2.2uf/50v, ok so far.
Umm, err ... that's why it says "AC/DC 12Vin". I guess you didn't realize the true awesomeness of this little amp!
I'm using a few different AC wallwarts wadapter and a 80V 5A Schottky for ps. (Schottky has quieter reverse recovery spike or some such ...)
Yep, you can use all those old beefy AC adapters--I had one from my old ART DIO DAC. !!
I have a stash of Blackgate N 1uF /50V caps. I may have to try those on another board.
Umm, err ... that's why it says "AC/DC 12Vin". I guess you didn't realize the true awesomeness of this little amp!
I'm using a few different AC wallwarts wadapter and a 80V 5A Schottky for ps. (Schottky has quieter reverse recovery spike or some such ...)
Yep, you can use all those old beefy AC adapters--I had one from my old ART DIO DAC. !!
Duh, I thought that was a typo or something on the board -- very interesting.
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My speakers only require .085W each to produce serious living room filling sound. What advantage could I expect by changing a component or two (diy?), I'm certainly not lacking in the bass department?But, but ... where's the DIY in that?
Perfect! If they're polarized just make sure the stripes are to the inside.
...Duh, I thought that was a typo or something on the board -- very interesting.
DC wallwarts have crappy diodes in them. This way, you control the AC to DC conversion. Start with one, then try a ... diamond with 4 ... on each side ...
... awesomeness!!!
PS cheap ebay sm stepped atten was the perfect addition for me. I have high eff speaks so I was always fiddling with the pre-9 O'clock positions on the stock vol (B50k). I subbed in my 10k sm stepped and ... perfect!!!
Lots of volume choice down low and ... perfect channel matching at the lowest volumes!
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My speakers only require .085W each to produce serious living room filling sound. What advantage could I expect by changing a component or two (diy?), I'm certainly not lacking in the bass department?
Well, since you are low power and have good bass I'm guessing you have high eff speakers (and maybe big ones with a 15")
Do you find you're fiddling with very low settings on the volume? If so, then the pot mod is for you!
Dact Type 21 Stepped Attenuator Potentiometer 50K D | eBay
DACT Type 21 Stepped Attenuator Potentiometer 50K
(I'd go for 20k or 50k not 10k like what I had lying around)
If you use angled pin headers on the inside, it fits perfectly!
Excellent channel matching, many low level settings, repeatable volume settings ...
Next would be the input caps and if you increase the value, also increase C4 so the mute stays on longer.
Then the ps reservoir and high freq cap (max voltage for the chip is 20V so you can use good quality, large 25V caps that fit the 5mm pin spacing)
The diode if you're doing AC (then more advanced diode networks--4) and maybe remove it if you'll always do DC and be careful and then
...
well there's no more parts to replace!
Ah, but then notice that the chip is really divided in two and has ps for left and ps for right ...
So you want a sweet ps network for each side! AndrewT setup ...
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They are big, 15 Ohm 15 inch dual concentrics and they just perform, to my ears, spectacularly with the $6 amp. The amp is on permenently and I rarely touch the volume pot but when I do, I personally have found no issues, I have 3 of 'em.Well, since you are low power and have good bass I'm guessing you have high eff speakers (and maybe big ones with a 15")
What is pre-9 O'clock?Perfect! . I have high eff speaks so I was always fiddling with the pre-9 O'clock positions on the stock vol (B50k).
If 12 is 0 then 9 O'clock is 270deg clockwise, no?
Most volume controls are set to the 6 o'clock position for 0dB. So basically turning the knob clockwise 90 degrees (increasing volume level) is 9 o'clock. I believe what AudioLapDance meant was any volume setting from the 6 o'clock to 9 o'clock (i.e., lower volume levels) tends to have a channel imbalance.
I have observed the same thing with my TDA7297 amp, which is why I purchased an economical, but effective, stepped attenuator like the one that AudioLapDance described. Perhaps, you have been fortunate to get three units that have good channel balance between the volume pot gangs. Which eBay seller did you get your amps from?
I have observed the same thing with my TDA7297 amp, which is why I purchased an economical, but effective, stepped attenuator like the one that AudioLapDance described. Perhaps, you have been fortunate to get three units that have good channel balance between the volume pot gangs. Which eBay seller did you get your amps from?
I started messing with pcb designing so, as I have one of this amps and I was a bit bored, due to the simplicity of the schematic I made a new pcb layout using "premium" components. Why I did this, cause I was bored, there is no more...
Here you have the eagle files and gerbers in case anyone is interested in trying it...
I did calculate more or less the cost per board using Jantzen cross 0.22uf cap for the inputs, using 0.1uf Wimas with 4700uf panasonic FC series, and including the cost of the IC and the board it would be around 8€, more or less around $11... Still not bad all...
Here you have the eagle files and gerbers in case anyone is interested in trying it...
I did calculate more or less the cost per board using Jantzen cross 0.22uf cap for the inputs, using 0.1uf Wimas with 4700uf panasonic FC series, and including the cost of the IC and the board it would be around 8€, more or less around $11... Still not bad all...
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Perfect, so any mod to increase fidelity in the bass will be perfect for you.
Let's see if we can make them perform better for less than dinner.
It's still a crappy volume pot with very little audio taper.
Then for the Love of MOSFETs just mod one and quit teasing me!
Step atten, sm 24 pos 10k
Silmic II 2.2/100V input caps
FC 2200uF/25V ps cap
100nF, 100V X7R ps cap
increased C4 mute cap
Schottky on the bottom. (That's what she said!)
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The 50k log tapered 21-step SMD ("SMT") stepped attenuators from auction sellers lasercollection and tube_buyer will fit nicely on the boards. However, you have to use wire like 20ga solid core wire to fabricate pins on these stepped attenuators to fit onto the board. It's not a big deal if you're handy with needle nose pliers.
A speaker that is cheaper than dinner to go with amp
If you guys want to try a speaker that sounds excellent and is cheaper than dinner to go with your lunch money amp, look at the new 0.4x scale Karlsonator that I built (plus others) using the Vifa TC9FD. Currently the driver sells for $10 at PE and the foam core enclosure can be made with a single sheet of $1 foam core board.
It sounds excellent and is a great match for a budget amp - even the Sure TPA3110 ($10) works well.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-16.html#post3722988
If you guys want to try a speaker that sounds excellent and is cheaper than dinner to go with your lunch money amp, look at the new 0.4x scale Karlsonator that I built (plus others) using the Vifa TC9FD. Currently the driver sells for $10 at PE and the foam core enclosure can be made with a single sheet of $1 foam core board.
It sounds excellent and is a great match for a budget amp - even the Sure TPA3110 ($10) works well.
http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-16.html#post3722988
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It is possible to connect a 1N5405 to each of those pins and then re-stiffen the power with good quality capacitors (possible range is from 100u to 660u) from Each ps pin to ground. That'll give you dual mono with just one power supply.
Added parts:
a diode and a cap for left
a diode and a cap for right
I haven't tried it with this amp yet, so I don't know the optimal amount of forward voltage drop nor the optimal amount of capacitance to follow it.
Typical is 0.65vf with 440u.
Our little amp doesn't quite have the resources to push an 83db efficient speaker hard enough to replicate a concert. A 3-1/2" full range speaker would also shake a lot and scramble the vocals if pushed hard enough to do a lot of flapping about.
No problem.
Extremely simple and easy filters can resolve this so the little things can do loud replay in high fidelity.
Concept: Remove/reduce pitches that are beyond speaker capacity, because less of what it can't do makes room for More of what it Can do. And that's a lot!
Optimize the bass frequency:
(cause less noise)
An electrolytic cap series to speaker negative and sized for a combined effect of more hear-able bass with less treble distortion (range 470u~1000u) (for excellent resolution, you can add an electrolytic bypass cap, range 2.2u~4.7u).
Optimize the treble frequency:
(play less noise)
An RC or nafbuster circuit mounted directly on the speaker terminals and sized to hinder noise without hindering audio (cap size range 47n~220n, resistor size from online RC calculator).
After installing both of the filters, then turning up your volume control now makes the very Specific request for the system to do more of what it Should do.
Seatbelts optional.
Amplifier's small signal coupling filters and the power circuit may also be customized to specific speakers rather than generic. Have fun!
How are you attaching the amp to the battery and the charger? Thinking about doing the same thing. Any pictures?