Now we're name calling..? Childish, my friend..
I have enough knowledge to know how long a battery is going to last. This isn't my first rodeo and not my issue..
Makes sense that a 4 ohm load is going to drain a battery faster than an 8 ohm load. If I don't get the length of usage I desire, add another battery! Duh.. No brainer..
**If it's that important for you to know, the batteries I use are between 6.8 aHr. to 20 aHr. @ 12 v.d.c. (10.5/12.6 Volts.. Depending on charge level) They will handle a surge draw of ~1 amp before the protection circuit kicks in. If I need more current capacity, I add another battery..
ICG.. Seems that you have no practical information to give me and I didn't come here to be ridiculed by some guy 1k+ miles away! It's obvious of your intent and I will not lower myself to your level.. (Where's a moderator when ya need one! Isn't this activity prohibited in the rules?)
And we wonder why noobs are afraid to post on this site..
I have enough knowledge to know how long a battery is going to last. This isn't my first rodeo and not my issue..
Makes sense that a 4 ohm load is going to drain a battery faster than an 8 ohm load. If I don't get the length of usage I desire, add another battery! Duh.. No brainer..
**If it's that important for you to know, the batteries I use are between 6.8 aHr. to 20 aHr. @ 12 v.d.c. (10.5/12.6 Volts.. Depending on charge level) They will handle a surge draw of ~1 amp before the protection circuit kicks in. If I need more current capacity, I add another battery..
ICG.. Seems that you have no practical information to give me and I didn't come here to be ridiculed by some guy 1k+ miles away! It's obvious of your intent and I will not lower myself to your level.. (Where's a moderator when ya need one! Isn't this activity prohibited in the rules?)
And we wonder why noobs are afraid to post on this site..
The forum asks you to keep it polite.
I already gave you a lot of practical information. On your current amplifier board, on the FM radio, on which other boards to buy. You just decided to be ignorant about it.
You ignore everything that's given on information and even after being pointed to the questions several times again, you still do not answer most important questions (about the speaker i.e.). You are absolutely uncooperative - And now you've got the nerve to complain?
No, not anymore.
Which class d amps have you used that caused FM interference? I'm wondering if the interference is a problem with the chip itself, or just an error in implementation?
The board you posted above (AliExpress tpa3116) to me has a couple obvious problems. First is they used the tpa3116 without a heatsink. This kind of design calls for the tpa3118 which is the same circuit, but with the heatsink interface down for using the PCB ground plane itself as the heatsink.
That said, if you're only supplying 12v, a simple/small glue-on heatsink will likely be sufficient (and hopefully you bought two you can run them in mono/pbtl mode).
But yeah, the tpa3116/8 needs an LC filter on it's output to avoid RF interference, and I didn't see any inductors on that board.
Now however the little brother of the tpa3116/8, the tpa3110 - that can be run with only ferrites on the output if the length of the cable is sufficiently short (30cm iirc).
Also, the tpa3116/8 has configurable switching frequency. So maybe changing the amp's Hz is another possible means of fixing the interference issue.
I can't remember, did you say how sensitive your speakers are? That's another angle to explore for lowering power requirements - higher efficiency speakers. I mean in terms of electrical efficiency, class d dominates everything else, with mature chips doing 90% or so. Class AB and A simply turn 50% or more of your battery power into heat. But if your speakers are super efficient, maybe the amp's electrical inefficiency becomes a non-issue.
There's always headphones
The Ali boards I refer to (TPA3116) are just something I seen with a good price so I decided to grab a couple to play with. I noticed they had no type of filtering. Direct feed from anything, not an FM receiver, seems to work..
Some examples - PAM8403.. PAM8406.. PAM8610.. TPA3116.. TPA3118.. TA2024..
All of the 5 volt boards were fed via USB bank batteries or regulated from a 12 volt source. (*My house battery) Any of the 12 volt applications were fed directly from my house battery (*8 - 6 volt Golf Cart batteries connected series/parallel) or LiPo battery packs, as listed above..
I have also discovered that some voltage regulators cause interference. Cell phone chargers are terrible! Laptop voltage converters! Even those little cheap lawn lights for a buck at discount stores! Not to forget A.C. inverters. Even my house battery charge controller puts crap in the lines during the day!!
As for speaker sensitivity, Things vary. Mostly in the 85dB/W area. Nothing expensive. Buyouts or car speakers. If they get too sensitive, bass is an issue, until I build a larger enclosure.. (Which defeats my goal) I'm just like all noobs.. Looking for the holy grail of big bass in a small box..
Efficiency is key. I understand digital amps win hands down but I want to find one that plays well with an FM receiver or a simple resolve. I've constructed some neat, great sounding units but I'm missing the FM function. If I don't include FM, I'm fine. Guess it's a challenge to have it, which makes the solution intriguing..
@ ICG..
Perhaps we got off on the wrong foot. I believe that you may have expected me to be more knowledgeable in the information that you provided or just a simple misunderstanding in language. I come here for knowledge and to be friendly with everyone. This is my open apology to you.
Some examples - PAM8403.. PAM8406.. PAM8610.. TPA3116.. TPA3118.. TA2024..
All of the 5 volt boards were fed via USB bank batteries or regulated from a 12 volt source. (*My house battery) Any of the 12 volt applications were fed directly from my house battery (*8 - 6 volt Golf Cart batteries connected series/parallel) or LiPo battery packs, as listed above..
I have also discovered that some voltage regulators cause interference. Cell phone chargers are terrible! Laptop voltage converters! Even those little cheap lawn lights for a buck at discount stores! Not to forget A.C. inverters. Even my house battery charge controller puts crap in the lines during the day!!
As for speaker sensitivity, Things vary. Mostly in the 85dB/W area. Nothing expensive. Buyouts or car speakers. If they get too sensitive, bass is an issue, until I build a larger enclosure.. (Which defeats my goal) I'm just like all noobs.. Looking for the holy grail of big bass in a small box..
Efficiency is key. I understand digital amps win hands down but I want to find one that plays well with an FM receiver or a simple resolve. I've constructed some neat, great sounding units but I'm missing the FM function. If I don't include FM, I'm fine. Guess it's a challenge to have it, which makes the solution intriguing..
@ ICG..
Perhaps we got off on the wrong foot. I believe that you may have expected me to be more knowledgeable in the information that you provided or just a simple misunderstanding in language. I come here for knowledge and to be friendly with everyone. This is my open apology to you.
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Definitely review the tpa3116/8 datasheet and see how the chip's switching frequency can be changed. It's worth a try I think.
Also, the tda7297 chip amp might be worth a try. See this thread. It's super cheap, so not a lot to lose. It's a class AB chip amp (not D), so won't be particularly efficient.
However, I have an amp based on this chip, the Folsom TDA7297. This is the same amp chip as the "lunch money" amp linked previously, just a premium implementation. But in both cases, this should be a purely linear amplifier, i.e. no high frequency switching circuits to pollute EMI.
I just hooked this up to my 4-ohm, 87 dB efficient speakers. I also have a Kill-a-Watt AC meter, so I can see how much juice this thing is actually pulling. Right now it reads 4 watts / 19 volt-amps, with occasional jumps to 5 watts / 21 volt-amps. The volt-amp number is probably more relevant for you running from batteries. I have a small room (10x11 feet, 9-foot ceiling), and have a preference for pretty moderate volume levels. So if you're trying to fill a bigger room and/or like it loud, you'll definitely need more power. But it gives you an idea. (And in fact, using the "lunch money" amp with direct DC power is a bit more efficient than this Folsom amp, because it loses some efficiency in AC to DC rectification, and also has an on-board capacitance multiplier.)
Now here's where it gets interesting: my normal amp in this role is based on the TI tpa3251 chip - another class D amp, basically TI's "next gen" class D tech after the tpa3116/8. See here - this amp uses basically the same amount of AC power, despite being a very efficient class D chip and powered by a similarly efficient switch-mode power supply. But, as I hinted to in my previous post, the efficiency isn't really seen until you get into somewhat more substantial power draw levels.
So given that, it's probably worth grabbing one of those cheap tda7297 "lunch money" amps from ebay or AliExpress. Presumably it won't affect your FM radio, and if the power draw doesn't drain your batteries too quickly, then the next step would be to do some mods to squeeze out some more performance, or consider something like the Folsom tda7297.
Also, the tda7297 chip amp might be worth a try. See this thread. It's super cheap, so not a lot to lose. It's a class AB chip amp (not D), so won't be particularly efficient.
However, I have an amp based on this chip, the Folsom TDA7297. This is the same amp chip as the "lunch money" amp linked previously, just a premium implementation. But in both cases, this should be a purely linear amplifier, i.e. no high frequency switching circuits to pollute EMI.
I just hooked this up to my 4-ohm, 87 dB efficient speakers. I also have a Kill-a-Watt AC meter, so I can see how much juice this thing is actually pulling. Right now it reads 4 watts / 19 volt-amps, with occasional jumps to 5 watts / 21 volt-amps. The volt-amp number is probably more relevant for you running from batteries. I have a small room (10x11 feet, 9-foot ceiling), and have a preference for pretty moderate volume levels. So if you're trying to fill a bigger room and/or like it loud, you'll definitely need more power. But it gives you an idea. (And in fact, using the "lunch money" amp with direct DC power is a bit more efficient than this Folsom amp, because it loses some efficiency in AC to DC rectification, and also has an on-board capacitance multiplier.)
Now here's where it gets interesting: my normal amp in this role is based on the TI tpa3251 chip - another class D amp, basically TI's "next gen" class D tech after the tpa3116/8. See here - this amp uses basically the same amount of AC power, despite being a very efficient class D chip and powered by a similarly efficient switch-mode power supply. But, as I hinted to in my previous post, the efficiency isn't really seen until you get into somewhat more substantial power draw levels.
So given that, it's probably worth grabbing one of those cheap tda7297 "lunch money" amps from ebay or AliExpress. Presumably it won't affect your FM radio, and if the power draw doesn't drain your batteries too quickly, then the next step would be to do some mods to squeeze out some more performance, or consider something like the Folsom tda7297.
I turned this up to a volume I consider fairly loud, around 85 db according to a free SLP meter smartphone app. The Kill-a-Watt isn't super precise, or fast, but just watching it for a few minutes, it never went above 15 watts / 30 volt-amps. I've been running it like this for over 3.5 hours, and the net power usage is 0.02kwh. Again, kwh may be a bit misleading for you, running off battery power. It's probably two or three times that for kv-amp hours.
Just throwing some numbers out there, hoping they might be useful for getting an idea what kind of power draw you could expect with a tda7297 amp.
A big "DUH" moment.. Thanks matt_garman!
I have a couple of these laying around and never considered them!
Amazon.com: SODIAL(R) AC/DC 9V-15V/12V 15W+15W TDA7297 Version B Dual Channel Amplifier Board Module: Car Electronics
Maybe the fact that they create heat made me side track them. I threw them on the back burner a couple of years ago, before my Bluetooth days.. (I'm still evolving from the stone age)
I did look at the TPA31XX data sheet and the sw.freq. change. For what I gather, the change was focused on AM broadcast subcarrier noise in an AM receiver in different parts of the band. Maybe the harmonics could alter FM issues too?
I've never really modified or built any amps from scratch. I did find a solution to the sw. freq. getting into the sub vol. control on these boards..
2.1 Hi-Fi Class D Audio Amplifier Board 2 x 15W + 30W 10-18 VDC
Cut the trace to the wiper pin on the board right where the pins from the connector go through the board. Install a 80 ohm surface mount resistor across the cut. (Using the solder pad of the pin for one connection to the resistor) Install a .02 pF. surface mount cap across the wiper pin and the common pin at the base of the connector on the solder side. (Across the pin solder pads) Works fine! (My BIG contribution to the modification world.. LOL)
You can bet that I'll be brushin' the dust off those amps I put in the corner. Thanks for the brain food!
BTW.. I did find a really nice unit that fits my needs but the wattage is a little to small but they work wonderful for a quick portable solution. I use a 12/5 volt regulator from a 12 volt LiPo battery and the little bugger will run for days! (The FM receiver is fantastic!)
New Mini 5V MP3 Decoder Board Bluetooth Call Decoding Module MP3 WAV U Disk & TF Card USB With 2*3W Amplifier Remote Controller-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
I have a couple of these laying around and never considered them!
Amazon.com: SODIAL(R) AC/DC 9V-15V/12V 15W+15W TDA7297 Version B Dual Channel Amplifier Board Module: Car Electronics
Maybe the fact that they create heat made me side track them. I threw them on the back burner a couple of years ago, before my Bluetooth days.. (I'm still evolving from the stone age)
I did look at the TPA31XX data sheet and the sw.freq. change. For what I gather, the change was focused on AM broadcast subcarrier noise in an AM receiver in different parts of the band. Maybe the harmonics could alter FM issues too?
I've never really modified or built any amps from scratch. I did find a solution to the sw. freq. getting into the sub vol. control on these boards..
2.1 Hi-Fi Class D Audio Amplifier Board 2 x 15W + 30W 10-18 VDC
Cut the trace to the wiper pin on the board right where the pins from the connector go through the board. Install a 80 ohm surface mount resistor across the cut. (Using the solder pad of the pin for one connection to the resistor) Install a .02 pF. surface mount cap across the wiper pin and the common pin at the base of the connector on the solder side. (Across the pin solder pads) Works fine! (My BIG contribution to the modification world.. LOL)
You can bet that I'll be brushin' the dust off those amps I put in the corner. Thanks for the brain food!
BTW.. I did find a really nice unit that fits my needs but the wattage is a little to small but they work wonderful for a quick portable solution. I use a 12/5 volt regulator from a 12 volt LiPo battery and the little bugger will run for days! (The FM receiver is fantastic!)
New Mini 5V MP3 Decoder Board Bluetooth Call Decoding Module MP3 WAV U Disk & TF Card USB With 2*3W Amplifier Remote Controller-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
An observation:
If you would "invest" (as you have in batteries) in some *sensitive* speakers, your electric power needs could be 1/10th of what you need now. Yes, this does mean "large" cone and box to cover the lower half of the spectrum. But it is arguable that, if you listen a lot, the reduced battery wear will pay-off large boxes and cones. (Of course if you have to expand your house to fit a foot-wide speaker, it does not make sense; though you could mount a concrete *horn* outside the house and have stunning electroacoustic efficiency and sub-Watt power needs.)
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I love the horn! ~1/4th of my house is already dedicated to water storage. A couple of feet here and there is no problem.. LOL.. Someday I'm sure..
I've constructed systems that are sufficient for my needs. I went micro voltage (~3v.d.c.) and constructed a Bluetooth mono system that operates on 2 - "D" Alkaline cells that will operate for weeks. Many using 5 volt bank batteries. These units are very nice..
Free Shipping!!! 5V 2.1 + 3D Surround subwoofer / mini amplifier board / USB subwoofer / Electronic Component-in Capacitors from Electronic Components & Supplies on Aliexpress.com | Alibaba Group
As for efficient drivers..(Not to derail this thread and perhaps start another)
I must question the advantage of paying a high price for a driver with the same sensitivity rating as one at a much lower price! I understand the specs on the lower cost drivers may be "Fudged" to make them look more appealing but couldn't this hold true for the pricy drivers to make the buyer feel better about the investment? Tonal qualities may be better in the higher priced units but is the difference really worth the difference in the cost?
I don't feel confident enough to purchase a high dollar driver to find out for myself, although I have listened to some expensive drivers and wasn't all that impressed compared to some of the budget units that I have constructed. If there is a distinct difference, in overall performance percentage numbers, it appears to be small, IMO..
3 of the biggest design discoveries that has changed my world.. Enclosure design/damping, the fantastic BSC circuit, and somewhat mastering the Piezo driver. Trust me.. If one takes the time, a silk purse CAN be made from a sows ear..
Update
I connected the A/B amp to one of these..
Newest TF Radio MP3 Decoder Board 5V/12V Micro USB Power Supply Audio Module for Car Remote Music Speaker-in MP3 Player from Consumer Electronics on Aliexpress.com | Alibaba Group
Connected to a 6.8 aHr. LiPo with isolation between the two. Works great!
I connected the A/B amp to one of these..
Newest TF Radio MP3 Decoder Board 5V/12V Micro USB Power Supply Audio Module for Car Remote Music Speaker-in MP3 Player from Consumer Electronics on Aliexpress.com | Alibaba Group
Connected to a 6.8 aHr. LiPo with isolation between the two. Works great!
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Very interesting.
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00001048.pdf
Look at figure 8 "Output Power vs Supply voltage." About 6 watts/channel from 12 volts; 10 watts/channel from 15 volts, with 8 ohm speakers.
With efficient speakers, this will be a decent amount of power.
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00001048.pdf
Look at figure 8 "Output Power vs Supply voltage." About 6 watts/channel from 12 volts; 10 watts/channel from 15 volts, with 8 ohm speakers.
With efficient speakers, this will be a decent amount of power.
This is the driver..
http://www.newark.com/mcm-custom-audio/50-14020/6-1-2-single-point-stereo-ceiling/dp/20T8743
It's mounted in a 2' internal enclosure and the port is 3" square. (12"x12"x24") Some internal bracing, a little fiberglass with a coat of spray on bed liner. Sounds a little muddy indoors but fantastic outdoors..
My goal is a unit to take to the drive-in movies. I easily get my entrance fee back jump starting cars before I leave! Yeah.. The Stink Finger Stadium can be profitable and fun..
They transmit the audio via an FM transmitter. (They need some guidance on levels and spectrum input!) I'm workin' with 'um..
There isn't anything from the big box stores in the $100 price range that can touch this thing..
http://www.newark.com/mcm-custom-audio/50-14020/6-1-2-single-point-stereo-ceiling/dp/20T8743
It's mounted in a 2' internal enclosure and the port is 3" square. (12"x12"x24") Some internal bracing, a little fiberglass with a coat of spray on bed liner. Sounds a little muddy indoors but fantastic outdoors..
My goal is a unit to take to the drive-in movies. I easily get my entrance fee back jump starting cars before I leave! Yeah.. The Stink Finger Stadium can be profitable and fun..
They transmit the audio via an FM transmitter. (They need some guidance on levels and spectrum input!) I'm workin' with 'um..
There isn't anything from the big box stores in the $100 price range that can touch this thing..
I don't think you can beat that speaker for the price.
In your car you can use a mobile power amplifier. I've seen them as cheap as $40 with RCA inputs. More power than your little unit, even into 8 ohm speakers. Draws more power too. I'd recommend you use a car power amplifier for your house too, but it would pull the battery down real fast. Plus some car audio electronics shuts off if the voltage goes below 12 volts - I ran into this problem when installing a stereo in a boat.
So you have a redneck 12 volt boombox for about $40. Not bad.
In your car you can use a mobile power amplifier. I've seen them as cheap as $40 with RCA inputs. More power than your little unit, even into 8 ohm speakers. Draws more power too. I'd recommend you use a car power amplifier for your house too, but it would pull the battery down real fast. Plus some car audio electronics shuts off if the voltage goes below 12 volts - I ran into this problem when installing a stereo in a boat.
So you have a redneck 12 volt boombox for about $40. Not bad.
I'm happy with 15 watts or less. One doesn't need huge wattage for good personal sound..
I tried the auto amps in the past. They are just power hogs and not that impressive for my situation. If I wanted to provide sound for a large group of people, then maybe..
My "Redneck Boombox" costs a little more than $40 in total. The battery costs ~$30 on its own! Perhaps $55-$60 in total, including the bed liner spray and all the other little stuff. (OSB, Bracing, Fiberglass, Screws, ect..)
I thank matt_garman for shakin' my brain cells to remember those amps I threw in the closet. They may not be as efficient with the battery but they solved my problem! Ran my unit for ~6 hrs. yesterday at a decent volume with no issue. I can combine the power leads from both units (Head and Amp) to a female chassis jack and then daisy chain as many batteries as I need..
It was a labor of love and I enjoy the results. Not quite finished yet but I'm sure it will outlast the garbage sold with the passive radiators that starts to fart out in about a year..
I tried the auto amps in the past. They are just power hogs and not that impressive for my situation. If I wanted to provide sound for a large group of people, then maybe..
My "Redneck Boombox" costs a little more than $40 in total. The battery costs ~$30 on its own! Perhaps $55-$60 in total, including the bed liner spray and all the other little stuff. (OSB, Bracing, Fiberglass, Screws, ect..)
I thank matt_garman for shakin' my brain cells to remember those amps I threw in the closet. They may not be as efficient with the battery but they solved my problem! Ran my unit for ~6 hrs. yesterday at a decent volume with no issue. I can combine the power leads from both units (Head and Amp) to a female chassis jack and then daisy chain as many batteries as I need..
It was a labor of love and I enjoy the results. Not quite finished yet but I'm sure it will outlast the garbage sold with the passive radiators that starts to fart out in about a year..
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