WAW / FAST, Class D Boombox build
So a few months ago I decided I needed a sound system for the back yard for a major work project.
So I started looking for woofers that could go into about 1 ft^3...that were reasonably priced and had reasonable efficiency.
Found a Goldwood GW-10pc4 that seemed to simulate well in about that space. (ended up with about 1.2ft^3)
In parallel with that I took a look at 3" "fullrange" from here:
Resources - Woofer Selection Guide
Liked what I saw in the Faital 3FE25 that worked in a sealed section.
I did some power and efficiency calculations and came up with putting two 4R 3fe25's in series in a 0.2ft^3 to come close to the output of the Goldwood.
Using a 24V supply gave me about 60W PBTL for the 4R Goldwood and 36W BTL per side into 8R for the Faitals.
Next was the CAD designing for the box...Then bought a sheet of 3/4" Maple plywood, got out the tools of destruction and started to make sawdust.
I wanted the Faitals rear mounted and the Goldwood front mounted.
Some construction photos in this post...no screws or nails-just glue at this point...more later about crossovers and class D amps.
So a few months ago I decided I needed a sound system for the back yard for a major work project.
So I started looking for woofers that could go into about 1 ft^3...that were reasonably priced and had reasonable efficiency.
Found a Goldwood GW-10pc4 that seemed to simulate well in about that space. (ended up with about 1.2ft^3)
In parallel with that I took a look at 3" "fullrange" from here:
Resources - Woofer Selection Guide
Liked what I saw in the Faital 3FE25 that worked in a sealed section.
I did some power and efficiency calculations and came up with putting two 4R 3fe25's in series in a 0.2ft^3 to come close to the output of the Goldwood.
Using a 24V supply gave me about 60W PBTL for the 4R Goldwood and 36W BTL per side into 8R for the Faitals.
Next was the CAD designing for the box...Then bought a sheet of 3/4" Maple plywood, got out the tools of destruction and started to make sawdust.
I wanted the Faitals rear mounted and the Goldwood front mounted.
Some construction photos in this post...no screws or nails-just glue at this point...more later about crossovers and class D amps.
Attachments
Last edited:
I had these active crossover boards made for possible three way active speakers. They were designed to provide differential (balanced) outputs for TPA311x amplifiers.
Only needed a two way and combining the sub channel was easy when using differential input amplifiers.
(Grounds and power are not shown on the block diagram)
Only needed a two way and combining the sub channel was easy when using differential input amplifiers.
(Grounds and power are not shown on the block diagram)
Attachments
Last edited:
What is the XO frequency and what are the filter types and slopes? Would you by chance be selling the boards at some point?
370Hz is a very good match for most FAST projects I do with a 10 to 12in wide baffle and a 3.5in full range.
The lack of a proper cross over upstream of the TPA31xxD2 has always been something that has h forced me to go down the miniDSP route. It would be nice to have a simple active circuit. Having balanced outputs is a bonus for low noise.
370Hz is a very good match for most FAST projects I do with a 10 to 12in wide baffle and a 3.5in full range.
The lack of a proper cross over upstream of the TPA31xxD2 has always been something that has h forced me to go down the miniDSP route. It would be nice to have a simple active circuit. Having balanced outputs is a bonus for low noise.
LTspice shows crossover is at about 285 Hz. I had originally been focused at a frequency of about 350Hz but found the Faitals ran lower in the volume I had for them.
Exact choice of frequency has more to do with economically priced film caps from Digi-Key that fit their area on the board than with anything else.
Here is how it all fit on the back.
Attachments
Very nice. What is the circuit on the bottom right? A speaker protection relay?
I see you went with big fat PBTL for sub and Gen 0 board for stereo? I still use that Gen 0 board for most of my testing and initial characterization of speakers. Sounds great.
I see you went with big fat PBTL for sub and Gen 0 board for stereo? I still use that Gen 0 board for most of my testing and initial characterization of speakers. Sounds great.
Bottom board is 24V to +/- 15 for crossover board and +10V 2A for Bluetooth/USB/SDcard/FM/AUX input module.
Stereo board is DUG-3. Has mode and frequency options...running at 500KHz.
Stereo board is DUG-3. Has mode and frequency options...running at 500KHz.
Attachments
Last edited:
I bet this thing can get pretty loud. 105dB?
You did not run into any ground loop issues? It looks like your secondary power converter did a good isolation job.
You did not run into any ground loop issues? It looks like your secondary power converter did a good isolation job.
I would like to setup something to measure the output to see if I need to adjust the levels of either of the amps. Have a mic and SW...just need a laptop so I can go in the back yard and point it up.
🙂
🙂
Use REW software - works very well. Even a cheap mic is better than guessing. Look forward to your measurements.
I wish the Chinese would make a good XO board like yours and sell it for $30 built with parts 😀
I wish the Chinese would make a good XO board like yours and sell it for $30 built with parts 😀
A $15 Chinese made TPA3116D2 amp (the Ybdz "wiener") costs less than the BOM if you were to build it yourself and sounds very nice - even stock. Good and cheap.
I use these for my reference sound system - just minor upgrade with oscon caps and added bootstrap snubber. They sounded very good before the mods that I live with them stock for 9 months.
Still $15
http://m.aliexpress.com/item/1586764360.html?tracelog=wwwdetail2mobilesitedetail
I use these for my reference sound system - just minor upgrade with oscon caps and added bootstrap snubber. They sounded very good before the mods that I live with them stock for 9 months.
Still $15
http://m.aliexpress.com/item/1586764360.html?tracelog=wwwdetail2mobilesitedetail
Last edited:
Yes the +/-15 is isolated from the +24 and the +10 is also isolated from the +24 and the +/-15.
- Status
- Not open for further replies.