The tale of two subs - solid state Consumer puffery (rant and solution).

[Bfpca]

Not a toroid. Cheap black EI transformer, maybe 100w max. I figure the low inductance in the primary combined with the small core gave it poor regulation so that it could not supply enough continuous power to overheat the output stage or driver.

 

[ostripper]

Ahh , EI trafo. Gets warm , very inefficient ... some lose (waste) 20-30% at idle (or operation). Can't figure why they would seal these up in a box.
The 50VA Polk I showed gets warm and saturates at <2A. 37VDC collapses to under 30V >2A. Most likely costs ... OMG $1.05 !! on Alibaba.
Alibaba 100VA 25-0-25 costs about $10. Soooooo , to save $$ per unit and make "Polk is a joke" they save 9$ per unit. With a 100VA and better caps , this
polk would of been at least "decent". Logitech has a 100VA 32-0-32 and 2 pair Nichicon 4700u caps for their 5.1 10 and 12" systems "decent".

Yup , the small core collapses and saves the driver from burnout. But .... the chipamp see's massive ripple , as does everything else. My new toriod stays above 50V @ 5A+. the 18-0-18V secondary does not budge , so my "evil chips" have nice clean power. Just to think , this toroid was from a 90's KLH amp rated at
80W RMS/ch. At least they were honest. I would rate my upgraded sub at 120W driving that 6 ohm sub. Most likely more.

 

[clpk]

There is no excuse for any of this - just outright greed.

(below) is under 40$ in semi's.

The input stage uses less current than most op-amps - needs no heatsinks.
Use any 100V to-92's and any 150V to-126 devices.
The output stage has been built and lasts 30 years - it is my old HK
integrated amp EF3 (AKA "slewmaster").

Assured >50ppm full power 20 - 150hz @2R load.
R13/C7/D3 "trick" allows for all day clipping (till doomsday).

I was looking at the M&K woofers and some of parts express's better
offerings. Why would you pair a POS dayton plate amp or any of
these OEM outsourced garbage amps with such nice drivers. The only
good thing I have seen today was that BK plate amp. 🙄

OS

Is everyone okay? Is there a PCB for this scheme?