The 3118 is the chip in the amp i use with my A6.2m in the portable system.
It may not be much more power, but the TD2024 is really dated, and has been ou tof production for some decade & a half… they still have some left? And don’t forget that quality of implementatin can make a huge difference.
How big is the box, the tuning?
dave
It may not be much more power, but the TD2024 is really dated, and has been ou tof production for some decade & a half… they still have some left? And don’t forget that quality of implementatin can make a huge difference.
How big is the box, the tuning?
dave
I built the box according to the Markaudio guidelines, basically 2 speaker cabinets sharing a wall (see my pics earlier in this thread). One thing I failed to count was the PSU + amp that I mounted inside the cabinet, taking up volume. Also I didn't count the foam. So it is very likely undersized.
I will try the TPA3118, but to answer my own question before, there is a data sheet with a nice set of graphs (page 10) for the PS voltage / output power function. With 12V supply I might be stuck at 15W - which is fine, because the Alpair are rated at 15W anyway. Oh well, it could make a nice birthday gift for my mom while I test a more efficient speaker...
However, I could get back to my DeWalt battery idea... remove the battery pack inside the cabinet, which also frees up volume, and plug in a 20V drill battery which should provide plenty more voltage. These batteries only have 1.5Ah, but I can swap them if I find a battery bay from a scrap DeWalt tool.
I had a taste of that when I connected the amp to one of my Audio Nirvana 10" speakers, which is rated at 96dB - it almost shattered my wine glasses (it actually didn't because I shattered them manually before).
Efficiency of class D-modules is in the ballpark between 80 and 90 percent, so the difference between chips is not an issue. Operating voltage, speaker impedance and their efficiency are the dominant data for your choice.
There are 2 kinds of plans you get from Mark Audio, either ones that Mark or another MA guy did (Evan in this case), or ones Scott has done. The former need checking.
Volume is near optimum, I would suggest increasing the vent length to 76mm. The tuning given is at best “strange”.
How much, where, and what kind of damping do you have?
Irrelevant.
You want more power stack two batteries.
dave
Excellent idea… i love my DeWalt 20v drill.
A bit expensive maybe, and one might want an 2nd charger (or at least the socket part) so you can really quickly swap batteries.
https://www.homedepot.com/p/DEWALT-...n-Battery-Pack-with-Charger-DCB203C/315470771
Not a new idea. It is (similar) the same technique Jeff used for his Pass RIAA amp, but he just uses alligator clips to hook them up.
dave
Attachments
I have 1/4" foam around the external sides, top, bottom and back. I did not add dampening in the middle partition to leave room for reconfiguring the boards.
What's irrelevant, the speakers' 15W rating or my 15W limit? (I assume it's the latter as you mention stacking batteries. But won't that push the drivers over their limit?)
Yes, a scrap charger or tool sold "for parts" should do. I already have 3 batteries and that was part of the original idea. Easy swap would be critical as I imagine the battery would get drained quickly.
You desoldered the one on the amp board? Or? How is it hooked up... I'd like to do something similar with mine, if possible?
The board I got is very basic, no onboard controls or jacks, just the input and output contacts. But I guess that unless your board is highly miniaturized, you should be able to desolder the potentiometer and move it somewhere else, or even replace it with one that fits your output/speaker setup better.
Sure enough, they have 3D-printed battery adapter for DeWalt and other brand tools: **Dewalt 20V Li-ion Battery Adapter RC Robotics Power Output Connector DIY** | eBay
Maybe more expensive than a scrap drill or dead charger, but prettier
Maybe more expensive than a scrap drill or dead charger, but prettier
One more thing... Dewalt doesnt have BMS in their batteries. You must have at least low voltage cut-off at around 15V. If you discharge them to a certain V/cell, they crap out permanently.
You can easily find a BMS for dewalt battery, its 5 cells series. They dont need balancing when discharging so only 3 wires have to be connected
Which means that your BMS can be located anywhere
Buuuuut... If you decide and find a super small BMS that can be fitted inside the battery you can use any 20V charger to charge it.
You can easily find a BMS for dewalt battery, its 5 cells series. They dont need balancing when discharging so only 3 wires have to be connected
Which means that your BMS can be located anywhere
Buuuuut... If you decide and find a super small BMS that can be fitted inside the battery you can use any 20V charger to charge it.
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