Volt BM220DS + D2905/9300 - Kord Tornado

[inrank]

Hi, been looking to improve my ATC SCM-7's and came across these, after being interested in a Volt Bass driver based speaker for quite some time now.
Got them home and they are not too bad. Treble detail is especially good, very smooth, accurate and clean! But it lacks midrange and the two drivers dont seem to integrate together.

The original speaker is called 'Kord Tornado', i believe that they were studio styel mid-field monitors from the late 80's (i guess).
They came with the Volt BM220 'DS' version and a Scan Speak D2008/8512, it was 'up graded' by the previous owner to a Scan Speak D2905/9300.

I dont think that the crossover has been changed. The enclosure seems to be around 32 Litres, and using the BM220.8 as a model, tuned to 36Hz with F3-35Hz.


Looking around, it seems that the SS D2905/9300 has been paired with the Volt BM220.8 in the Wilmslow Audio HSM and the Solen HSM kits.

Would these crossovers be a better starting point?

Does anyone know the differences between the older BM220DS model and the newer BM220.8 model?

Thanks, Rob

[inrank]

Here is a picture of the crossover, cant seem to work out the schematic

The bottom shows the connections (rotated and flipped)

I believe that it shows the tweeter out of phase? so should it be wired at the tweeter in or out of phase?

[Inductor]

Hi Rob. It's a type 2Way 2nd order xover with a resistor before C1 on tweeter. I don't know what is after C1 (box/rele? look alike, can't see). The phase is very much related with distance in the front baffle between drivers and xover frequency. It can be one or the other. Sometime ago we were checking this same problem in another manufacturer (ATC?) with both connections or different setups.

[inrank]

C1 = 2u2 (2.2uf??)
L1/L2 = not marked
C2 = 2x 2u2 (2.2uf??)
R = 2r2 (2.2 Ohms??)

After C1 it goes to the coil and 2x 3.3uf capacitors.

On the crossover, the right hand side is the mid/bass and the left is the tweeter

I was asking about the phase as when the tweeter was changed, not sure if the has tweeter polarity has been changed, would this cause the midrange suck out?

[Charles Darwin]

Rule of thumb: If the xover is second order hp & lp the tweeter needs to be inverted.

[inrank]

Cheers, so i think this is right then.... (just dont know the values of the coils)




It does not look like there is any baffle step compensation, even considering the bass i well balanced...

[Inductor]

Yes, 3rd Order on tweeter. (I can see now the inductor/cooper on the side of the double caps, that looked like a "box")

C2 = 2x 2u2 (2.2uf??)

C2 = 2x 2uF2 parallel =4.4uF
Your xover should be fine, with inverted phase on tweeter.

After C1 it goes to the coil and 2x 3.3uf capacitors.

C3 = 2x 3uF3 parallel =6.6uF

[Inductor]

Originally Posted by inrank

It does not look like there is any baffle step compensation, even considering the bass i well balanced...

You don't know, but it should be integrated with the 2.Order xover. You just can't "see" it. Maybe a bigger coil.

[inrank]

Ah ok, just had a look at the other crossover, the two 3.3uf have been replaced with a single 6.0mfd cap. Will that make a huge difference?

The main problem is that with the ATC's (xover @ 2.8Khz) you could hear voices coming out of the mid/bass driver which gave vocals weight, on these all the vocals come out of the tweeter, and looking on the web, the xover seems to be in the simmilar area (2.5-3.0Khz) using the capacitor values on a second order network. Hence the lack of integration between the drivers, and the lower midrange suck out.

[Inductor]

Originally Posted by inrank

Ah ok, just had a look at the other crossover, the two 3.3uf have been replaced with a single 6.0mfd cap. Will that make a huge difference?

No. That's small adjustments, from repairs or components tolerances.

Originally Posted by inrank

The main problem is that with the ATC's (xover @ 2.8Khz) you could hear voices coming out of the mid/bass driver which gave vocals weight, on these all the vocals come out of the tweeter, and looking on the web, the xover seems to be in the simmilar area (2.5-3.0Khz) using the capacitor values on a second order network. Hence the lack of integration between the drivers, and the lower midrange suck out.

Yes, again. You must be right (if you say so). Somewhat the C1 cap of 2.2uF is fishy to me, unless was tested that way (with another tweeter?).
If you want to go trough the pain change xovers or test new implementations from scratch.

We have:
Volt BM220.8 (Volt BM220 'DS' version is used, is it the same/similar?).
Scan Speak D2905/9300 https://www.madisound.com/store/prod...roducts_id=910
You go to this xover that is used with similar drivers
Design of the Month

Or if you start with a new (different) approach. This xover (second order) also might work but is for another, not very different driver ScanSpeak 18W/8545
SpeakerBuilding.com - Making of M1 - Print
Good luck Rob.

I would like to add this as reference, when people ask if they should use sealed or BR.
http://www.pinkfishmedia.net/forum/a...p/t-26358.html