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Old 7th July 2003, 09:53 AM   #11
StuartH is offline StuartH  South Africa
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Hi Pierre

Looks like you have already had the run around. Personally I have only just ventured into HiFi DIY audio. Up to now my main interest has been PA. From a PA perspective the suppliers in SA are extremely good and their prices are not at all bad. They have also been extremely helpful, by providing speaker specs etc. It really is disappointing that "companies" can get away with such mediocre service. Unfortunately it seems to be an industry wide phenomenon. The company I work for has now started to source a lot of our components internationally, simply because the local suppliers refuse to carry stock and demand really inflated prices.

Back to speakers: I have found a supplier of no name brand speakers, which incidentally look a hell of a lot like really expensive branded products. Im going to give them a try. At R250 a piece one can hardly go wrong even if they are junk. At any rate they will do fine for experimentation.

In ordering from overseas, do you buy directly from the manufacturers, or from a buying house, and if so which one?

You say you are final year at stellenbosch. How is it going? I finished about 4 years ago from RAU. Man, do I miss the student life.

Cheers, Stuart
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Old 7th July 2003, 10:33 AM   #12
PWatts is offline PWatts  South Africa
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Stuart,
The cheap company I think you're talking about is Scotronics...am I correct? A professor of mine bought some of their 6" kevlar drivers at R160 each. I haven't yet had a chance to play with them too much, but they seem to be OK. Their tweeters are utter junk though, especially considering you can get quality Vifa tweeters for as little as $10 overseas). Their subwoofers seems to be neat, until you look at their T/S parameters. To get the same perfomance as a $110 12" subwoofer in a 90l enclosure, you have to use 2 of their 15" drivers in a 400l enclosure (about the size of a washing machine).

None of them a touch on Scan-Speak though, and at R650 for a highly respectable 6.5" (used in the ProAc Response 3.5 which went for $30 000 until it was replaced by the 3.8), I'd rather pay a little more. One doesn't use hundreds of speakers, so I'd prefer to have decent ones if I'm going through all the trouble of designing, tweaking, building and obtaining parts. The project I'm working on now uses 2x 8543s (6.5" polypropylene) and a 9500 tweeter in an MTM configuration, with an 8552 (8" treated paper) in a floorstander. The 6.5"ers are sealed for fast, tight bass and the 8552 ported to make up for some bottom-end oomph. This is IMO the best way to maintain speed. The lower 3 octaves can always be filled with an active sub later on... I believe that bass is only truly omnidirectional at <40Hz.

I've bought a lot of my components straight off the manufacturers. Just say you are a small niche-market company (invent a nice name). Living in a country they know little of can actually be used to your advantage. Some of them only asks me to pay for shipping, others even ship for free! If you badly want something you can always throw a "historically disadvantaged" line... does wonders particularly with Scandinavian & Dutch manufacturers. Even if you get the stuff for free and only have to pay for shipping (which was almost R600 once for 2 caps & 2 coils), the beauty is that the value is stated as $0- i.e. customs just let it pass through. What I normally do with speaker drivers is I have them mailed to a relative/friend in the same country, or close nearby. He then unwraps it, "damage" it a little (reversible of course), remove the sticker with name & model number, re-wraps it and surface-mail it personally to me. Customs rarely charge parcels not from a company. If they do, you just tune them that it's a used product a relative asked you to repair or crap like that. If they still insist on payment, give them a value of a cheap Pro-Audio/Car Audio driver (even though it may be a $700 Scan-Speak slit-paper driver!), and pay WAY less than it's worth.

Sneaky, perhaps, but the only way for DIY can survive. I cannot afford the normal routes, and I doubt many others in SA can. The best place to shop in the US is PartsExpress. They stock all the major brands for Pro, home and car audio (except SEAS), plus any other accessory you may need. In the UK I've found AudioCom International to be quite good, especially for crossover components. Germany is exceptional with Intertechnik and Schuro. Holland's Speaker&Co is also not bad, provided you van read Dutch & German.

I was in my final (4th year), but the last exam results have practically extended it to a 5-year course. Actually a blessing in disguise, it gives me an extra year of access to topclass spectrum analyzers, anechoic chambers etc. Now that I think of it: If you were at RAU, is your 1st language Afrikaans?
Pierre
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Old 7th July 2003, 10:48 AM   #13
Shaun is offline Shaun  South Africa
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Default Anechoic chambers.. Heerlik!!

Pierre

Do you have the facility to calibrate measurement mics?

BTW I got very good results using the 8" paper driver from Scotronics. Was matched with a Philips tweeter culled from an old Philips 3-way speaker.

I also have their 6-inch "Kevlar". Fair sound quality in my so-far unfinished 2-way. But I also heard the pair McCully Music built with this unit, and it sounded good. Heard it in their studio in Cape Town.
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Old 7th July 2003, 10:51 AM   #14
PWatts is offline PWatts  South Africa
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Not in that sense though, but the electromagnetics room is fairly close to being totally inert. Then it's fairly easy to calibrate with a jig and software such as Speaker Workshop.
Pierre
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Old 7th July 2003, 11:48 AM   #15
StuartH is offline StuartH  South Africa
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No 1st language is English, although I do speak Afrkaans.

The company Im talking about is known as Mr Speaker, and basically runs from a garage. They mainly supply PA speakers and perform speaker repair. I took a pair of 150W PA drivers to them which a mate of mine had powered with a 400W RMS amp. Ouch! They were anihilated! Now they sound better than they did when new. The speaker I am after looks exactly like a 15cm SEAS Excel! Carbon copy: Makes one think?

The plan is to build a pair of small 2-way bookshelf speakers, no idea what to build yet. Im still busy mucking around with gainclones. Awesome fun!

At a later date Id like to start work on a pair of Ariel's. I have had a lot of woodworking experience over the years, and access to a fairly good woodworking shop. This will be the spare no expense project.

Thanks for the contacts. Unfortunately my works firewall will not allow me access to Partsexpress. Having a look at the others now.

Stuart
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Old 7th July 2003, 02:41 PM   #16
Shaun is offline Shaun  South Africa
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Default FYI

The company that makes the Scotronics drivers is Infinity Dynamic, and they are based in Durban. A comment made by the then Scotronics rep is that the manufacturer would not commit to T/S parameters, as this allows them to chop-and-change parts according to availablility. I don't know if this still holds true, but the lesson here is to measure first.

Regards
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Old 7th July 2003, 06:32 PM   #17
PWatts is offline PWatts  South Africa
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Shaun,
I have borrowed my professor's Scotronics drivers. Given the price the woofers are OK, the tweeters remain crap. However, I'd still not use them as the price of the cabinet materials, connectors, coils, caps, connectors etc. will far outprice the drivers. The kevlar woofers I have's cones are much heavier than my B&W CDM-7's or the Scan-Speak 18W-8554. They also distort much quicker than other drivers, and have much lower xmax. All in all I still think it's wise to invest a little more for some proper drivers, tweeters at least.
Pierre
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Old 8th July 2003, 10:22 AM   #18
Shaun is offline Shaun  South Africa
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Default Pierre, I agree

I think these are more "practise" units, and your comment about cost of materials is right on the mark.

I also doubt that the cone material is real kevlar. I do think that the mid-bass drivers are far better than the the tweeters, which are the generic kind you can find almost anywhere; probably not made by Infinity Dynamic.
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Old 8th July 2003, 06:24 PM   #19
JDeV is offline JDeV  South Africa
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Default Hi SA guys

I am also a SA hi-fi enthusiast "wannabe" - Cape Town. So far I tried my hands to some Pass Labs projects, the by now - well known "Gainclone" and some valve amps. My next project is to try and build some reasonable speakers. I listened to a pair of Klipsch KG4.5 speakers a while ago, and just love the combination with my valve amps. My idea is now to clone this design and see what appears (and how long it will live ). I also just got some prices from Mr. Foglar - tooooo expensive - on the Vifa woofers. I also see TVAudio is now in partnership , or something, with SkyTronic of the UK. They still do the SEAS drivers and abit more now, but am sure at abit more price as well. I had a look at the PartsExpress stuff, seems to be quit reasonable priced. How much could I expect to pay on customs and postage more or less? I would like to order some 10" woofers, if it is not to heavy $$$

Can anybody suggest to me which Vifa 10" woofers are the better ones and I also would like some suggestions for good , not too expensive - compression horn drivers.

Thanx to all.
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Old 8th July 2003, 08:00 PM   #20
PWatts is offline PWatts  South Africa
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JDev,
Welcome to the world of speakerbuilding in a 3rd world country! Soon you'll realize what a frustration it can be. I can give you a few tips that I've learned on the hard way though.

1) Try building a design that has been built before. At least use a driver combination that has been proved to work. For example: a certain Scan-Speak woofer & tweeter, though in the same price bracket and from the same company, just would not integrate. I thought it was just my fault but after numerous crossovers (even active ones), I read on the Net somewhere they're not very compatible. They simulated flawlessly. Overseas you can just buy a new driver, here it's not so easy.

2) Keep the crossover simple. The problem with this is, this only works with certain drivers. Once again it is better to buy quality components (for example a tweeter with fs < 1kHz), as they're usually better suited with low-order crossovers. Little use to save on the drivers and having to spend a fortune on a complex crossover.

3) Try to steer clear of difficult cone materials such as magnesium, aluminium, kevlar and carbon fiber. They need complex correction networks to compensate for cone breakup etc. The best choices are still good ol' papercone (and all its treated varieties) and polypropylene.

4) Try to use a tweeter that uses ferrofluid. Expensive tweeters doesn't use it (like the Scan-Speak D2904/990000), but at the expense of a less flat SPL & impedance curve, requiring yet more correction networks. 1" tweeters are generally easier to work with, and fabric-dome models tend to be more forgiving of crossover imperfections than metal domes.

4) Buy at least the coils commercially. I used to turn my own coils, but have long since stopped. Why? Because 1 coil had to have almost 12 more turns than the other to measure the same inductance, causing DCR inbalances. Furthermore, homemade coils' DCR is almost always higher than commercial copper foil ones. You cannot use cheap coils to experiment and then buy good ones, as their DCR will differ, and it often isn't just a matter of padding.

5) Keep the prototype crossovers external, and make them easy to add other components while listening for immediate A/B changes. Even if you follow a documented article word-for-word, you often still have to tweak the crossover to suit your amp, source, room, filter components and taste.

6) Once again, if you are going to go through the trouble of importing, rather spend more for quality drivers. The crapload of cash you're going to pay for shipping & customs will usually dwarf the difference between Vifa & Scan-Speak/Focal/Seas drivers. The taxes have changed last year, but a rough estimate would be around 20% import tax and 14% VAT. Shipping obviously depends on the country, weight & method, but for normal non-priority surface mail you can be sure of at least $60 for a pair of tweeters. The woofers will be considerably more. That's why it's wise to use the method of relative/friend overseas to bypass both the shipping & taxes.

I'd recommend you buy your woofers from Foglar (the cheap old stock they have) and just import the tweeters. In fact that is what I'm doing at the moment for a stereo pair and centre speaker, amounting to 6x 6.5" S-S woofers from Foglar and 3x imported S-S tweeters. I can make you a deal: I'll help you with your speakers (design methods, driver sourcing etc., I can even try getting you some drivers free of Shipping&customs) if you can help me with a badass tube preamp. I just don't have the time to do all the research on tube design.

Regards,
Pierre
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