Are you listening to your plate amp???

[Count Dacula]

I carefully worded the title. This thread is about how crappy loose parts on plate amps can ruin a powered sub, and even a whole system. Hair-splitting system tweaks and file format wars are moot points if your sub is not happy.

My old KEF B30 pwr sub amp blew up, so I'm converting it to passive w/a TPA 3255 power. I'm glad I didn't proceed with an amp recap fix, and it's not because of AC draw, lol.



I did a little minimum tweaking of the foam padding, with wedges in the corners and the back foam 1"x12"x12" was found attached to the woofer magnet, so I pulled it back to the rear and added one more softer foam square to it on the inside. facing the woofer. Drilled in holes for the lead wires, that's it, I figured, easy peasy.

I stripped the transformer off the plate amp to save a few mindless pounds, not expecting to go any further. When I reattached the plate to the back of the sub while it was playing, holy crap does this thing rattle and buzz! You can hear it loose in your hand by just tapping it. I tried removing the main caps, then smaller ones, and the buzzing was reduced, but the boards had to go too, they were alive. I hacked all the boards off, but the speaker-in connects and micro switches buzz like hell, and they blow air out! I removed and reinstalled the RCAs all caulked up, but it really didn't help much. You can still feel air blowing thru,and it sounds like crap.

It sounds better with no back, since 1in foam is tight across it. lol, no way will this buzzy plate EVER work right unless it's potted inside and out, lol. I need to forget the aluminum plate and go over it with wood, plywood inside and out. If I can find 8" dimensional lumber, III use in on the outside. Plate amps SUCK. I always thought it sounded slappy, but usually had it stuffed around the outside rear. I'm afraid to check my other ones, but....

Glad I didn't undertake a "repair" of the amp.

 

[Count Dacula]

I guess they can't put foam padding directly over the plate if its' operating hot, duh.

 

[bluefuzz]

When I built my DIY sub it was fairly rubustly braced with a separate completely enclosed compartment for the Hypex plate amp. Here under construction. Main driver is facing up toward the camera. Passive radiator cutout towards upper left and plate amp compartment bottom right towards floor which is of course the back of the sub when finished. The whole thing is lined with acoustic felt. No rattles or buzzes! At least not from the sub itself. The windows do rattle occasionally though ...

 

[Count Dacula]

Yes, nice. The point is, people need to test and listen critically to their Big Box subs too.

 

[bluefuzz]

The point is, people need to test and listen critically to their Big Box subs too.

Of course. But you can't really expect a plate amp not to rattle if it's not completely isolated from the sub cabinet itself. And you can't expect the cabinet not to rattle if it's not adequately braced.

 

[Count Dacula]

I would not expect a premium product intended to produce clear sound at lower frequencies to produce high frequency distortion. I'm not sure why that's acceptable.

 

[Chrispy]

I have a few "store-bought" subs with plate amps but would never use one for my diy subs. I only had one just outright fail and was replaced under warranty, no particular vibration or other issues with the plate amps, tho.

 

[bluefuzz]

I'm not sure why that's acceptable.

It isn't. But premium price doesn't always equal premium quality ...