Quick reply if possible, please

[mazeroth]

17 minutes until the deal is over at Parts Express ($30 each). Was going to use the 3" Tang full-range discussed a lot on this board and was looking for a woofer to cover the low-end better. Something to make a nice full-range bookshelf/small tower. I was going to go with (2) of these per speaker:

http://www.partsexpress.com/pe/pshow...32&dotd=092404

They're only 83db sensitive but if I use 2 per speaker it will boost it, theoretically, to 89db efficient, AND 8 ohms if I wire them in series (they're 4 ohm nominal).

I am going to run the full-range off the receiver and will be using a 250w plate amp to run the 4 woofers. I'll use the variable crossover in the plate amp to adjust their crossover (it's 24db slope) and let the full-range run full-range, or possibly install a cap to cut out some of the bass.

What do you guys think? Thanks!

[johninCR]

Mazeroth,

For future reference, doubling the number of drivers gets you only 3db of additional sensitivity. Many people talk about a 6db increase because if they are wired in parallel, the amp sees half the impedance and sends double the power. In your example you'd have to go parallel to get the 6db increase. That assumes the 2ohm load is no problem for the amp.

[mazeroth]

I thought you gained 6db with still 1w at 1m? Hmmm, maybe I'm wrong then

I was going to do series so 8 ohm to each speaker, then both to a plate sub amp so the plate amp would see a 4 ohm load. Still not sure if I should go with something like these 6.5" Tangs for the mid-bass and bass or something else. I think they would look killer with that huge surround and 11.5 mm xmax. In a ported box in WinISD these should hit -3db at 38hz, not too shabby.

Forget the time constraint. I called Parts Express and they said I have until midnight, so please help me out

Oh, and the Tang I'm looking to use is the Tangband W3-871.

[johninCR]

I wish is was a 6db increase. That would give the line arrays I'm about to build over 110db at 1 watt. Unfortunately doubling drivers only gets you 3db and doubling power only gets you 3db. It's a real shame that going from 500 to 1000 watts only gets you 3 more db of volume, just like going from 1 watt to 2 watts. There's just no getting around those laws of physics.

[planet10]

John is right... double the drivers get 3 dB.

6 dB is a red herring propagated by guys who assume everyone is running the (non-existant) perfect voltage source SS amp (so that you gain 3 dB more power from the amp by halving the load impedance). Of course you get about twice the distortion from the amp.

If you are going active, what do you really care about trying to match the efficiency of the woofs & mid-tweets?

dave

[johninCR]

Dave,
That brings up a question that's been bugging me. If you biamp and have 2 different sensitivities of drivers, do you have to constantly mess with 2 volume controls to get the levels of each balanced?

[mazeroth]

I was just trying to get them close in sensitivity...for no reason at all I guess

Aside from the Tang 6.5", what other woofer(s) would you recommend to go with the Tang 3" that could be used to fill in the low end and is RESONABLE? I'm actually a poor college student but am dying to build a set of nice speakers. Also, I'd really like to use 2 of the Tang 3" speakers up top mounted as close as possible because I do like a bit of volume, but am sticking to a full-range driver because I'm still learning about crossovers and want a simple speaker to start with. OR, if you think I should follow John's design with 1 3" Tang, then I'm all ears:

http://home.new.rr.com/zaph/audio/audio-speaker11.html

THANKS! Believe it or not, every reply is greatly appreciated, even if they're 100% criticism!

[planet10]

Originally posted by mazeroth
Aside from the Tang 6.5", what other woofer(s) would you recommend to go with the Tang 3" that could be used to fill in the low end and is RESONABLE?

The Apex Jr Super 8s -- $70/pr all the time.

http://www.apexjr.com/speakerstuff.html

dave

[planet10]

Originally posted by johninCR
That brings up a question that's been bugging me. If you biamp and have 2 different sensitivities of drivers, do you have to constantly mess with 2 volume controls to get the levels of each balanced?

You need to have a master level control in your XO (or the amps) -- you only really need it on one side, generally to attenuate the bit that plays louder (speaker + amp). This can be one of those nice sounding (and relatively cheap cermets) mounted on the XO... you only need to set it once to match relative levels.

dave

[Grahamt]

The 871 is a good choice, and if you cross it over to a mid woofer it will go loud. A 871 on its own sounds great as a near field monitor but they distort if driven too hard of course. If you can wait, the Adire Extremis is coming out in Nov. It has a linear 13mm Xmax and would work great as a mid bass. So would the Koda 8 if you could swing it.