Peerless SLS 6.5" (830946) project

[Veke76]

Hi

Just placed in order for a Peerless SLS 6.5" (830946) subwoofer driver. I'm planning using it in bass reflex box. Acoustic volume would be 5.55L and tuning 47Hz. Tube would be 29mm diameter and 140mm length.

I'm going to use this subwoofer with my TangBand W4-657SC speakers what I build earlier. Just a second speaker set for fun use in summer cabin or something. I don't expect this to go really low frequencies, just a little lower than TBs. It wouldn't play really loud.

Has anyone build anything similar with this driver? Any concerns with my plans?

I saw some plans with 12L bass reflex and 50mm diameter tube at 178mm length (tuning 48Hz). Only benefit what I saw was much lower port air velocity and some lower frequency response. Didn't like how it boosts bass close to 50hz. Bigger box would give close to 43Hz response. My box would give close to 50Hz response. TBs go low as 74Hz so the subwoofer would be nice.

With this small box size it would be difficult to fit any longer tube in it. Just thinking should I use bigger diameter tube L shaped to get the air velocity lower? Now it would get 17 m/s at max spl and cone excursion.

This is my second DIY project so I'm not assuming I know enough to perfect this. I have WINISD to help me. All the details how to power this thing, use of crossovers and so on I have to think later on.

What box size and tuning would you go? The tube selection is pretty limited here in Finland so diameters are close to 30/45/50/70/100mm and not that big lengths.

[Veke76]

Another plan I saw was with 8L bass reflex and 50mm diameter tube at 381mm length (tuning 42Hz). It would use L shaped tube. Slight drop in output in 50-100Hz region. Maybe not a problem. This box would go close to 43Hz response. Something like 400mm L shaped might fit inside this box.

It would be nice to end up closer to 43Hz response so maybe my plan needs to be changed...

[Okv]

I made a test box for these, 8l with 36Hz tuning, gives you flat down to just below 40Hz.

Used a slot port of 14cm2 area, 31cm long, easy to implement by adding a wall inside the cabinet.

Hornresp sim data and even measurements are available, if you are very interested in seeing those.
Meas. shows nothing spectacular; reasonably low distortion for such a small driver, reasonable output, reasonable freq response - a good design for its size and complexity.
You can get approximately the same information from Winisd, using the 8l 36Hz tuning.

[Veke76]

I think I have revise my plan because of too much air velocity at port. I think I'll make square port of 170x10mm and 326mm length. It will fold inside box or so to speak two walls inside box. Box size would be 8L and tuning 42Hz. It would give response down to 42Hz. It seems anyway that long bass reflex ports are needed with this driver.

[Veke76]

It seems I have to use 9:1 ratio so square port would be 170x19mm and length little bit over 655mm. Tuning at 39Hz and response down to 42Hz.

[Okv]

Originally Posted by Veke76

It seems I have to use 9:1 ratio so square port would be 170x19mm and length little bit over 655mm. Tuning at 39Hz and response down to 42Hz.

Yes, I forgot to mention about the port area.
Your assumptions are correct, it is a bit too small at 14cm2, you will get some noise and compression in that.
My box was built for testing puposes only, so I guess I just confirmed that the port is a bit too small, and left it at that, seeing as the box worked for its purpose and was soon retired.

A very long port may give problems with resonance, but 655mm should be worth trying.

A good flaring around the port exit will also help a lot.

[Veke76]

I will update my plans here with more accurate info. So it's 8L bass reflex enclosure tuned at 40.5 Hz. Port is 170x19mm and 690mm in length. I haven't yet assembled the enclosure. I could have been good to add one more wall inside to get the tuning <36Hz. Maybe it would be better always aim at fs or lower.

[Veke76]

Here is some pics made with Google Sketchup:

[Veke76]

Ok I'll go ahead with my plans and just try if it works out. If it doesn't I'll make a 3.35L closed enclosure. Because my plate amp only amplifies 30-180Hz range the difference isn't too big to use closed enclosure. Just pump up the wattage and lower crossover frequency it might work also. I have 22mm MDF as material and I had them precision sawed. Made a hole for the driver and only thing is missing is assembly+screwing+glueing. If I end up with closed enclosure I might change glued pine board as material because it could look better.

[Veke76]

Finally I got to work and assembled the box so far that I could do sound check and evaluate what to do next. It seems that there are port noises coming out of the subwoofer. The problem occurres with sertain bass test cds and couple of techno songs. Otherwise rock+metal+pop plays pretty nicely. It adds nicely to my main speakers. Frequency test shows that the sub wasn't placed in optimum location which is corner of room. Now it was center of one wall. I was expecting it to hit 32Hz in room. I didn't test maximum SPL this time. Most of tests I run in 95dB SPL. Now I think I'll finish my sub and add some flaring to port.