After chasing the dual woofer version of the speakers in post #4 pix 3 and not finding anything I stopped looking
Last week I got one of those eBay emails telling me about a Sansui listing and I put in a bid thinking I was bidding on a dual 6 inch woofer speaker
I won the auction with an $89- bid and on picking them up they are actually a dual 8 inch woofer\
Usually cheaper speakers are made with 4R woofers in series to get a nominal 8R impedance but these have 2 * 16R drivers in parallel
Bass in the bigger boxes is better as I would expect but the upper midrange is a little muddy compared to the smaller speakers even tho the bigger speakers have better grade of components.
I am seriously considering using the bigger boxes for the bass and a pair of the 6 inch boxes as the dedicated midrange and moving the better tweeter to a pair of the smaller boxes with the 5inch drivers [ cheap 20mm tweeter]
Thoughts?
At the cheapest I can just use a decent coil and use them as a .5 set of woofers
Maybe even 2 coils each with different values to really boost the lower bass?
Big boxes are 1100 tall / 225 wide and 380 deep
16mm chipboard but 25mm front baffle and reasonable bracing
Last week I got one of those eBay emails telling me about a Sansui listing and I put in a bid thinking I was bidding on a dual 6 inch woofer speaker
I won the auction with an $89- bid and on picking them up they are actually a dual 8 inch woofer\
Usually cheaper speakers are made with 4R woofers in series to get a nominal 8R impedance but these have 2 * 16R drivers in parallel
Bass in the bigger boxes is better as I would expect but the upper midrange is a little muddy compared to the smaller speakers even tho the bigger speakers have better grade of components.
I am seriously considering using the bigger boxes for the bass and a pair of the 6 inch boxes as the dedicated midrange and moving the better tweeter to a pair of the smaller boxes with the 5inch drivers [ cheap 20mm tweeter]
Thoughts?
At the cheapest I can just use a decent coil and use them as a .5 set of woofers
Maybe even 2 coils each with different values to really boost the lower bass?
Big boxes are 1100 tall / 225 wide and 380 deep
16mm chipboard but 25mm front baffle and reasonable bracing
Attachments
Things must be busy in the workshop this W/E
I expected a few posts telling me to make a proven design or similar.
This is only for Home Theatre so I am prepared to settle for a lot less than near perfection
Not much time or money to spend on these as we still haven't finished our major renovation on the bedroom/ensuite and kitchen so near enough will have to be good enough
Book values XO at around 300 with a second order electrical or throw all caution the to winds and simply use a cap in series on the midrange and one coil on the paired woofers?
My initial thoughts were to use a second on the mid box and a two part first order on the woofers but component values on 16R drivers are quite high
No testing I do not yet have any test gear
I expected a few posts telling me to make a proven design or similar.
This is only for Home Theatre so I am prepared to settle for a lot less than near perfection
Not much time or money to spend on these as we still haven't finished our major renovation on the bedroom/ensuite and kitchen so near enough will have to be good enough
Book values XO at around 300 with a second order electrical or throw all caution the to winds and simply use a cap in series on the midrange and one coil on the paired woofers?
My initial thoughts were to use a second on the mid box and a two part first order on the woofers but component values on 16R drivers are quite high
No testing I do not yet have any test gear
Hi Ted, re:"she says "They're a keeper" ' - good one, make the most of it 
re: 'using the bigger boxes for the bass and a pair of the 6 inch boxes as the dedicated midrange' - that's the kind of solution that appeals to me, (in fact I was doing that last weekend to loosen up some old roadkill woofers - took quite a lot of rock & ale to get the job done...)
most woofers have an impedance of ~ Re in the low mids, so you could use that as a
starting point:
Baffle step freq is ~ 500Hz & assuming Re ~6 ohms, gives woofer inductor of ~ 2mH, mids cap ~53uF, if you've got something close in your parts box give it a go, & then upgrade to a Low R ferrite core inductor?
300Hz it would be ~3.3mH & 90uF
Alternatively, connect them in series, with the cap across the woofers to get an idea of how they'll perform
so if you have a multimeter measure the DCR of the two cabs & let us know.
How did the midrange sound with the 5.6mH inductor connected?
cheers, Pete McK
re: 'using the bigger boxes for the bass and a pair of the 6 inch boxes as the dedicated midrange' - that's the kind of solution that appeals to me, (in fact I was doing that last weekend to loosen up some old roadkill woofers - took quite a lot of rock & ale to get the job done...)
most woofers have an impedance of ~ Re in the low mids, so you could use that as a
starting point:
Baffle step freq is ~ 500Hz & assuming Re ~6 ohms, gives woofer inductor of ~ 2mH, mids cap ~53uF, if you've got something close in your parts box give it a go, & then upgrade to a Low R ferrite core inductor?
300Hz it would be ~3.3mH & 90uF
Alternatively, connect them in series, with the cap across the woofers to get an idea of how they'll perform
so if you have a multimeter measure the DCR of the two cabs & let us know.
How did the midrange sound with the 5.6mH inductor connected?
cheers, Pete McK
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It sounded much clearer Pete but I think it needs something more
I've just pulled all the XO's out of the boxes and checked them
XO for the 25mm tweeter is the same in all boxes [ which makes sense as it is the same tweeter] 3.3uF in series and a 0.31 coil shunted to ground
Attenuation network is 1R5 in series and 15R in parallel
The big difference between boxes is the capacitor quality MET 250V in the bigger boxes and an electrolytic 100V in the others
DCR in the series coil is on the high side at 0.83R tho and that could be robbing a dB or two
Re is 5.6R on the 6 inch but if possible I'll go lower than 500 / 300Hz preferred with a first order on the woofers
33uF in series and 4mH shunt?
I've just pulled all the XO's out of the boxes and checked them
XO for the 25mm tweeter is the same in all boxes [ which makes sense as it is the same tweeter] 3.3uF in series and a 0.31 coil shunted to ground
Attenuation network is 1R5 in series and 15R in parallel
The big difference between boxes is the capacitor quality MET 250V in the bigger boxes and an electrolytic 100V in the others
DCR in the series coil is on the high side at 0.83R tho and that could be robbing a dB or two
Re is 5.6R on the 6 inch but if possible I'll go lower than 500 / 300Hz preferred with a first order on the woofers
33uF in series and 4mH shunt?
I've often wished for a tapped inductor, so I could easily make changes before I spent $$ on the final part. Maybe I'll get off my butt & wind one some day, but I've never been able to get nice even windings when I do it by hand.
re: "33uF in series and 4mH shunt" - 4mH would give an xover freq of ~ 240Hz on the woofers, but you'd need ~ 110uF on the mid box to match (I'd buy a mixture of 47 & 22uF BPs from Jaycar & try different combos...)
re: "33uF in series and 4mH shunt" - 4mH would give an xover freq of ~ 240Hz on the woofers, but you'd need ~ 110uF on the mid box to match (I'd buy a mixture of 47 & 22uF BPs from Jaycar & try different combos...)
33uF & 4mH is what I found in my box
I am thinking the mid box will need a 2 part High pass; just a cap in series may not give me the correct separation of signal a good midrange needs for best clarity
It is a real shame W8 and my version of Excel are not working with my old programs
hard for me to do even moderately accurate simulations
What do you suggest for a LR second high pass at around 300Hz on the 6R driver??
I am thinking the mid box will need a 2 part High pass; just a cap in series may not give me the correct separation of signal a good midrange needs for best clarity
It is a real shame W8 and my version of Excel are not working with my old programs
hard for me to do even moderately accurate simulations
What do you suggest for a LR second high pass at around 300Hz on the 6R driver??
Hmmm Using you calc where would a 5.6mH shunt place the XO point? With appropriate cap of course I happen to have quite a few of the cheap Jaycar 5.6mH laminated core coils in my box from salvaged projects
Give the low tuning of the 6 inch box I could go as low as 150Hz I think even if that did mean a much more expensive coil on the woofers
Give the low tuning of the 6 inch box I could go as low as 150Hz I think even if that did mean a much more expensive coil on the woofers
Works OK with the solution you suggested
not Hi-Fi but good enough for movies
Second order cleaned up the vocals really quite well but the bass unit is still a little too much mid coming through with just the 5.6 coil in series
Some stuffing in the tops should help as well
I'm wondering if volume filling the bass boxes would have any real effect on the bass tuning?
Playing with various cap values and resistors while I listen to music
47uF seems to work
not Hi-Fi but good enough for movies
Second order cleaned up the vocals really quite well but the bass unit is still a little too much mid coming through with just the 5.6 coil in series
Some stuffing in the tops should help as well
I'm wondering if volume filling the bass boxes would have any real effect on the bass tuning?
Playing with various cap values and resistors while I listen to music
47uF seems to work
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