Hello,
Could you please help in choosing audio amplifier IC for DIY home speaker system?
I am thinking of this because I am not happy with my TV sound which doesnot have equalizer options.
Q. how many watts system do I need?
When looking at my TV specs, it has 10w+10w speakers, and when increasing the volume it gets sufficiently loud. So I am thinking 20w per channel speaker system will be enough for me. Please comment if my understanding is ok
Q. Which amplifier IC to use for the speaker system?
I am looking for a Class D/T amplifier, thinking that they are more efficient and cooler, so i can get a smaller power supply and no or small heat sink, and overall a compact system.
Please comment if my thinking is ok or do I need to consider a Class AB amplifier IC also?
Looking at various forums and reviews, i could see below ICs getting good reviews:
tripath amp ICs like TA2020, TA2024, TA2021, TK2050 etc.
maxim amp IC MAX98400
IR amp IC IR2092
and some TI and analogCircuit Class D ICs.
Please comment, currently which IC will be good to use for good sound quality. It need not be very cheap if gives good sound quality.
Q. For equalizer, what is the better option :
i. between the audio source and the main amplifier (filtering before amplification), using:
a. passive filters
b. active filters using opamps
ii. using crossover circuits between main amplifier and speakers (ie. filtering after amplification)
thanks and regards
S Sarath
Could you please help in choosing audio amplifier IC for DIY home speaker system?
I am thinking of this because I am not happy with my TV sound which doesnot have equalizer options.
Q. how many watts system do I need?
When looking at my TV specs, it has 10w+10w speakers, and when increasing the volume it gets sufficiently loud. So I am thinking 20w per channel speaker system will be enough for me. Please comment if my understanding is ok
Q. Which amplifier IC to use for the speaker system?
I am looking for a Class D/T amplifier, thinking that they are more efficient and cooler, so i can get a smaller power supply and no or small heat sink, and overall a compact system.
Please comment if my thinking is ok or do I need to consider a Class AB amplifier IC also?
Looking at various forums and reviews, i could see below ICs getting good reviews:
tripath amp ICs like TA2020, TA2024, TA2021, TK2050 etc.
maxim amp IC MAX98400
IR amp IC IR2092
and some TI and analogCircuit Class D ICs.
Please comment, currently which IC will be good to use for good sound quality. It need not be very cheap if gives good sound quality.
Q. For equalizer, what is the better option :
i. between the audio source and the main amplifier (filtering before amplification), using:
a. passive filters
b. active filters using opamps
ii. using crossover circuits between main amplifier and speakers (ie. filtering after amplification)
thanks and regards
S Sarath
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The sound quality of a chip has mostly to do with its support circuit (amplifier board + components + power supply). In theory, any audio IC chip could work fine if it were properly supported and not incomplete.
For example, the peakish LM3886 sounds just fine on the MyRef Fremen amplifier board.
A rather easy project with 22 watts per channel is the LM1875 QK50 kit or K50 kit. Some of the resistor values and one of the cap values is inappropriate. But that is easily swapped for values, like those on the LM1875 schematic in my signature line. I would also suggest two of the made-for K50 power boards and two of 36va transformers so you can make monoblocs. The reason to make monoblocs with 36va transformers for LM1875 is this: 36VA*0.62=22 Watts. Thus we can avoid putting more in than can come out. Also stereo separation is more fun with monoblocs. Monoblocs = pair of 1 channel amplifiers. This is also less complicated--make one that works and then copy it.
Edit: Also suitable is Dual Mono, which is the same electronically, but there is only one amplifier enclosure.
On your second question, an improved speaker crossover (which is merely driven like the speaker) doesn't remove as much detail as line level options like inserting a baxandall or retail equalizer (the effects of which are exposed to the amplifier's gain).
For example, the peakish LM3886 sounds just fine on the MyRef Fremen amplifier board.
A rather easy project with 22 watts per channel is the LM1875 QK50 kit or K50 kit. Some of the resistor values and one of the cap values is inappropriate. But that is easily swapped for values, like those on the LM1875 schematic in my signature line. I would also suggest two of the made-for K50 power boards and two of 36va transformers so you can make monoblocs. The reason to make monoblocs with 36va transformers for LM1875 is this: 36VA*0.62=22 Watts. Thus we can avoid putting more in than can come out. Also stereo separation is more fun with monoblocs. Monoblocs = pair of 1 channel amplifiers. This is also less complicated--make one that works and then copy it.
Edit: Also suitable is Dual Mono, which is the same electronically, but there is only one amplifier enclosure.
On your second question, an improved speaker crossover (which is merely driven like the speaker) doesn't remove as much detail as line level options like inserting a baxandall or retail equalizer (the effects of which are exposed to the amplifier's gain).
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if you have old crt tv what is not working you can pull out amplifier ic , find datasheet and build that , that chips are usualy stereo on one chip with 2*10-20w what is more than enough for home use if you ask me ... and with dual mono blocks stereo separation that is hardly noticeable but thats just my opinion (i like simpler stereo on one ic if i would do dual mono that will be something discrete ) i find lm3886/75 chips that are targeting diy population intentionaly to make money to texas instruments...i prefer tda chips like 7294 what is cheaper a lot at least where i live
also i would reccomend tda 7265 thats stereo 15w and simple to make p2p
edit: just found this http://www.ebay.com/itm/NEW-TDA7294..._Audio_Amplifiers_Preamps&hash=item51b0040ad1
this looks like it has eq and also a extra sub channel i hope with crossover
and this would i take on your place :
http://www.ebay.com/itm/New-30W-2-D...178?pt=LH_DefaultDomain_0&hash=item3a86707552
forget d-class it just doesnt sound right no matter what people of this forum say..and as i like to switch my speakers there is lot diffrence on 4/6/8 ohms speakers on d class amps most are made for 8 ohms speakers(filter problems i suppose) so i use it for sub channels only(0>80hz only)
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Yes.
Yes,
TDA7265 + bass, treble, volume
Also, I see signetics and regs in the photo, and that's good news too.
P.S.
For best results, we could de-solder the blue screw block terminals that don't grip reliably, and instead, just solder the input and output cables to the board securely.
Thanks for the inputs.
To compare different amplifier ICs, looked at their datasheets. But there was not much difference in the graphs of "THD+noise vs output power" , "THD vs frequency" for ICs: TA2020, TK2050, TPA3116, LM1875, TDA7265. For all of these the THD was at least below 0.1% across the output power values under the given max for the chip. Among these graphs TK2050 was looking very slightly better than others (near 0.01 %).
Can we use above observation in selecting the IC? But it shows all were more or less similar.
thanks and regards
S Sarath
To compare different amplifier ICs, looked at their datasheets. But there was not much difference in the graphs of "THD+noise vs output power" , "THD vs frequency" for ICs: TA2020, TK2050, TPA3116, LM1875, TDA7265. For all of these the THD was at least below 0.1% across the output power values under the given max for the chip. Among these graphs TK2050 was looking very slightly better than others (near 0.01 %).
Can we use above observation in selecting the IC? But it shows all were more or less similar.
thanks and regards
S Sarath
.
I might as well toss in my 2 cents, although some will demand change back.
Audio Quality: This is not an issue, which is the point with little black chips in the first place. A tenth of a percentage point here and there is not audible, partly because the speakers (any speakers) introduce far more distortion than any chip amp possibly could.
Power Supply: You can never use "a smaller power supply," and if you do audio quality will suffer. For a 20 watt (VA) amp, use a 30 watt power supply.
Class A, Class D, Class Whatever: With vacuum tubes class this or that is significant, but usually not with little black chips. The power supply transformer and capacitors take up far more space than the chip's heat sink will unless you're running really high power. Like the man says, watts is watts, and if you're running a 20 watt amp, then you're going to have to deal with that amount of heat, no way around it.
With class, an additional factor is the complexity of the circuit. You'll do best by a mile to stick with a simple(ish) factory circuit.
Equalizer: These don't take much power in, and don't put much power out. You'll be using the headphone, or line-out, connector on your TV, so probably you'll want:
TV ~> buffer with gain ~> active equalizer with preamp ~> amp
The buffer, equalizer, and preamp are usually all one unit. No reason the amplifier can't be in the same box also.
Crossover networks are not filters per se. They divide an amp's output to feed high (tweeter) or low (woofer) frequency speakers. If there's a sub-bass it has its own amp.
The selection of amplifier chips seems to me something of a no-brainer. Up to 30 watts use an LM1875, up to 60+ watts use an LM3886. These are pretty much the world standard, "the way you do it," what could possibly be the point of running anything else?
The big deal with these two chips is that they're available, affordable, they produce excellent audio, and the circuits are about as simple as electronic circuits can get. These are the reasons for the "chip amp" in the first place.
I've attached a redrawn schematic for an LM1875 because I flatter myself it's a bit easier to read than the data sheet schematic. I'm also attaching a representative (only that) schematic for a dual power supply.
With these chips power output is determined by the voltage of the power supply. The data sheet has a voltage/output chart. Bear in mind that the chart refers to a plus-and-minus dual power supply, and that AC voltage rectifies to a higher DC voltage.
VERY IMPORTANT: The amp you're running now is almost certainly 10 watts per channel "music power." This "music power" is an advertising term with, conveniently, no legal definition. The real power you're listening to is probably about 6 watts per channel max, which as a matter of fact is about all that ever gets used in an average living room. But you'll be using new, larger speakers? My own prejudice is that 20 watts (per channel) will do the job in any average size room. Nothing really wrong with 15 if you're not a metal head, but the cost is about the same as 20, so what the heck.
.
I might as well toss in my 2 cents, although some will demand change back.
Audio Quality: This is not an issue, which is the point with little black chips in the first place. A tenth of a percentage point here and there is not audible, partly because the speakers (any speakers) introduce far more distortion than any chip amp possibly could.
Power Supply: You can never use "a smaller power supply," and if you do audio quality will suffer. For a 20 watt (VA) amp, use a 30 watt power supply.
Class A, Class D, Class Whatever: With vacuum tubes class this or that is significant, but usually not with little black chips. The power supply transformer and capacitors take up far more space than the chip's heat sink will unless you're running really high power. Like the man says, watts is watts, and if you're running a 20 watt amp, then you're going to have to deal with that amount of heat, no way around it.
With class, an additional factor is the complexity of the circuit. You'll do best by a mile to stick with a simple(ish) factory circuit.
Equalizer: These don't take much power in, and don't put much power out. You'll be using the headphone, or line-out, connector on your TV, so probably you'll want:
TV ~> buffer with gain ~> active equalizer with preamp ~> amp
The buffer, equalizer, and preamp are usually all one unit. No reason the amplifier can't be in the same box also.
Crossover networks are not filters per se. They divide an amp's output to feed high (tweeter) or low (woofer) frequency speakers. If there's a sub-bass it has its own amp.
The selection of amplifier chips seems to me something of a no-brainer. Up to 30 watts use an LM1875, up to 60+ watts use an LM3886. These are pretty much the world standard, "the way you do it," what could possibly be the point of running anything else?
The big deal with these two chips is that they're available, affordable, they produce excellent audio, and the circuits are about as simple as electronic circuits can get. These are the reasons for the "chip amp" in the first place.
I've attached a redrawn schematic for an LM1875 because I flatter myself it's a bit easier to read than the data sheet schematic. I'm also attaching a representative (only that) schematic for a dual power supply.
With these chips power output is determined by the voltage of the power supply. The data sheet has a voltage/output chart. Bear in mind that the chart refers to a plus-and-minus dual power supply, and that AC voltage rectifies to a higher DC voltage.
VERY IMPORTANT: The amp you're running now is almost certainly 10 watts per channel "music power." This "music power" is an advertising term with, conveniently, no legal definition. The real power you're listening to is probably about 6 watts per channel max, which as a matter of fact is about all that ever gets used in an average living room. But you'll be using new, larger speakers? My own prejudice is that 20 watts (per channel) will do the job in any average size room. Nothing really wrong with 15 if you're not a metal head, but the cost is about the same as 20, so what the heck.
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Attachments
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<< why do you promote this PSU design? >>
My intention is to bring some clarity to the subject.
<< I don't think it is the best option for a chip-amp >>
OK by me. But that statement doesn't really give any information about power supplies. It would probably be more helpful to readers of this forum if you explained your objection, and offered your preferred alternative.
Or if you're referring to toroid power transformers, in my view they're a complete rip. Although they do prove (yet again) that good advertising can overcome good sense.
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<< why do you promote this PSU design? >>
My intention is to bring some clarity to the subject.
<< I don't think it is the best option for a chip-amp >>
OK by me. But that statement doesn't really give any information about power supplies. It would probably be more helpful to readers of this forum if you explained your objection, and offered your preferred alternative.
Or if you're referring to toroid power transformers, in my view they're a complete rip. Although they do prove (yet again) that good advertising can overcome good sense.
.
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<< Most of the better amps have a PSU that resembles something like this...It has a cleaner ground and if implemented correctly it will reduce ground loops with multichannel amps. >>
Cleaner ground, reduced ground loops, and used in most of the better amps. Well heck, I'm sold.
On the other hand, I don't know what this particular ground is cleaner than, but I think "reducing" ground loops is something of a exercise in futility. One ground loop puts an amp out of action, so reducing them is not the idea at all, you want to eliminate them. Or not want to, got to.
In any case I wish you'd explained what "implemented correctly" means, and what happens if you implement incorrectly. Without this knowlege the whole thing seems something of a crapshoot.
Hey, just messing with you. I'm sure the circuit you posted works fine. But I don't personally agree that the added complexity has any real-world benefits.
Much more importantly, as they say on Madison Avenue, consider your target audience. I think in cases like this the KISS rule very much applies.
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<< Most of the better amps have a PSU that resembles something like this...It has a cleaner ground and if implemented correctly it will reduce ground loops with multichannel amps. >>
Cleaner ground, reduced ground loops, and used in most of the better amps. Well heck, I'm sold.
On the other hand, I don't know what this particular ground is cleaner than, but I think "reducing" ground loops is something of a exercise in futility. One ground loop puts an amp out of action, so reducing them is not the idea at all, you want to eliminate them. Or not want to, got to.
In any case I wish you'd explained what "implemented correctly" means, and what happens if you implement incorrectly. Without this knowlege the whole thing seems something of a crapshoot.
Hey, just messing with you. I'm sure the circuit you posted works fine. But I don't personally agree that the added complexity has any real-world benefits.
Much more importantly, as they say on Madison Avenue, consider your target audience. I think in cases like this the KISS rule very much applies.
.
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What kind of TV do you currently have? I have a fairly generic Visio and found that it had a TDA2020 amp already inside it. The speakers were by far the most limiting factor. All I did was cut the wires and wire the amp leads to plugs I installed on the bottom of the TV and now I use "real" speakers. The sound is so much better, and the solution so much simpler.
<< All I did was cut the wires and wire the amp leads to plugs I installed on the bottom of the TV and now I use "real" speakers. >>
Whoa! Sounds like a very good idea. The engineers put the best speakers they can into they space they have available, but that space is pretty much zero so what can you do?
Now that you make me think, there's also such a thing as "powered speakers," which are simply what the name implies: speakers with an amp built into the speaker cabinet (back to the future, shades of the 50s). These would plug directly into the headphone connection on the TV (headphone connectors are low impedance).
I guess the cost would be much more, or maybe not so much, depending on what the final plan turns out to be.
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Whoa! Sounds like a very good idea. The engineers put the best speakers they can into they space they have available, but that space is pretty much zero so what can you do?
Now that you make me think, there's also such a thing as "powered speakers," which are simply what the name implies: speakers with an amp built into the speaker cabinet (back to the future, shades of the 50s). These would plug directly into the headphone connection on the TV (headphone connectors are low impedance).
I guess the cost would be much more, or maybe not so much, depending on what the final plan turns out to be.
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Fenris,
was the modified TV a double insulated product?
If so, then you are risking your life by bringing ClassII product wiring to the outside.
We in the UK are not allowed to modify ClassII products.
I presume that other Countries will have similar prohibitions to protect their populations.
was the modified TV a double insulated product?
If so, then you are risking your life by bringing ClassII product wiring to the outside.
We in the UK are not allowed to modify ClassII products.
I presume that other Countries will have similar prohibitions to protect their populations.
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