Hi,

I’ve always been curious about the actual acoustic transfer functions of stethoscopes versus the marketing claims, so I put together a DIY acoustic test bench to run some frequency response measurements.

The Setup & Methodology:

(Attach your measurement graphs here)

Graphs & Traces:

Acoustic Observations & Takeaways:

Questions for the acoustics & audio folks:

Appreciate any insights or critiques on the methodology!

It’s more a sound system question, but since it is self built, I am hoping the DIY Audio community might have some good insights as well.

I got this Subwoofer for 12 bucks since my Old BLG Subwoofer died with its voice coil rubbing. Good or shit?

I have a lovely pair of ML810 JPW speakers i now use as my rear speakers.. using some slightly worse speakers as my surrounds because this tweeter on the left is not playing any sound. Having 0 knowledge i used AI which led me to think the tweeter is blown.. AI suggested the speakers on the left as it would be a perfect drop in replacement.. oops my dumbass fell for it twice and now i have this tweeter i definitely have to return as it's waay to big and not a match at all . The last thing I want is to drill into these amazing cabinets and ruin them with the wrong tweeter. Checked online and they are not for sale anywhere.. the mids and lows are soo amazing i really hope one of you amazing people have a suggestion on how i can save these speakers..

I tested with a multimeter (with AI as i have no clue what im doing) it seems the crossover is working.

Hi everyone, I'm building a DIY subwoofer for my home theater and could use help finalizing the enclosure. I want solid output down to ~20 Hz.

Driver — Dayton Audio RSS390HF-4

Amplifier — Dayton SPA500DSP: 500 W RMS @ 4 ohm, with onboard DSP

Use: Home theater (movies/music), target deep output near 20 Hz. Constraints: I can build a fairly large cabinet, but I'd like to know the real trade-offs.
Room is roughly 23.6 ft × 12.1 ft × 9.8 ft (about 2,822 ft³), with an adjacent room to the right (no dividing wall) that is roughly 14.1 ft × 7.2 ft × 9.8 ft (about 1,002 ft³).

Questions:

1. Ported vs sealed for my 20 Hz goal — which alignment do you recommend and why?
2. What port diameter/area and length keep port air velocity acceptable at ~500 W?
3. Where should I set the subsonic high-pass filter to protect the driver below tuning?
4. How much EQ/boost will I need to flatten the response to 20 Hz, and roughly where?
5. Any recommendations on box dimensions, MDF thickness, and bracing?

Got this cassette player and speakers from the side of the road. Owner said the things worked but they couldn’t move with them. Not sure though how I connect these speakers as they have basic red/black wire but not the right connections for the ports on the back. This is my first time messing with this stuff and I know it isn’t a fancy unit, but my kids and I are excited to hear if we can. Willing to buy some items but trying to keep it low cost if possible. Thanks for any advice ahead of time!

Is this fabric suitable for DIY acoustic panels, or should I return it?

Hey everyone!

I'm currently building four acoustic panels for my small home studio in my living room. Each panel measures 120 × 60 × 10 cm and will be filled with rock wool.

For the fabric covering, I bought a material made of 60% polyester and 40% viscose (rayon). The fabric is relatively thin, actually thinner than a regular T-shirt, and has a fine woven texture. It's also somewhat translucent. When I hold it up against a flashlight, I can partially see what's behind it.

My main concern, however, is its breathability.

I tried the so-called "blow-through test" to find out whether the fabric is suitable for acoustic panels.

Here's what I noticed:

- I can blow air through the fabric, but there's noticeable resistance.

- For comparison, I tried blowing through a regular T-shirt. Air passes through the T-shirt much more easily, almost without any resistance.

- With the fabric I bought, however, it feels like significantly less air passes through.

- When I stretch the fabric slightly or pull it taut, air passes through more easily.

- Both sides of the fabric feel the same, and I couldn't find any obvious coating.

So now I'm wondering: Is this fabric still suitable for my 10 cm thick rock wool acoustic panels despite the noticeable airflow resistance?

Could the relatively low breathability cause certain frequencies, especially higher frequencies, to be reflected more strongly, making the absorbers less effective?

I mainly want to use these panels for vocal recording, but also for mixing and mastering. That's why it's really important to me that they work as effectively as possible.

Would you keep and use this fabric, or would you return it and buy something more breathable instead?

I honestly love the way this fabric looks, which is why I'm having a hard time deciding whether to return it.

Thanks so much for your help!

I need a "gut check" from the experts here. I pulled the amplifier ("brains") from a keyboard amp to mess with, and the thought occurred to me: Is it ok to power on a solid-state amp with no speaker load? I know this is a very dangerous no-no with tube amps, but I've never thought about solid state amps.

I know you can take your average off-the-shelf Peavy power amp and turn it on without a speaker plugged in and it will happily sit there and do nothing, so I assume it's ok, but better safe than sorry!

KEF CS7

Little excerpt of me playing my chaotic pointcloud system, in which the particles are being audioreactive to the incoming audio signal in real-time. What do you guys think?

Full video at: https://www.youtube.com/watch?v=UFSy6N3HU1U

Project files accessible through Patreon, or the Studio.

Drag the box size, tuning and power, hit play, and push it past Xmax to hear it fall apart (headphones help)