4 ohms on 802di

[zork]

hi
can i run a pair of monoblocks 4ohms (635w per channel)on 802 di's
i see that the 802di is 8ohms speaker

[mjb]

Yes, 4 or 8 ohms relates to the amps power rating (ie, 635W @ 4 ohms), not the suggested load impedance. The speaker probably isn't 8 ohm across its whole bandwidth either, they can dip to 4 ohms (or lower) too.

[zork]

thanks
i am running a rotel rmb1095 bi amp on my 802's
400 w per channel
if i go with the mono's will it make a difference(better)?
pre is a rotel rsp1069

[Kal Rubinson]

Yes, 4 or 8 ohms relates to the amps power rating (ie, 635W @ 4 ohms), not the suggested load impedance. The speaker probably isn't 8 ohm across its whole bandwidth either, they can dip to 4 ohms (or lower) too.

With most amps, that is true. With transformer output amps, such as the McIntosh MC-303 I am currently using, there are separate outputs for each specified load. That said, the 802D and the 800Di are 4ohms from below 100Hz to almost 1000Hz and sound better on the 4ohm tap. We have not measured the 802Di.

Kal

[mjb]

That said, the 802D and the 800Di are 4ohms from below 100Hz to almost 1000Hz and sound better on the 4ohm tap. We have not measured the 802Di.

Kal

You might have used the "4 ohm tap", but you still haven't changed the listed amplifier rating

A agree, the 800/802 are practically 4 ohm speakers, so where an output transformer is involved, the 4 ohm tap will provide a better match. This does not apply to Solid state amps which have a close to zero output impedance anyway.

[mjb]

thanks
i am running a rotel rmb1095 bi amp on my 802's
400 w per channel
if i go with the mono's will it make a difference(better)?
pre is a rotel rsp1069

Zork, at the risk of opening a can of worms, a bi-amped rmb-1095 cannot really be considered as a 400 watt amp. A dedicated 400 watt amp will always sound much better.

[zork]

i can get a pair of
NuForce Reference 9SE V3 monoblocks
will it improve my sound

[mjb]

i can get a pair of
NuForce Reference 9SE V3 monoblocks
will it improve my sound

Highly possible!

[Skyblue]

What exactly do I do to change to 4 ohm mode? Its not clearly described in the manual. At least not to the point where I get it

[Kal Rubinson]

What exactly do I do to change to 4 ohm mode? Its not clearly described in the manual. At least not to the point where I get it

??? What amp do you have? Does it have such an option?

[Skyblue]

??? What amp do you have? Does it have such an option?

I have 600 watts diy icepower asx250 modules. No such option no.

[Kal Rubinson]

I have 600 watts diy icepower asx250 modules. No such option no.

Those work automatically! :T

[Pedro]

The "old" 802D down below 2 ohms according to stereophile reviews in low frequencies. I dont think so about the new model the impedance curve but they should down to 3ohms minimum. In my experience picking an excelent amp with good current for 2 ohm like Krell Evolution or something that "doubles" the output power is the best choice :T

[stuofsci02]

Being stable into 2 ohms is certainly nice. I don't think the doubling the power output from 8 to 4 to 2 ohms is really that important. Usually this just means the manufacturer has derated the output into 8 and 4 ohms.

[zork]

so it will be better?
on the nuforce mono's there is also no setting to go from 8 to 4 to 2 ohms
does it do it itself,how does it know which ohms to use?

[mjb]

on the nuforce mono's there is also no setting to go from 8 to 4 to 2 ohms

Please forget about this - it does not apply to solid state amps!

It only applies to valve amplifiers with big output transformers. Required because a valve is a very high voltage device, with a high output impedance. A transformer is used to convert the output to be compatible with audio loudspeakers, and in order to do this as well as possible, sometimes more than one winding tap is offered (4 ohm, 8 or 16).

Solid state amplifiers have low (or zero) impedance outputs, and do not require a transformer.

[mjb]

so it will be better?

Thats your call I'm affraid