My first DIY project with some kef sp1022, any ideas?

[VvvvvV]

I have just got hold of some kef b200 sp1022, what should I do with them? I was hoping to make some transmission lines and I'm completely confused where to begin research for hours on what I should do, I think someone should walkie me through this because I'm a noob!

I actually was going to make a burly old subwoofer and with a couple of the best stereos that I could do, and I got these parts because they were available and now I'm all in limbo! I'm planning a 12 inch driver for a subwoofer...uh oh

http://homepage.mac.com/tlinespeaker...200_SP1022.gif

[wintermute]

Others may correct me here, but as a first project I think TL's might be a bit dangerous/ambitious, unless you are doing something that someone else has already proven to be a good design

I'd be looking at getting a hold of winsid or unibox (unibox requires you have MS excell) and doing some modelling.

I personally prefer to do the research before outlaying any cash, but that's me

http://www.linearteam.dk/ for winisd/winisdpro

http://home20.inet.tele.dk/kou/ubmodel.html for unibox

http://ldsg.snippets.org/index.php3 good place to start when researching speakers

Tony.

edit: niether winisd or unibox will let you model TL's as far as I know.

[paulspencer]

Others may correct me here, but as a first project I think TL's might be a bit dangerous/ambitious, unless you are doing something that someone else has already proven to be a good design

Not at all, you can easily do a TL as a first project, many have done it successfully. It's not that hard at all. Just get Martin King's stuff and get experimenting

[Dave Jones]

Originally posted by paulspencer


Not at all, you can easily do a TL as a first project, many have done it successfully. It's not that hard at all. Just get Martin King's stuff and get experimenting

Martin's software is great stuff, that's fer shur. Design isn't the only issue though. With those T/S parameters, a TL would have to be rather large.

[Dave Jones]

Originally posted by VvvvvV

I actually was going to make a burly old subwoofer and with a couple of the best stereos that I could do, and I got these parts because they were available and now I'm all in limbo! I'm planning a 12 inch driver for a subwoofer...uh oh

http://homepage.mac.com/tlinespeaker...200_SP1022.gif

Sorry, my first language is Texan. I didn't understand that last part at all. Those KEF 8 inchers would make a heck of a sub, or a pair of subs. You're not planning on using both the 8" woofers and a sub are you? If so, why?

[wintermute]

There you go I've allways thought of TL's as a bit of a black art, and was concerned that a bad experience (as the first project) might turn one off diy altogether

since no one else has mentioned it you might want to check out dave's site. http://www.t-linespeakers.org/

I must admit, not having access to mathcad, and hence the inability to do any modeling has also kept me away from TL's..... All seemed to hard to me.

Tony.

[VvvvvV]

Sorry Texan guy, I just meant that one plan was to have some standard and perhaps compact stereo speakers and a large powerful homemade subwoofer. Of course a 12" subwoofer and a transmission line using two 8" subwoofers would be way over the top.

If I made a transmission line subwoofer from ready-made plans using two of these 8" drivers, would it be able to compete in depth of bass with a 12" subwoofer?

having seen the wealth of transmission line designs around, I thought there must be plenty of ready-made plans with the kef sp1022, but it turns out it's a rare driver, used in only one commercial speaker, so I'm surprised the transmission line web site moderator reckons it so good.
To make a decent TL, don't I just have to match the harmonics of the driver with a line length matching a corresponding wavelength? this gives some choice for the length of the line.
In retrospect, this was a completely illogical buy, because unconsciously I know that the best solution for me the some powerful all-purpose monitors and subwoofer. But I like transmission lines so much and saw this was supposedly one of the best drivers for a TL and made some last-minute bids, I would love to try and throw anything together, especially really strange transmission line, perhaps as a side project, but I'm certainly confused!
Thanks for some excellent links, I wish there were some easy solutions to DIY in UK like one of those neptune or aphelion designs that everyone seems to be making-

[paulspencer]

I've allways thought of TL's as a bit of a black art

In the past yes, not now. Martin King has made TL design accessible to diyers without having to buy anything. You can run it with a demo version of MathCAD (you just can't save results, but you can print screen, and paste into word, or save in a graphics application). This is good enough for the occasional TL for personal use.

I must admit, not having access to mathcad, and hence the inability to do any modeling has also kept me away from TL's..... All seemed to hard to me.

How can this be so? You can get a free demo version, there is a link on Martin's site.

http://www.quarter-wave.com/

Now that you have the drivers, it's time to start modelling to see what you can do with them. Get MathCAD demo, download Martin's stuff, ang get going! From there you can easily get help.

Of course a 12" subwoofer and a transmission line using two 8" subwoofers would be way over the top.

I may not be a Texan, but I don't think anything is over the top
For movies I'd still add a sub.

If I made a transmission line subwoofer from ready-made plans using two of these 8" drivers, would it be able to compete in depth of bass with a 12" subwoofer?

Those drivers have a displacement limited bass output that is only slightly more than my TLs with a pair of 6.5" midbass drivers (approx +3db). You should be able to get quite decent output to 25Hz in room, and should do a decent job for movies as well as music. A high excursion sub like the Shiva will play louder and deeper as it will move quite a bit more air. Depending on the design, TL's can have a response either like a sealed box or a vented box. Keep in mind, the bass output is always limited by how much air the driver can move. Many diyers like TLs as they consider that they combine the best features of sealed and vented boxes - the depth and extension of bented boxes with similar or better transient response than a sealed box, and a more natrual and less coloured bass.

To make a decent TL, don't I just have to match the harmonics of the driver with a line length matching a corresponding wavelength?

You mean the driver free air resonance? (fs)
As a starting point, choose the fs of the driver and find the quarter WL ... in this case fs = 25 Hz
344/25 = 13.76m
13.76 x 1/4 = 3.44m
In this case the fs of the driver is very low and tuning this low means a crazy long line. With 4 folds in the line it is about 1m tall but very large and deep. You might instead try tuning at 40 Hz, which requires a 2.15m line. You can then experiment with line lengths between these two and see what results you get. Room lift tends to help below 40 Hz.

I'm certainly confused!

Keep reading, discussing and start modelling and you will clear up your confusion

[wintermute]

Originally posted by paulspencer


In the past yes, not now. Martin King has made TL design accessible to diyers without having to buy anything. You can run it with a demo version of MathCAD (you just can't save results, but you can print screen, and paste into word, or save in a graphics application). This is good enough for the occasional TL for personal use.



How can this be so? You can get a free demo version, there is a link on Martin's site.

http://www.quarter-wave.com/

Thanks Paul As you said later in your post, I was interested in TL's for the low extension, with good transient response, but thought I wasn't going to be able to do anything (modeling wise).

I'll have to double check, but I have a feeling that my Vifa 10" woofers had some characteristics that made them less than optimal for TL's and since I didn't think I could model them I discounted it as an option.... looks like it's time to revisit it

Tony.

[paulspencer]

I'll have to double check, but I have a feeling that my Vifa 10" woofers had some characteristics that made them less than optimal for TL's and since I didn't think I could model them I discounted it as an option.... looks like it's time to revisit it

How many of them do you have and how are they used at the moment?

It's best not to assume too much IMO. Just model, it's not that hard, then you find out what you can do with something. This is on the "after purchase" side of things. Before you buy, that is when you think about what you think it will be suitable for, and what you want to do.

The first thing that comes to mind is it might be quite large to get optimal extension, given the SD. The vifa 10" drivers have a fairly low Qts, especially the P25, while a slightly higher Qts than typical is considered more suitable ~Qts 0.5. This should not automatically stop you from trying it out. There was a discussion in a previous thread in which MJK challenged the idea that low Qts drivers can't be used.

Hmmmmm, sounds like a new thread coming on perhaps ...