using 4 ohm driver with 8 ohm xover

[davenicol]

I'd like to use the dayton RS tweeter in a speaker, but the impedence of the driver is 4 ohms. how should I correct for the impedence? can i simply add a resistor in series with the tweeter? how much could it attenuate the level, and how would it affect the response curve of the tweeter if i used a non-inductive one?

[davenicol]

Im not too great at crossovers, so any help would be great...

[johnastockman]

> I'd like to use the dayton RS tweeter in a
> speaker, but the impedence of the driver is
> 4 ohms. how should I correct for the
> impedence? can i simply add a resistor in
> series with the tweeter? how much could it
> attenuate the level, and how would it affect
> the response curve of the tweeter if i used
> a non-inductive one?

I'm no XO expert, but adding a resistor won't work, it's not that simple. Do you already have a XO? You can calculate the values for 8 ohms the same as for 4 ohms. You can go to <A HREF="http://www.pvconsultants.com/audio/frdgroup.htm">www.pvconsultants.com/audio/frdgroup.htm</A> for a lot of helpful downloads for calculating XO values. Some are simple "textbook" calculations (not ideal!), or you can try Jeff B.'s PCD program (more involved, but it uses actual measurement files). Some of the guys here have used it to design some great XO's/speakers. For someone just getting into speakerbuilding, Ray Alden has a great book "Speaker Building 201". Good luck!

John A.

[Paul K.]

IF the existing crossover was truly designed for an 8-ohm resistor, you could insert a 4-ohm tweeter with a series 4-ohm resistor in its place. The new tweeter's signal would be attenuated by 6 dB which may be too much, plus there's little likelihood that the SPL responses of the two tweeters would be very similar, much less nearly identical. Last, most drivers are not really 8 ohms or 4 ohms but some other impedance which also varies with frequency.
Paul K.

> Im not too great at crossovers, so any help
> would be great...

[davenicol]

> I'm no XO expert, but adding a resistor
> won't work, it's not that simple. Do you
> already have a XO? You can calculate the
> values for 8 ohms the same as for 4 ohms.
> You can go to
> <A HREF="http://www.pvconsultants.com/audio/frdgroup.htm">www.pvconsultants.com/audio/frdgroup.htm</A>
> for a lot of helpful downloads for
> calculating XO values. Some are simple
> "textbook" calculations (not
> ideal!), or you can try Jeff B.'s PCD
> program (more involved, but it uses actual

> measurement files). Some of the guys here
> have used it to design some great
> XO's/speakers. For someone just getting into
> speakerbuilding, Ray Alden has a great book
> "Speaker Building 201". Good luck!

> John A.

OK I'll give the calculators a try. I already have a first order XO, but it crosses at 3k and the woofer can produce up to 2k. Ideally, since i want to power these speakers with a tube amp I want to avoid using a low pass filter so the impedance is more stable. I have been building speakers for a while using pre-made Xovers, and if the tweeter was 8 ohms id look at the dayton 2k crossover. This brings me to another question: what would happen if I were to use the 4 ohm tweeter with the dayton xovers?

Thanks for the advice

Dave

[Andy_G]

IMO... you are paying for the RS tweeter, and also a woofer, (which you don't mention type etc for) and driving off tube amps . Surely it is time to get the x-o part right, even if you try to get someone to design it for you.

This putting any old driver onto a stock x-o is no way to get anything more that very mediocre sound.

[davenicol]

> IMO... you are paying for the RS tweeter,
> and also a woofer, (which you don't mention
> type etc for) and driving off tube amps .
> Surely it is time to get the x-o part right,
> even if you try to get someone to design it
> for you.

> This putting any old driver onto a stock x-o
> is no way to get anything more that very
> mediocre sound.

I will be using the 8" Dayton RS and dayton RS tweeter in a two-way configuration using the .75 cu ft two way finished cabinet. If someone could design it for me that would be great but i wouldnt learn anything. I can build first and second order networks when the impedance is the same for both drivers. But since the woofer is 8 ohms and the tweeter is 4 ohms i dont know how to deal with that.

I just contacted PE to see if there are plans for an 8-ohm version of the RS tweeter. If so I would wait for that, but otherwise I'll keep looking for an answer.

[Andy_G]

in a new thread, ask if anyone has an x-o for that combo. I'm in Australia so I can't help, but they are very popular drivers over there and I suspect someone is bound to have done an x-o for them.. Good luck

[madrok]

Assuming that the xover is meant for 8 ohm tweeters, you could add a 4 ohm resistor in series. That makes the tweeter 8 ohms, and a very flat impedance it is. It would attenuate by about 6 dB.

[duanebrown]

Provided Link: http://www.htguide.com/forum/showthread.php4?t=13154


> I'd like to use the dayton RS tweeter in a
> speaker, but the impedence of the driver is
> 4 ohms. how should I correct for the
> impedence?
You change the value of all your crossover parts. To what I don't know.
> can i simply add a resistor in
> series with the tweeter? how much could it
> attenuate the level, and how would it affect
> the response curve of the tweeter if i used
> a non-inductive one?
Download lspcad demo. Parts Express has the frd and zma files you'll need.
BTW: The RS have very nasty brakeup just above their useable responce, requiring high order crossovers to tame. For more on this look at the HTGuide forum.
good luck!

[BillDitmas]

I too would like to use the 4 ohm Dayton RS tweeter with the Dayton crossover calling for 8 ohms. Same thoughts on my part; Use a resistor in series which will reduce output (and quality), use another crossover (which I don't want to do), another tweeter(which I don't want to do), or contact Dayton Audio and also inquire about a RS tweeter in 8 ohms. Any answers on any of this yet?

[Chris Roemer]

I too would like to use the 4 ohm Dayton RS tweeter with the Dayton crossover calling for 8 ohms. Same thoughts on my part; Use a resistor in series which will reduce output (and quality), use another crossover (which I don't want to do), another tweeter(which I don't want to do), or contact Dayton Audio and also inquire about a RS tweeter in 8 ohms. Any answers on any of this yet?

First of all, pre-built XOs that are NOT designed for any specific driver compliment just plainly DO NOT WORK.

Second, even if they DID work, the RS drivers have metal cones that have a very loud resonance (ringing) that would make them unacceptable to use with pre-built (non driver specific) crossovers.

Try to locate an existing design using the drivers you want, and either borrow that XO design, or (better yet) just build that speaker. You'll be glad you did.

Chris