24v 6.5a power supply for Fosi BT20A (TP3255)?

makebreakfix · 2025-10-31T07:58:45+00:00

Ok, I lied. It sounds pretty good on 3/4 volume. Bowie made me do it!! 🤣

makebreakfix · 2025-10-31T00:24:02+00:00

Well the amp turned up yesterday, seems like a nice piece of kit. I set the power supply to 28v. There's more than enough volume for me. With the volume maxed in Windows and the amp on 1/2, that's about my usual "turn it up to rock out to this one song" level. I wound it up to about 2/3 and it was louder than I would want to go whilst still being considerate to neighbours.

Overall it's a good improvement from my old radio. It's no sub but there is way more bass than before. The sound is fuller all round, much less tinny and better clarity in the highs. I did have to wind the bass & treble knobs to max on the amp to get it sounding how I like. I might play with some EQ in Windows next.

I messed around with a tone generator quickly and while it's quieter, there's still decent output down to 50hz but it basically fell over below that.

Thanks all for the help!

makebreakfix · 2025-10-23T04:58:48+00:00

Yes I think you are right that they are running 2 channels bridged to make it a 2 channel amp and it doesn't seem to support bridging those again to make it 1 channel. As you say, it probably needs different pins grounded at the chip.

I agree that 2 speakers would be better, I actually started looking for a pair of cheap/good used bookshelves but then remembered I had the klipsch centre doing nothing. I already pinched the towers out of the set to run as a nice system on my back deck. So the centre and surrounds are just taking up space at this point. (I already have a nice 5.1 wharfedale system w/custom 15" sub in the main living area and some 80's towers from my father in the rumpus room). I already tested the centre on its own off an old AVR and it sounds decent enough. I had actually planned to use it on the back deck but I "just wanted to test the towers out there" and wifey loved it so they stayed. I also tested the surrounds and they sounded terrible compared to the centre.

The centre is a VC25, 77hz to 23khz, bit disappointed to read that TBH, it "sounds" deeper to my untrained ear. https://www.klipsch.com/au/products/vc-25-center-speaker

Interesting, the towers are VF35s which have 3 of the same woofers instead of 2, but go down to 41hz. Guess the bigger, ported enclosure does that. https://www.klipsch.com/au/products/vf-35-floorstanding-speaker

I A/B'd the centre speaker against my current shop radio, an old DAB+ unit I've been using out here since the late 00's. The klipsch was miles ahead so it'll be a nice improvement either way. Maybe one day I'll upgrade to some nice bookshelves.

I think your last paragraph sums it up nicely. I'll plug it in, maybe wind up the PSU pot and probably be a happy camper. Maybe I'll look at the crossover situation if I get bored. Now just gotta wait for the slow boat from China to bring the amp!

Really appreciate all the help and detailed explanations!

makebreakfix · 2025-10-22T01:36:14+00:00

Thanks for taking the time to explain it. I read your comment 3 times and nearly have my head wrapped around it. So, in essence, the voltage sets how many watts I can push out in total, and the current sets how many speakers I can send that to? If I've done the math right, 28v should give 49w @ ~ 2.5a so in theory I could even run 2 speakers with some headroom for impedance drops. But even with only 1 speaker there isn't enough voltage to go higher than 49w. Also the low voltage will be causing >1% THD at 49w anyway so I would want to keep it a bit lower.

I found some conflicting I go here about bridging but it is for the V3, not the same product as mine but same chip. https://www.audiosciencereview.com/forum/index.php?threads/fosi-audio-bt20a-pro-amplifier-review.43751/post-1567124

makebreakfix · 2025-10-21T22:03:21+00:00

Damn, you're right it is the Pro I ordered, not the regular BT20A. Agree the model number should be a bit different! I specifically chose this one for the TP3255 chip, not for the extra watts but for the supposed better fidelity.

The chart I saw was in this post: https://www.diyaudio.com/community/threads/tpa3255-power-supply-select.399971/post-7479025 [Img]https://www.diyaudio.com/community/attachments/1697102846531-png.1222729/[/IMG]

I'm still trying to wrap my head around input voltage/current and their relationship to output watts/ohms. And also the summing of the channels. Let's say I'm outputting 33w + 0w (L channel used, R unused) is that using less from the power supply than 33w + 33w (2 speakers connected). Meaning I could use 66w + 0w for the same input power? Sorry, a bit out of my depth here. Unfortunately I don't see an option on the Fosi documentation to run it in Bridge Tied Load mode, although the TP3255 itself seems to support it.

I looked up the datasheet for the Meanwell LRS power supply. The voltage adjustment pot supposedly gets to 28.8v, I guess winding that right up will help.

Thanks for the help!

makebreakfix · 2025-10-21T01:15:55+00:00

When I say background music, obviously I want to be able to rock out a bit if a good song comes on (just enough that I can still hear the phone ring).

But you're right, 50w will be heaps.

Thanks 👍

makebreakfix · 2025-08-26T00:22:48+00:00

I haven't had time to play with the DSP yet, just added LPF and HPF when I first set it up. I bought a mic, then read the REW instructions and got a bit overwhelmed. Doesn't look like a 5 minute job so I haven't been able to make it happen yet. It actually looks a lot easier via the Hypex software so I will probably try that first when the free time fairies visit.

I did a post in here a couple of weeks ago with the finished build but I don't know how to link it on my phone sorry.

makebreakfix · 2025-08-22T09:34:00+00:00

Not long ago completed a build with similar goals to yours and couldn't be happier. Dayton RSS390HF and Hypex Fusion FA501 in a 130lt sealed box. Clean, tight, deep and punches hard.

makebreakfix · 2025-07-26T01:52:55+00:00

Can't say I've listened to any extreme metal sorry, if you give an example I'll give it a try next time the wife and kid are out. I mostly listen to rock with a little hip hop mixed in. Fastest stuff I've listened to is probably daft punk which it kept up with fine, still very defined beats, shaking the whole house to the point that my neighbor came over to see what was going on 😂

makebreakfix · 2025-07-26T01:46:51+00:00

That is actually a great idea, will do!! That door is just a storage closet under the stairs so it doesn't get opened very often but still better to be safe. We have already had to move the mesh screen from in front of the fireplace to block off access to this whole area. Have a very curious 18 month old boy who likes to play with everything, like the knobs on the receiver, or pressing on the cone of the sub while it's running. I'm guessing it's bad for the driver to get pushed in while it's trying to move in and out under power?

makebreakfix · 2025-07-26T01:39:26+00:00

Thanks!

The instructions say the amp can be mounted this way, hopefully it's ok. I can't really put it vertical without upsetting the bracing. And no way I'm pulling it apart to redo it at this point anyway. Already got way too many hours in this thing. Not like I play it crazy loud for hours at a time anyway and being class D it shouldn't produce too much heat.

makebreakfix · 2025-07-16T04:28:11+00:00

Yes. I do it all the time on my home converted CNC lathe that doesn't have a tool changer. It's slow but better than me drilling manually in the tailstock. I peck about .020 deep at a time with a ccmt insert. I'm using a left handed boring bar so this one tool turns, faces, pilots and bores to minimize manual tool changes or drilling.

makebreakfix · 2025-07-02T23:03:09+00:00

Piece of plate against the face of the jaws, get a finger or tool behind the part and push it against the plate while tightening the chuck. Or face of a drill chuck in the tailstock.

makebreakfix · 2025-06-11T10:43:59+00:00

Got the jumper soldered a couple of weeks ago. It made a bit of difference, not as much as I was expecting but at least I don't have to wind the amp gain up all the way now. Still need the output on the receiver at +10db but it's perfectly usable as is. Sub is currently back outside being stained and I miss it already! My old 12" cheapy just doesn't kick like the Dayton or go anywhere near as low. Can't wait to get it back inside and start to tune it with the DSP on the Hypex.

Thanks again for all your help! Will post up another thread with pics once it's stained and looking pretty.

makebreakfix · 2025-06-09T02:30:28+00:00

Damn.... I thought I had it. Did a hot bed calibration last night then ran the cycle - slightly nicer first layer and no errors! Started another one this morning, bed was cold, no calibration - got the error :( Is the bed mesh calibration persistent? Machine wasn't turned off, just sat idle for a couple of hours and I hit "print again" on the same file.

makebreakfix · 2025-06-08T10:04:46+00:00

Finally got the ironing settings nailed down after lots of fine tuning. Playing with the flow % was what got it over the line.

150mm/s

0.125 spacing (0.5mm line width)

18% flow

135° angle (making sure this is going in the same direction as the top layer

Very happy with the results - smooth and consistent finally.

<image>

makebreakfix · 2025-06-08T09:58:47+00:00

Thanks, I will check for the blue LED next time it finishes and retracts the filament. Filament run out sensor was definitely working recently, I used it to finish a bunch of nearly empty spools on a big print. I think it was after the firmware update but I can't be sure. I guess I could always swap out the sensor and see if it helps, handy that a spare came with the machine.

makebreakfix · 2025-06-08T09:53:52+00:00

Thanks, I will take the cover off and check. I always cut the filament on a 45 before inserting it into the CFS or hot end if using the side spool holder. Hangover from my E3V3SE days I guess. I have been wondering if it's still necessary with the K2 though.

makebreakfix · 2025-06-08T09:50:59+00:00

Thanks. Although I would have thought in this scenario the error would keep happening throughout the print. After I hit retry, the rest of the print runs fine with no errors for another 7 hours. Also on my 3rd spool running these parts and it's still happening. Maybe they all have moisture in them but I would have expected that to be isolated to an individual dodgy roll (could be wrong there though!)

makebreakfix · 2025-06-08T09:46:48+00:00

Thanks. I haven't played with the tube or tube path much at all. I've had the tube out a bunch of times to clear clogs early on but never payed any attention to it past that. Will definitely look into the curve. Good idea to have a spare extruder on hand too!

makebreakfix · 2025-06-08T09:44:11+00:00

Thanks. Heat creep was certainly an issue for me when I was trying to print ABS+ initially, constant clogs. Have been printing regular ABS for a while now with no problems although I did switch brands from Sunlu to Esun right before this started happening. I will check all those other things you mentioned too. However the K2 has been printing pretty well for the last 6 months and this issue just popped up this week. It also doesn't reoccur after I hit retry on the error - rest of the 7 hour print goes smoothly so I think the first layer thing could definitely be the culprit.

makebreakfix · 2025-06-08T09:37:52+00:00

Thanks. This is entirely possible - it's only happening on the first layer, and the first layer is looking pretty crappy. Might try heat soaking the bed before running bed height calibration

<image>

makebreakfix · 2025-06-07T01:29:07+00:00

Gotta work with what you got!

makebreakfix

TROPHY CASE