Building subwoofer from 2 x Scanspeak 25W/8565-01 any good ideas?

[fredde1972]

Hi, I have 4 scanspeak 25W/8565-01 on the shelf. Leftovers from earlier project.

I am looking to put two of these into a subwoofer in a isobaric system since I want the volume to be as small as possible. But I still want to achieve around 20hz. Do you think this is a good idea? If so do you have any recommendations on volume and bass port size for such a system?

I plan to use and Adcom GFA 5500 2 x 200 watts as amp.

All suggestions are welcome 🙂

Brgds Fredde

 

[Inductor]

Yes, it's my opinion that drivers Scanspeak 25W/8565-01 will achieve ~20Hz@F5 attenuation and they are good for sealed or in this case BR >100L (each driver). You can start simulating in (download) WinISD, Unibox, for a start with yours be it isobaric, BR, bandpass. So be prepared for the type of setup you gonna find for the extension you're looking for. It's not a very flexible driver in the frequency range, but with 90dB a strong one. Also is a 30W driver whatever it means. (power needed for max.excursion.)

 

[fredde1972]

I am afraid you are talking a little over my head here 😉

Does anybody have the possibility to calculate volume and bassport size with these two drivers playing in a isobaric system? I do not have any experience with any simulators unfortunately.

But I was thinking about something close to the drawing attached.

 

[Inductor]

Are the connections series or parallel? That would be 12-13 Ohms (S) vs. 3 Ohms (P).
If the space between drivers is 15cm x (30cmx30cm) = 13.5 L (#1 case)
If space b.d. is 20cm x (30cmx30cm) = 18 L (#2 case)
Now the volume for the box. You will have to count the (net) internal volume (have ~60L here), plus the size of the port and driver (use ~15L, if using 1" ply/MDF for the construction). This using a square port 12 cm x 5 cm (would give a length close to 77/78 cm).
Total internal volume 75L (net).
This will give a speaker, for a first impression only, this needs to be calibrated later, if you're building it with 1" ply/MDF: 55 cm x 47 cm x 41 cm.
Edit: I was missing the space for the drivers isobaric so this have to be added too +15/18L.
75L + 15L = 90L (#1 case)
75L + 18L = 93L (#2 case)

 

[bjorno]

I am afraid you are talking a little over my head here 😉

Does anybody have the possibility to calculate volume and bassport size with these two drivers playing in a isobaric system? I do not have any experience with any simulators unfortunately.

But I was thinking about something close to the drawing attached.

Hi fredde,

If I had 4 of those Drivers: I would make 2 closed boxes of ~68 L and a ~213L T-TQWT with paralleled Drivers, none would be of an isobaric type.

b🙂

 

[Inductor]

Edit: I was missing the space for the drivers isobaric so this have to be added too +15/18L.
75L + 15L = 90L (#1 case)
75L + 18L = 93L (#2 case)
What would give something max. external dimensions 60cm x 51cm x 44cm (3cm ply/MDF).

 

[fredde1972]

Hi fredde,

If I had 4 of those Drivers: I would make 2 closed boxes of ~68 L and a ~213L T-TQWT with paralleled Drivers, none would be of an isobaric type.

b🙂

This sounds very interesting. I had to google T-TQWT 😉 but seems like a exiting project. I found a lot of different pictures bjorno, do you have a picture or a drawing of what you would recommend?

Just a really basic sketch is what I need to understand it fully 😉

 

[bjorno]

This sounds very interesting. I had to google T-TQWT 😉 but seems like a exiting project. I found a lot of different pictures bjorno, do you have a picture or a drawing of what you would recommend?

Just a really basic sketch is what I need to understand it fully 😉

Hi fredde,

Here are some example Photos showing a single folded T-TQWT :... And a single folded 25W_8565-01 sim. using two Drivers in parallel with two different Filter settings. :..
...+ one siim. showing a dual-folded sheme for an OD-TQWT wit an Infinity Driver.

A single folded layout:
http://www.diyaudio.com/forums/subwoofers/181506-35hz-120litre-th-2.html

b🙂

 

[fredde1972]

Thanks, will definetly have a look at that option 🙂

Thanks for the help.