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.

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!

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

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!

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!

Hey guys, doing some digging before I start cutting wood. I'm building my first real system and want to start small and add to it.

Phase 1 is one Cubo Sub (the 18") loaded with a B&C 18TBX100 (8Ω, 6.2Ω min, 1200W nominal / 2400W program) and one Celestion CKT-TF1225 top (8Ω nominal, 6.5Ω min, 250W AES woofer, 400W EIA system). Phase 2 is a second sub and top, and later I want to add Cubo Kick 15s in the middle.

Use is backyard hangs and small gatherings, maybe a festival camp for 30-40 people. Not a concert rig, I just want it to sound good and not be underpowered. I'll run a miniDSP 2x4 HD for crossover/EQ and have a friend helping me tune with a mic. Planning to cross the sub around 80-90Hz and the top above that.

Where I'm stuck is amps. Budget isn't super tight (a few hundred over is fine) but I'd like to keep it in check:

- Crown XLS 2502 (open box, ~$539) for the sub, XLS 1002 for the top(s) later
- Behringer NX3000D (~$339) with the built-in DSP, or an NX4-6000 (~$469) to cover everything with 4 channels
- CVR D-1002 (~$699). A friend says plenty of people run these without issues

What I keep going back and forth on:
- Is the Behringer's listed 440W @ 8Ω real or just peak, and does it matter for a sub at my listening levels?
- Has anyone had Behringer NX amps die on them?
- Would you take the CVR over the Crown for subs?
- Should I use the 4Ω version of the TBX100 to get more out of the amp?

What would you run? Any gotchas with the Cubo Sub + TBX100 combo I should know about? Appreciate any help.

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!

Would superglue be enough? Or would i have to reinforce it with something?

I’m starting to get into audio to add to my truck and I want to add subs but I’m not sure what I need in regards of amp, speakers etc. I plan on building the box myself and it’s going under the back seat but not sure if I need to change anything in the radio

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?

Hello! I am a software engineer that's trying to get more into electronics. I recently bought some 25W speakers online and decided to design my own circuit to drive them from a 3.5mm aux input. I would love some feedback on the design, as I'm still quite new to audio and electronic engineering in general.

The first half of the circuit uses a TL074 for filtering and voltage gain and the second half provides current gain using a class B push/pull stage built on a Sziklai pair. The filters have cutoff frequencies at approximately 100Hz and 15Khz. The class B push/pull stage provides a feedback signal to one of the opamps which corrects crossover distortion quite well.

I use a USB-C power delivery capable supply at 20V 2.25A to power two instances of this driver (stereo). It appears to be thermally stable as it can operate for several hours without issues.

Here are some images of the final product. I built the cabinet out of (crudely cut and joined) 9mm thick MDF. The cabinet was sealed with silicone from the inside for the most part, except for the removable back panel which uses a foam gasket to provide a decent seal.

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.

I wanted something that looked like mid-century hi-fi rather than "obviously 3D printed." The wood-fill walnut does a lot of the work there, and the matte orange baffle keeps it from looking too serious. The 3D printed aesthetic is part of the charm though and they’re a good conversation piece.

Printer: Bambu Lab X2D

Setup: They're on my workbench desk with a Yamaha AV receiver underneath, which sits under a plywood shelf propped on stacked bricks. Very scientific. lol

How they sound: Very surprised by the quality. I’m a beginner audiophile so I don’t have the language to describe these as accurately as I might like but the iPhone video doesn’t do it justice at all. In person they sound fantastic.

Would I do it again: yes, I probably could have achieved the same quality with a pair of RP 600M or similar for the same price, but I had fun building the kit and it gave me a better appreciation for the intricacies of speaker design.

Happy to answer questions about the build!

Hey everybody!

This is a simple LM1875 BTL sound system I made a while ago. I wrote up some documentation, but I never shared it. I figure that document is worth sharing, so the Github page I made for it is linked below.

https://github.com/Amperegeist/LM1875-Single-Rail-Bridge-Tied-Load-with-Receiver/blob/main/README.md

This is basically the single rail version of the modualud power stage, as well as the 'easy receiver.' I'll be making new documentation for each block as I rebuild them. I do intend to rebuild this prototype, especially the receiver.

The previous power stage I posted is the dual rail version, which I designed after this.

The main advantage of this power stage is that you can run it from a random ~24V power brick.

The quality of the power supply does affect the sound quality, but you can run it with unregulated rails if you have the right transformer. That is what I will do in the future, but a cheap 24V power brick is great for prototyping. The built in protecting circuitry is particularly helpful.

I no longer have this specific version of the prototype, but it developed a slight DC offset at the output which I had to block with output capacitors. I just noticed those are not included in the schematic. The dual rail version doesnt have this problem.

I may have damaged this prototype during testing. I'll investigate that problem further when I rebuild it, but I will be pointing people to the dual rail version in general. I will not be making another perfboard version of this power stage, the next one will be on a dry film PCB.

The best information in this document has to do with the receiver. All DAC's have some amount of noise that needs to be filtered out. I show an example of the noise in a cheap Amazon bluetooth module, and how you can build a simple analog front end to remove it. This receiver is also convenient to use as a portable function generator for testing.

If anybody is interested in providing feedback, the feedback I'm most interested in is how to improve my documentation in the future. I plan on making it quite different from the documentation linked below. It will have more information and be more professional.

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

Got this when I'm running a sweep through the crossover (3-way 1st order) with only the woofer connected. I get a normal sweep going to the woofer directly, or the woofer through the inductor off-board. Only going through the board do I get this weirdness. I understand that electrically this is telling me something is shorting. But it's a 5 component x-over (2nd order on the tweeter, l-pads are off-board and physically out of circuit for this sweep). I promise you it's all separated visually with no questionable short spots potential. Obviously electrically we see I'm wrong. I suppose some weird air coupling is possible. 16awg stranded hookup wire that has a few overlaps. But even if I pull them apart (~1cm of air, plus the plastic wire coatings) the sweep looks the same.

Companion speaker shows a normal sweep through the crossover. Identical layout/build.

Could I have shorted something while soldering? Could I just have a bad from the factory component? Dreading de-soldering the whole board, any pinpointing testing that would be valid without taking each component out of the circuit?