What’s On the Bench Tonight (OBT)

[von Ah]

I’m excited to dive into measurements, x-over simulation, and implementation next week.
Working title options:

• B-Stock Bevels
• Stereo Seconds

 

[xrk971]

On the bench tonight… I made a thing!

I got some ‘seconds‘ cabinets from Xrk a while ago. Finally did enough research to find potential driver candidates that would fit* and went headfirst into it this evening.

Elbow grease and MDF dust led to this!

• SB16PFCR25-8 MidWoofer
• PT2522C-4 Tweeter
• SB15SFCR-00 Passive radiator

The cabinets are around 18L internal. Initial listening with passive 1st order crossover at about 2700 Hz is promising! I think I will be able to get somewhere with these…

Can you show us what the XO and measurements look like? How do you like the bass from that passive radiator?

 

[von Ah]

I will share measurements next week. Don’t have any yet. I just added a cap and resistor to the tweeter and a coil to the woofer. The bass with the PR is pretty good.

 

[von Ah]

Rudimentary measurements. Crossover is a 2uH coil on the woofer, 18uF cap and 7R resistor on the tweeter. dB figures aren't absolute. Nearfield woofer and PR also included.

With some DSP EQ in piCorePlayer to tame the bigger valleys and peaks, they are sounding pretty good. Good enough that I will certainly build another one!

More crossover futzing will continue. If I have the parts, I'll try 2nd order passive. I'll also get a WT3 impedance measurement on the woofer.

 

[xrk971]

Nice work!

 

[von Ah]

A little better with 2nd order on the woofer... Sounds good.

 

[xrk971]

That looks pretty good. Try adding a 20ohm in parallel with the woofer’s 2mH inductor to shelve the response for the baffle step correction a bit. It will make the bass sound more full.

 

[von Ah]

Thank you. 20R connected and sounding fine. mH, yes. I had a typo earlier.
Gotta break down this testing rig soon. Will continue playing with it this week.

 

[xrk971]

Glad the 20R is sounding good. You can play with that value. The point is to reduce the rising response of the woofer.

 

[adason]

Almost finished 15" subs. Mostly from leftover wood. Gave it 'adason' style gorilla glue surface. This time i decided to try white for finish. Ok so far. Most importantly, great deep bass due to open back. Fs measured by dats 18Hz.

 

[adason]

Will be comparing three subwoofers, so i made this little gadget.

 

[xrk971]

I’m thinking of offering the XSD style dipole woofer box separately as a subwoofer / stand for stand mount speakers.

 

[uncola]

wow, so a narrow open baffle subwoofer tower using small woofers? that would be a unique offering
edit: actually isn't that similar to the upcoming magnepan subwoofer offering? except I recall that was like $8k+

 

[xrk971]

Sort of like this but without the 5 deg lean. Just a straight tower with a platform on top for a speaker.

 

[uncola]

just need 4 of them for each corner of the room for the duke lejeune's swarm technique
https://www.theabsolutesound.com/articles/audiokinesis-swarm-subwoofer-system/

 

[wcwc]

What would be a normal crossover point to the base unit?

 

[jimk04]

470hz iirc?

 

[xrk971]

Yes, 470Hz if you want to take advantage of the natural falloff. This way, a second order electrical will get you 4th order overall. But below this, you can apply whatever curve you want if in DSP (or passive with 4th order electrical etc).

470Hz is based on 7in depth of slot chamber. If we went with 8in woofers then it would be 370Hz I think and goes lower as size goes up. Dual 12’s would be about 230Hz.