diferences between the lm3875 and the lm3886? - diyAudio
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Old 12th May 2005, 08:23 AM   #1
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Default diferences between the lm3875 and the lm3886?

Hi all,

I'm just trying to get my head into all this chip amp stuff, and Im wondering what the differences between the lm3875 and the lm3886 BrianGT kits are, audibly and physically.

I did a search and it seems that the 3875 is the slightly better SQ chip. I plan on building a couple of stereo BrianGT amps to run front and rear speakers.

Any recommendations??

Any input greatly appreciated,

Cheers.
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Old 12th May 2005, 11:09 AM   #2
wxn is offline wxn  Lithuania
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LM3875 has less pins to connect and also no mute
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Old 12th May 2005, 02:51 PM   #3
macboy is offline macboy  Canada
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Internally, there are big differences. The output current limiting of the 3886 kicks in at around 11.5 A, but the current limiting of the 3875 kicks in at 6 A. The 3886 has a higher rated instantaneous power output. Obviously, the 3886 is a lot more robust, and a lot better suited to low impedance loads (anything below 8 ohm). The rated noise and distortion figures are very similar. If your speakers are 'easy' to drive and are rated at 8 ohms or higher nominal impedance, then try the 3875. If you have notoriously difficult speakers, or they are rated at less than 8 ohms, try the 3886. Of course, you could build both types and compare for yourself, but you could do a lot worse than to choose the more appropriate chip based on the load it will be driving.
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Old 12th May 2005, 03:19 PM   #4
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I can relate my personal experience here, I have built two virtually identical stereo amps using both chips. Both had identical power supplies which consisted of one 500VA/25V dual secondary trafo with a subberized PS from Brian at chipamp.com.

My experience opinion is that the 3886 sounds better all around, but when you have very efficient speakers (8+ ohms) the 3775 is quite close. But even for efficient speakers I liked the LM3886.

But by far my favorite AMPs are my dual mono paralelled LM4780s. I had these driving a pair of very hard to drive DIY 3-4 ohm speakers and they really sing.

Best bang for the buck in my opinion is the 4780 in parallel, but if you are doing P2P it would be a lot harder than the 3886 or 3775. If I were doing P2P (which I have) I would choose the 3886 over the 3775 simply because it sounds great, and you will have more options open to you down the line.

Just my 2C

Have fun!
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Old 12th May 2005, 04:11 PM   #5
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If everything is done well and the system is suitable to show differences, LM3875 is still the best sounding chip.

LM4780 in stereo is not that far behind, but it lacks the last bit of refinement and precision. Same goes for LM3886. The opinion is based mostly on response I'm getting from people using the kits, as well my own personal observations.

LM4780 in parallel mode has more driving power, but shows even less of that refinement, which in most systems isn't that obvious anyway.
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Old 12th May 2005, 11:52 PM   #6
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well the speakers i'm using (and will be adding) are all 8 ohms.

Whats the go with the power supplies? and whats this snubberized stuff?

Presuming i went with the 3875 what ps do i need and any recommendations on where to buy the trafo? Same question reguarding the 3886.

Thanks for your help everyone,

Ashlin.
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Old 13th May 2005, 12:09 AM   #7
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Some info on snubberized supply can be found here: The (high-cap.) unregulated PSU for chipamps

A comparison between snubberized and not snubberized supply was posted here: Result from comparision: Classic GC, snuberized GC and ESP101 amp....

I would suggest trafo at least 2 x 22V and 300VA. Best way to buy it locally to save on shipping.

The snubbers are easy to apply, the first impression is usually positive. Later, you might come to conclusion that they alter the sound a bit, but again, it greatly depends on personal preference and equipment used.
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Old 14th May 2005, 11:39 AM   #8
loong is offline loong  United Kingdom
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Default Re: diferences between the lm3875 and the lm3886?

Quote:
Originally posted by kemicalx
Hi all,



Any recommendations??
Depend on your speaker as well. At high voltage (> +-30V) , LM3886 is optmized for 4 Ohm speakers while LM3875 is for 8 Ohm speakers.

If you believe that shorter singal path in feedback loop better, you might prefer LM3875 as it's without the mute function.

Cheers,
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Old 14th May 2005, 01:40 PM   #9
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The 3875 does sound better but is far from a night and day difference. Amusingly, neither can really drive my Signums as well as a 12w tube amp.
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Old 14th May 2005, 01:49 PM   #10
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...Amusingly, neither can really drive my Signums as well as a 12w tube amp.

I hope he has a strong desire to do good, sooner or later .
Probably only a "hybrid" is able draw near

Ciao

Mauro
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