Phil Starr Posted June 3, 2017 Share Posted June 3, 2017 Thanks Geoff, I have visitors this w/e. I'll have a look on Mon. Quote Link to comment Share on other sites More sharing options...
geoffbyrne Posted June 6, 2017 Share Posted June 6, 2017 (edited) OK, I sat down on a stool in front of the cab with the grill removed & had a right good listen. The 'flutter' was coming from the piezo unit. I disconnected it & screwed it back on, but the sound was still there - coming *through* the slots in it - it's not a sealed unit!. I removed it leaving a 75mm diameter hole. No flutter. Any suggestions for a sealed replacement would be welcome, or, alternatively, the best way to seal up the hole that's left. G. Edited June 6, 2017 by geoffbyrne Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted June 6, 2017 Share Posted June 6, 2017 (edited) [quote name='geoffbyrne' timestamp='1496750612' post='3313591'] OK, I sat down on a stool in front of the cab with the grill removed & had a right good listen. The 'flutter' was coming from the piezo unit. I disconnected it & screwed it back on, but the sound was still there - coming *through* the slots in it - it's not a sealed unit!. I removed it leaving a 75mm diameter hole. No flutter. Any suggestions for a sealed replacement would be welcome, or, alternatively, the best way to seal up the hole that's left. G. [/quote]i am sure Stevie will comment later. But the tweeter from the original MK2 design was pretty good and not too expensive. From Stevie's post "The first HF unit we will be working with is the P. Audio PHT-407, available in the UK from Blue Aran for a very reasonable £13. Don’t be put off by the price; it’s a quality unit." I will let Stevie comment on crossover arrangements. Edited June 6, 2017 by Chienmortbb Quote Link to comment Share on other sites More sharing options...
Phil Starr Posted June 6, 2017 Share Posted June 6, 2017 Glad you've tracked the fault down. Piezo horns are really cheap, as little as £1.00 https://www.bluearan.co.uk/index.php?browsemode=category&category=Speaker_Components&masthead=High_Frequency_Drivers&subheadnew=Piezo_Tweeters The easiest way to seal the hole is to cut a square of ply, or any wood you have to hand, slightly bigger than the hole. Then simply glue it on the back of the hole. You may be able to seal the old horn though with a generous dollop of decorators mastic or even silicone sealant. Use neutral cure silicone though as the fumes from the acid cured silicone (acetic acid, smells of vinegar) aren't too good for speakers. using Stevie's design for horn and crossover will upgrade you speaker though, it's a nice painless project and I can say the results do sound nice. Quote Link to comment Share on other sites More sharing options...
geoffbyrne Posted June 6, 2017 Share Posted June 6, 2017 (edited) Just ordered the P. Audio PHT-407, seeing it's the same diameter hole. Just got to find the crossover info now.... OMG I've just found the info & diagrammes. I'm afraid all that is just so much gobbledegook to me. G. Edited June 6, 2017 by geoffbyrne Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 8, 2017 Share Posted June 8, 2017 Geoff, I could probably help you with the crossover - either build it for you or just offer assistance. Anyone put a parts list together with suppliers for the xover bits? Richard Quote Link to comment Share on other sites More sharing options...
geoffbyrne Posted June 8, 2017 Share Posted June 8, 2017 Diagrams on Page 6, Richard. Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 9, 2017 Share Posted June 9, 2017 (edited) Yes, I have seen the diagrams - there's a better laid out one on the first page as one of the PDFs for download - in fact if you look at that you might feel more confident in building it, as it's properly laid out. I was just wondering if the gurus of this thread had a component list from a particular supplier put together (rather than me stumbling round RS/CPC/eBay/other audio component suppliers, as that would be helpful for anyone wanting to assemble the crossover. EDIT - apologies, I was thinking back to the rough drawings. The ones on page 6 are different from the PDFs that are in the first post - can we get clarity on which are the most up to date versions please? The ones on P6 have additionals coils compared with the PDFs. Edited June 9, 2017 by RichardH Quote Link to comment Share on other sites More sharing options...
stevie Posted June 9, 2017 Author Share Posted June 9, 2017 The drawing you need is the crossover for the Beyma SM212 and the P Audio 407 tweeter, which is attached to post # 1 of this thread. I did try to add the more complex crossover (for the Celestion compression driver) in the same place, but there seems to be a limit to the number of PDFs you can attach to one post. You can get all the parts from Blue Aran, although I doubt they will have every value in stock. If you have problems, send me a message and I'll see if I can put together a package with all the components for you. For the tag strip, look up "solder tag terminal strip" on eBay. The current link, which may change over time, is: http://www.ebay.co.uk/itm/2-x-36-way-Solder-Tag-Terminal-Strip-on-Paxolin-Bakolite-Board-2-Strip-/132211098217?hash=item1ec8654269:g:MvgAAOSwBLlVfzCU Just as a matter of interest, I did originally design a simple crossover with just a few components on the tweeter and nothing on the bass unit, which is the de facto configuration on most commercial cabs. However, the slighly more complex version with a few components on the bass unit sounded so much better that I didn't even bother mentioning it in the thread. Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 9, 2017 Share Posted June 9, 2017 Ahh - so the circuit on P6 is the one for the compression driver - I see. Maybe edit the first post and add the image inline if you can't do an extra PDF - or maybe just edit the crossover PDF to have all crossover stuff in it, labelled to specify which drivers it is for. Didn't think of looking at Blue Aran for components - since they do complete crossovers I assumed they wouldn't bother! Will check it out. I have access to some turrets and board, so may be able to knock up something on that. Geoff - I will have a poke around at the weekend and see what the component cost comes out at, and then we can take it from there. Quote Link to comment Share on other sites More sharing options...
geoffbyrne Posted June 9, 2017 Share Posted June 9, 2017 OKDKY!! G. Quote Link to comment Share on other sites More sharing options...
stevie Posted June 9, 2017 Author Share Posted June 9, 2017 I'll see what I can do, Richard. The crossover information for the first version of the speaker is on page 4. Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 9, 2017 Share Posted June 9, 2017 ...which looks to be the same as per the PDF on P1 - coolio. Seems like a good idea to try and get the definitive version of everything in one place at the start of the thread. Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 10, 2017 Share Posted June 10, 2017 Unfortunately Blue Aran don't list 0.6mH or 0.17mH air core inductors on their site. Closest is a [url=http://www.bluearan.co.uk/index.php?id=MON124860&browsemode=category]0.56mH[/url] and a [url=http://www.bluearan.co.uk/index.php?id=MON124800&browsemode=category].18mH[/url]. Europe Audio (now branded as Loudspeakerfreaks) do them - [url=https://loudspeakerfreaks.com/Product.asp?Product_ID=9630]0.6mH[/url] - though the only 0.17mH is a [url=https://loudspeakerfreaks.com/Product.asp?mfr=Jantzen%20Audio&part=000-1049&Product_ID=9777]chunky 1.2mm wire version[/url] - a lot more choice at [url=https://loudspeakerfreaks.com/Product.asp?mfr=Jantzen%20Audio&part=000-1421&Product_ID=9293]0.18mH[/url]. I don't know enough to know if that is close enough - I guess you could buy a .18 and remove some of the coil to get down to .17, but not sure how much wire that would be. Actually we could do the same with Blue Aran stuff - buy a size higher and remove, so long as we know how much to take off. Europe Audio are based in The Netherlands - I'd had stuff from them before and they are good with shipping etc, but it's hardly worth buying one crossover's worth of bits from them - though it might be as cheap in the end as buying from Blue Aran as their prices are higher for the coils anyway. Quote Link to comment Share on other sites More sharing options...
LukeFRC Posted June 10, 2017 Share Posted June 10, 2017 Hello - I've been out the loop for a bit but keeping track of this mk2 version - It looks good. Are we at a point where there if I asked there is a definitive "this is the design" way of recommended building? One of the things with the MK 1 is that to build the thing you would have to read through pages of posts looking for the sizes etc and then read a few pages later that there was still discussion about tuning and size of ply. If there is a near definitive design and it would help then it would be great to help by pulling together a single PDF of how to build it. If Stevie or whomever bung me a PM if you'd like to do that. Of course the complication I guess is over things like 12mm vs 18mm ply and the like and the various pluses and minus of both with the different proponents of each - ideally there would be one design... Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 10, 2017 Share Posted June 10, 2017 The PDFs on the first post do give this info - the assumption is 15mm ply, and they include a cutlist. The diagrams are pretty clear as to how the pieces go together, though I am sure a step by step guide would be of help to less experienced builders. Quote Link to comment Share on other sites More sharing options...
stevie Posted June 10, 2017 Author Share Posted June 10, 2017 I've attached a PDF to post #1 showing the crossovers for both versions of this speaker. I am about to assemble my own version of this box (500W neo driver with expensive 1" horn) and will try to make a photo record of each stage of assembly. I don't think this cab is difficult for anyone with basic woodworking skills to assemble, but a step-by-step guide might help. Richard, if you would care to take some photos of the crossover you assemble, that might help, as I suspect building the crossover is more of a challenge to many people than building the box. Quote Link to comment Share on other sites More sharing options...
stevie Posted June 10, 2017 Author Share Posted June 10, 2017 (edited) Luke, the two designs for the Mk II are complete. There is a low cost version with a tweeter and a more advanced version with a compression driver. They both use the same cab, but that's it. Chienmortbb assembled the more advanced version and I measured it to make sure everything worked as intended. When I have time, I'll try to post some building guides in post #1 - but everything you need should be contained in the thread. If not, please ask. The cab is based on the use of 15mm poplar ply, which I thought would provide the optimum balance of light weight and strength, and this has indeed proved to be the case. There is, of course, nothing to stop you using another material, but if you want a proven lightweight design that will outperform 90% of equivalent commercial cabinets, go for the poplar ply and compression driver. Edited June 10, 2017 by stevie Quote Link to comment Share on other sites More sharing options...
Chienmortbb Posted June 10, 2017 Share Posted June 10, 2017 Luke the latest drawings can be used for the MK1 or MK2. Just leave out the HF unit home and that is a MK1 on a different shape. I would suggest you use the big port though and don't stand in front of it. It is amazing how much air comes out of that port. Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 11, 2017 Share Posted June 11, 2017 (edited) Right, before I can do anything re a crossover, we will need to find a source for the correct values of inductor. The only 0.17mH inductor I have found is a beast with 1.2mm diameter wire. Also, the PDF doesn't specify if it's an air wound coil - I assume so. Without being able to accurately measure the effect of removing wire from a 0.18mH inductor, I think we will need to get two to make up the value - a 0.8 and a 0.9. The only place I am finding a decent selection of parts is Europe Audio (now branded as Loudspeakerfreaks) - or hificollective, though they don't keep stock. If there is interest, I might be up for buying in components for (say) 3 crossovers worth of parts.... but I don't want to end up carrying heaps of stuff that nobody is interested in. Alternatively, if there is somewhere in the UK (as I said above, Blue Aran don't list anything like the required values on their site) that can be used to supply the parts, then it would be helpful to potential builders if someone could provide links and part numbers. EDIT - actually, [url="http://www.falconacoustics.co.uk/audio-inductors-ferrite-air-core-iron-dust/ac071-high-power-air-core-up-to-0-20mh-audio-inductor.html"]Falcon Acoustics[/url] might be the way to go for inductors - but they only offer up to 0.5mH. Edited June 11, 2017 by RichardH Quote Link to comment Share on other sites More sharing options...
Beer of the Bass Posted June 11, 2017 Share Posted June 11, 2017 How tight is the tolerance on a typical inductor? Is the difference between 0.56 and 0.6, or 0.17 and 0.18mH all that critical in this application? Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 11, 2017 Share Posted June 11, 2017 I was just wondering the same thing - 0.17 to 0.18 is only around 5% anyway... Quote Link to comment Share on other sites More sharing options...
RichardH Posted June 11, 2017 Share Posted June 11, 2017 (edited) ...sorry to whiffle on. Re-reading the thread, when discussing the port: [quote name='stevie' timestamp='1486548855' post='3232603'] They're called flared ports, MoonBass. I have a selection of them here, including some very nice Precision Ports 4" ones. Unfortunately, availability is a bit of a problem in the UK, but they do work really well. I considered using the Precisions, but their external diameter is about 18cm and there wasn't enough room on the baffle. Also, a single flared 4" port wasn't going to be long enough to tune the cab to the target frequency. The performance of the 5" we are using is equivalent to a flared 4" port. The ideal would be a 5" flared port on the back of the cab, but nobody makes one. [/quote] ...at the time of this decision, am I correct in thinking that the cab tuning was expected to be 40Hz, but in the end you went with closer to 50Hz? Does this mean that actually one of the 4" flared ports WOULD be long enough to get the desired tuning (by my calcs it would need to be just under 4")? Though I guess you would still have the issue of baffle space. Edited June 11, 2017 by RichardH Quote Link to comment Share on other sites More sharing options...
stevie Posted June 11, 2017 Author Share Posted June 11, 2017 The .56 and .18mH coils are close enough, but don't waste money on thick wire for the .17mH. - 7mm or thereabouts is fine. All the coils are air cored. Quote Link to comment Share on other sites More sharing options...
stevie Posted June 11, 2017 Author Share Posted June 11, 2017 The port tuning was always going to be 50Hz. Quote Link to comment Share on other sites More sharing options...
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