Tannoy TS12 has suddenly very low output

Hello everyone,

I need some help diagnosing a problem that occurred on a Tannoy TS-12 subwoofer. It's made with a 500W BASH plate amp.

My sub was working good, then I had it turned off (unplugged) for one week. When I came back and replugged it, it has lost its sensitivity. With a good musical feed, it's only whispering, even at maximum gain.

I wonder if there's any known issue that could lead to that result.

As I'm not familiar with Class-D or SMPS, any help will be greatly appreciated.

Regards,
Martin.
 
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The problem on mine seems to be from the power-supply module. I decided to replace the whole plate. I was lucky to find a used 500W O-Audio plate amp that has the exact same measurements and screw locations. It was a simple swap...

Good luck with yours, it's really a great sub.

Martin.
 

Tekko

Banned
2005-01-01 3:33 pm
I think the size of plate amps are a standard and not unique to this brand. And even if the screw holes are not in the same place on the replacement amp, it doesent matter as the plate covers up the old screw holes in the box anyways.

The fault kinda sounds like the input stage gets damaged by things like the capacitively coupled currents from the mains input filter in things like the psu in a computer and pretty much every other smps that has the three prong mains input.

What you can do is bypass the input module and send a signal straight into the poweramp board itself, assuming the amp is a separate board and the input and lowpass filter is a separate board.

If its all on one big board it gets harder to find the poweramp input without a full schematic. This test however would verify if it is the input circuitry or the poweramp circuitry thats damaged.
 

Jamie85

Member
2013-02-20 2:29 am
I had the same issue with my TS12. There is a capacitor C208 between LFE MODE and XOVER FREQ. on the pre-amp PCB. Mine was very slightly pregnant. Almost not even noticeable. After heating the cap silghtly the amp started to work. Replaced the cap and now all is good. Hope this helps.
 

Jamie85

Member
2013-02-20 2:29 am
After changing C208 the amp seemed to work then as the surrounding caps cooled down the amp volume cut out again. I reheated compnents individually and the real culprit was C101 22uf 16v Bi-Polar cap. It showed no visual signs of a problem but if you heat from the solder side carefully as not to damage the tracks the amp should turn back on. Make sure power is turned off from the switch first. Cheers!
 
After changing C208 the amp seemed to work then as the surrounding caps cooled down the amp volume cut out again. I reheated compnents individually and the real culprit was C101 22uf 16v Bi-Polar cap. It showed no visual signs of a problem but if you heat from the solder side carefully as not to damage the tracks the amp should turn back on. Make sure power is turned off from the switch first. Cheers!

That was exactly it... C101 :) (mine was rated at 35V)

I changed all the electrolytics on that board while being at it. Work as new.
 

Enot

Member
2015-05-28 7:27 pm
Tannoy TS8, same problem: very low output on good feed.
Changed all caps on preamp board (Indigo 630137-00) with no result.
In my case it was Bi-polar capacitor C100 (rated 4,7 uF x 35V) on main power amp board (Indigo 650038 rev:0) splitting audio input of amp from DC. Measured 0.0 uF but not shortened.

Thanks wxn from this forum for Tannoy TS8 schematics!