Isaac_Blanc

Advise needed on compact HiFi componentary for school project

34 posts in this topic

Super Wammer

Make sure that cabinet is very strong and resonance free.

The iPod may fall off too when things get rocking, try to angle it back or support it in a different way.

The drive units look quite revolutionary, unless thats the tweeters in the middle, in which case you need to move them to the outer edge to get the best stereo image, but you could try some of the Full Range units that Cambridge Audio are using.

Looking good. :cool:

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Yes, looking good Isaac. As Mike says, it's a good idea to make the cabinet strong. Another point is that what seems to impress a lot of people (the sort of people you won't find on a hifi forum) from a small box is its bass. To kill two birds with one stone you could make a divider for each speaker so that t has it's own enclosure and this would brace the cabinet more.

You can go one step further and leave a small 'port' in the front on the driver side of the divider so that there's a small gap at the front, to one side of that gap would be the divider and to the other would be a similar divider but shorter so the sound coming from the back of the drive unit goes around the back, turns a corner and comes out of the front. This would provide extra bracing as well. It's hard to describe but I'll try to draw a picture.

In a commercial system the dimensions would have to be modeled for the enclosure size, port length etc. to get the best out of the drive units but those ones http://www.diyaudio.com/forums/full-range/171707-chinese-taiwan-4-dual-cone-speakers.html seem pretty forgiving of different enclosure types and sizes and the front port should help out with bass.

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... something like this

ssa-dcon-10-transmission-line-single-fold.jpg?w=1024&h=787

With the driver on the face that says 9". Whether you angle the internal wall is up to you but without measurements it's a case of guesswork and as much for the looks and a bit extra bass than anything else so use the measurements that fit your plan, I posted that to give you an idea of the basic shape.

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Sorry for taking so long to get back to you two! I've had a lot on recently.

Thanks to both of you for the "looking good" messages. :)

To Mike, about the drivers: that computer-rendering is of an old model from quite a way back in the design process of my product. Since then, I've scrapped the idea of using tweeters altogether and have instead ordered a pair of 4" full-range drivers. That's a very good point though about the iPod falling off the dock. Perhaps I'll find a way to isolate it somewhat from the vibration.

About strength: throughout the project I have been only too aware of the need for strength in the design. As I may have said before, I'll be building it entirely out of Baltic Birch plywood. My current plan is the build the whole thing out of "slices" (see exploded image below) and then perhaps tidy up the whole product with a veneer. Whilst this isn't ideal, its considerably easier and more fool-proof than the alternative options. I just really hope that, with bracing, it'll be strong enough.

Funnily enough, a divider has actually also been part of my design for a while now. However, your idea of incorporating the divider into a port is definitely a new one for me. I'd love for my final product to provide decent bass so, if you think a ported enclosure is the way to achieve this, then I'll go for it.

Explosion%2B02.jpg

NOTE: the silver block towards the back is a dimensionally accurate model of the amp I've bought. The drivers aren't as accurately modelled (because they're more complex) but all of the key dimensions are correct.

Enclosure size, length etc...

I've already ordered my drivers so I'm afraid its too late to buy the ones you suggested. How drastic an effect is the size and shape of the driver's enclosure really going to have on sound quality? Of course, if the answer is "very drastic", then I will learn the necessary maths but if the effect is a very subtle one, then, for the sake of time and my own sanity, I may just build the enclosures to the size and shape that best fit my current design.

Sorry if I've missed stuff out in this reply or if its badly written. As I said, I don't have a whole-lot of time at the moment :-)

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Here's a little model I threw together on Sketchup of a possible enclosure I could build. I tried to base it on what I understood of your example only resized and redesigned slightly to fit my own design. Please ignore the fact that this enclosure ignores the curved ends of my actual design, I simply left them out for speed when modelling this.

Any thoughts on this enclosure design would be greatly appreciated. From experience, I've found that I learn best from trying stuff and then being corrected :-)

Ported.jpg

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Hello Isaac, sorry I've been off radar for a while. As I say those drivers seem pretty forgiving of enclosure types and sizes and being full range helps. Your second drawing is just what I was thinking of in terms of ports but leave a small compartment in the middle for the amp (tripaths run very cool so ventilation shouldn't be an issue) and use the whole depth for all three sections. Your first drawing looks nicer than a rectangular cabinet.

If you look at the small speakers (not the Frugel 3's) made by electricbeach http://www.electricbeachaudio.com/ those have a very thin vent/port at the top/back so you could probably get away with reducing the size of your ports. I'd be guided by what it looks like rather than trying to measure or work anything out for this job.

It might not make much of a difference with anything other than a high powered subwoofer but if you're using slices then I'd seal the inside of the speaker enclosures because the cross grain of ply might have some gaps or voids in it. Some sort of paint would do it.

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Hello all,

Just wondering whether you're still following this thread. There haven't been any replies for quite a while now. Obviously no worries if you've lost interest, I'd just quite like to know. Thank you once again for your help so far!

Isaac :-)

- - - Updated - - -

Sorry, didn't see that there was a second page to this thread! I'm reading your reply now.

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I'm still with you Isaac! Just a thought about securing the ipod, on ebay there are stacks of car adaptors for ipods, why not check those out and modify one, a few of them 'clamp' the ipod in place.

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Hey Steve,

Great to know that I still have your support! I'm very grateful for it.

Following your advice about ported speaker-enclosures, I've made some pretty major changes to my design. To update you on these changes, I'll post some renderings and orthographic diagrams below. I hope they make sense.

COMPUTER RENDERING:

Final%2Bdesign%2B-%2BNo%2Bchamfer.jpg

CROSS-SECTIONAL DIAGRAM OF SPEAKER ENCLOSURES:

Enclosure%2Bdiagram.jpg

A FEW NOTES TO HELP YOU UNDERSTAND THIS DIAGRAM:

1. Everything is 100% accurate as far as scale is concerned however I'm afraid to say that I only had time to add the dimensions that are directly relevant to the speaker enclosures. Obviously, once this diagram is finished, everything will be properly dimensioned and annotated - in the meantime however I only have time to dimension the parts we're discussing.

2. In regards to the lower of the two diagrams (the actual cross-section one), only the shaded parts refer to solid material. The other lines show joins between slices etc... Basically, only pay attention to the shaded areas.

3. All units are in millimetres.

4. Whilst I am most certainly British, my software is American. Therefore 115,5 on the diagram actually means: 115.5

I'd be very interested to hear what you think of my alterations as I've tried to follow your advice. As I assume you've noticed, the amp is placed in a separate enclosure to the drivers with plenty of space for any wiring. Talking of amps, its great to know that my amp won't get too hot! Everything will of course be as air-sealed as possible either with paint or (as I originally planned) some sort of silicone product like this. Whilst I did originally intend my design to feature an iPod dock, I'm now more in favour of a simple mini-jack input as it would make the product a lot more versatile. Nonetheless, thank you for the suggestion. Another development is that I've reduced the number of 'slices' in the design by deciding to use 30mm baltic birch plywood.

Finally, may I just add that you saying, "I'd be guided by what it looks like rather than trying to measure or work anything out for this job" was frickin' music to my ears. I've been worrying about the scary-looking maths often involved with enclosure building and its great to know that I won't need to go into it.

Okay, I think that's all for now. These are my updated designs, admittedly now a lot less aesthetically pleasing than I'd originally envisioned but will hopefully sound great. Besides, perhaps a nice finish or veneer will improve things later down the road. Any comments or further advice on this latest development would be greatly appreciated but is, of course, entirely optional. The way things are looking, I hope to be off the laptop soon and into the workshop.

Once again, sorry if I've missed anything or if this post is badly written. As usual I have a lot on, not much time and, being 15, I'm not the best at time management.

Hope you're well,

Isaac :-)

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Hello Isaac, I'm the same, not a lot of free time at the mo. I'm really impressed by your drawing tools/ability. When I get the chance I'll draw freehand what I think would be better and photograph it, dropbox it etc. If I were you I wouldn't partition the cabinet horizontally like that, I'd rather give the speakers as much space as you can and have three 'vertical' partitions with the amp in the middle on its side.

Depending on whether you'll be controlling the volume with the amp or the ipod then you could make the enclosure so that the rear connections of the amp are exposed at the back and you have a volume control at the front - with maybe a small extension to get it through the front face. I also think those ports could be a lot thinner without having too much effect and this would make more room for your amp in that central compartment. I hope that makes sense?

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No worries about the lack of time. We both know the feeling ;-)

Very well explained advice! I'm pretty sure I understand what you're talking about. If I have the time, I'll try to make some of these changes to my design however my school teacher is starting to nag. Sadly, my design needs to be finalised soon.

Thank you btw for the praise on my drawings :) In case you're interested, I use Autodesk Inventor Professional 2016 to model, assemble and produce drawings & renderings for almost everything I design. As a student, I get Autodesk software for free. Its nothing to do with the school I'm at, nor is the software some only semi-functional 'free trial', Autodesk genuinely offer all of their software, for free, to students. Its taken me a little while to teach myself how to use it but the time sacrifice was definitely worth it. Inventor is pretty much the industry standard when it comes to design and engineering software so being able to use it is very useful when it comes to sharing designs with other people either for collaborative purposes or when sending designs off to be machined.

Sorry for the digression there! In short, I think Autodesk Inventor is really excellent software and definitely worth learning. That said, I still learnt to hand-draw orthographic, isometric, one, two, three point perspective drawings etc before teaching myself how to do it on a computer.

I'll send you some new designs soon. :)

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As I said on WHF Wow looks amazing and I wish you well, In case your interested you could do some drawings for me, I'm putting together some Hypex Amps, I also builds speakers perhaps we could help each other, PM if you are interested, Colin~

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Hello Isaac, blimey that's a nice turn up. I wish you both well.

I've not been around for a while so how is your project doing?

I have access to all sorts of design software at work but I just do the licensing arrangements for things like Autodesk; the learning curve is too high for me and in my spare time I'd rather play my guitar or new (old - 1950's Soviet era) balalaika :)

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Hey Steve,

Wow, I haven't heard from you in a while!

The project is still going, albeit quite slowly. The vast majority of the pre-construction work (designs, documentation etc) is done but it's the tying-up of loose ends that is now taking longer than I would ever have expected. It seems that the more I get done on the project the longer everything takes.

My school teacher is very good but also very strict. He won't allow anyone to start building until all of their design work is completely finished. For this reason, I have yet to start any practical work. That said, all of the componentry has arrived and I will hopefully be building very soon.

Sorry for never sending you those designs btw. In the end, whilst I did like your idea, I just didn't have time for any more changes to the design.

The balalaika looks like a pretty funky instrument. It's nice to know that you're a fellow musician (I play sax). If I may ask, what do you do for a living? Any job involving "all sorts of design software" sounds awesome!

I'll try to keep you posted on how it goes and definitely send you some pictures once it's finished.

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