In the same vein as the ever popular "Lunch Money" amp, here is the Coffee Money Headphone Amp. It uses the little TDA2030 chipamp capble of nominal 9w into 8ohm loads and is single-rail capable. The fully built mono amp can be bought for under $1. With a few choice (but not expensive) upgrades, it makes a very capable headphone amp. Of course, can also double as a circa 8w speaker amp,
Here is what you get for $0.99 shipping included:
For example, from eBay:
https://www.ebay.com/i/192163691131?chn=ps&dispItem=1
Or Aliexpress:
https://www.aliexpress.com/item/1PC...er-Supply-Module-Electronics/32479079894.html
Specs from manufacturer STM are here:
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000128.pdf
So here is the suggested schematic from STM for single rail use:
The manufacturer of the $0.99 fully built PCB obviously cannot follow this, and they save some money by using SMT, but in the process, made the layout very tight and compact which is very good from reducing stray noise pickup - ad modded - the amp is dead silent with inputs shorted.
Here are my mods (designations on the PCB not the schematic):
- input cap, I replaced pot with 10uF 35v Elna Silmic II, removed C3 and bypassed with wire jumper
- replaced C1 decoupling cap with higher voltage 100uF 35v part
- added 6000uF 25v power supply rail de-coupling cap on bottom (doubles as the stand mount for the amp). This is to increase stereo separation when using a common PSU.
- Replaced output cap C7 with 2200uF 25v low ESR cap and bypassed with 1uF 63v Wima MKS filmcap (optional - not really needed).
- Reduced gain from 31x to 12.4x by changing out 4700k R4 with 12.1k resistor. This is the only SMT operation you need to do but needed since gain is too high for headphone use and lends itself to hiss. You can even use 15k here for 10x gain and it will still be plenty. Some people only like 3x gain on headphones so you could even put 47k here for 3x gain. Your choice.
Closeup of single amp module with mods:
Amp as mounted on base with hot glue and PSU:
Closeup of stereo amp:
For PSU, any low ripple regulated (i.e. 7815 or 7818) type supply should work. I am using a pre-made LT1963A from eBay, modded with a Panasonic FC 4700uF 25v on output and 100nF100v film bypass. I am using an HP 19v SMPS laptop brick to power the linear supply with linear regulator set at 17.5vdc.
Not including PSU and headphone jack, the parts cost me $2 for amps plus another $1.50 (those red Wima's were most expensive parts). I am using all discount Chinese caps except the Silmics and Wima's which I got from Mouser.
So $3.50 total - the price of a Latte at your most popular coffee shop in the USA.
How does it sound? Well, I have dozens and dozens of nice headphone amps, of course it won't be as good as my SE Class A designs, but for $3.50 - not bad at all. Very admirable performance and as powerful as hell. If you had difficult to drive cans, step up your caps to handle 35v and use bigger heatsink and set PSU rail at 35v for big output swing.
The amp is silent - very quiet with no music playing. The overall presentation is neutral, with maybe a bit more top end and that can be adjusted via choice of output caps. I think Panasonic FR is very nice. Or even use 1000uF Panasonic OSCONs.
Try it! Cost is about the cheapest DIY project one can have. You can save money by using a CBB 1uF film on input cap and output bypass cap (spec sheet schematic only calls for 1uF).
Enjoy!
Here is what you get for $0.99 shipping included:
For example, from eBay:
https://www.ebay.com/i/192163691131?chn=ps&dispItem=1
Or Aliexpress:
https://www.aliexpress.com/item/1PC...er-Supply-Module-Electronics/32479079894.html
Specs from manufacturer STM are here:
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000128.pdf
So here is the suggested schematic from STM for single rail use:
The manufacturer of the $0.99 fully built PCB obviously cannot follow this, and they save some money by using SMT, but in the process, made the layout very tight and compact which is very good from reducing stray noise pickup - ad modded - the amp is dead silent with inputs shorted.
Here are my mods (designations on the PCB not the schematic):
- input cap, I replaced pot with 10uF 35v Elna Silmic II, removed C3 and bypassed with wire jumper
- replaced C1 decoupling cap with higher voltage 100uF 35v part
- added 6000uF 25v power supply rail de-coupling cap on bottom (doubles as the stand mount for the amp). This is to increase stereo separation when using a common PSU.
- Replaced output cap C7 with 2200uF 25v low ESR cap and bypassed with 1uF 63v Wima MKS filmcap (optional - not really needed).
- Reduced gain from 31x to 12.4x by changing out 4700k R4 with 12.1k resistor. This is the only SMT operation you need to do but needed since gain is too high for headphone use and lends itself to hiss. You can even use 15k here for 10x gain and it will still be plenty. Some people only like 3x gain on headphones so you could even put 47k here for 3x gain. Your choice.
Closeup of single amp module with mods:
Amp as mounted on base with hot glue and PSU:
Closeup of stereo amp:
For PSU, any low ripple regulated (i.e. 7815 or 7818) type supply should work. I am using a pre-made LT1963A from eBay, modded with a Panasonic FC 4700uF 25v on output and 100nF100v film bypass. I am using an HP 19v SMPS laptop brick to power the linear supply with linear regulator set at 17.5vdc.
Not including PSU and headphone jack, the parts cost me $2 for amps plus another $1.50 (those red Wima's were most expensive parts). I am using all discount Chinese caps except the Silmics and Wima's which I got from Mouser.
So $3.50 total - the price of a Latte at your most popular coffee shop in the USA.
How does it sound? Well, I have dozens and dozens of nice headphone amps, of course it won't be as good as my SE Class A designs, but for $3.50 - not bad at all. Very admirable performance and as powerful as hell. If you had difficult to drive cans, step up your caps to handle 35v and use bigger heatsink and set PSU rail at 35v for big output swing.
The amp is silent - very quiet with no music playing. The overall presentation is neutral, with maybe a bit more top end and that can be adjusted via choice of output caps. I think Panasonic FR is very nice. Or even use 1000uF Panasonic OSCONs.
Try it! Cost is about the cheapest DIY project one can have. You can save money by using a CBB 1uF film on input cap and output bypass cap (spec sheet schematic only calls for 1uF).
Enjoy!
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I'd advise a certain amount of caution in reducing the gain. The DS says that the minimum closed loop gain is 24dB so 16X. Going below this risks turning the amp into an oscillator.
Hmm - interesting usually lower gain is less chance of oscillation. So maybe 8k6 is good value then? What about adding say 22pF NP0 across output pin and feedback pins?
Can you show me where it says keep gain above 16x? Spec sheets just says if you make R2 too big, gain is low.
I will look at output on scope to make sure it's not oscillating at 12.3x (21.8dB) gain. Seems like a perfectly normal Class AB amp gain to me.
Can you show me where it says keep gain above 16x? Spec sheets just says if you make R2 too big, gain is low.
I will look at output on scope to make sure it's not oscillating at 12.3x (21.8dB) gain. Seems like a perfectly normal Class AB amp gain to me.
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Lower gain is less chance of oscillation via circuit parasitics yes, but here lower gain = higher feedback. Running a decompensated amp (which is what this is) at lower than its minimum gain is an art needing a certain level of understanding of feedback. TI's AN1604 is a useful place to begin : http://www.ti.com/lit/an/snoa486b/snoa486b.pdf
Thanks for the tech note link from TI. Will report back of output is exhibiting any oscillations on scope.
Checked with my 100MHz 1Gs/s Owon SSO-8192v scope. Used various music and 1kHz test tone. No oscillations seen on scope ot in FFT, but I switched to 8.2k resistor just to be on the safe side. Gain is 18.3dB now so gets a bit loud and volume knob doesn't go past 12 o'clock. On the other hand, it is a useful combo to be able to drive speakers with some volume.
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xrk971,
How does this compared to lunch box tda7297 as a speaker amp ?
Is there any fake tda 2030 ?
thanks
kp93300
How does this compared to lunch box tda7297 as a speaker amp ?
Is there any fake tda 2030 ?
thanks
kp93300
Very similar sounding to TDA7297 with nice bass and great mids and highs. I only played with small full range speakers (Dayton RS100-8 in XKi enclosure) so could not test power limits. It is rated 9w max on 8ohms - much lower than 7297. Which is sort of why I am using as headphone amp. Other reason is it is monoblock - so easy to get great stereo separation for better sound stage.
For stereo speakers I actually tried this amp, which requires a dual rail supply for the PSU. The mains based PSU doesn't have enough filtering to be silent with headphones though. Works ok as speaker amp though.
https://www.ebay.com/i/301874034606
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Here is oscope screen shot playing music. The amp has 0.47R in series with headphone outputs to ensure stability. Permanent 47ohm 2w load resistors installed on headphone jack ensures caps are drained when plugging in phones for first time to prevent pops and also serves as test load when doing measurements.
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Measurements
Here is FFT for 700mV into 47ohms just to get a sense of how clean the power supply and general profile looks. I am told that internally, TDA class AB amps have a quasi-complimentary output stage. That's good - and we see here a dominant 2nd harmonic with monotonically descending higher orders, but they don't stop at H4. Not bad for a $3.50 amp.
You can see that it is absent of any mains that would be audible. Noise floor is not quite as low as my SE Class A amps, but respectable at -114dB. THD is about 0.016%.
Well, that's about all I am going to do with this amp. Seems to do what it was intended to do - provide a cheap source of relatively clean amplification, suitable for small speakers or even headphones. I hope folks give it a try - nothing to lose. And of course, you are welcome to put it in a case. I think I like mine free breathing and open for viewing on a plank of carbonized bamboo. 🙂
It's actually a cool looking desktop amp, sure to be the topic of conversation in the office...
Here is FFT for 700mV into 47ohms just to get a sense of how clean the power supply and general profile looks. I am told that internally, TDA class AB amps have a quasi-complimentary output stage. That's good - and we see here a dominant 2nd harmonic with monotonically descending higher orders, but they don't stop at H4. Not bad for a $3.50 amp.
You can see that it is absent of any mains that would be audible. Noise floor is not quite as low as my SE Class A amps, but respectable at -114dB. THD is about 0.016%.
Well, that's about all I am going to do with this amp. Seems to do what it was intended to do - provide a cheap source of relatively clean amplification, suitable for small speakers or even headphones. I hope folks give it a try - nothing to lose. And of course, you are welcome to put it in a case. I think I like mine free breathing and open for viewing on a plank of carbonized bamboo. 🙂
It's actually a cool looking desktop amp, sure to be the topic of conversation in the office...
Attachments
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In the same vein as the ever popular "Lunch Money" amp, here is the Coffee Money Headphone Amp. It uses the little TDA2030 chipamp capble of nominal 9w into 8ohm loads and is single-rail capable. The fully built mono amp can be bought for under $1. With a few choice (but not expensive) upgrades, it makes a very capable headphone amp. Of course, can also double as a circa 8w speaker amp,
Here is what you get for $0.99 shipping included:
For example, from eBay:
https://www.ebay.com/i/192163691131?chn=ps&dispItem=1
Or Aliexpress:
https://www.aliexpress.com/item/1PC...er-Supply-Module-Electronics/32479079894.html
Specs from manufacturer STM are here:
http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000128.pdf
So here is the suggested schematic from STM for single rail use:
The manufacturer of the $0.99 fully built PCB obviously cannot follow this, and they save some money by using SMT, but in the process, made the layout very tight and compact which is very good from reducing stray noise pickup - ad modded - the amp is dead silent with inputs shorted.
Here are my mods (designations on the PCB not the schematic):
- input cap, I replaced pot with 10uF 35v Elna Silmic II, removed C3 and bypassed with wire jumper
- replaced C1 decoupling cap with higher voltage 100uF 35v part
- added 6000uF 25v power supply rail de-coupling cap on bottom (doubles as the stand mount for the amp). This is to increase stereo separation when using a common PSU.
- Replaced output cap C7 with 2200uF 25v low ESR cap and bypassed with 1uF 63v Wima MKS filmcap (optional - not really needed).
- Reduced gain from 31x to 12.4x by changing out 4700k R4 with 12.1k resistor. This is the only SMT operation you need to do but needed since gain is too high for headphone use and lends itself to hiss. You can even use 15k here for 10x gain and it will still be plenty. Some people only like 3x gain on headphones so you could even put 47k here for 3x gain. Your choice.
Closeup of single amp module with mods:
Amp as mounted on base with hot glue and PSU:
Closeup of stereo amp:
For PSU, any low ripple regulated (i.e. 7815 or 7818) type supply should work. I am using a pre-made LT1963A from eBay, modded with a Panasonic FC 4700uF 25v on output and 100nF100v film bypass. I am using an HP 19v SMPS laptop brick to power the linear supply with linear regulator set at 17.5vdc.
Not including PSU and headphone jack, the parts cost me $2 for amps plus another $1.50 (those red Wima's were most expensive parts). I am using all discount Chinese caps except the Silmics and Wima's which I got from Mouser.
So $3.50 total - the price of a Latte at your most popular coffee shop in the USA.
How does it sound? Well, I have dozens and dozens of nice headphone amps, of course it won't be as good as my SE Class A designs, but for $3.50 - not bad at all. Very admirable performance and as powerful as hell. If you had difficult to drive cans, step up your caps to handle 35v and use bigger heatsink and set PSU rail at 35v for big output swing.
The amp is silent - very quiet with no music playing. The overall presentation is neutral, with maybe a bit more top end and that can be adjusted via choice of output caps. I think Panasonic FR is very nice. Or even use 1000uF Panasonic OSCONs.
Try it! Cost is about the cheapest DIY project one can have. You can save money by using a CBB 1uF film on input cap and output bypass cap (spec sheet schematic only calls for 1uF).
Enjoy!
really curious about this setup, but I am not technical enough to figure out the connections on my own, could you kindly draw a block diagram on how to connect PSU, input jack and output jack, and i don't see a volume pot?
This is a basic block diagram, not a wiring schematic. It will be obvious that the connections require two wires (positive and negative). You can add a pot as follows: connect ring of 3.5mm input jack (right) and tip (left) to one side of pot where wiper rests when turned to full volume (CW - usually pin on right with pins on bottom when looking at pot from front), then connect amp audio inputs to wiper (middle pins) and sleeve (common) to ground or left pins on pot, which also goes to -ve of amp audio input.
On linear PSU regulator, 19v SMPS brick feeds DC input of regulator, and adjust output to be lower by whatever minumum dropout voltage is. For LT1963, that's 0.34V, and I decreased to 1.5v to ensure good margin for regulation. So set pot to 17.5v output.
On an LM317, you may have to drop voltage down to 16v as it requires a 3v differential. The LT1963 has a lower dropout voltage of only 340mV. So I could have set this as high as 18.5v and would have been fine.
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Heya
newbye here. You recommend total newbye to use this one if want to learn to solder, dunno how to solder can learn right?
TDA2030A Electronic Audio Powers Amplifier Boards Mono 18W DC 9-24V DIY Kit PR | eBay
What you say? Can? Or you can recommend another coffee money one to learn on
newbye here. You recommend total newbye to use this one if want to learn to solder, dunno how to solder can learn right?
TDA2030A Electronic Audio Powers Amplifier Boards Mono 18W DC 9-24V DIY Kit PR | eBay
What you say? Can? Or you can recommend another coffee money one to learn on
How can you possibly go wrong with a through-hole kit, complete with parts and shipping for $1?
Go for it!
Here is a stereo kit for $3.25 and includes heatsinks:
Electronic DIY Kit Set Dual-Channel TDA2030A Power Amplifier Amp Module
Excellent recommends, and also good! TY TY.
Will try, must learn some time, burn finger never mind, must learn anyhow must learn 🙂
Will try, must learn some time, burn finger never mind, must learn anyhow must learn 🙂
Hi X, have you tried this stereo DIY kit? I wonder how does this one compare to the setup you proposed on first post of this thread?
I have not tried this particular stereo version. But have tried this prebuilt stereo one and am using it to power a pair of XKi speakers with Dayton RS100-8 as lab speakers. Although I am using a pretty nice shunt regulated linear PSU (Juma design/Prasi layout) so it's very quiet. But the stock on board bridge rectifier and meager caps are not enough to make it quiet enough for headphone use. For speakers they are adequate but still some audible hum with ears pressed next to speaker.
no low Noise OCL or BTL Circuit TDA2030 Amplifier Board
no low Noise OCL or BTL Circuit TDA2030 Amplifier Board
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