Foam Core Board Speaker Enclosures?

[xrk971]

GR Research X-LS kit

Here is my first pre-designed kit speaker build. It is the X-LS by GR Research. I got it mainly because it is a fantastic deal in drivers and hardware. All high quality stuff (Peerless coated paper cone woofer, all air core inductors, poly film caps, thick PCB for XO, all wires, screws, port tube, terminal cup) for only $110. Anyhow, it went together easily as I had an old foam core enclosure that needed to be cut down to size. The ideal size is 8.5in wide baffle for best XO efficacy but I was lazy as this was lying around.

X-LS Classic kit

I am using it as a kitchen speaker with an SMSL 36A amp and my phone as the source.

Here are some measurements on a stand at 0.5m:

I think my foam box needs more bracing as the back wall and top are single layer foam core. The baffle is 3 layers with CLD on the last outer layer.

 

[bolexsbm]

That's interesting that you put the tweeter as a pass through to a k tube. Why did you not let tweeter come through the middle and combine with mid a la synergy?

Hi xrk.
Nice work on the TL speakers and the X-Ls Kits! (do you even have time to sleep?😀)

Anyway, there are 3 reasons I used the K-tube for the tweeter.

One is that I read about some high frequency problems in the Paraline, and thought maybe bypassing the HF altogether will be better.(or is it? 😕)

Second is that I wanted to try out the coaxial arrangement for Paraline from Patrick Bateman's posts.

And the third reason is that I became a big K-tube fan, and I've been trying to use the K-tube wherever I had the chance.(and as far as I'm concerned, the Paraline with the K-tube didn't look that much different from the Faerber speaker with the K-tube poking through the Tractrix...)

 

[xrk971]

Bolexsbm,
Thanks! No, I don't sleep much 😀

Here are some sound clips in stereo of the TL at my computer desk as monitors. The bass is quite profound - flat to 30Hz. It can handle electronic dance tracks without a hiccup.

http://www.diyaudio.com/forums/multi-way/281778-low-cost-pmc-inspired-tl-monitor-dc130a-dc28f-8.html#post4540130

Here is one driver (with stereo, an average 91dB level is easy with distortion below 2% in the bass region and under 1% everywhere else)

 

[BP1Fanatic]

Nice, look at the F3! Have you watched any movies with them?

 

[xrk971]

Hmm, no movies yet. I suppose YouTube will have to do as I don't do HT. I was surprised how well it could play Knife Party's Centipede - the go-to track Danley uses to demo his TH's.

 

[JLOP]

Hi X

Very interesting, thanks for sharing with us. A question : is the foam core flexible, you see where I want to arrive : is It possible to prototype multi-cell horns for compression drivers ? If yes, what building advises would you give ?

Thanks
Jean-Louis

 

[xrk971]

Jlop,
Great question. I have been wanting to build myself a multi cell horn too. The material is stiff but vibrates easily so needs bracing. The nature of multi cell has inherent bracing so that is good. I would build each cell individually then glue them together with latex caulking to provide CLD damping. Alternatively, build it layer by layer with flat sheets where you glue little sections of dividers for each row. The layers can even be curved along the off axis layers. This method is faster and has thinner cell walls but may have more induced vibration distortion. It may be quick to prototype this way for quick and dirty test. Then make individual cell with CLD for more permanent version.

Let me know how it goes.

Good luck.

 

[xrk971]

Just an update to the foam core thread list of foam core speakers. Latest is uTrynergy with 2.5in SB65WBAC25 driver and four 5.25in woofers in open back dipole bass:
http://www.diyaudio.com/forums/full...trynergy-full-range-tractrix-synergy-120.html

Sounds fantastic - deep bass for 2-way FAST with quasi transient perfect Harsch XO.

 

[Eldam]

Super X !

Do you find it better at ears than the first 5" inch throat with the 10F/8425G00 ?

 

[xrk971]

I never used 10F with 5in throat. 2in throat with 10F actually sounds better as it is lower harmonic distortion. But the open baffle bass on this small one is very nice and integrates well. For ultimate sound quality the bigger 2in throat with 10F and 6.5in woofers in open back dipole bass with partial enclosure may also be the ticket. It's nice to get a full range 2 way FAST that goes from 40Hz to 20kHz.

 

[xrk971]

Copy of Curvy wall Tabaq with P830986

This was a fun and easy build using score and fold technique. The Tabaq with a BSC sounds balanced and has surprising bass extension for 3 in driver.

http://www.diyaudio.com/forums/full-range/88787-tabaq-tl-tang-band-119.html#post4556798

 

[Eldam]

Oups sorry, I was mistaken : 5 cm throat I meaned ! You guessed it 😉... (=2")

Thank you for the input, well I will ask myseld about the opportunity of 10" OB when it will be the time for that !

 

[gychang]

I stumbled over an idea that might be fun to decorate one of these foam core builds:

good idea!!

 

[BP1Fanatic]

X, you are a foam core building monster!

 

[adason]

X, may be try this to strengthen the foam core enclosure...
http://www.diyaudio.com/forums/multi-way/284460-why-arent-we-building-horns-way.html

 

[xrk971]

I saw that thread too. A thick polymer paint coating is one way to stiffen and waterproof. Probably adds damping too.

 

[xrk971]

X, you are a foam core building monster!

Thanks. There are 35 projects listed on the index.

 

[EddieT]

Thanks. There are 35 projects listed on the index.

The inside construction of your projects is so neat and precise that it's a shame it has to be hidden.

 

[xrk971]

Thanks for the kind words EddieT

The insides are actually quite sloppy - I just don't take closeups!

The insides are based on "measure as you go add as you see fit" philosophy and it's purely to generate enough bracing stiffness to combat wall flex and resonances of the this 3/16in foam core.

My favorite internal bracing is the XKi dual sub.

The Nautaloss sub was fun too.

 

[bknabe]

Hi X
Probably an old question, but how do you temporarily seal the top while tuning the stuffing? Thanks,
Bob