Kaiju with KEF r700

[rhynolite]

Happy Crack user here, considering building a tube power amp for my living room. I wonder whether a single Kaiju will be powerful enough for a pair of r700s. The sensitivity stated by the manufacturer: 89dB/2.83V/m. Impedance: 8 ohms nominal. If my calculations are correct, Kaiju's 8W/channel should be slightly over 95 dB/M. However, the spec sheet states that "Amplification required: 25–200W". I am confused :/

[Tom-s]

A rule of thumb, mentioned by PJ and others on here aims for 102dB peaks for optimal amplification.
So with your speakers +- 16W is optimal to start with. But tube amps have "headroom", as they clip gently and can be "run harder". "Tube amps will sound more powerful".
I'd say 8W into your speakers will be ok. But it's all personal preference. Maybe for your day to day music it's ok, but not for movies. Or your listening habits demand even more volume. Can't tell.

And from my own experience, even 96dB max is ok *(0.5w into 99db speakers).

Edit" here's a topic for you
https://forum.bottlehead.com/index.php?topic=9930.0

[rhynolite]

Thanks for the reply, Tom-s!

[jjvornov]

Happy Crack user here, considering building a tube power amp for my living room. I wonder whether a single Kaiju will be powerful enough for a pair of r700s. The sensitivity stated by the manufacturer: 89dB/2.83V/m. Impedance: 8 ohms nominal. If my calculations are correct, Kaiju's 8W/channel should be slightly over 95 dB/M. However, the spec sheet states that "Amplification required: 25–200W". I am confused :/

My personal experience with a range of speakers using SET amps is that the impedance curve of the speakers will have a big influence on the quality of sound- the control and slam from the speakers. The Stereophile measurements https://www.stereophile.com/content/kef-r700-loudspeaker-measurements show that for a lot of the range it's a 4 ohm speaker, but without big dips below. So probably it will won't play as loud as you might expect, but it's pretty well behaved otherwise.

James

[Deke609]

Another option might be to use a solid state power amp (even a DIY kit type) and put a BeePre in front of it. I haven't personally tried this, but I am pretty sure there are others on this forum using such a setup and perhaps they will read this and comment.  The BeePre is a helluva nice pre-amp. I won't even listen to my Stereomours without it - and that's saying something, b/c I really like my Stereomours.

cheers, Derek

[rhynolite]

Thanks for the reply James! The stereophile link is very interesting. I have a noob question: from "... for a lot of a range it's 4 ohm speaker ... won't play as loud ..." I infer that SET amplifiers rely on high impedance, and from there I infer that the SET amplifiers are based on AC current amplification, vs. voltage. Is this a correct conclusion, or am I reaching the wrong conclusions?

[rhynolite]

Another option might be to use a solid state power amp (even a DIY kit type) and put a BeePre in front of it. I haven't personally tried this, but I am pretty sure there are others on this forum using such a setup and perhaps they will read this and comment.  The BeePre is a helluva nice pre-amp. I won't even listen to my Stereomours without it - and that's saying something, b/c I really like my Stereomours.

cheers, Derek

That's an interesting idea, I admit I have not considered it at all. I was thinking of using the solid state preamp in my integrated receiver, and routing that to the tube power amp to drive the speakers in a more convincing manner.  Now I am reconsidering my thinking.

[Deluk]

Your receiver preamp is unlikely to have the quality to make the most of the Kaiju. If you need bells and whistles you'll need a much better dedicated pre that is well matched to drive a valve amp and be well matched sound wise as well.

[Tom-s]

Did anyone mention a tube pre could just be perfect for that? https://bottlehead.com/product/beepre-300b-preamplifier-kit/