Speaker impedance... I would say you'll be OK with the LM1875. Its a complex subject, the amp will have a max current it can deliver and a max voltage and a max total power dissipation. So the quoted 4 ohms "covers all bases" for the published spec. Use the amp at full voltage swing into a below than 4 ohms load and it will limit. Abuse it too much and its reliability may suffer despite the inbuilt protection.
In the real world I would say 3.2 minimum (that figure will be at some specific frequency, other frequencies will have much higher impedance) will be OK.
In the real world I would say 3.2 minimum (that figure will be at some specific frequency, other frequencies will have much higher impedance) will be OK.
impedance curve :
An externally hosted image should be here but it was not working when we last tested it.
Where's the graph come from ? 
It seems odd seeing the impedance drop to "zero" around 4K.
As to the LM1875, it's rated for 4 ohm which is as "good" as any small chip can drive. I still think it would be OK given the low supply voltage but that leads to another question. Are you going to be able to get the levels you need with the power available ?
It seems odd seeing the impedance drop to "zero" around 4K.
As to the LM1875, it's rated for 4 ohm which is as "good" as any small chip can drive. I still think it would be OK given the low supply voltage but that leads to another question. Are you going to be able to get the levels you need with the power available ?
first curve is with PLLXO (passive line level xover)..
This one is without :
This one is without :
An externally hosted image should be here but it was not working when we last tested it.
At +/- 12v supply. The peak voltage swing from the amplifier with 3 ohm load is 10v or less or about 7 volts rms max. 10v/3ohms= 3.33a peak or 2.33a rms. Well within the safe limit of the 1875. The 2050 has 5a peak current so there's more wiggle room. Another benefit of the 2050 is that it is able to output a bit higher voltage swing than the 1875 at a given supply voltage so this means a bit more output power. 1 to 1.5w, I'd guess.
Hi John,
Thank's, I had seen TDA2050 here :
DIY TDA2050 Hi-Fi Chip Amplifier (chipamp)
So you think it's better in my case (3 Ohm)
Problem is I am not found it in my country..
TDA2050 vs LM1875
Thank's, I had seen TDA2050 here :
DIY TDA2050 Hi-Fi Chip Amplifier (chipamp)
So you think it's better in my case (3 Ohm)
Problem is I am not found it in my country..
TDA2050 vs LM1875
Thanks for the graph details.I still don't see how it can fall to zero ohms impedance (which is a short at those frequencies)... wouldn't the voice coil set a minimum value... not my thing speaker theory and design... it just doesn't sound right though
No matter
So are we going for the TDA2050 ?
No matter
So are we going for the TDA2050 ?
I looked at the price from CPC/Farnell and its £2 ish without VAT.
TDA2050V - STMICROELECTRONICS - AMP, AUDIO, 25W, 2050, PENTAWATT | CPC
That's a guaranteed STM part.
TDA2050V - STMICROELECTRONICS - AMP, AUDIO, 25W, 2050, PENTAWATT | CPC
That's a guaranteed STM part.
Thank's Mooly,
good idea, also available from UK and better shipping..
I found in Germany too :
eBay | TDA2050V HI-FI Audio Power Verstärker 32W TDA2050
It's secure too..
good idea, also available from UK and better shipping..
I found in Germany too :
eBay | TDA2050V HI-FI Audio Power Verstärker 32W TDA2050
It's secure too..
"says me who doesn't have a Paypal account and has never used ebay"
Me
But for about 10 euros I'm willing to take the risk, for more no..
Finally I found in France LM1875, but on Ebay too
In fact diy is very easy, if you find the components you expect !
I'll take the time to look again..
At this time, the best way is Farnell.
@ csom, nice project
Me
But for about 10 euros I'm willing to take the risk, for more no..
Finally I found in France LM1875, but on Ebay too
In fact diy is very easy, if you find the components you expect !
I'll take the time to look again..
At this time, the best way is Farnell.
@ csom, nice project
Hi all,
Lucky day, I found TDA2050 on a good french online shop !
It's on stock and I can order this.
Now, question is : may I can use the schematic in single rail for LM1875 with TDA2050.
This two chips seems similar ?
While I believe this page :
Single Chip 25W Amplifier (Project 72)
Thank's..
Lucky day, I found TDA2050 on a good french online shop !
It's on stock and I can order this.
Now, question is : may I can use the schematic in single rail for LM1875 with TDA2050.
This two chips seems similar ?
While I believe this page :
Single Chip 25W Amplifier (Project 72)
Thank's..
I use a bipole speaker system too. Quoted sensitivity is 91 Db 1 Watt 1 Meter. They are very much suited to low power amplifiers . have great bass weight and depth but also are very dynamic because of the small drivers very articuate too..... Chip amps and bipoles are a good combination LOTS! of bang per buck.. LOTS! Good for battry life too
Follow the circuit and application on the data sheet, either figure 1 or figure three depending on whether you want dual or single rail. In figure 3, R1 and R2 connect to R3 and not C1 (the little dots are not very clear on the pdf)
http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1461.pdf
http://www.datasheetcatalog.org/datasheet/stmicroelectronics/1461.pdf
Thank's Mooly, I note your comment..
So it looks good for the future
At this time I want shaw you a complete schematic of full system, to see if nothing was wrong about supply :
So it looks good for the future
At this time I want shaw you a complete schematic of full system, to see if nothing was wrong about supply :
An externally hosted image should be here but it was not working when we last tested it.
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