I've noticed tiny class D amps on taobao and ebay are getting popular, however, all(ok, most) of them had external SMPS, and usually it's an awful industrial/LED or power brick for a laptop. I like a challenge, so I decided to design the same sized amp but with a good quality "audio grade" SMPS onboard.
Specs roughly: PCBA 139x100x29mm, 2x125W@1kHz@THD+N=1%, 2x115W@20Hz@THD+N=1%, 1/2 max Power THD+N = .04%, S/N <-105db, regulated LLC SMPS with frequency shuffling 230VAC/110VAC. USB high resolution audio input CM6631A, BT stream I2S input(not ready yet), System control and BLE smartphone control(IOS/Android apps are not ready yet but I hope about 30 parametric EQ + LPF/HPF 2-4order, and probably frequency response calibration for particular speaker) Ti CC2540. Due to very light case-heatsink, the amp running quite warm, and actually off by OTP during couple minutes of 125W+125W 1kHz sine at 4ohm load, however, amp never off on a music and 4ohm speaker load. So it is the compromise to meet a high-density power in a tiny case for real world 😉
^7C2E7898B5C2544FED7EA0A70D1BF5898416EAE3C2BD8C1DBE^pimgpsh_fullsize_distr.jpg
Specs roughly: PCBA 139x100x29mm, 2x125W@1kHz@THD+N=1%, 2x115W@20Hz@THD+N=1%, 1/2 max Power THD+N = .04%, S/N <-105db, regulated LLC SMPS with frequency shuffling 230VAC/110VAC. USB high resolution audio input CM6631A, BT stream I2S input(not ready yet), System control and BLE smartphone control(IOS/Android apps are not ready yet but I hope about 30 parametric EQ + LPF/HPF 2-4order, and probably frequency response calibration for particular speaker) Ti CC2540. Due to very light case-heatsink, the amp running quite warm, and actually off by OTP during couple minutes of 125W+125W 1kHz sine at 4ohm load, however, amp never off on a music and 4ohm speaker load. So it is the compromise to meet a high-density power in a tiny case for real world 😉
^7C2E7898B5C2544FED7EA0A70D1BF5898416EAE3C2BD8C1DBE^pimgpsh_fullsize_distr.jpg
Commercial project?
Such a tight layout is too difficult without mechanical cad, at least for such stupid nerd as I'm(can u see ugly heatsink edge?). So let me advise you, guys, pay more attention to Solidworks/Autocad/Freecad etc, whatever commercial project or not.
Untitled-2.jpg
Untitled-2.jpg
Last edited:
BOM is not really cheap yet, let's count together:
CM6631A for $5.5(really too expensive for 8051 junk with external flash!), and $3.5 for TAS5558(it is quite ok if 8ch involved but for only stereo, it's expensive too), TAS5624 $.78, CC2540 $.9, stm8s003f3 $.17, SMPS mosfets $.8 for a pair, irs2101s $.3, 4 coils Sagami 7g14c $1.6 for all, LLC and trafo maybe $1.2, aluminum caps $2 for all, PCB 2layers 2oz $1, +$1.5 for all others I guess. Total: about $20 for PCBA.
CM6631A for $5.5(really too expensive for 8051 junk with external flash!), and $3.5 for TAS5558(it is quite ok if 8ch involved but for only stereo, it's expensive too), TAS5624 $.78, CC2540 $.9, stm8s003f3 $.17, SMPS mosfets $.8 for a pair, irs2101s $.3, 4 coils Sagami 7g14c $1.6 for all, LLC and trafo maybe $1.2, aluminum caps $2 for all, PCB 2layers 2oz $1, +$1.5 for all others I guess. Total: about $20 for PCBA.
well, I had Pro audio project with similar BOM cost, however, it was 2-way monitor 400W+100W + DSP+BT_TWS/aptx-ll. I mean the compact design is more expensive than normal one.
BTW, just sent PCB order to the supplier, so next 4-5 days will be ready BT Stream option 😉
BTW, just sent PCB order to the supplier, so next 4-5 days will be ready BT Stream option 😉
Attachments
This is Taobao's prices, cm6635a 35RMB, TAS5624 5RMB etc. And I guess I know why Sagami stopped 7G14C, take a look closely at my "Sagami" on the picture, it is cloned "MIDEN" coils from Hangzhou 😉 Usually, I ordering custom flat/strip wire coils from SHZ Senija, or from Foshan, depends on a customer. Sometimes custom coils look unusual and futuristic 😱
Attachments
It seems BT A2DP streaming nearly always 44.1/16. I didn't found on my iPhone and Android way to switch Fs to 48kHz, which is supported along with 44.1kHz in IOS. So the only practically needed is 44.1/16, am I right?
well, it is 16bit but nothing special I think. However iPhone's A2DP stream sound worse VS USB 44.1/16, probably isn't so steady sound and isn't neutral as well. Maybe I've to check EQ settings in the iPhone's setup, I believe they affect the streamed audio. The original idea was an ultra-compact Hi-Fi "true-digital" amp with high-resolution USB input, and BT LE DSP control by iPhone/Android. So BT streaming just an auxiliary feature. USB 24/96 sounds quite wonderful, and 100.0% pop/click noise free, whatever you taking off power plug or off USB, just player stop and starting again when plug USB/Power in. So when you turning amp On, you've no idea about it does or doesn't work until start play music. This fact is pretty impressive to me.
- Status
- Not open for further replies.