zog Posted January 23, 2015 Share Posted January 23, 2015 Tried using the calculators to give me an enclosure volume, but not having much luck I'm afraid. Any advice? I found the specs on the jaycar website for the driver, but most of the calculators only give me a bunch of frequencies and ask me to specify the enclosure volume myself.. I'll confess I haven't used the online calculators much, I've used WinISD (free for download windows app). Which Jaycar driver is it? It looks like an AS3032? I just had a bash at using that calculator I provided the link for and it wasn't that good, sorry! I'll give it a bash in WinISD. Link to comment Share on other sites More sharing options...
Janus77 Posted January 23, 2015 Author Share Posted January 23, 2015 I'll confess I haven't used the online calculators much, I've used WinISD (free for download windows app). Which Jaycar driver is it? It looks like an AS3032? I just had a bash at using that calculator I provided the link for and it wasn't that good, sorry! I'll give it a bash in WinISD. Yup 3032 Link to comment Share on other sites More sharing options...
Dave Tomic Henry Posted January 24, 2015 Share Posted January 24, 2015 I've put a set of these together (sort of) - I found some lovely cabinets on line for cheap and slapped the driver in. Super simple. Very cheap. And I was blown away by the sound that the little things could achieve. http://www.markaudio.com/Plans/itemlist/category/15-CHP-70-Natural Slim Line Bass Reflex Box Driver can be sourced here (and they're on sale $89 for a pair including binding posts!!) http://av.darcher.com.au/index.php?route=product/product&product_id=173 2 Link to comment Share on other sites More sharing options...
TMM Posted January 24, 2015 Share Posted January 24, 2015 If you want a 'proper' amp for next to nothing, there was a stereo amplifier sold by Dick Smith about 5-6 years ago which can be modified into a reasonably high performance amplifier (as good as anything under $1000) http://tinyurl.com/kjhvlh9 - the article is probably a little technical for a 'building kits' level hobbiest (sorry about that!) I see them go for $50-100 every now and then on ebay and gumtree. Link to comment Share on other sites More sharing options...
zog Posted January 24, 2015 Share Posted January 24, 2015 Yup 3032 I just had a play with the free "WinISD" package.. it wouldn’t let me make a sealed box - threatened to crash but this could be a bug in WiniSD... so, if I was knocking up a quick box for this I'd try.... For AS3032 try 1.5 one litre volume enclosure (e.g. 10cm x 10cm x 15cm per side or slightly greater, to take into account volume of the driver). With 3cm diameter port length about 7 cm (to tune at about 120hz). From messing about with winISD this has not much response at all under 100hz, but a slight boost from 100hz-500hz. But then the driver doesn’t have much response under 100hz. This could be mocked up with some stiff cardboard braced with gaffa tape or similar, even, I reckon, advantage of a small speaker. Graph below is the "transfer function" of the 1.5L box with one 3cm diameter, 7.6 cm port.. Link to comment Share on other sites More sharing options...
TMM Posted January 24, 2015 Share Posted January 24, 2015 (edited) The Q of the 2" driver is way too high for a ported enclosure - that's why you just get a massive sharp peak at the tuning frequency instead of a nice wide boost. Also if you use a ported box with such a high tuning frequency for a full range speaker you will need to add a highpass filter just below the tuning frequency otherwise it will unload hard when it tries to play bass notes below the tuning frequency. 1-2L sealed would be my recommendation for those drivers and just live with them not having any bass unless you use them at a very low volume and add an electronic bass boost. The 3" driver (AS3034) is a much better choice for a full range system. Cone area is doubled, excursion is doubled, resonant frequency is more than halved. However even with those you will not be able to achieve decent low end output without them being driven into serious distortion. If you place them up against a wall or in a corner you can drastically improve the bass quantity but at the expense of midrange and treble flatness. They will sound the best placed in sealed boxes on stands and with a Baffle compensation network however will only go as loud as their excursion allows. FWIW I have 3" full range speakers in small sealed enclosures on stands, with BSC networks, and adding an 8" subwoofer crossed at 130Hz was an enormous improvement. Edited January 24, 2015 by TMM Link to comment Share on other sites More sharing options...
zog Posted January 24, 2015 Share Posted January 24, 2015 The Q of the 2" driver is way too high for a ported enclosure - that's why you just get a massive sharp peak at the tuning frequency instead of a nice wide boost. Also if you use a ported box with such a high tuning frequency for a full range speaker you will need to add a highpass filter just below the tuning frequency otherwise it will unload hard when it tries to play bass notes below the tuning frequency. 1-2L sealed would be my recommendation for those drivers and just live with them not having any bass unless you use them at a very low volume and add an electronic bass boost.OK thanks, happy to stand corrected! Link to comment Share on other sites More sharing options...
Janus77 Posted January 24, 2015 Author Share Posted January 24, 2015 Thanks very much for the help and advice, I was thinking maybe I make a box where the base of the box is cut to sit flush in the box, then I can slide the base in and out to get different volumes, would this be a decent idea? Link to comment Share on other sites More sharing options...
Janus77 Posted January 24, 2015 Author Share Posted January 24, 2015 Do the dimensions odd the box make much difference, or is volume just volume? Link to comment Share on other sites More sharing options...
henry218 Posted January 24, 2015 Share Posted January 24, 2015 Do the dimensions odd the box make much difference, or is volume just volume? baffle size make the differences, but yes in general volume is volume. make sure you have enough space for the woofer to breathe. Link to comment Share on other sites More sharing options...
TMM Posted January 25, 2015 Share Posted January 25, 2015 Thanks very much for the help and advice, I was thinking maybe I make a box where the base of the box is cut to sit flush in the box, then I can slide the base in and out to get different volumes, would this be a decent idea? While it's a novel idea, it might be difficult to implement well. There isn't a huge difference in response from 1 to 2 litres anyway. You'd need a way of solidly clamping the base into position and not cause any air leaks. If there is even the slightest gap it effectively becomes a ported box. A small gap will result in a low tuning frequency (<50Hz) which won't do anything overly detrimental to the frequency response but it can cause an audible chuffing/buzzing noise. As above, making the baffle (front face) of the box as large as possible has the benefit of lessening baffle diffraction effects. There is also some merit to making the inside dimensions of the enclsure ratios of an irrational number such as the Golden Ratio (shown below). This ensures that the frequencies which enclosure resonances occur at don't all pile on top of each other. Link to comment Share on other sites More sharing options...
Beyer guy Posted January 25, 2015 Share Posted January 25, 2015 Have a look at Jim's Audio on eBay - excellent service, good quality parts and also they respond to emails quickly and also give advice after the sale if you run into trouble - saying that you do need to start with some knowledge so a few small amp builds wouldn't go amiss - many are 'ahem' based on some more famous designs (for example the CRC power supply board I used is called the FTRST Watt :-) - they can (and do from my direct experience) compete with commercial amps up in the silly money many 000's if built well and with a good power supply - you need to learn a bit about grounding and layout to achieve this also. Link to comment Share on other sites More sharing options...
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