Hi all,
I made a new clone today just because I have two spare LM3875.. I am trying it now.
I made the same circuit as in data sheet. Just added an input load resistor (27K) and output zobel (2R7-100n) and the gain is 27/1K.
Before I made LM3886 and LM4780 amps. But the 3886 has a bass boosted NFB circuit (linkwitz transform) and the 4780 has a preamp. But this is pure Gain Clone no preamp no bass boosting.
However I feel no difference on sound between the old ones and that except bass performance.
Has anybody tried all that three National chips together? And feel any sound difference?
I asked that because as I remember somebody mentioned that the LM3875 has better sound characteristics (I dont remember who).
Best regards,
I made a new clone today just because I have two spare LM3875.. I am trying it now.
I made the same circuit as in data sheet. Just added an input load resistor (27K) and output zobel (2R7-100n) and the gain is 27/1K.
Before I made LM3886 and LM4780 amps. But the 3886 has a bass boosted NFB circuit (linkwitz transform) and the 4780 has a preamp. But this is pure Gain Clone no preamp no bass boosting.
However I feel no difference on sound between the old ones and that except bass performance.
Has anybody tried all that three National chips together? And feel any sound difference?
I asked that because as I remember somebody mentioned that the LM3875 has better sound characteristics (I dont remember who).
Best regards,
If you hear no difference, then isn't it possible the LM3875 DOES have better sound, since you don't have the preamp on it this time? Better question is whether the pre added anything to the other amp or if it also, sounded same either way.
These three are very very similar chips though, given the rest of the amp is the same they should sound very similar. LM4780 is just two LM3886 die in the same package, it only gives up a slight bit of thermal disadvantage with both die heat sources in close proximity, and a tigher, lower impedance path between shared power rails.
LM3875, looking at the schematic it's the same topology internally minus the mute feature, though presumably different integral transistor output pairs and a little less aggressive biasing.
Essentially, if you had a deliberate goal to use 3 different chips to arrive at amps that sound the same, these 3 are what you would choose to use, so having it happen in reality isn't so surprising.
Here's a nice page to look at,
http://home.pacific.net.au/~gnb/audio/lmcomp.html
These three are very very similar chips though, given the rest of the amp is the same they should sound very similar. LM4780 is just two LM3886 die in the same package, it only gives up a slight bit of thermal disadvantage with both die heat sources in close proximity, and a tigher, lower impedance path between shared power rails.
LM3875, looking at the schematic it's the same topology internally minus the mute feature, though presumably different integral transistor output pairs and a little less aggressive biasing.
Essentially, if you had a deliberate goal to use 3 different chips to arrive at amps that sound the same, these 3 are what you would choose to use, so having it happen in reality isn't so surprising.
Here's a nice page to look at,
http://home.pacific.net.au/~gnb/audio/lmcomp.html
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