better.
This is well regarded and there's loads of info as well:
Nuuks Site
HTH
evo
I've built the 3875 kit and have used it with a Meridian206/Pioneer DV535 and a passive pot with no problems at all.
Although i believe driven by a pre-amp it will sound better.
This is well regarded and there's loads of info as well:
Nuuks Site
HTH
evo
a good preamp helps
I've got an LM3875 amp similar to the audiosector kit and I have driven it from a DVD player though a simple 10K passive preamp and it sounded fine. This was in a fairly modest system.
I've also taken the amp to the house of various friends and gotten some interesting feedback saying that it sounds good but not great when driven by the wrong preamp but amazing with the right preamp. Examples of the "wrong preamp" include the 10K passive preamp and a tube preamp with relatively high output impedance. Examples of the "right preamp" were a transformer volume control preamp or a transformer coupled tube preamp. Both of these have pretty low output impedance so I'd draw the conclusion that is the key to getting the best out of an LM3875 amp.
---Gary
I've got an LM3875 amp similar to the audiosector kit and I have driven it from a DVD player though a simple 10K passive preamp and it sounded fine. This was in a fairly modest system.
I've also taken the amp to the house of various friends and gotten some interesting feedback saying that it sounds good but not great when driven by the wrong preamp but amazing with the right preamp. Examples of the "wrong preamp" include the 10K passive preamp and a tube preamp with relatively high output impedance. Examples of the "right preamp" were a transformer volume control preamp or a transformer coupled tube preamp. Both of these have pretty low output impedance so I'd draw the conclusion that is the key to getting the best out of an LM3875 amp.
---Gary
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