To Bridge Or Not To Bridge

Schipo -- ROTFLOL!!!

Leo -- Bob R. makes an excellent point. In bridged mode an amp will see the speaker impedance x 0.5. The Thiel is rated as 4 ohm nominal, 3 ohms minimum. Therefore in bridged mode the amp will see 2 ohms nominal, 1.5 ohms min. I looked at the amp manual, http://www.krellonline.com/archive_pdfs/KAV500/KAV500_V990_MAN.pdf, and I see nothing that provides confidence that the amp will be able to handle that acceptably.

Regards,
-- Al

Almarg, that was my concern as well. I don't see anything confidence inspiring in the manual either. But Bret D'Agostino said it would be fine. I'll call again to double check, I don't have the bridging wires anyway it turns out.

Douglas, the KAV-500 is lifeless and monotonous in my opinion. But its just fine for HT which is why I don't swap it out. The Classe has lots of synergy with the older Thiel 1.5s as many before me have discovered. Also, the power of the Classe is 400W@4O and the Bridged Krell is 400W@4O so you must be thinking of a different amp when you say there is more power.

Schipo - I am not worthy!

Well, an email from Krell customer service contradicts what Bret told me.

I guess the answer is Not To Bridge.

Maybe I should run some speakers to the porch...

Hey guys, not so fast!
A bridged amp is effectively two amps wired in series, one amp has inverted phase, so each amp is half of a bridged push-pull "composite amp".
This doubles the available output voltage, NOT the current.
Since Power = V squared/impedance, bridged power is quadrupled into 8 ohms.
However, if each non-bridged amp is specified to drive a 4 ohm minimum load, two amps in series will drive confortably 8 ohms (4+4), nothing lower than that.
Otherwise a bridged amp would be contradicting the laws of electricity.

To double the current and be able to drive half the impedance load, we need amps connected in paralell, and that's exactly how most manufacturers scale up the power: by adding more transistors in paralell at the output stage.
Load impedance is the main crippling factor of bridged amps: they have lots of theoretical power, however, for those amps that I have auditioned, bridged amps have a hard time driving current-hungry speakers.

In your case, the ideal solution would be vertical bi-amping, one amplifier for the bass, one for the remaining drivers, if only Thiel made bi-wired speakers!