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Old 22nd April 2004, 03:25 PM   #1
tonitze is offline tonitze  Singapore
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Default lm1875 gainclone lack speed

Has anybody any idea why my lm1875 gainclone lack the speed compared to the tda7375? Could it be the 2x12vac 120va trafo and 8x byv28 sharing for both channel? The sound is indeed quite good but the music tend to slow down. I follow exactly Brian Gt lm3875 based gainclonce components value on my lm1875 gainclone. Is it ok to apply the value to lm1875?

Toni.
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Old 22nd April 2004, 03:36 PM   #2
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It can be something about available power. You maybe need a more powerful amp with more current and more speaker control?
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Old 22nd April 2004, 03:49 PM   #3
tonitze is offline tonitze  Singapore
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Thanks Peranders,

may be I should upgrade the trafo with higher rating like 2x18 300va perhaps?

Toni.
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Old 22nd April 2004, 10:39 PM   #4
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12 volt per rail is tethering on the edge~!! I suppose you mean 12VAC...yeah might wanna go higher something in the region of 18-22VAC will do pretty well for you...I use a 22V dual trafo with 4.5A of current...seems to work well for 2 channels...
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Old 23rd April 2004, 02:12 PM   #5
tonitze is offline tonitze  Singapore
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Thanks anyway. I stop listening to the lm1875. Back to the tda7375 which had more speed. I'll try with bigger trafo the next time. Maybe it should solve the problem.

Toni.
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Old 23rd April 2004, 02:38 PM   #6
CRFX is offline CRFX  United States
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I'v been using a lm1875 for a while and haven't nocticed any problems like that, and im running 8 channels on a 12V 3A transformer. Althogh I never turn them up high enogh to max the transformer.
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Old 23rd April 2004, 03:25 PM   #7
tonitze is offline tonitze  Singapore
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Oops..! Then what might had gone wrong with mine? Maybe the component value being used thru out, I follow exactly the value use for lm3875 by Brian GT and Peter Daniel. What about BYV28, are these good for GAINCLONE?

TONI
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Old 17th July 2004, 11:53 PM   #8
philb is offline philb  Canada
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Exclamation which pcb

i'm building am amp using the lm1875, and wanted to know which pcb to use. The National datasheet gives two pcb's one for plit supply and one for single, what does single and split mean, and which one do i use for 5 channels?

thanks
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Old 18th July 2004, 12:06 AM   #9
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single supply applications require only one side of a supply...BUT u have to use at least 12V if u're aiming for +/-12V originally...split supply means u use a centre tap rafo or a dual sec trafo and produce +/- voltages...a spilt supply system will require slightly less parts...
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Old 20th July 2004, 04:25 AM   #10
philb is offline philb  Canada
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Default That makes a lot of sense

Thank you very much li_gangyi, that really makes sense and i can't beleive that i did not figure it out myself. Thanks for the help now it's time to go make some pcb's. I'd like to post some pics of thm when they are finished.
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