Help needed for 2.1 project b3n and peerless

[Havoc08]

Hello dear community.
Being an avid reader I now need some help if possible by you higher gifted individuals [/*** kissing off ]

I have a project in mind but my skills are limited to basic electronic knowledge and soldering.

Project:

I would like to make a 2.1 system using the Hivi B3N and construction like http://www.zaphaudio.com/audio-speaker18.html

For the .1 I have acquired a peerless 8" subwoofer which resembles sls8 in frequency response (parameters on request as I'm not sure how many you want ).
The sub is DVC 4+4ohm and shielded.

I know according to Zaph the best way to couple these is via a receiver but I would like to know if it is possible to use an AMP-9@24v from 41hz (Tripath TA4100 chip) and parallel the inputs and outputs from 4 to 2 and run the outputs in tri-mode or parallel 2 outputs only so 2x normal for sats and 1x parallel for sub. Signal for sub going through LPF of course.

Alternatively, can you parallel only inputs and run 2x sats from 2 channels and run 1 channel to each VC (going through a LPF first of course)?



Zaph says that passive filtering would be expensive for the sub, is their a cheap (DIY?) active filter I can make like the ones normally on subs?



Also I'm considering whether to cross over at 150hz or 200hz. The increased power capability at 200hz appeals to me, but I'm unsure of how problematic placement of sub is at 200hz comparable to 150hz. Your opinions and/or empirical knowledge is greatly appreciated.


I will make a drawing to clarify the amp connection theories.


Thank you in advance

[Havoc08]

Clarification

[Havoc08]

Peerless parameters:

Zn 2ohm
Zo 28,6ohm
Re 2,2ohm
Le 0,9mH
Fs 34,7hz
Qms 4,13
Qes 0,33
Qts 0,31
F ratio 112
Rms 1,36 Kg/s
Mms 25,7g
Cms 0,82mm/N
D 17,3cm
Sd 235cm3
Vas 62,2
Bl 6.0

sensitivity @ 2,83v @ 1m @ 211hz = 95,5dB


I calculated af ported box of 23,4L with tuning frequence of 49hz equalling a 7,5cm port of 17,7cm length.

[Havoc08]

Due to the tremendous response I'll post some more on design ideas.

After having talked it over on 41hz, the project shifted to this:


Sub:
4th order bandpass enclosure. X-over frequence at 200hz 99.5uF cap and 6.366mH coil.
http://img204.imageshack.us/img204/3848/peer.jpg
Pink = ported, yellow = closed, blue = 4th order BP.


Full range:
Keep the notch filter, add 12dB linkwitz-riley x-over. 49.75uF cap and 12.732 mH coil for 200hz xover frequency.
Not quite sure about the function of L1 and R2?


Amp:
Amp 9 with pot on input signal for gain matching of fullranges with sub.



General questions:
1. When making a 1st or 3rd order x-over you get 90 or 270 degree fase shift. Is that a phase difference between the tweeter and woofer or is both tweeter and woofer shifted 90degrees (i.e. 90 degrees out of phase with input, but in phase with each other)?


2. Do you only make the filter for removing >200hz in bandpass, as the closed part of the box limits the sub speaker from having more excursion than it can handle?


3. Is 150hz and 200hz too high to cross over in a 2.1 system? Will it degrade stereo imaging even if you place sub <1/4 wavelength away compared to sattelites? http://sound.westhost.com/subcon.htm


4. When looking at the winisd sim it looks like the box inherently makes a 12dB roll off at >100hz or does that require a filter?


5. I've read that 4th order band pass sub has the second best transient response (only topped by closed sub), but when I look at the winisd the 4th order BP has the highest delay and phase shift compared to closed or ported. Is this bad?

[Havoc08]

So.. I'm halfway finished with the B3N cabs as per Zaphs recommendations.



Cabs will be white piano with weather worn teak wood front pieces ( current idea, subject to change ).

I've purchased an active x-over as it was cheaper than a passive one. http://www.reckhorn.com/index.php?ln=de&prod=f1 @ 35euro.

I'm going to use the notchfilter from zaph, but are still unsure about the other filter.

The sub will be a 4th order bandpass sub with the 8" peerless crossed at 150hz.

[peter_m]

I wish I had read your initial post sooner...

I've built this design and was amazed at how it sounded. It was great to hear "big" sound come from such a small enclosure. I was happily impressed. The only thing I dislike about it is that as soon as you move away from the speaker's centre line, the high frequencies almost disappear. They would make great computer speakers where you sit in the same spot almost 100% of the time, but NOT so amazing if you plan on moving about the room. I don't regret building them as they were an experiment that led me to bigger and better things. Just wanted to let you know.

Good luck.

Peter

[Havoc08]

Hi peter
Thx for your post

You thinking they have bad off axis response, does that have anything to do with the values chosen for L1 R2?
Or is it inherent to the small membrane size?