I'm very new to this forum, and after a fair amount of reading and a little bit of impulsive posting, I decided I need to ask for some advice. Thanks in advance for braving to read this whole post, I can get a little long winded 🙁.
I have a background in music and audio, and I'm currently studying electronics. I have access to a nice soldering setup w/microscope, so soldering surface mount chips is not out of the question if that's the best answer. I have not, however, built an amp before. I do have enough experience playing around with other things that it doesn't scare me though.
The project:
I've been renovating my house and I'm about to install some ceiling speakers. I've been collecting some older airport expresses to use as audio sources for these with itunes / iphone controller for a front end, but I need an amplifier to fit between them 🙂. I need 14 channels (7 stereo zones), though if it makes a big difference, two of the zones might be mono. I was planning on just using DVC speakers, but I could also make a little summing mixer and run those two off of individual channels, meaning I only need 12 channels. I must be a cheapskate though, because the commercial amps with that many channels are just to stinking expensive.
I'd like to build my own (or bolt together pieces for a) 12 to 16 channel amp.
Required specifications:
Output Power
15-50W clean (<0.1% distortion) power???. I'm not really sure how much I need, but some rooms will require more than others. The speakers I'm getting are spec'd at 89dB/W, and the largest room will have two speakers and is 10.5' x 20' x 8'. The majority of the listening will be low level background, but I don't want to be in danger of driving it hard enough that it will distort.
Input Level Adjustment
Since rooms are different sizes, I'd like to have a way to adjust the input level so I can equalize the volume for each room at a given 'volume' setting from the itunes / iphone ecosystem. (granted this could be added to any amplifier, but I'm just trying to get everything down on paper)
Size
I have a small rack space I'm building out for network patch bay and stuff, so I was planning on putting it all in a 2U 14", 17", or 20" deep rack case from par-metal. I'm installing a thermostat controlled vent fan in the closet to pull hot air into the attic, so heat shouldn't be a problem.
Here is my laundry list of desires, roughly in order of priority:
Affordable
I'd like to get out the door for less than $500. Case, switches, and connectors will be about $80-120, PS will be another $40-80, leaving $300-380 for the amplifier boards and components or materials for mods.
Dead quiet while not playing
This could be taken care of by the next request, if the amps are put into some type of standby mode. Basically, it's always going to be on, and the speakers will be all over my house. I don't want to hear them at all unless they are playing.
Low standby system power with <0.5s wake time (if applicable)
This thing will be on 24/7, so I don't want to unwittingly build something that will cost me $100/year just to have on. If the amp chosen to use has a standby or low power setting, I was thinking of designing a low power input level detector that would wake up the amp when a signal came in, and put it to sleep when it hadn't heard any input for a certain period of time. With that said, I don't want it to be noticeable that the amp is 'waking up' when I start playing a song, so it needs to wake up quickly.
Sound Quality
This is later in the list for a reason. Since I'm cheap and this system is just for background music around the house, I'm using relatively cheap in ceiling speakers. I don't want it to sound horrible, but I imagine that anything you guys recommend will make the speakers the weakest link rather than the amplifier.
Ease of Building
I don't mind spending some time on the build. It sounds fun to me, actually. With that said, getting this thing done before Christmas is a priority, so if there are two options that are equal except for how put-together they are, I will choose the ready-made boards where all I have to do is put stuff together.
My Ideas So Far
Please don't limit yourself to these, but these are what I have seen so far:
TC2000 / TP2050 4 channel boards from sure electronics
I realize the 2 channel boards are more tested and easier to mod, but the 4 channel board wins for budget reasons. Also, the quiescent current when muted on the TP2050 is stated at 28mA@30V, and the TC2000 is 60mA@5V. At one TP2050 per channel and one TC2000 per stereo pair, that's 1W/channel when idle. If I'm thinking of this right, that should be okay, but I wouldn't want to go too far above that.
Building my own LM3886 modules with boards from chipamp.com
(I know it's not class D, sorry if this is against forum rules, but I'm trying to decide between options here)
Roll my own TI TAS5615 / TAS5611 / TAS5613 / TPA3123D2(not sure if the last one has enough power)
I haven't found any cheap ready-built modules for these yet. Some at around $75 per stereo pair, but that puts it above the budget at $525 for the amp boards instead of $300-$380. If that really is a better option for me though, tell me, as I might be persuaded to budge on the budget. Otherwise this would be a more complex endeavor, especially in the design phase.
Roll my own ST Microelectroics TDA7498 or TDA7293
Again, I know the second one isn't class D, but I'm not entirely sure class D is the best solution for my application. This would also be a complex option, I assume developing my own design and board since I haven't seen any ready-built modules.
Questions
What is the low current draw for the SMPS modules? (meanwell or similar)
I can't find anything on their data sheets which says how much current it draws with zero or a small load being attached, unless that is what "Leakage Current" means. This enters into the power calculation for the whole system, so I'd kind of like to know before I get in too deep. I suppose it would be possible to have a smaller 5V supply that ran my input detection circuit that then actually powered up the whole unit when audio came through, if necessary.
How many watts output do you think I need?
Given the application, how much power per channel would you suggest? I'm not really sure here.
What chip or assembled board do you suggest?
I'm all ears. Grill me, question my desires, whatever it takes. I just need some help getting pointed in the right direction.
Thanks!
I have a background in music and audio, and I'm currently studying electronics. I have access to a nice soldering setup w/microscope, so soldering surface mount chips is not out of the question if that's the best answer. I have not, however, built an amp before. I do have enough experience playing around with other things that it doesn't scare me though.
The project:
I've been renovating my house and I'm about to install some ceiling speakers. I've been collecting some older airport expresses to use as audio sources for these with itunes / iphone controller for a front end, but I need an amplifier to fit between them 🙂. I need 14 channels (7 stereo zones), though if it makes a big difference, two of the zones might be mono. I was planning on just using DVC speakers, but I could also make a little summing mixer and run those two off of individual channels, meaning I only need 12 channels. I must be a cheapskate though, because the commercial amps with that many channels are just to stinking expensive.
I'd like to build my own (or bolt together pieces for a) 12 to 16 channel amp.
Required specifications:
Output Power
15-50W clean (<0.1% distortion) power???. I'm not really sure how much I need, but some rooms will require more than others. The speakers I'm getting are spec'd at 89dB/W, and the largest room will have two speakers and is 10.5' x 20' x 8'. The majority of the listening will be low level background, but I don't want to be in danger of driving it hard enough that it will distort.
Input Level Adjustment
Since rooms are different sizes, I'd like to have a way to adjust the input level so I can equalize the volume for each room at a given 'volume' setting from the itunes / iphone ecosystem. (granted this could be added to any amplifier, but I'm just trying to get everything down on paper)
Size
I have a small rack space I'm building out for network patch bay and stuff, so I was planning on putting it all in a 2U 14", 17", or 20" deep rack case from par-metal. I'm installing a thermostat controlled vent fan in the closet to pull hot air into the attic, so heat shouldn't be a problem.
Here is my laundry list of desires, roughly in order of priority:
Affordable
I'd like to get out the door for less than $500. Case, switches, and connectors will be about $80-120, PS will be another $40-80, leaving $300-380 for the amplifier boards and components or materials for mods.
Dead quiet while not playing
This could be taken care of by the next request, if the amps are put into some type of standby mode. Basically, it's always going to be on, and the speakers will be all over my house. I don't want to hear them at all unless they are playing.
Low standby system power with <0.5s wake time (if applicable)
This thing will be on 24/7, so I don't want to unwittingly build something that will cost me $100/year just to have on. If the amp chosen to use has a standby or low power setting, I was thinking of designing a low power input level detector that would wake up the amp when a signal came in, and put it to sleep when it hadn't heard any input for a certain period of time. With that said, I don't want it to be noticeable that the amp is 'waking up' when I start playing a song, so it needs to wake up quickly.
Sound Quality
This is later in the list for a reason. Since I'm cheap and this system is just for background music around the house, I'm using relatively cheap in ceiling speakers. I don't want it to sound horrible, but I imagine that anything you guys recommend will make the speakers the weakest link rather than the amplifier.
Ease of Building
I don't mind spending some time on the build. It sounds fun to me, actually. With that said, getting this thing done before Christmas is a priority, so if there are two options that are equal except for how put-together they are, I will choose the ready-made boards where all I have to do is put stuff together.
My Ideas So Far
Please don't limit yourself to these, but these are what I have seen so far:
TC2000 / TP2050 4 channel boards from sure electronics
I realize the 2 channel boards are more tested and easier to mod, but the 4 channel board wins for budget reasons. Also, the quiescent current when muted on the TP2050 is stated at 28mA@30V, and the TC2000 is 60mA@5V. At one TP2050 per channel and one TC2000 per stereo pair, that's 1W/channel when idle. If I'm thinking of this right, that should be okay, but I wouldn't want to go too far above that.
Building my own LM3886 modules with boards from chipamp.com
(I know it's not class D, sorry if this is against forum rules, but I'm trying to decide between options here)
Roll my own TI TAS5615 / TAS5611 / TAS5613 / TPA3123D2(not sure if the last one has enough power)
I haven't found any cheap ready-built modules for these yet. Some at around $75 per stereo pair, but that puts it above the budget at $525 for the amp boards instead of $300-$380. If that really is a better option for me though, tell me, as I might be persuaded to budge on the budget. Otherwise this would be a more complex endeavor, especially in the design phase.
Roll my own ST Microelectroics TDA7498 or TDA7293
Again, I know the second one isn't class D, but I'm not entirely sure class D is the best solution for my application. This would also be a complex option, I assume developing my own design and board since I haven't seen any ready-built modules.
Questions
What is the low current draw for the SMPS modules? (meanwell or similar)
I can't find anything on their data sheets which says how much current it draws with zero or a small load being attached, unless that is what "Leakage Current" means. This enters into the power calculation for the whole system, so I'd kind of like to know before I get in too deep. I suppose it would be possible to have a smaller 5V supply that ran my input detection circuit that then actually powered up the whole unit when audio came through, if necessary.
How many watts output do you think I need?
Given the application, how much power per channel would you suggest? I'm not really sure here.
What chip or assembled board do you suggest?
I'm all ears. Grill me, question my desires, whatever it takes. I just need some help getting pointed in the right direction.
Thanks!
Have you had a look at the site "41Hz" ?
They have a 4 channel amp kit available (amp 9) which has a good reputation. It's all through-hole components and with power supply on board and it's compact in size.
Worth a .look
They have a 4 channel amp kit available (amp 9) which has a good reputation. It's all through-hole components and with power supply on board and it's compact in size.
Worth a .look
Have a look at connexelectronic too. Here's a quick review of their TDA8920 module, including power measurement: http://www.diyaudio.com/forums/connexelectronic/158602-class-t-audio-amplifiers.html#post2091843
Thanks for the tips guys!
The TAA4100A option from 41Hz looks like a good one to consider. I have narrowed down the options, the requirements have changed a little, and I'd like to ask for some more advice.
Options:
Sure Electronics TK2050 based board @32V
41Hz Amp9-basic (TAA4100A based) @24V
Design my own TK2050 board
Design my own TAA4100A board
Requirements:
A. Design an input detection circuit
When audio is detected at the input, it should pull the mute and/or standby pins to logic high/low so that the amplifier turns on. I would also like to use the signal level to drive a signal LED for user feedback. This circuit will need to be low power, and not compromise the input audio signal to the amplifier.
B. Design a clip detection circuit
Both of these chips have an overload pin (OVRLDB), which is driven to logic low whenever clipping occurs. I would like to wire this to a red 'clipping' LED that will illuminate when a clip occurs and STAY illuminated until the user presses a clear button, so that I know if my amp is clipping (and then need to pad the input)
C. DC Offset control
The TAA4100A wins here, since it does this automatically. If I went with a TK2050 chipset solution, I would want to create an automatic DC offset-correcting circuit, similar to what is shown in the EB-TK2050-6 eval board datasheet, also talked about here:
http://www.diyaudio.com/forums/clas...w-class-d-amplifier-board-19.html#post2190860
D. Design a case fan circuit.
I'd like to put in some case fans that are variable speed based on the heat of the chips. I'm thinking this is doable by using a few TC649B or similar chips, and some sort of multiple thermistor network on the heatsinks.
Questions:
1. Can you point me in the right direction for #A, #B, and #C?
I'm pretty confident I can do #D (the fan circuit) by reading the data sheet, but I'm not sure about the others.
2. Which chip?
With the TAA4100A, I don't have to bother with #C and the standby current draw is lower, but if it doesn't sound as good and the TK2050 based system and it's feasible to do a TK2050 based system, I'd rather do that.
3. Mod or design from scratch?
Are these additions feasible to do by modding the 41Hz or the sure electronics boards? Or am I better off just designing a new board from the TK2050 or TAA4100A datasheets that include these bells and whistles I'd like to add?
4. Is there any reason to isolate the power for any of these sub-circuits by using different power adapters or other means, or can I just use a system-wide 5V or 12V for the fan, peak and input detectors, and DC offset circuits?
Thanks a million!
The TAA4100A option from 41Hz looks like a good one to consider. I have narrowed down the options, the requirements have changed a little, and I'd like to ask for some more advice.
Options:
Sure Electronics TK2050 based board @32V
41Hz Amp9-basic (TAA4100A based) @24V
Design my own TK2050 board
Design my own TAA4100A board
Requirements:
A. Design an input detection circuit
When audio is detected at the input, it should pull the mute and/or standby pins to logic high/low so that the amplifier turns on. I would also like to use the signal level to drive a signal LED for user feedback. This circuit will need to be low power, and not compromise the input audio signal to the amplifier.
B. Design a clip detection circuit
Both of these chips have an overload pin (OVRLDB), which is driven to logic low whenever clipping occurs. I would like to wire this to a red 'clipping' LED that will illuminate when a clip occurs and STAY illuminated until the user presses a clear button, so that I know if my amp is clipping (and then need to pad the input)
C. DC Offset control
The TAA4100A wins here, since it does this automatically. If I went with a TK2050 chipset solution, I would want to create an automatic DC offset-correcting circuit, similar to what is shown in the EB-TK2050-6 eval board datasheet, also talked about here:
http://www.diyaudio.com/forums/clas...w-class-d-amplifier-board-19.html#post2190860
D. Design a case fan circuit.
I'd like to put in some case fans that are variable speed based on the heat of the chips. I'm thinking this is doable by using a few TC649B or similar chips, and some sort of multiple thermistor network on the heatsinks.
Questions:
1. Can you point me in the right direction for #A, #B, and #C?
I'm pretty confident I can do #D (the fan circuit) by reading the data sheet, but I'm not sure about the others.
2. Which chip?
With the TAA4100A, I don't have to bother with #C and the standby current draw is lower, but if it doesn't sound as good and the TK2050 based system and it's feasible to do a TK2050 based system, I'd rather do that.
3. Mod or design from scratch?
Are these additions feasible to do by modding the 41Hz or the sure electronics boards? Or am I better off just designing a new board from the TK2050 or TAA4100A datasheets that include these bells and whistles I'd like to add?
4. Is there any reason to isolate the power for any of these sub-circuits by using different power adapters or other means, or can I just use a system-wide 5V or 12V for the fan, peak and input detectors, and DC offset circuits?
Thanks a million!
If you use it in PA system,I think TI tas series should have excellent sound quality than the others switch amplifier system,it's my experiences.
if you like analog audio chip ,I think lm3886 should best.
only my experiences,I have developed lots of Public Address system in last 10 years.and compared many times.
if you like analog audio chip ,I think lm3886 should best.
only my experiences,I have developed lots of Public Address system in last 10 years.and compared many times.
Help with circuit
So I've made some scribblings for the input detection circuit.
It's basically a comparator feeding a retriggerable one-shot. I put in a buffer opamp, but I'm not sure whether it needs it, or whether it's even hooked up right (biased at the right point, etc).
I've also included the opamp DC offset corrector as shown in Tripath's 6 channel eval board. I just copied it over, does it look ok?
Also, on Tripath's 6 channel eval board, they have a 150K resistor from signal to ground at the input, but this is not present on the TK2050 datasheet or any of the other eval kit sheets. Any idea why?
Any help or comments you guys could provide would be great, I'm sure I"m sticking my foot in my mouth here somewhere.
So I've made some scribblings for the input detection circuit.
It's basically a comparator feeding a retriggerable one-shot. I put in a buffer opamp, but I'm not sure whether it needs it, or whether it's even hooked up right (biased at the right point, etc).
I've also included the opamp DC offset corrector as shown in Tripath's 6 channel eval board. I just copied it over, does it look ok?
Also, on Tripath's 6 channel eval board, they have a 150K resistor from signal to ground at the input, but this is not present on the TK2050 datasheet or any of the other eval kit sheets. Any idea why?
Any help or comments you guys could provide would be great, I'm sure I"m sticking my foot in my mouth here somewhere.
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