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Vandersteen question

It's time to upgrade my speakers. I'm very impressed by the Vandersteen 3A Sig. but am concerned that I don't have enough power. I just got a pair of Quicksilver MiniMite monoblock tube amps that are 25 watts/channel matched with the Eastern Electric MiniMax preamp (20 db gain). Presently I've got Klipsch Heresys that are very efficient at 96db/1watt. I can barely turn the volume past the 9 o'clock position before the sound gets to ear bleeding levels.

My question relates to the active preamp with 20 db of gain. I believe there's a formula that everytime you double the wattage, this increases the SPL by 3 db. With this in mind, 20 db of gain in the preamp would equate to an amp having 6 2/3 times the wattage or 166 watts/channel matched with a passive preamp in my case.

I notice that Vandersteen recommends 100 to 200 W/ch with the 3A Sig while the 2Ce Sig recommends 40 to 60 W/ch. I find this confusing considering that the 3A is more efficient at 87db. The 2Ce is rated at 86db.

Vandy fans - Please enlighten me. Thanks.
mootsdude
bsal
41 posts
 
I run my Vandy 3A sigs with Quicksilver V4 monos at 120W into 8 or 4 ohms. Richard Vandersteen recommended the amps. I can't give you a definitive answer on the minis, but I'd be concerned trying to run 25 watts into a speaker that dips to 4 ohms. The only way to know for sure is to go to the source -- Vandersteen himself. He'll take your call and give you his honest opinion.
mootsdude OP
51 posts
 
After giving some thought to my original post, I realize that 20db of gain in the preamp cannot add 20db SPL (Sound Pressure Level) to the speakers. My calculation was incorrect with regards to the formula - everytime you double the wattage, the speaker SPL will increase 3db. If the speaker SPL increased 20db with a 25 w/ch amp, it would equate to an astronomical wattage - roughly 2666 w/ch. hooked into a passive preamp.

Note: the 3A Sig has an impedance of 6 ohms nominal, 4 ohms minimum. The 2Ce Sig has 7 ohms nominal, 4 ohms minimum.

Can anyone shed some light on how an active preamp with gain will effect the SPL of speakers?
mikej
172 posts
 
I can't give you an engineering perspective on this...rather a practical one. You can only drive your amp up to it's ability to output power. Therefore, it's less important how much gain your preamp has as to how much power your amp can generate.

You will want at least 100wpc with the 3A Sigs. The Quicksilver V-4s are a great choice. If you want other options there are plenty out there. However, the absolute bare minimum I would use is 50wpc.

Good luck!
swklein
136 posts
 
My Vandersteen dealer runs his 3a Sigs with an Audio research tube amp that puts out 50-60 wpc. Sounds perfectly fine and loud enough for me.
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