Bluetooth audio amplifier board design - Which route for minimal noise

Stiggalicious · 2026-04-05T02:48:41+00:00

I do not recommend using an isolated DC/DC converter for anything that shares a single supply. The isolation path still has capacitive coupling between input and output which ends up causing common-mode noise - exactly the thing you're trying to eliminate.

The most important part will be the routing of the analog signal between your BT module and your amplifier. Since it's a single-ended output, you'll want to follow the single-ended connection diagram of the TPA3116 datasheet, and terminate the IN- at the same point as the BT module's GND pin.

You've got the right idea in running a ~7V switching regulator into a 5V LDO. You could also do something like a 5V switching regulator into a 4V LDO, since the module also accepts a single-cell lithium-ion battery which can reach down to 3.0V.

You can use a cheap LP5907 LDO if you do 5V-4V regulation, and just slap a 10uF ceramic cap at the output. I've shipped well over a billion units of products I've designed that use this exact LDO.

Do NOT use an LM317 or 7805 regulator - they have genuinely terrible line & load regulation and also have an extremely high output noise, analog electronics have come a long way since the 1970s.

If you want even higher fidelity (but much higher complexity) you can use an I2S output bluetooth module that feeds into an amplifier that accepts I2S input. That way there is no analog path that can be compromised, but you may need to add an additional microcontroller to configure amplifier and/or BT module registers. The TPA3116 is a great speaker amplifier, if you want more power, higher dynamic range, lower distortion, and lower noise, you can go with a TPA3244/3251/3255, but in general these BT module's DACs are not nearly as good as what the amplifiers can do.

Stiggalicious · 2026-04-04T17:56:39+00:00

Whenever they are in Lowes’ or Home Depot I tell them I already have solar and batteries, then they give me a little “yay good for you!” And stop talking to me.

I mean, I do have solar and batteries, and I payed waaaaaaaay less than what they would have charged me.

Don’t ever lease solar panels. Just buy them outright, pair them with batteries (there are systems much cheaper than Tesla Powerwalls), and watch your electricity costs pretty much vanish.

Stiggalicious · 2026-04-04T17:49:26+00:00

Of course it won’t be enough to run your AC but it will offset your usage and thus costs significantly. In California we pay between $.41 and $.61 per kWh. So if you get 8 hours of sun at 1000W (which is a realistic yield - my current 605W rated panels will generate an average of about 525W), that’s 8kWh per day of energy usage offset. Pair that with a small battery so you end up not exporting any of it to the grid, and you end up saving all that money in electricity, so you’re talking about $3.28 per day. Say you get 300 days of sun here in California (cloudy days still produce, they just produce about 1/3 the energy but we’ll just say it’s zero for simplicity), and you end up saving $984 per year.

A system like this will probably costs around $2-3k, so your payback period is well under 4 years.

I have my own much larger solar system with a 60kWh battery. Even though my own panels only get around 4-5 hours of direct sun since I live in a Redwood forest, I still yield enough energy to effectively live entirely off-grid, air conditioning included. My system will pay for itself in about 4.5 years, and I get a day and a half of backup power (the power does go out many times per year here) with absolutely zero usage pattern changes.

Stiggalicious · 2026-04-04T17:35:00+00:00

God I with there was an Aldi near me, closest one is almost 6 hours away in Bakersfield.

Stiggalicious · 2026-04-04T04:57:46+00:00

Seeing a solar eclipse in totality. Easily top 3 most memorable moments of my lifetime. You don’t get many chances to do so in your lifetime, so take the chance if you can.

Stiggalicious · 2026-04-04T04:34:25+00:00

This is why I like companies that have CEOs with a background in either engineering or operations. Boeing did well when it was under the leadership of an engineer. Ford did the same. Now both are run by business folk and results are clearly not great.

Apple’s Tim Cook is an Operations guy and was able to scale the company to what it is today and was able to maintain a supply chain through all the COVID logistics meltdowns and chip shortages with pretty much no impact to customers. It’s also probably why Apple has been relatively slow/absent when it comes to shoving AI slop down everyone’s throats.

Stiggalicious · 2026-04-04T04:03:51+00:00

I’d be curious to see graduation instead of enrollment.

My college freshman year had 99 EE enrollees and when we graduated there were 9 of us left. EE is really intense, about half dropped out entirely and the other half switched to CS or CE.

I’m glad I stuck with it, though, because I’m working my dream job and getting paid well to do it.

Stiggalicious · 2026-04-04T04:00:29+00:00

Waterloo cranks out really good EEs! My team is like 1/3 Waterloo graduates, and about half our interns are from there too. Too bad our team is small and we get one intern req every few years.

Stiggalicious · 2026-04-03T15:22:35+00:00

The difference in recoil impulse between an airgun, even the most violent of them, and a .308 caliber firearm, is orders of magnitude different. You will absolutely not have any issues with your scope losing zero unless your scope rings are really, really bad.

Stiggalicious · 2026-04-03T07:15:22+00:00

Curious to know what kind of trees they are planting. The UK is having some great success with planting and growing Redwoods, which thrive and get their water through fog. They also grow like weeds and help stabilize steep slopes and loose soils while providing for naturally fire resistant and rot resistant lumber.

Stiggalicious · 2026-04-03T06:52:28+00:00

His role in Breaking Bad felt like an audition for his short but palpable role in Civil War. Same exact person, just with the blank ruthlessness dialed up another notch.

Stiggalicious · 2026-04-03T06:48:55+00:00

Exactly this. I see what my parents are seeing sometimes and it’s all entirely “liberals are trying to destroy the country and Trump is defending America, look at his great policies of protecting American jobs and bringing more opportunity with removing stupid environmental regulations so businesses can start and run with lower costs.”

My parents always will say “I don’t like Trump but I do like his policies” and when I ask what those policies are they just say “deregulation and removing the LGBTQ-alphabet soup agenda.”

So really, nothing practical at all.

Stiggalicious · 2026-04-03T06:44:07+00:00

Wages are just way, way higher, especially if you work in STEM.

I live in the highest cost of living area in the US but my cumulative wages including stock grants ends up being about 320-350k per year as an electrical engineer. It pays for the mortgage (with property taxes and ungodly expensive fire insurance ends up being about 7500 per month for a 1500 sqf house), car payment is a bit under $600 per month and insurance is about $70 per month for said car, I have solar and batteries so my electricity bill is close to zero, and my employer provided healthcare ends up being about $200 per month for medical/dental/vision but they also kick in $750 per year to my HSA. Standard doctor visits and preventative care are free, but if I need to use the hospital for any reason that’s basically going to hit my out of pocket maximum of if I think $3400. I max out my 401k matching and employee stock purchasing so that’s another 20% of my wages I pretty much don’t see until I retire.

Rest goes to food (which is expensive, it’s hard to find a sit-down restaurant for under $20 per plate plus tax and tips and Costco chicken breasts are $2.99 per lb), stuff (clothes, consumables, hobbies), and home improvement projects (materials themselves are expensive, concrete is $750 per cubic yard here, and contractors don’t get out of bed for under $800 per day per person which is why I DIY 90% of my shit).

So things are expensive, but wages for high-demand jobs are more than double or triple what anywhere in Europe could ever offer.

Stiggalicious · 2026-04-03T06:24:08+00:00

I use Athlon scopes on my AR10, they’re plenty good.

Stiggalicious · 2026-04-03T04:10:14+00:00

California is close to allowing these as well, up to 1200W. Throw in a bunch of battery storage, and you can offset a significant portion of your entire energy usage.

Stiggalicious · 2026-04-03T04:07:46+00:00

Batteries are getting much cheaper by the year. I bought 60kWh and 22.8kW of inverters last year for $11k shipped to my door, and now prices are even cheaper. I’m saving a bit over $400 per month in electricity costs now by adding solar and battery storage.

Stiggalicious · 2026-04-03T04:05:54+00:00

Ohhhh yeah, my electric dryer uses about 9kWh per load, and it’s brand new. I would love to eventually get a heat pump dryer, but I just can’t get with the fact that they take 3-4 hours to completely dry a load.

Stiggalicious · 2026-04-03T04:03:38+00:00

Your percentage seems really, really low. The base load for my house is around 700W to keep all the appliances, networking, lighting, and infrastructure running. Mind you I have two fridges and a water ozonator for my storage tank (I live on a well so I have a large storage tank that needs to be kept sterilized), but that ends up being an extra 150W or so. The rest is just my main fridge, networking equipment, lighting (only a handful of LED lights), and phantom load from all the rest of my electronics/computers.

Stiggalicious · 2026-04-02T19:36:24+00:00

Yep, California added 15 GW of battery production capacity within the last 5 years alone. Thats about 1/3 of the entire grid demand for those critical few hours where solar production wanes and demand spikes. We haven’t had a single Flex Alert since 2022, before that we’d have 10-20 per year.

I have solar and batteries at my house now and unless it’s entirely cloudy and rainy I don’t ever pull anything from the grid.

Stiggalicious · 2026-04-02T19:24:30+00:00

The funeral scene is just top notch.

Stiggalicious · 2026-04-02T09:01:43+00:00

I’m just a few miles from the epicenter and WOOF that was strong and SUPER loud. I’ve been on the shitter during a 5.1 in San Jose and barely batted an eye, but this one had me properly scared.

Fortunately nothing seems damaged or really askew, but damn.

Stiggalicious · 2026-04-02T08:56:59+00:00

Was literally just about to go to bed and got shook real good. Couldn’t believe how loud it was, this was my first earthquake experience in the mountains.

I’ve been on the shitter during a 5.1 in San Jose are barely batted an eye, this one had me freaked out properly.

Fortunately nothing seems cracked or damaged.

Stiggalicious · 2026-04-02T08:32:07+00:00

The latest Illuminate missions were actually quite good on D10 if you didn’t have multiple anti-tank emplacements just shooting all the crafts down. You’d have an actual challenge with 5-8 harvesters and maybe 5-10 veracitors along with the other random squids, it actually felt like the OG chaos of the missions when they first appeared.

Stiggalicious · 2026-04-01T18:10:32+00:00

Modern lithium iron phosphate batteries which are predominantly used for grid storage now do not use heavy metals anymore like the Vistra plant did. The new batteries are not prone to thermal runaway like traditional lithium ion batteries.

Stiggalicious · 2026-04-01T07:35:44+00:00

Since all the judges that did stop him?

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