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Old 9th March 2010, 11:36 AM   #1
Boydk is offline Boydk  Denmark
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Default Instead of LM 1875

Just a little tip for all you guys building amps wit LM 1875.
Having built an enormous amount of amps during my life, I thought Iīd share a little secret with you. LM 1875, along with TDA 2020, 2030 & 2050 and a lot of others are meant to amplify sound, the downside is that they really donīt do that very well. Similar to LM 1875 National Semiconductors also manufacture the LM 675 T. Itīs supposed to be an up to 4Ampere DC motorcontroller, the thing is, that given the right enviroment not very different to that of the 1875 it produces an almost heavenly tubelike sound, that if youīre careful with your surrounding components is actually high end.
Just thought I would share this. Letīs hear if anyone tries.
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Old 9th March 2010, 01:33 PM   #2
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The LM675 has higher distortion, under identical operating conditions, than the LM1875. It also costs ~20x the LM1875, if you can find it. There's no particular advantage that the LM675 has over the LM1875.
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Old 9th March 2010, 03:09 PM   #3
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it's just the same chip.
regards

Last edited by Juergen Knoop; 9th March 2010 at 03:17 PM.
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Old 9th March 2010, 05:04 PM   #4
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Quote:
Originally Posted by Juergen Knoop View Post
it's just the same chip.
The equivalent circuit schematics shown in the Natsemi datasheets for the LM675 and LM1875 differ. The LM1875 has a more elaborate input section as well as output section, with a higher overall transistor count.

(It's possible that National is fibbing in the LM675 datasheet, and showing a simpler equivalent circuit. However, the specs differ - for instance, the quiescent current of the LM675 is lower than the LM1875, which is consistent with a lower transistor count.)
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Old 9th March 2010, 08:25 PM   #5
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I didn't noticed that.
thanks
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Old 10th March 2010, 11:10 AM   #6
Boydk is offline Boydk  Denmark
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Quote:
Originally Posted by linuxguru View Post
The LM675 has higher distortion, under identical operating conditions, than the LM1875. It also costs ~20x the LM1875, if you can find it. There's no particular advantage that the LM675 has over the LM1875.
Well Linuxguru, not if you look at the specs, but did you try and listen to it, I promise, youīll hear the heck of a difference in soundquality compared to the 1875, and isnīt that what itīs all about?
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