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 Post subject: LM1875 Chip Amps...
PostPosted: September 10th, 2016, 12:07 pm 
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Joined: February 28th, 2013, 10:38 am
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Many have heard these at my place or at CAF in '15. Here's the schematic and a few pictures (with the smaller 24VCT transformers I used to use). If you want to build a stereo version, you'll need to substitute a 36VCT/3A transformer....

Everything except the power supply:
Image

Interior view:
Image

External, they're mirror images:
Image

Schematic:
Image

Roscoe


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:07 am 
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Joined: March 12th, 2013, 11:12 am
Posts: 486
Why the 1875?


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:14 am 
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Best sounding one I tried....

Roscoe


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:25 am 
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Joined: January 13th, 2016, 9:14 pm
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If someone needs some LM1875T's let me know.

Probably have 10 new in a tube from Digikey. Should be latest production.


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:26 am 
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Joined: January 15th, 2015, 7:19 am
Posts: 841
Location: Baltimore MD
I already ordered some and hopefully they are on the way


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:29 am 
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Joined: January 15th, 2015, 7:19 am
Posts: 841
Location: Baltimore MD
heatsinks will be a problem though
going through parts shelf, I have most everything else


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:32 am 
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You don't need much, an old CPU cooler would probably be enough.... I've never noticed mine being more than barley warmer than room temperature... The 47labs GainCard just used the chassis, without any real heat sinks...

Roscoe


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:46 am 
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Joined: March 12th, 2013, 11:12 am
Posts: 486
Are both of the caps on the chip 0.1uF? Did you reverse signal connection to get polarity corrected?


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 14th, 2016, 11:51 am 
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Yeah, both. Value here isn't critical, that's the local PS bypass right at the chip pins. When I originally built these amps, they were non-inverting, so the output is inverting, I just flip the output connections. Feel free to hook up your output to the black binding post & the red one to ground, then you won't have to think about it when they got hooked up...

Roscoe


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 Post subject: Re: LM1875 Chip Amps...
PostPosted: September 28th, 2016, 3:07 pm 
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Joined: January 15th, 2015, 7:19 am
Posts: 841
Location: Baltimore MD
maybe a noob question but....
are the chips insulated from heatsink/ground. I see the thermo paste but curious it there is a piece of mica in there also


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