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New member Username: MeideolianPost Number: 2 Registered: Apr-18 | Hello, Could you please help in choosing a audio amplifier IC for building DIY home speakers (2.1 system)? Whether to go for class AB amplifier like LM1875 or TDA7295. Or go for a class D/T amplifier like TPA3116 or TA2020 or TK2050 etc. Looking at the datasheets of these class-AB and class-D amplifiers, the performance are looking similar, referring the graphs for THD+noice vs frequency and output power etc. For all of these the THD was at least below 0.1% across the output power values under the given max for the chip. "THD vs Frequency" graphs were more smoother for TK2050, and LM1875 and on TPA3116 graphs THD was bit higher at around 5KHz region. From what I have read, class-D is more efficient and so I may have a smaller power supply driving it and will have smaller or no heat sink. Thus a overall compact and small amplifier will result. But heard they have some EMI issues. On the other hand with class-AB amplifier, sound quality will be very good and not sure if these currently available class-D amplifier are producing such sound quality. But they need bigger power supply as they are less efficient, and need a bigger heat sink, so overall it will be bit bulky. Please help in selecting the suitable amplifier IC for DIY 2.1 channel home speaker system. thanks and regards, Elijah |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 18521 Registered: May-04 | . Elijah, you're looking at the gain stage as an individual element removed from all other components in the reproduction chain. While you cannot fully divorce yourself from inspecting each part of the system, by doing so you divorce each piece from its function as a link in a successful chain capable of supporting the weight of much more than THD alone. "For all of these the THD was at least below 0.1% across the output power values under the given max for the chip. 'THD vs Frequency' graphs were more smoother for TK2050, and LM1875 and on TPA3116 graphs THD was bit higher at around 5KHz region." IMO this is BS. You're starting out on the wrong foot and, once you commit to this route, you can only head further into the weeds until you can no longer see the ultimate goal - which is reproducing music as it was created by the artists. No music is constructed, or performed, with THD in mind. Most $200 solid state mass market receivers have specs for THD and FR that are no worse. THD only tells you how to get to Lubbock. Turn left. FR does not tell you about slew rates, rise times, power bandwidth, squarewave response or other significant issues which should be judged objectively in any amplifier design to detect its flaws. Not its successes, only its flaws. And, if the measurement looks bad but the music sounds right, trust the music. Then go looking for the right measurement to instruct you and to teach you how to look and, more importantly, how to see. No measurement taken on a conventional testbench can predict the electronic stage's performance under a real world load, under real world conditions of signal source. Music is dynamic and temporal. Tests and measurements do not reflect what the stage is being asked to do within a chain of music reproducion components. Therefore, tests and measurement do not tell the end user what they need to know. They can only inform the user of the results under test - and you don't use music to test and measure any amplifier on a bench. Measurements only confirm, they do not inform. If you have yet to signify what load the amplifier will work into, then you are simply doing mental masturb@tion with your amplifier questions. Use a class D amp with a battery power supply to start. Do not get hung up on the "class" of the output devices. Any half way decent component can be made to work well in isolation if you pour enough time, money and effort into the system - which, on your end, includes system set up and room treatment. Listen and then make adjustments. That's how you build a successful music system. You begin with the music and say, "f### it", to all the numbers. In other words, if you do not know the difference between a rock and roll shuffle beat and a blues shuffle beat, you are reading the ending chapters of the book without any of the preceding exposition, tension and release. What you want is to come to a conclusion without asking the questions first. Without learning how to ask the right questions to achieve the most correct answer. If you are not at this time intimately familiar with the sound and emotional impact of live music played in front of you in a real world venue, then you have missed the most important component in the equation. The system is only there to support the music, not the other way around. Nothing else matters. Learn about music first. Without that knowledge, you are flying blind when putting together a successful music reproduction system. Consider this, good electrical engineering is timeless. Many a 60 year old vacuum tube amplifier can be said to offer music reproduction which has not been bettered in the intervening six decades. Why would that be? Sixty years ago, designers had very "simple" goals, to build a gain stage that did not interfere with the music. Specs were simply guide posts, not goals themself. Today, any second semester EE student can build a gain stage that measures well. There's literally no magic in that. Imaging, soundstaging and a "palpable presence" were not goals before they became goals of the uneducated and uninformed reader. When they became goals, music ceased to be the only goal that mattered. Today, people who want imagaing attend a live concert to determine whether the "real thing" images as well as their system does. That is ludicrous! Sixty years ago, these values occurred when the music was served first and foremost. They were not goals unto themself, they simply were. They were not the result of direct injecting a guitar's output into the mixing board and they were not the result of close mic'ing a performer or of riding the gain levels of the board. There were no such things sixty years ago. Sixty years ago, musicians gathered in front of the microphones and they performed as though they were playing a live performance. Imaging, soundstaging, depth and so forth were not thought of as distinct values used to judge a system's performance, only the music mattered. They were a component of the live event but they were not the event itself, as they exist today in the mind of the average "audiophile". Listen to a superior amplifier designed to simply pass music through without interference to understand what these values truly are as a part of music's power. Then do some research to find how each value individually became larger than the music itself. The theme of that story is that music doesn't matter, only a writer's influence is what matters when you introduce "imaging" and "depth" to the goals of a sound system. More importantly, THD tells you nothing about an amplifier's ability to image or display depth. To achieve their end goals in 1961, you can bet each well respected audio designer of the day was attending live concerts, as they attended a live music performance as often as possible. They understood the idea that even a fifth grade school recital provided them important clues into how music works on the human system. Specs were only on paper goals, not the be all and end all of a design. No amplifier left the shop of these designers without meeting the individual designer's concept of how music affected them. Measurements only served to confirm they had done their work with significant errors. Measurements confirmed the idea that extending the gain stage's power bandwidth to 150kHz +/- 0.5dB benefited the music in a way which also benefited the listener. Start there, class D with a battery, keep the music as your one overriding goal for the system and you can't go wrong. . |
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New member Username: MeideolianPost Number: 3 Registered: Apr-18 | Hello Jan, Thanks for your speedy reply, also a brilliant one, i am very appreciate it, most impressive: "keep the music as your one overriding goal for the system and you can't go wrong" Copy that, i will keep that in mind surely. Thanks again Jan. |
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New member Username: MeideolianPost Number: 4 Registered: Apr-18 | Jan, I am trying to build is for home purpose, to connect it to my TV for movies and to my mobile for songs. My TV is having 10w+10w speakers and if raised to high volume it gets sufficiently loud. So thinking a 20w+20w+20w speaker system will be sufficient. Please comment if my understanding on watts required is ok. Regarding the power supply for the amplifier, thinking if i can use the 65w, 19.5v laptop power supply. Is it ok or its better to go for transformer based linear power supply? Regarding speakers, I was thinking to use car speakers, as here we can get branded car speakers like from JBL, sony etc, with 4ohm, rms 30w, and 90 - 93db sensitivity (which seems to be good sensitivity which will give loud sound with relatively less power). With branded speakers we may trust the quality of the speakers(i guessed). Best regards, Elijah |
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Platinum Member Username: Jan_b_vigneDallas, TX Post Number: 18522 Registered: May-04 | . "I am trying to build is for home purpose, to connect it to my TV for movies and to my mobile for songs. My TV is having 10w+10w speakers and if raised to high volume it gets sufficiently loud. So thinking a 20w+20w+20w speaker system will be sufficient. Please comment if my understanding on watts required is ok. Regarding the power supply for the amplifier, thinking if i can use the 65w, 19.5v laptop power supply. Is it ok or its better to go for transformer based linear power supply? Regarding speakers, I was thinking to use car speakers, as here we can get branded car speakers like from JBL, sony etc, with 4ohm, rms 30w, and 90 - 93db sensitivity (which seems to be good sensitivity which will give loud sound with relatively less power). With branded speakers we may trust the quality of the speakers(i guessed)." Using the same loudspeaker, you will need to add approximately 10 times the power to play approximately twice as loud. Adding power in terms of watts tend to go to the top volume peaks, preventing them from clipping the amp. The average SPL remains the same but the peaks are cleaner. If you want higher SPL's buy more sensitive speakers. Going from a 90dB @ 1 watt speaker to a 93dB speaker is the equivalent to doubling the amplifier wattage. Don't jerry rig the power supply. Speakers are not one single impedance load. Make sure the speaker does not dip beneath 4 Ohms at any frequency and make sure your amplifier can deal with low impedance loads. Most chip based amplifiers will react to impedance values. . |
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Gold Member Username: MagfanUSA Post Number: 3486 Registered: Oct-07 | I use a Parts Express DTA-1 for my 'Garage System'. With my iPhone as music source. The speakers were some 'cast off' which I had used a decade or more ago in a surround sound experiment. Specs Unknown. THEY say 15x2 but that's optimistic and at higher distortion. Going for 25$ these days But in the garage? Gets plenty loud enough using the wall wart power supply and the phone BELOW maximum output. With proper input, I could see this working for your TV listening needs. It actually sounds pretty good and I'd expect it to really shine with some very high sensitivity speakers. It would be fun to hook it up to something like a pair of KlipschHorns or other 100db sensitive speaker. |
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Gold Member Username: MagfanUSA Post Number: 3487 Registered: Oct-07 | If you are bound and determined to go Full-DIY? Go to Elliot Sound Products and graze around. Several amps in your category. They'll sell you JUST the board and you can source the rest yourself OR maybe even get an entire kit? |
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Gold Member Username: Joe_cAtlanta, GA USA Post Number: 1477 Registered: Mar-05 | Or you could take the $$ you would spend on DIY and buy a vintage amp - like Jan said - they dont make them like they used to should be able to pick up a used 80's NAD PE (power envelope) amp for <200 - maybe even <100 on CL |
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Bronze Member Username: FertooosFratees, Aklan Филипп... Post Number: 11 Registered: Dec-19 | Elijah, you're looking at the gain stage as an individual element removed from all other components in the reproduction chain. While you cannot fully divorce yourself from inspecting each part of the system, by doing so you divorce each piece from its function as a link in a successful chain capable of supporting the weight of much more than THD alone. |