My first quick attempt at B139 DIY sub

[ToTo Man]

I wanted something quick to tide me over until the summer where I'll have 3 months off to spend on building a 'proper' one taking into account all the dreaded calculations, so I thought why not make a sealed enclosure sub out of the boxes my Wharfedales came in . I can feel all you audiophiles cringing right now at the thought of using cardboard as a speaker enclosure, but it actually works not bad. Starts to rattle a bit when you crank the volume but hey, it's cardboard so its forgiven . Bass is pretty flat down to 35hz. The box is empty inside except a pillow stuffed down the back end. Not bad for a first attempt!.........

BTW - The wharfedales you see in the photo are part of my HT setup not my stereo setup. The wharfedales i'm using for my stereo setup are identical but further out from any walls, hence why i need subs those ones but not for my HT ones.......

 

[bolly]

richard, I must say I've never seen a coffin-sub quite like that one before! :thmbsp:

 

[ToTo Man]

Oooops, when I dug it out of the loft I forgot to check if the dead body was still in it .......

 

[M Jarve]

Wharfedale Valdus 500's... Don't get me started on those. Let me just say that your KEF driver and the pillow are the best things to ever occupy a Valdus container (though I was pretty impressed with the Valdus 400 SE).

 

[ToTo Man]

Yeah I've heard quite a few people slate the Valdus range but I can't work out why? . Apart from a large 60hz peak, to me they're the most all round refreshing speaker I've heard (I especially like the treble). Is the 400 meant to be better than the 500?

 

[M Jarve]

Yeah I've heard quite a few people slate the Valdus range but I can't work out why? . Apart from a large 60hz peak, to me they're the most all round refreshing speaker I've heard (I especially like the treble). Is the 400 meant to be better than the 500?

My after school job while I was in high-school was working at an audio shop that sold (mostly) Wharfedale speakers and Denon electronics. (there was some Technics and h/k thrown in there too, but we pushed the Wharfedale/Denon stuff more)

All at once, Wharfedale introduced the Diamond 7's, Modus MFM, Modus Music, Modus Vivendi, and the Valdus ranges. The Modus 8, MFM 5, and Valdus 500 were all in the same $1000/pr price range. The Valdus 500's looked impressive, but they sounded hard, harsh, and boomy compared to the much more (sonically) impressive MFM 5's and Music 8's. The original sales literature actually touted the Valdus range as the successor to the legendary E series, but the Valdus 500 could not even compete with the E-50 IMHO.

The Valdus range also had a problem with the tweeter protection failing and killing the tweeter. The later version of the Valdus' (with rubber surrounds and the white "W" logo on the dust cap) had better tweeters, but the natural rubber surrounds were prone to cracking.

For my money, I was much more impressed with the MFM 5 and even more so with the Music 8.

The redeeming qualities of the Valdus range was their relatively high efficiency, and pretty good mid-range. The Valdus 400 SE (and 200 SE) were also a little bit smoother and more tamed compared to their “normal” counterparts.

 

[hifi_nut]

KL,
Thats a "funny", time killing, thing to do. But forgive me if I sound too blunt: how can you say that it is flat down to 35 hz? Have you actually measured it?

Besides, one thing is going down to 35 hz with reasonable output level, which considering the size of the box and the B139 driver, it just might, but another thing is being flat to 35 HZ. I would risk to say that with all the resonant modes of the cardbox , your sub, such as it is shown here, is anything but flat.

OTOH, this experiment certainly works to increase your knowledge and experience, which is allways a good thing.

Jorge

 

[ToTo Man]

The ones I have are the ones with the shiny cones and white W. I auditioned those ones and the earlier model (both when I was 10yrs old) and the newer model sounded much better, with a tighter faster punchier bass kick to them. It wasn't until I recently hooked them up to my Yamaha CR-2020 that they suddenly became better than they ever sounded in the past 8 years of me owning them; the treble now sparkles and the harshness is gone. I've never had trouble with the protection but then I haven't ever exceeded 10watts on them so I don't really need the protection anyway. The only thing lacking for me is bass under 40hz (hence the subs). FWIW I also own the Valdus 100 and 200 and they both sound very harsh compared to the 500. $1000 seems pretty high, - I paid $450 new for my first pair and $300 new for my 2nd pair......

 

[ToTo Man]

KL,
Thats a "funny", time killing, thing to do. But forgive me if I sound too blunt: how can you say that it is flat down to 35 hz? Have you actually measured it?

Besides, one thing is going down to 35 hz with reasonable output level, which considering the size of the box and the B139 driver, it just might, but another thing is being flat to 35 HZ. I would risk to say that with all the resonant modes of the cardbox , your sub, such as it is shown here, is anything but flat.

OTOH, this experiment certainly works to increase your knowledge and experience, which is allways a good thing.

Jorge

You're right Jorge, its probably not flat, but I ran test tones from 100hz down to 25hz, and judging roughly by ear, all frequencies sounded roughly the same volume to me down to about 30hz where it got quieter, but obviously i won't know how flat it is unless i get a meter........... That said, although it might not be flat, it does help to beef up the wharfedales

 

[hifi_nut]

You're right Jorge, its probably not flat, but I ran test tones from 100hz down to 25hz, and judging roughly by ear, all frequencies sounded roughly the same volume to me down to about 30hz

Young man, ( don´t mean to be patronizing, take it as a compliment instead ) I´ve been reading your posts with interest for quite some time now.
Your learning curve seems to me to be headed just in the right direction, i.e., keep an open mind, ask away, listen carefully, try different things, learn with your own mistakes...the lot. :thmbsp:
Keep up the good work. Fellows like you are the future of this hobby, in a time where fewer and fewer are to be found.
Jorge

 

[M Jarve]

The ones I have are the ones with the shiny cones and white W. I auditioned those ones and the earlier model (both when I was 10yrs old) and the newer model sounded much better, with a tighter faster punchier bass kick to them. It wasn't until I recently hooked them up to my Yamaha CR-2020 that they suddenly became better than they ever sounded in the past 8 years of me owning them; the treble now sparkles and the harshness is gone. I've never had trouble with the protection but then I haven't ever exceeded 10watts on them so I don't really need the protection anyway. The only thing lacking for me is bass under 40hz (hence the subs). FWIW I also own the Valdus 100 and 200 and they both sound very harsh compared to the 500. $1000 seems pretty high, - I paid $450 new for my first pair and $300 new for my 2nd pair......

$1000/pr was the MSRP for A stock units. After Wharfedale got some returns due to bad tweeters, my boss bought up a bunch of B stock refurb/return units, and we sold them for $500/pr. The 100's were horrible, but the 200 SE was much better (more like a Diamond 7).

If you have the W woofers, your tweeter should be fine. The earlier version blew if you looked at it wrong. I still have a pile of them sitting in my workshop from my own set of Valdus 300s. I use the magnets to hold screws.

The best combination is the original woofer (non-gloss w/ foam surround) and the second generation tweeter.

 

[ToTo Man]

Young man, ( don´t mean to be patronizing, take it as a compliment instead ) I´ve been reading your posts with interest for quite some time now.
Your learning curve seems to me to be headed just in the right direction, i.e., keep an open mind, ask away, listen carefully, try different things, learn with your own mistakes...the lot. :thmbsp:
Keep up the good work. Fellows like you are the future of this hobby, in a time where fewer and fewer are to be found.
Jorge

Cheers Jorge :thmbsp:

 

[rbneron]

Great to see someone experimenting. A suggestion: a cardboard concrete form tube, such as those sold at any home improvement center, could make a decent and much stiffer and stronger cabinet at a very low cost (assuming you can find one with a large enough diameter for your driver). A cylinder is much less like to deform or expand than any box of the same thickness and material. Just think of the mass of wet concrete these cardboard tubes must support! Further, the tube could be finished easily by wrapping it with cloth or fabric to make a reasonable cabinet without any (or very limited) woodworking skills.

Adding some wooden support rings inside for additional cross bracing would make it even better. I believe HSU research, and perhaps SVS, uses a spiral-wound cardboard tube for their cylinder subwoofers.

I've also read of folks using these to make bass traps by filling them with sand or concrete.

 

[dnewma04]

I used the Valdus 500 for a few years (bought off ubid for 300.00 per pair). Not the best speakers I have ever used, but for the money, they were excellent. At 1000.00 per pair, i wouldn't recommend them. My biggest problem was cabinet construction. It was a bit light for the retail price. But, for a few dollars, you could add some bracings.

 

[HWF1]

I think a little fine tuning is all you need. Duck tape that sucker and for the the eye candy put 7 holes across the top evenly spaced so the diameter cloesly matches a dixie cup. Now set a cup in each hole, now add a little weight to each cup starting at the left and increase the weight in each cup till you get to the last one. You may now have the first speaker to be sold at sporting events. You could call it the wave. :thmbsp:

 

[Nat]

Actually, corrugate cardboard is not the worst material for an enclosure, but you need multiple layers. I built a pair of large cabinets out of six or eight layers of corrugated cardboard and ploped the drivers from a Magnavox or Zenith console in it. All dimensions were determined by the size of the boxes that bulk shipments of breakfast cereal came in (I had plenty of these boxes because I was the cook at a teenage camp, and the speakers were for their dances). They were astonishingly good speakers -- no cabinet resonances at all that I could tell, and it was startling how fine a bunch of old cheap drivers could sound in a non resonant infinite baffle enclosure.
So wrap more layers of cardboard around the thing, and scoff at critics.

 

[ToTo Man]

I've found a joiner who is willing to build 4 subwoofer boxes for me out of 1-inch MDF, which is great 'cos its gonna save me a LOT of time and effort . So, I need to decide on the cabinet dimensions :scratch2:. I'm not gonna bother doing any speaker calculations 'cos they're too complicated for me , but going by the free space I've got in my room I could accommodate four simple 16H x 16W x 24D sealed cabinets. This gives each cabinet a volume (I think) of 3.55 cubit feet. Does this size sound okay for a sealed enclosure? I know that KEF recommend a volume of 1 to 2 cubic feet for a sealed enclosure but I want to try and get as low bass as I can. Any other suggestions? What do I need to add in the way of dampening, e.g. 2-inch thick foam on all internal sides?

 

[Clmrt]

2.5 feet. Don't forget to subtract material thickness x 2 for every dimension.

 

[ToTo Man]

Silly me .....

Does that count for foam wadding too?

 

[Clmrt]

2.5 ft with a 3" x 10" vent = -6db @ 29hz, max SPL = 113db @ 56hz.

You only have 6mm peak to peak Xmax, so be careful.

Foam (I prefer pink fiberglass batting, but Advent used typical foam to fill the large sealed Advent loudspeaker) will increase the apparent volume, but I don't know how much. I assume it will account for port, brace and driver displacement so I never try to cancel them in my calculations.

http://members.shaw.ca/t-linespeakers/diy-11-apr-99/B139small.GIF