My first DIY: Cyburgs Needles with HiVi B3S

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Thought I'd share my first DIY speaker project. Chose the needles since they're quite easy to build, although the tricky part was getting perfectly straight edges and trying to make do with only 6 clamps :whazzat: Nonetheless they came together quite well!

Here's a pic of them in my study:
An externally hosted image should be here but it was not working when we last tested it.


and just before the drivers went in (I originally put 4x too much stuffing, getting it out and putting the correct amount in through the 70mm hole was quite a challenge!) :
An externally hosted image should be here but it was not working when we last tested it.


I followed the standard needle design, except with the front and back thickened to 16mm and a HiVi B3S driver rather than the TB which I couldn't source here in Australia. The front side and top edges have been rounded off with a 9.7mm radius bit. Cabinet hasn't been painted yet as I want to match the driver well, which hasn't yet been decided (see below.)

Because the door is to the left of the table, I have to live with an off-centre arrangement for now, but I don't seem to be getting any bad corner effects or anything. Soundstage is much bigger with the speakers aiming straight forward, although the sweet spot is much wider when the speakers are aimed more inward.

Overall the sound is quite impressive, if not a bit bright and slightly tinny. The 8kHz breakup node was handled by (the second half of) Zaph's B3S filter, without which some songs are almost painful to listen to. The needles reach down to about 100-something Hz but very quickly fall off and require the help of a sub (you can see my 12" unit in the corner.) I suspect other more suitable drivers (TB W3-871S, Mark Audio Alpair6) will have more bass.

The only speakers I can compare these to are my previous stereo pair of LSK M5's. The needles are hugely more ambient and much less fatiguing to listen to, and surprisingly blend much better with my 12" sub (the M5's exhibit a bit of a mid-bass black hole by comparison.) Even more surprisingly, the needles seem to handle hard rock better, although admittedly it does get quite muddy.

I'd like some opinions on my next step. I'm pretty sure I can eek some better sound quality by using more appropriate drivers (TB or MA) but can anyone help set my expectations for improvement with the needles? If the needles are inherently treble-happy, would I be better off building another pair of totally different speakers?

Happy to hear all comments/suggestions!
 
ttan98 said:
871 is 3" and 1320 is 4" don't think they are direct replacement even you cut a larger hole.

I tried the 871 in open baffle I was not impress, in needle cabinet maybe ok because many people reported good results.

try contact timn8ter, http://www.diyaudio.com/forums/member.php?s=&action=getinfo&userid=7563,

he may have a few left, I bought mine from him.

I think he ran out, contacted him already. My sights have since been set on the alpair6, as this graph (courtesy of Henkjan in the main needle thread) shows:

An externally hosted image should be here but it was not working when we last tested it.


from top to bottom, they are:

1) alpair6
2) bb3.01
3) w3-871
4) w3-1285 / hivi b3s
 
Or alternatively, as I suggested for someone via a PM discussion WRT a box for the Alpair6, a simple MLTL should provide more gain & somewhat less ripple (baffle-step aside, which also applies to the Needle)

30in x 6in x 4.25in, Zd = 2.5in, Zp = 29in, vent 2in diameter x 4in long. Line top, back & one sidewall with 1/2in wool felt, stiff fiberglass or similar.

YMMV of course. Just a thought.
 

Attachments

  • mltl.gif
    mltl.gif
    5.8 KB · Views: 1,306
Scottmoose said:
Or alternatively, as I suggested for someone via a PM discussion WRT a box for the Alpair6, a simple MLTL should provide more gain & somewhat less ripple (baffle-step aside, which also applies to the Needle)

30in x 6in x 4.25in, Zd = 2.5in, Zp = 29in, vent 2in diameter x 4in long. Line top, back & one sidewall with 1/2in wool felt, stiff fiberglass or similar.

YMMV of course. Just a thought.


Thanks scott! that response curve makes the needle seem a bit unrefined to say the least.

Forgive my noobness, but would you be able to point out what the Zd and Zp are? My guess is that the Zd is the width of the thin end of the line (making the thick end 3.5in, discounting barrier thickness and assuming your 30x6x4.25 dimensions are internal) and that Zp is the distance from the centre of the port to the bend in the line, i.e. 1in from the thin end and thus right up against the end of the line?
 
You're welcome.

Zd = Zdriver. The distance of the driver-centre from the throat / sealed end of the line / whatever you want to call it.

Zp = Zport. The distance of the port-centre from the throat / sealed end of the line / whatever you want to call it.

No bends, no taper, no internal panels. It's a straight, unfolded, mass-loaded QW line, i.e. an MLTL. So you have a simple, rectangular cabinet with internal HxWxD dimensions of 30in x 4.25in x 6in (you can swap the WxD dimension if you feel so inclined), with the driver-centre 2.5in down from the top, & the cylindrical vent 1in up from the bottom. The top, back & one side-wall of the cabinet lined as described above. Note that this was for the Alpair6 -other drivers will give of their best in cabinets designed for them.

FYI, the Needle is technically a mass-loaded horn. if a line expands toward the terminus, it's a horn.
 
Thanks for the explanation; so this would be one of those QW designs that less knowledgeable people call bass reflex boxes? (I read the whole thor clarity thread yesterday, I'm quite aware of where you and dave stand on that subject :))

It makes sense that the needle is a horn. I was explaining to friends on the weekend that I had just built "a mass-loaded, tapered, quarter-wavelength tube" and I just got blank looks. Horn sounds nicer. (And mass loading simply means that the port is significantly smaller than the line's end cross section, at which the port is positioned?)

Is it OK to position the driver in the middle of the baffle, or should I offset it?

I appreciate you letting me ask this many questions :)
 
A Bass Reflex enclosure by definition utilises Helmholtz resonance, and assumes a uniform air particle density within the enclosure, with no standing waves. An MLTL deliberately generates and uses standing waves; it's primary resonance action is QW, not Helmholtz.

Actually, a TQWT historically was the exact opposite of what is generally described as a TQWT today. Originally, TQWT refered to a cabinet that narrowed toward the terminus, not one that expanded. Such cabinets are inherently mass-loaded, due to their negative taper. Almost nobody uses the term in that sense these days, but I thought a bit of history might be of interest. ;)

Right -as I noted above, technically, if a cabinet expands toward the terminus, then it's a horn, and if the terminus is then choked / restricted, then it's a mass-loaded horn. Doesn't really matter all that much & arguably we're in the realms of semantics as they're all variations on resonant behaviour, but IMO, the definitions do have uses on occasion, like when you're examining the harmonic behaviour of different types of line.

Re horizontal offset of the driver, there wouldn't be room if you went with the narrow / deep option to do much, so personally, I wouldn't bother. You could if you felt so inclined with the wide / shallow option, but TBH, again, I probably wouldn't worry about it all that much. You're unlikely to hear a difference.
 
Interesting technical history lesson! I'm an engineering-based person, so any hint of absoluteness in what is an unabsolute world provides a bit of comfort :angel:

the alpair6 design almost seems too good to be true... extension down to 50Hz! the relatively huge chili chang barely manages this, despite using an fe167e! (see attached)
 

Attachments

  • chilichangfr.png
    chilichangfr.png
    23.7 KB · Views: 1,252
Right, but I didn't design Chili for LF extension.

It's not too good to be true from the POV of extension. However, you must keep in mind that it's a very small driver, that doesn't shift much air; therefore, maximum SPLs will be limited. That's also a quasi-anechoic / IB sim, which doesn't take baffle-step loss into consideration (these remarks also apply to the Needle sims BTW).
 
Scottmoose said:
Right, but I didn't design Chili for LF extension.

It's not too good to be true from the POV of extension. However, you must keep in mind that it's a very small driver, that doesn't shift much air; therefore, maximum SPLs will be limited. That's also a quasi-anechoic / IB sim, which doesn't take baffle-step loss into consideration (these remarks also apply to the Needle sims BTW).

Fair point, that was a misjudgement on my part. Big speaker = big sound = hefty LF was my (rather incorrect and naive) thinking.

From my next set however I want that big sound; a stereo pair with excellent SQ and doesn't need a subwoofer (at least for music; for HT i might want to integrate it with a sub later). in the thors clarity thread, i believe you mentioned that although the small thor would easily match a £2-3000 commercial system, you would rather build the PMS if starting from scratch.

Are there any speakers you would recommend over the PMS? I understand you can't possibly have listened to them all, but from your perspective and given your knowledge, if you had to build the ultimate stereo no-subwoofer-needed pair, which would it be?

(apologies for taking this thread off topic so much :cannotbe: )
 
Cheers! Thanks for answering such a hard question, now I know where to start looking for my next multiway project.

As cost will be a major factor in my next project though (GAF...), I will probably build either a level 3 frugelhorn or a chilli chang. As I want to see how much LF extension I can get from an FR driver, the frugelhorn looks the go.

That said, greenie512 (a fellow aussie speaker builder) has very maturely suggested that I cool down a bit, and not to rush ahead too much. So this weekend I'll be tweaking my needles with various BSC filter settings and also a zobel network. I plan to convert some of my favourite songs to mono, put the needles side by side, and do A-B comparisons that way to determine the right amount of BSC needed (thanks to MJK for his excellent BSC article (pdf).)

Will be sure to come back with the results! :)
 
Ok just spent the evening playing with the zobel, notch and bsc filters! Lots of trial and error but still sorta fun, and most definitely worth it.

First thing I tried was a trick I found on the internet: solder a small poly cap across electrolytic caps to improve the sound quality. So I added a 27nF cap to my 43uF (10+33) caps in my notch filter. Difference in SQ? None that I can hear :)
An externally hosted image should be here but it was not working when we last tested it.


Next thing I tried was a zobel network, which apparently smoothes out the driver's apparent impedance at higher frequencies or something. Supposed to allow the bsc filter to work more accurately, but it ended up just making all my singers (especially female ones) sound like they were under water... very muddy, no detail. Threw these into the spare parts drawer very quickly.
An externally hosted image should be here but it was not working when we last tested it.


The last and biggest thing was the addition of a BSC filter. I originally tried a 0.82mH coil with an 8R2 resistor, but that took all the life out of the sound. So I grabbed some more resistors and tried 0 (bypass), 4.1, 4.9, 5.6 and 8.2. Throughout all my testing tonight I had the speakers right next to each other, playing my favourite songs remixed to mono, and me switching between left and right channels so I could do a direct A-B test. Result is that the sweet spot (bright enough to have ambience, and rounded enough to prevent shouting) was between 4.1 and 4.9, perhaps slightly closer to 4.1. This is right on the money with MJK's BSC calculator so I'm quite happy :)
An externally hosted image should be here but it was not working when we last tested it.


The upshot of all this is that the needles are much easier to listen to now, and still have the same magic they did before of transparency and detail. These little things ain't half bad! :D
 
> as I suggested for someone via a PM discussion WRT a box for the Alpair6, a simple MLTL should provide more gain & somewhat less ripple

A beginner's silly question :

If I understand correctly, a MLTL uses the length of the housing as a resonator. So I should expect higher order resonances than the fundamental, which need to be damped out by stuffing.

The SPL response you showed looks almostly perfectly flat, and yet the cavity is only damped somewhat on the sidewalls.

Any scientific explanations ?


Patrick
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.