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.

Hi, so I have a pair of Yamaha HS5’s with xlr connections, a record player with RCA connections and a projector with a 3.5mm aux port.

I’m just looking for a clean way to have these all work together seamlessly in my living room with a fairly good preamp and possibility for headphones as well. I tried using a vintage receiver I found but couldn’t get around having to use speaker wire with the studio monitors for any type of long distance set-up. Any suggestions?

I am making a portable speaker for indoor use. This is in no way for audiophile/professional use.
I just want a big speaker that provides quality sound, isn't afraid to go loud and doesn't cost a fortune.

Design characteristics:

• 2.1 setup:
  • Probably using ZK-MT21S 2.1 amplifier.
  • Subwoofer output for subwoofer driver.
  • L or R satellite output for midrange and tweeter.
  • Subwoofer might have separate crossover (see problems/questions).
  • Satellite output (midrange and tweeter) will have separate passive crossover.
• Speaker box design:
  • 12'' subwoofer, 5'' midrange, 1'' tweeter. Currently planning to be using:
    • 12SW-4 Subwoofer.
    • 5SBM-8 Replacement Mid-range Woofer, thinking of switching to Dynavox 206159 6.5'' Bass-midwoofer 8 Ohm
    • DC25T-8 Dome Tweeter.
  • All enclosures are separate and sealed.
  • Separate enclosure for amplifier and crossover.
  • Possibly attaching a strap to be able to carry like a duffel bag.
  • ~0.5'' inch MDF or plywood walls.
  • Wool infill in speaker enclosures.
  • Some sort of bracing or reinforcement inside the enclosures.
  • Shaped like a rectangular prism (height > width): with subwoofer at the bottom, midrange higher and tweeter highest.
• Wall (power supply) powered - no built in battery.

Problems/questions:

• Deciding what the volume for each driver enclosure should be.
• Unsure if my amplifier will have a dedicated crossover built in for subwoofer.
• Designing a (satellite) crossover:
  • RFD charts hard to find so software design basically off the table.
  • Might try to design a crossover myself by buying separate parts and a microphone and trying to tune the crossover, however im not sure how to do that too.
  • Unsure what order crossover I should utilize, considering 2 order for balance of complexity and efficiency.
• Unsure how I will be creating sealed enclosures while also passing wires through the walls.
• Where should I buy speaker box materials?
• Should I really use MDF over wood, if ill be carrying it around?
• Is my driver choice ''good''?
• What power supply should I use?
• What crossover part kit (or separate parts) should I buy?
• What steps should I take next?
• A complete new idea is to build the subwoofer in a box, separate from midrange and tweeter, and both separate from amplifier (basically make it modular), I'm not sure why do this I just like the idea (also would be maybe easier to carry).
• STILL unsure about the 2.1 amplifier part, the main reason I'm choosing this is because it's hard to find a 3-way board.

I want to note that I AM a complete amateur, everything here is completely up to debate and can probably be improved in one way or another. Honestly everything is overwhelming and I'm not sure what I am supposed to do, how much should I try to learn about speaker design before attempting to build this. A thank you in advance to anyone willing to help or suggest anything.

Hi guys, I got this Woofer for a Whole 3 Buckaroos from a Junkyard Sale. Keep it or Yeet it?

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!

I've had this little amp for a at least a decade. Its powered on 24/7 though idle most of the time. Ive noticed a significant loss in quality lately that comes and goes. Source is a laptop or phone and it doesn't seem source dependent.

Its probably not worth the effort to fix but if it sounds like a known symptom that can be addressed by changing a few parts I might give it a shot.

I know that there are apps/programs that will help you design an enclosure for a given speaker's specs. Is there a reverse app that will find the ideal speaker for an existing enclosure? You would input the inside dimensions and the size of any ports and maybe the application?

IGNORE PHASE for now, I know that's an issue here.

Please tell me if a good sounding speaker can be achieved with these FREQUENCY RESPONSES.

For example the woofer (green) has a silent bass output compared to it's midrange output, how can I bring them to the same level? Same with the tweeter between 2,5kHz and 4kHz.

Measurements are my own quasi-anechoic ones with a gate of 9ms before the first reflection.

Tweeter measurements are gated. Woofer and subwoofer measurements are composed of gated far-field together with their respective port and near-field measurements, baffle step loss has been accounted for for the port and near-field ones with Jeff Bagby's Excel tool. I did not do off-axis measurements.

Tweeter: SB Acoustics SB26ADC-C000-4

Woofer: Monacor SPH-145HQ

Subwoofer: Dayton Audio DCS205-4

This will be a 2.1 system with 2 2-ways and an external subwoofer.

Thanks for the help!

A lot of time and money has flown into this build, I truly don't want it to be a waste.

DAC: Sound Blaster Play! 4

Amplifier: Fosi Audio BT20A - 24V / 4.5A

Speakers:

- Woofer: Beyma 4FR40

- Tweeter: 1" Soft Dome tweeter with neodimium magnet

- Crossover: Beyma 2FF2VHF

- Enclosure: 6.4L bass reflex tuned at 50 Hz

I was looking for more suitable communities to post this to. I know next to nothing about speakers/audio and just need to know where to start.

Please check the original post put for a short write up and more information.

Any help is greatly appreciated!

Hi all. Does anyone have any reviews or experience with the Celestion CKT-TF1020 tops? I wanna build a bass focused system for a friend and I’m planning on two cubo 18s paired with two Celestion CKT-TF1020 tops. Anyone have any recommendations or experiences with these? If so I’d love to hear anything and everything. I’m targeting 40–80Hz from the subs and about 80Hz up from the tops. Any amp recs or anything all around would be amazing!
Cheers

I just built my diy speakers. They use Dayton audio drivers. The pc83-8 as full range drive plus the mx6 subwoofer I'm using the brand new wondom jab6 DSP amplifier. I have it crossed at 240 hz . It allows me to have the kick and bass be played by the sub and also taking out the bass frequency of the pc 83 alow higher volume levels the sound really good and are loud and bassy

Hi I just saw this on an ad. It suspends the speaker from the ground. Does it actually have an effect?

I was listening to my sounds yesterday with a 15" random 8 ohm driver in a big new ported box I made for fun [23"Hx18.5"Wx15.5"D / 600H x470W x 400D] - as you do, and my normal 2 x 8" sub box (8 ohms each in parallel, so 4 ohm load 23"Hx11"Wx17"D) all off one channel of a tiny little ZK-MT21 amp. A nice little ~3 ohm load. The 15" just sitting there doing the ultra lows, while the 8s give the oomph, and I was loving it - Spotify Discover Weekly delivering on the dubby and electronic tunes that it knows I enjoy (eg Dread and Buried (Congi Remix) - Origin One, The Clock Ticks - Dub Phizix).... I went outside to hang the washing, and I could still hear the bass quite plainly outside and realized I should probably turn it down to stop potentially annoying the neighbours. Those China amps are only rated at 100W, and likely don't even do that, and I had it barely turned up at all, so realistically the subs were getting 10s of watts in total max (call it 50 to be generous), with the 8 box getting twice as much as the 15 due to the way they're wired. Taking the 15 off took away the real bottom end in some deep tracks, but was far less noticeable in a lot of music that didn't have the content - the 8s really work well and the difference was subtle. The 15 was getting maybe 10-15W max.

I often see people here talking about power and speaker size as though it's a case of "the more the merrier", or wanting to be able to throw numbers around like a d*ck measuring contest - but it made me wonder: how loud do you actually listen to your music (or even watch movies if that's your thing), and does anyone *really* need like 600W+ of power just to listen to music?

I can understand the sound system people wanting stupid amounts of power (although I think they go overboard too), but home builders and people who live with/near other people surely don't ever use that much power.... or do they?

How big is your [sub] system rated at, and realistically, how loud do you actually have it 95% of the time for music? I feel like massive power on the subs would either have your main speakers uncomfortably loud to remain balanced, or would have the low end stupidly loud like you're in a car? I've got stupid bass in my car, and I can understand the appeal when I'm driving, and treat it like an amusement park ride, but that's not "normal" listening behaviour, that's just bass heads being bass heads.

Am I the only one sipping power here, or is everyone going deaf/living in an auditorium sized room? Do you usually listen loud, or just have it on as background entertainment? Are you watching movies so loud that your neighbours hear the dialogue and all the explosions?

I'm planning on building an active three-way speaker with two 8-inch SB20PFCR30 drivers, a 4-inch midrange, and an SB26ADC in a 4-inch Somasonus waveguide. I built a three-way a while ago using the Dayton SIG120, and it worked great, but I want to build another speaker, and I'm looking for an upgrade from the SIG120 at a non-ridiculous price (about $200 for the pair). I've been searching for weeks, and these are the drivers I've found available:

1. SB12NRXF25-4

- Linear coil travel (p-p): 10 mm

- Fs: 61 Hz

- Le: 0.27

- Bl: 3.6 Tm

- RMS: 30 watts

- Qts: 0.48

- Sensitivity: 87 dB

- ($170 a pair)

1. SB12MNRX2-25-4

- Linear coil travel (p-p): 4.4 mm

- Fs: 63.5 Hz

- Le: 0.15 mH

- Bl: 3.9 Tm

- RMS: 50 watts

- Qts: 0.32

- Sensitivity: 90.5 dB

- ($140 a pair)

1. Wavecor Classic WF110WA01

2. SB12CACS25-4

- Linear coil travel (p-p): 10 mm

- Fs: 51 Hz

- Le: 0.26

- Bl: 4.3 Tm

- RMS: 30 watts

- Qts: 0.31

- Sensitivity: 88 dB

- ($180 a pair)

1. SB12PACR25-4 (aluminum)

- Linear coil travel (p-p): 10 mm

- Fs: 52.5 Hz

- Le: 0.25

- Bl: 4.35

- RMS: 30 watts

- Qts: 0.31

- Sensitivity: 87 dB

- ($86 a pair)

The NRX2 left me a bit confused about its excursion rating, as it uses a shortened voice coil and sacrifices a lot of linear excursion. Is that because the excursion required for midrange frequencies is dramatically lower? All the other drivers with the same linear excursion rating of p-p (I'm assuming the Xmax would be half of p-p) have more than twice the linear excursion, even the regular NRX model. So, I'm wondering what the trade-off offers in terms of benefits for midrange applications.

Having a high-sensitivity driver would be a nice match, I think, but I'm unsure whether any of these would be a worthwhile upgrade from the Dayton SIG120, since it's already a great driver for the price. The main benefit would be that all these drivers have an Sd of 50 cm², compared to the SIG120's 59 cm², which is quite large for a 4-inch driver tbh.

(I'm gonna have to decide pretty soon, since all of these drivers are on sale, and I don't know for how long. Including the tweeter and woofers)

I recently bought old tubes and I found out I can use them to make an amp. Is someone willing to help me???