90-91 dB sensitivity w/Kaiju?

Ravenshead · 1296

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Offline Ravenshead

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on: October 18, 2020, 08:27:10 PM
Hi gang,

Brand newbie here, so apologies in advance for my ignorance!

I'm in the planning stages of my first real HiFi system, and I'm very much drawn to the DIY arena and your wonderful community here and elsewhere. I love what I've read of the 300B in general and the Kaiju specifically. I'm thinking that building one will be my first real plunge. In short, my question is... will one be enough??

I've read many posts and articles about speaker sensitivity, which I *barely* understand. For a variety of reasons, the speakers I'm looking at building are Troels Gravesen's "Quattro," which he claims are 90-91dB sensitive. In the meantime, I'm currently using an old pair of Speakerlab S9s that my dad built as a kit some 40-ish years ago. Digging up an old catalog, I found that they are coincidentally listed at 91dB sensitivity. The Kaiju information page mentions speakers w/sensitivity as low as 93dB. So if I'm using a smaller set of monitors in the 91dB range, am I pretty much resigned to needing two Kaijus as monoblocks? FYI I'm also currently using a MJ Pro50 sub. My amp right now is a home theater receiver - a Pioneer Elite VSX-53 (also inherited from my dad  ;)), which I'm thinking I will be using as a pre for the Kaiju(s) until I'm ready to take the next plunge. As far as listening levels, I pretty much never "crank it," and the vast majority of my listening is jazz and classical chamber music.

So I don't know... am I going about this completely upside-down? Any and all recommendations for a n00b would be welcome and appreciated. I was given Robert Harley's "The Complete Guide..." which I've found helpful for identifying my priorities and areas for potential growth. In fact, his somewhat humorous description of the SET phenomenon was part of what drew me here. Do you veterans have any other recommended reading materials?

Thanks, all!

Ben Prima
Lodi, CA



Offline bernieclub

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Reply #1 on: October 19, 2020, 01:33:17 AM
Don't forget that the room and listening distance are just as important as all the specs.   Also, I believe sensitivity numbers are specified at an impedance rating which in reality drifts all over the place, and 90db at 8 ohms equals 87db at 4 ohms.   Plus, the voicing of the speaker may influence perceived loudness one way or the other.   My least sensitive speakers are rated 86db at 6 ohms, and my Kaiju on the 4 ohm tap drives them to satisfying levels, ie as loud as any sane person would listen for extended periods, in my 12 by 13 room, listening distance 6 to 8 ft.   I also listen to jazz and rock....probably a little more demanding than chamber music.    The only thing you won't be able to do is shake the walls.    It may be helpful to go to an actual audio shop and listen to a few speakers rated at different sensitivities so you can determine how much of a difference it makes.  A second Kaiju will double your power and get you 3db. 

Bernie Zitomer


Offline Doc B.

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Reply #2 on: October 19, 2020, 09:11:38 AM
I would guess that unless your room is the size of an auditorium you will be happy with a single Kaiju for jazz and chamber music. Certainly two will play louder, but you could always start with one and add a second if you felt you needed it.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline Ravenshead

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Reply #3 on: October 19, 2020, 07:40:34 PM
Thanks, guys! Yes my room is a cozy living room, certainly not an auditorioum. And not being able to shake the walls is a limitation I'm willing to accept.

Great (and now rather obvious ;)) suggestion Doc on starting with one and going from there. Just kinda getting a rough idea of how much I might be spending, and where those dollars are going. Just need to save up a little cash for that first one... maybe a self Christmas present!

Can't wait to get started!