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Boxes for external cossover

J

julian2002

pfm Member
hi,
i'm about to start building a pair of IPL S5TL speakers and am going to make the crossovers external.
this means i'll be needing some boxes to put them in.
the size of one crossover board is 230 x 120 x 70(aprox height) but i was looking for something bigger to accomodate future tweaks. i was thinging about 300 x 300 x 140 to be on the safe side.
i'd prefer black aluminium or at least black plastic but the size is more important than colour or material as i could always paint it.
i've looked in a few obvious places (maplins, rs, farnell) but cannot find what i'm looking for. The closest i found was a 270 x 270 x 170 grey abs box which would do at a pinch but is quite pricey at 34ukp iirc for something that isn't exactly what i want.
so can anyone recomend a retailer / manufaturer who could help?
cheers


julian
 
Hi Julian

I know someone on here made a case for something power supplyish (DIY Geddon?) from flat metal and extruded aluminium angles or some such but I can't for the life of me remember who or when. Try a search for DIY Geddon and see what turns up.

Mick
 
Originally posted by julian2002
i'd prefer black aluminium or at least black plastic but the size is more important than colour or material as i could always paint it.
Click to expand...

This one is all-chrome rather then chrome bumper, but maybe they can customize...
Yair
 
Twas I wot made them cases. I used 3mm ali for top bottom and sides and 1.6mm for front and back. glued to angle to make it square. sounds a bodge but came up pretty well.

email me for a diagram and a supplier for the ali if you're interested

Tim

timhurnell at 0800dial dot com
 
I recall a review by Martin Colloms of some European speakers (can't remember what-sloped baffles), that didn't impress until the designer replaced the aluminium external X/O boxes with MDF.

The L-V OBX's also use MDF for the X/O box.

Naim use plastic.
 
I use solid Sapele timber ...

1674855-lg.jpg


James
 
Originally posted by Mick Seymour
Hi Julian

I know someone on here made a case for something power supplyish (DIY Geddon?) from flat metal and extruded aluminium angles or some such but I can't for the life of me remember who or when. Try a search for DIY Geddon and see what turns up.

Mick
Click to expand...
i suspect it was Jason Hector. He used to make his own PSUs etc with nice shiny cases. Sounded good to.
 
James

Very nice looking crossover. In fact it looks so good I'm going to assume you have more than a good idea of what you're doing.

So, I have a couple of comments and questions.....

I've currently got my crossovers in 3 separate boxes per speaker located behind the speakers. I bought these plastic boxes from Maplin, but am considering going for one larger box per speaker, to be made from wood and to be placed in my equipment rack.

This will mean reversing the arrangement of 3m cable from amp' to crossovers followed by a short run to speakers, to an arrangement of a short run from amp to crossvers followed by a 3m run to the speakers. Do you have any thoughts on the merits or othewise of what I'm considering regarding the placement of the crossovers? The cable I'm currently using from the amp' to speakers is 3 lengths of CAT5 braided per speaker. This makes for a lot of twisted pairs.

I'm also interested in how you've arranged the layout of what look like bobbin type inductors? I have mine with the plastic ends facing upward. Is there any particular reason why you set them up the way you have? There was no reason for how I've arranged mine, I just did them that way.

I'm trying to find out some information about the Audax HD3P piezo electric HF unit. Do you know anything about it? I'm currently using these in the HIFI World KLS3 loudspeaker, but I may change this to the standard tweeter and use the HD3P in an alternative, smaller 2-way design. I'm just not sure of whether this tweeter really does need to be used with a midrange unit or not, it crosses over quite high at over 4.5Khz I believe.

Any help will be appreciated.

Thanks
 
Hi Brian,

"Very nice looking crossover. In fact it looks so good I'm going to assume you have more than a good idea of what you're doing."

Thank you for your kind comments. I think I know what I'm doing most of the time ...

"Do you have any thoughts on the merits or othewise of what I'm considering regarding the placement of the crossovers? The cable I'm currently using from the amp' to speakers is 3 lengths of CAT5 braided per speaker. This makes for a lot of twisted pairs."

The only real consideration is how much reliance on the loudspeaker cable (prior to XO) is placed by the amp. I use Naim amps, and the NACA5 cable I use is part of the design. Placing the XO box closer to the loudspeakers also means a single run of cable per cabinet from the electronics stack.

"I'm also interested in how you've arranged the layout of what look like bobbin type inductors? I have mine with the plastic ends facing upward. Is there any particular reason why you set them up the way you have? There was no reason for how I've arranged mine, I just did them that way."

Inductors are mutually inductive; the degree dependent on their proximity and orientation. In an ideal world, they should be as far apart as possible, but orienting them so that their coils are on different planes 90-degrees from their others helps. The XO layout that you see here has been revised quite extensively (actually rebuilt completely) so that wiring is more point-to-point but the inductors are even closer together, but oriented onto different planes. If you want to relay your XO onto one bigger board, it would be worthwhile working out the best locations for the inductors before committing.

"I'm trying to find out some information about the Audax HD3P piezo electric HF unit. Do you know anything about it?"

No, I'm afraid not.

"I'm currently using these in the HIFI World KLS3 loudspeaker, but I may change this to the standard tweeter and use the HD3P in an alternative, smaller 2-way design. I'm just not sure of whether this tweeter really does need to be used with a midrange unit or not, it crosses over quite high at over 4.5Khz I believe."

If this tweeter is happier crossed in the region of 4.5kHz, then you will be limited to using very small midbass drivers that can reach beyond 10kHz cleanly. Depending on the crossover order, and even allowing for a steep 4th order cross, that is a tall order for any driver being asked to cover 8 octaves (40Hz - 10kHz). I haven't heard the Audaxes, but I'd be surprised it's the end all and be all of tweeters. It doesn't get mentioned much on the DIY forums I frequent, where the likes of Morel MDT33, Scan-speak 9500/9700, Seas Millennium, Vifa XT25 and Hiquphon OWs are the perennial favourites. Most of these operate cleanly down to 500Hz and can be crossed at 2kHz and still reach 25kHz or beyond. In my view, only super-tweeters can justifiably require a cross at 4.5kHz and then they'd better be capable of extending to beyond 40kHz.

A two-way system that is expected to do decent bass is ideally crossed at between 2kHz and 3kHz, whereas a three-way system gives more latitude with 100-500Hz on the lower cross and 2-5kHz for the upper cross.

Hope that helps.

James
 
James

Thanks for that reply.

For interest, I've used a Wilmslow Audio kit that uses the Scanspeak 9500 I believe, in conjunciton with a Volt 8" bass driver. I like Scanspeak, it must be said.

I suspect part of the reason the HD3P may not be mentioned on other sites you visit may be because it's unavailable. I think it was discontinued some time ago, it's just that I already have them in this particular kit design I currently use.

There is a photo and a very small description here.... just scroll down a couple of inches..........HD3P
 
Hi Brian,

I didn't realise the HD3P included its own filter nor did I know it costs nearly 200 Euros each! Must be a very special driver, and sufficiently attractive to little kiddies to have a poke ;)

Do you have the specs to the HD3P and its filtered response? If you do, we may have a slightly better chance at find a suitable midbass driver to go with it for your 2-way. I note it is a 92dB driver, which means you will probably need two or more midbass drivers to deliver the correct sensitivity to match.

James
 
James

I don't have much info about the HD3P, that's why I've been scouring the 'net trying to find out about it. I can't get any replies out of Audax, which was an obvious route I tried a while ago. I'll keep looking around, if I find out anything more I'll make another post.

I have a number of ideas about loudspeakers but I'm miles from being an expert. As I mentioned earlier I've used a Wilmslow kit. Well, the best Wilmslow kit I actually heard but didn't buy was using a 10" bass driver. I think there is an entirely different tone to music coming out of a system using a 10" bass, it just sounds much more realistic to me. What I'd really like to do is convert my current 3-way with an 8" bass to a 3-way with a 10" bass.

Regarding the HD3P in particular, all I know about the HD3P right now is that HIFI World recommended using it in their 3-way KLS3, which I use right now. It does sound very good imo, the midrange is really outstanding using the Audax HM130CO dedicated midrange driver. I put this down to the fact that the crossover frequencies are well outside that critical midrange area. The bass unit is again an Audax, but is the HM210CO 8" driver.

HFW also recommend using the HD3P with an Audax HM170CO in a 9Ltr 2-way design, but this is what I'm wondering about. I'm concerned that it just may not be really ideal for a 2-way with any bass/mid unit given it's high crossover frequency. It may well be that it would need to be a Linn Kan type of loudspeaker that doesn't really go down low, but has very fast, punchy bass instead. The liquid like treble from the HD3P though would be very nice with this I think.

It's all about experimenting really, I like to dabble although I'm not very sure about what I'm doing, but it's a part of learning and that's what I like to do.
 
"I think there is an entirely different tone to music coming out of a system using a 10" bass, it just sounds much more realistic to me"

It's all about moving air really. There is a visceral impact that is denied loudspeakers that agitate air with little cones. For real impact, a gentle but firm stir works much better.

"It may well be that it would need to be a Linn Kan type of loudspeaker that doesn't really go down low, but has very fast, punchy bass instead. The liquid like treble from the HD3P though would be very nice with this I think."

Actually, there is a small handful of 5-inch midbass drivers that can do the job. If you want tight and fast bass in a sealed box, there is really only one - the Scan-speak 15W8530K00 ...

foto_15w_8530k00.jpg


"It's all about experimenting really, I like to dabble although I'm not very sure about what I'm doing, but it's a part of learning and that's what I like to do."

That's a fantastic attitude. But in order to avoid going around in circles, work out what it is you want (your design criteria and deliverables) and then find out what works and what doesn't along the way in the design, construction and tuning stages. DIY loudspeakers is a lot like life, the more you learn the more you realise you don't know ...

James
 
Thanks Mick

When Audax was taken over, all of their products were reduced in quality as the company which took them over decided to make 'improvements in efficiency'. As a part of this improvement, the HD3P was discontinued, imo because it was so expensive, it didn't matter that it was a high performance unit. :(

This 'improvement' in the product range by Audax's new masters made it impossible for HiFi World to continue offering their loudspeaker kits, which all used Audax drive units. Apparently Audax suddenly demanded that a huge number of drive units be purchased by HiFi World for resale purposes, which as a magazine offering kit designs as a bit of side line, they rightly did not wish to do. This is why everything to do with speakers on their website has gone, although it is only recently that it has gone.

I do have some articles about the KLS3 I use, and also about the KLS10, which is their 2-way using the HD3P. These don't include response curves etc, it's only text about the design goals and diagrams of how to build the cabinets if someone wants to build them. I think finding out specifics about this drive unit is going to be very, very difficult. I may try Ivan, because I know that IPL at one point offered a tranmission line kit which utilised the HD3P.
 
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