Fast, fun, Inexpensive OB project

[Pano]

That's a very interesting idea, Mr. T

Effectively you are giving the inductor a lower impedance to work into, as well as a smoother one.

That will have 2 advantages:

1. Lower impedance means smaller inductor for the same crossover point. (That's why 4 ohm drivers are good - or 2x 8)
2. The parallel resistor acts like a Zobel on the top end of the impedance curve, flattening it out.

However, that 3 ohm resistor in your schematic will pull the impedance way down, to about 2 ohms.
So I simulated an 8 Ohm parallel and 3.5mH series on the SLS woofer - in place of the single 13mH that was there.

Not bad, not bad! Impedance never drops below 4 Ohms, and the overall sensitivity is much better. I did have to change the HP on the tweeter to get it to work, but no big deal.

I'll see if I can find a 3.5mH coil nad give it a try. Hope reality mirrors the sims

[Pano]

I tried the parallel resistor/smaller inductor trick. It worked.

In place of the 13mH on the woofer I did 4mH + 9.2R parallel (cause it what I had). Then used 10uF on the tweeter instead of 5uF+5.5R.

Overall the midrange came up, but the sims said it would. Not too bad, just need about 2~3R series with the tweeter to balance it out.

Will play and report further.....

[peterbrorsson]

Panomaniac,
How's it going?
I think I will try this concept as I have holiday the whole December.

I have these in mind, curvy linear cone, cloth surround and a decent lower midrange. Specs seems ok. I also have Dynaudio Esotec 260 laying in the scrap box, should be ok.

http://vissokogovoriteli.plc.bg/prod...-12211_311.htm

Peter

[Pano]

Hi Peter - yes, those woofers look like they should do the trick. Qts and Fs are similar to the Peerless 12.
We can hope that they play up to 2K with no big problems.

Which tweeter will you use?

BTW, you can use an 8ohm resistor in parallel with the woofer and a smaller coil if you want to. Something around 5 or 6 mH. Then tune the tweeter crossover a bit to meet it.

[peterbrorsson]

Hi,

We can hope that they play up to 2K with no big problems.

I have used them before and do not think it will be a problem if those Peerless functions. For the moment I have not decided if I'm going to order a new pair or buy four used 16 ohm version.

Tweeter will be Dynaudio Esotec D260, they should be able to handle a low second order filter or maybe even first order.

Peter

[Pano]

Very cool.

At the moment I'm running mine with the old ScanSpeak 3806 mid/tweeter. Crossover is 100Hz low pass (1st order) on the woofer - 1100Hz L/R (2nd order) hi pass on the tweeter with about 9dB attenuation.

This basically makes a LP shelving filter for the woofer that fits the baffle size nicely.

Keep us up to date on the project!

[peterbrorsson]

1100Hz L/R (2nd order)

I know that your tweeter is a beast but that is quite low isn't it? What's the fs on these?

[Pano]

It is a beast of a tweeter. A mid/tweeter, really.

Fs is about 330Hz - from my mesurements. More than an octave below the x-over point. It was designed to be used from 1K up - no worries.

[peterbrorsson]

Ok, beast of burden it is....

Thanks for replying!

Peter

[Pano]

Hi GRKN,
got your email, replied, but it bounced back. It was your <tr****@s***.no> address.

Also the website linked to in your profile goes nowhere.

Drop me another email, I'll get back to you.