I have mine (Brian GT's standard kit) drive my Dynaudio Audience 40 (4 ohm, min 3.9ohm) with ease... but I use 2x18V (25V rail)...
I believe the datasheet says 40W into 4ohms but with those rails check the graphs in the datasheet to see the power youd have.
According to the datasheet the power of the LM3875 steeply drops below 8 Ohm. Use the LM3886 instead.
Mick
Mick
According to National´s calculator you´d still get around 50W out of it but the required heatsink theoretically would be too large.
(amp will be current limited as well)
Beyond 10W output power the power dissipation grows quite fast.
If you don´t need high power and install big enough heatsinks I don´t see a reason not to use it.
If you´d have to buy the chips first though get the LM3886 obviously or parallel two 3875.
(amp will be current limited as well)
Beyond 10W output power the power dissipation grows quite fast.
If you don´t need high power and install big enough heatsinks I don´t see a reason not to use it.
If you´d have to buy the chips first though get the LM3886 obviously or parallel two 3875.
In my reply I was assuming that you mean 24-0-24V ACWith 24-0-24V?
so around +-35V DC.
If your rails are +-24VDC there´s no problem at all.
I already did and guess what : nothing special happened; besides it gets hot very quick.Please dont try this at home
Of course I do assume that audioPT wants to build something with parts he´s got on hand.
If the transformer still has to be bought I wouldn´t choose 24VAV-secondaries. (rather 18VAC max.)
There are quite a few threads about this BTW. 😉
greets
I can't, the amp is ready!Mick_F said:According to the datasheet the power of the LM3875 steeply drops below 8 Ohm. Use the LM3886 instead.
Mick

joensd said:According to National´s calculator you´d still get around 50W out of it but the required heatsink theoretically would be too large.
(amp will be current limited as well)
Beyond 10W output power the power dissipation grows quite fast.
If you don´t need high power and install big enough heatsinks I don´t see a reason not to use it.
If you´d have to buy the chips first though get the LM3886 obviously or parallel two 3875.
Is this heatsink enough? 20x10x4 cm
An externally hosted image should be here but it was not working when we last tested it.
Leolabs said:Please dont try this at home,unless u use lower supply voltage.Check the datasheet of LM3875.
It will be feeding this babes!!
An externally hosted image should be here but it was not working when we last tested it.
I've tested it in my bench with a 22-0-22V 150VA transformer with 10.000uF in each rail with 4 Ohm speaker and it didn't get hot...
An externally hosted image should be here but it was not working when we last tested it.
My doubt is if the chip live enough at mid power...
There is no problem at all running LM3875 into 4 ohm loads with +/- 34V rails. But it will also depend how much you will be pushing the amps.
The heatsinks in a picture are fine.
The heatsinks in a picture are fine.
Peter,
As I live in an apartment, the power can't go very loud... 😀
They will be running at half power, more or less...
Well, I'll try it in my room for a wile. If it gets
, I'll just turn it off...
BTW, the speakers I showed aren't finished yet 😎
As I live in an apartment, the power can't go very loud... 😀
They will be running at half power, more or less...
Well, I'll try it in my room for a wile. If it gets




BTW, the speakers I showed aren't finished yet 😎
audioPT said:BTW, the speakers I showed aren't finished yet 😎
Do you need help, this weekend?😉

I'll go to Famalicão saturday night...
But, we can have dinner friday or lunch saturday 😎
At this moment I don't have any amplifier working... But I'm working hard to let you hear my modest sound
I'm changing my system and, as I said to you by phone, I'm painting some rooms in my place.
BUT,
You WILL see and ear my system.
And after it, feel free to
and put in this forum your opinion about my system.
Of course, friday

But, we can have dinner friday or lunch saturday 😎
At this moment I don't have any amplifier working... But I'm working hard to let you hear my modest sound

I'm changing my system and, as I said to you by phone, I'm painting some rooms in my place.
BUT,
You WILL see and ear my system.
And after it, feel free to

Of course, friday













audioPT said:I'll go to Famalicão saturday night...
But, we can have dinner friday or lunch saturday 😎
As you wish, for me it's the same.
Next is your time to come to Lisbon.
audioPT said:At this moment I don't have any amplifier working... But I'm working hard to let you hear my modest sound![]()
Worry not, just make your paintings, that's more important.
I'll take an amp and a pre.😀
audioPT said:And after it, feel free toand put in this forum your opinion about my system.
I'm not there to judge, just


audioPT said:Of course, friday...
Friday it is, then.

PS: Just listening to The Sound, "Missiles".
Who the hell makes the missiles?


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