series crossover with 2.5 way bass

[madinoz]

Hello all, I would appreciate your thoughts.
I have just constructed a speaker using two Peerless HDS 5.5inch
mid/bass drivers and the XT25 tweeter. The HDS5.5 are a sheilded variety available thru a distibutor here in Australia.
One HDS sits on the front of the baffle with the XT25 underneath.
The other HDS5.5 sits on the side of the enclosure. The side-firing
bass is intended to be crossed over at 150hz with the front woofer to augment bass. The enclosure is aligned so as to have a low tuning point which hopefully will avoid any mid-bass lumps.

I have an open mind with regards to the crossover.
I have fiddled with a few parallel passive
setups but I would like to know how you would set up a series
crossover using the HDS drivers in a 2.5 setup as mentioned above?

Also, if anyone has successfully used the ARSXO, could the 2.5 way design be used successfully in this topology?

Any ideas appreciated.

Regards
MADINOZ

[rabbitz]

I cheat as I use a 1st order series for the 2 -way and roll off the 0.5 woofer using a standard 1st order.

Haven't worked out how to do it all in a series xo yet.

[angel]

You don't actually want to cross over the side-firing bass at 150Hz in this setup. You want to cross it over at (115Hz/W) where W is the width of the front baffle, in meters. This is to achieve baffle step compensation.

To do this, a capacitor should be in paralell with the bass, and an inductor should be in paralell with the tweeter, and the - of the tweeter should be connected to the + of the HDS. The side firing driver should be in series with an inductor, and paralelled across the input terminals of the speaker.

If you search the net, you will find a few designs using this setup.

[sreten]

It is not possible to build a 2.5 way with a full series crossover
as the two bass units must be in parallel for the 0.5 way to
work correctly.

The 0.5 way driver and inductor can be placed in parallel with
the input, or theorectically in parallel with the series bass unit.

However in the latter case the series inductor would be
handling both bass drivers currents, not a good idea.

sreten.

Example :

[rabbitz]

Originally posted by sreten
The 0.5 way driver and inductor can be placed in parallel with
the input

Yep, that's the way I do it.

[madinoz]

The crossover to the 0.5 way at the baffle step point sounds good
(I mean I actually set it up and it sounds good!).
Many thanks
PS Does anyone know what this woofer in parallel might do to the inductance and DCR of the front mounted woofer (if anything)
Thanks
MADINOZ

[Lionel]

Does someone already used or tested the serial crossover by LC audio (the exemple given by Sreten ?).
Any comments would be appreciated, thanks.
Lionel

[madinoz]

Well, I have finished the design with much thanks to those who offered advise.

Firstly, I tryed a number of parallel crossovers and i was not impressed with the results, so, I moved on to series crossovers......

I have ended up utilising a 0.39 and 0.33 inductor in parallel (low DCR) for the tweeer and a 10uf and 4.7uf (bypassed) for the woofer. This is a theoretical 3700hz zeta series filter though the woofer is rolled off lower that this point to compensate a little for baffle step.
The side firing woofer is run in parallel to the woofer/tweeter (which allows bi-wiring of this speaker to separate the high-low frequencies). The side firing woofer has a 0.56mh inductor in series to roll it off at a nominal 660hz.

The result is a very pleasing, good bass extension with a nice punchiness and a lovely fluid midrange and a bright clear treble.

This crossover did not use any resistor to the tweeter or any zobel networks for the tweeter or woofers. I listened to the speakers with a wide range of values and combinations and I didn't like what the zobels or resistor to the XT25 tweeter did.

The result may be a little treble forward to other peoples' tastes but I think they sound wonderful and my Wife even commented on how much she liked the sound (HALLELUYAH!!!!!!)
The low box tuning (14litres, tuned to 43hz) turned out to be on-target in my listening room and I don't feel any need to employ a sub-woofer to suppliment the bass.

If anyone is thinking about using the Peerless HDS 5.5 woofer, then take it from me, they are a great little unit.
Likewise the XT25 tweeter, with the caveat of limited off-axis response is an excellent value for money unit.
If you don't want to spend big-dough, have a good think about these units!

MADINOZ
PS will post picys if any one wants..........

[BAM]

pictures!

[rabbitz]

I'll second that on the Peerless 5" HDS....... great driver.

Can you add a sketch of the xo as I'm having a little trouble visualising it.

Cheers