Sage Audio Supermos 2

Many thanks for your explanation and reassurance Felix.

I'll set about changing the power supply torroids and caps in the hope of giving these amps better longevity.

I'll give them a listen as they are first though.

Jeff

 

Hi Jeff,

I own a pair of Supermos 1 modules, and did own a pair of Supermos 2 modules - I say did, as one failed approx. 6 months ago in a spectacular fashion. If they all eventually fail in the way this one did, then have a fire extinguisher ready! They are potted, and if running at the full +/-70V (which mine were), the potting compound only encourages the fire.

I love the sound of the units though - very clean and punchy with superb control of the woofer (due to their low output impedance).

Your units do seem to be fine though. The power led is green, and will turn red in the event of a short circuit at the speaker.

 

Hi nevebloor

As I said in an earlier post 'I have heard of these modules going "bang" big time'. Your experience along with others I have heard about does warn me off using them as a "go to" power amp. I have never heard of anyone complaining that the amp's failure took out their speakers though, so there is a little bit of comfort there. Did your speakers survive?

I would never forgive myself if I allowed a catostrophic failure of the amp to take out my recently restored 37 year old AR-16 speakers.

Jeff

 

Why not put a fuse in the speaker line? If the amp doesn't already have one.

 

Hi Jeff, luckily the amp was not connected to the speakers at the time, so only the module itself was damaged.

 

Fuses in the amp-speaker link are notoriously tricky to make useful; the fuses have to be rated at surprisingly low-ampere/'fast' rating to actually work at all, and these add a significantly non-linear element in series. Not good as an add-on.

I'd suggest instead something like the Vellemen K4700 kit built into a box and used to pass -through - ie placed close to and plugged into the amps, with the spekers pluggged into the protection box. It's self-powered (requires a mains lead as a standalone box not built-into an amp) but provides reliable DC offset protection. Example supplier, with datasheet:

http://cpc.farnell.com/1/1/53028-k4700-2channel-loudspeaker-protector-k4700-velleman-kit.html

 

It's an easy thing to do though, and may offer an increased change of speaker voice-coils not melting. A slightly under-rated fuse could be used in the mains plug too and might not have negative sonic effects.

For what it's worth I ran the Kensai / Advantage (active speaker) with 0.68amp slow blow fuses in the mains plug (so 163watts uk mains) for a long time with no issues. It was only at a hi-fi show when I really turned up the wick that it eventually blew and I decided to up-rate it. Amps in each speaker are rated 180watts total.