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Deep End DIY - My first speaker project


acg

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Mate, why try to blend them in. You think you can hide them?

Make them the feature they deserve to be.

 

Glossy and bright!

 

You are probably right @@joz.  Although if I am not happy with matt black it would be easy enough to spray some gloss over the top. 

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I purchased some steel today so that hopefully I can make my lathe tool this weekend, family permitting.

 

post-139669-0-16725900-1423023317_thumb.

 

Pretty sure I annoyed the guys at the steel shop with 300mm of this one and 120mm of that one and so on and so forth.

 

 

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  • 1 month later...

How's the project coming along Anthony?

 

Pretty well thanks Simon.  I have been building a duplicator tool and a reinforced outboard turning table along with some lathe modifications the past month or so.  About five full days spent getting this right, including three days on the duplicator tool itself.  At present I am waiting on a slot drill to turn up so I can finalise the duplicator tool and then I will start turning straight away.  Assuming Australia Post gets the slot drill to me this week (been waiting two weeks already - apparently Sydney is on the other side of the planet) I reckon I will make some dust this weekend.

 

post-139669-0-22534500-1425856024_thumb.

 

I painted the tool satin black.  All I have left to do before turning can commence is to cut down the cutting tool end (12mm key steel) so that the carbide cutter matches the lathe turning-centre (I need the slot drill for this) and then shape the bottom plates so that I get unimpeded movement on the horn profile that will be screwed to the outboard table.

 

With the table itself I will fill the countersunk screw holes and then permanently mark the lathe centre and some offsets (already marked up in pencil - need a white permanent marker to finish the job) so that I can easily place the cutting profiles.

 

Cheers,

 

Anthony 

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So you will attach the horn to the chuck at the top of the yellow section. The table will have the stencil placed on the correct spot and then the tool used to trace and carve the horns accurately? I guess you will need a different tool and table height when it comes to turning those bass horn monsters?

 

Love your work Anthony.

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So you will attach the horn to the chuck at the top of the yellow section. The table will have the stencil placed on the correct spot and then the tool used to trace and carve the horns accurately? I guess you will need a different tool and table height when it comes to turning those bass horn monsters?

 

Love your work Anthony.

 

First of all an MDF "adapter plate" is screwed to an aluminium faceplate (not a chuck) which is screwed onto the outboard side of the lathe and then turned into a perfect circle and then trimmed to a thickness to make best use of the screws used to mount the horn to the adapter plate.  The idea of the adapter plate is so that I can cut the entire throat of the horn out without worrying about about hitting the aluminium faceplate or metal screws with the cutting tool.  You are right about using the duplicator tool to accurately trace the horn stencil.  The picture below will give you a better idea than my abuse of the English language I just subjected you to: note from bottom to top is the aluminium adapter plate then MDF Adapter Plate and then the Midrange Horn.

 

post-139669-0-64580900-1425899814_thumb.

 

At this stage I plan to turn about half of the big Upperbass Horn with the current setup and then make a judgement call about whether it is safe to carry on in the same manner but with a lower table and a taller upright section for the tool.  I will mount two sealed bearings or roller wheels to the end of the lathe table and use them as a support for the 1m long turning and if I deem it necessary I can mount a different cutting tool on the duplicator tool.  This different tool is in fact a grinder that runs a 100mm carving wheel.  I can then turn the big horn by hand while the grinder churns away at the wood and running against the stencil.

 

That is the idea.  We will see how it all goes.

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So, out of the blue something happened last night that in my wildest dreams I never thought could happen.  I found a pair of very nice but very unobtainable bass drivers for a bargain price on ebay and I snapped them up without hesitation.  

 

Now I have to seriously think about my overall bass solution...perhaps, now that I have acquired this driver I "need" another bass horn from 40Hz to 100Hz...that would make six channels...at least four of them horns...maybe five horns if I go tapped horn below 40Hz (may be able to fit it in the floor like Paul Spencer has managed).  I think an exponential profile would be best in that 40Hz to 100Hz range, and I would have to seriously consider some sort of delay, funky horn positioning or even DSP to get the bass right within the room...[start Yoda voice - hand on chin] lots of thinking to do I have [end Yoda voice].

 

Exciting...funny how one little eBay search has opened up a whole new avenue of thought.

 

I welcome any thoughts on designing a 40Hz horn, sub 40Hz tapped horn or methods of analogue or digital line level delay.

 

Cheers,

 

Anthony

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Quick fire thoughts.

 

  • DSP (delay) isn't a big deal to have in your system.    It makes the system design a whole bunch easier, and lets you achieve better results (understatement).... but the good thing about electronic components is that its possible to switch them in and out of the system at the press of a button if you like ...... so it is much easier to work out for sure if they are harming the sonics.     IMHO any DSP which is inherently audible (I mean aside from what you're asking it to change) is "faulty".

 

  • A 40hz to 100hz FLH is very big if you're prepared to take some ripples.    If you want a 'properly' sized mouth, then the horn is enormous.
  • Filters in this range (40 or 100hz) are quite impractical with passive components, so I assume you're talking about some type of active crossover and multi-amping?
  • One luxury of a channel only running up to 100hz  (assuming a reasonable slope LPF) is you can place this channel anywhere in the room
  • Which driver do you have coming?     How will you go about designing a horn for it? ....  what about building that horn?

 

  • A tapped horn which can reach below 40hz is also enormous.... but can be made a lot smaller than a FLH.    Although with the luxury of (I assume) not being limited to a pre-determined driver.... then you can choose an already hatched TH or FLH design (there are quite a few) and get that built to spec.   Easy.
Edited by davewantsmoore
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Quick fire thoughts.

 

  • DSP (delay) isn't a big deal to have in your system.    It makes the system design a whole bunch easier, and lets you achieve better results (understatement).... but the good thing about electronic components is that its possible to switch them in and out of the system at the press of a button if you like ...... so it is much easier to work out for sure if they are harming the sonics.     IMHO any DSP which is inherently audible (I mean aside from what you're asking it to change) is "faulty".

 

 

Yes, it will be interesting to test.

 

 

  • A 40hz to 100hz FLH is very big if you're prepared to take some ripples.    If you want a 'properly' sized mouth, then the horn is enormous.
  • Filters in this range (40 or 100hz) are quite impractical with passive components, so I assume you're talking about some type of active crossover and multi-amping?

 

I did some quick maths this afternoon and a 45Hz horn with a full size mouth would have a radius of 1.21m.  If I shifted back to quarter-mouth and perhaps coupled it to a ceiling or wall or floor or two of those I could probably be very happy with a mouth of 11,500cm2 (square 1.07m x 1.07m or round 61cm radius).  Horn length in both cases would need to be at least 2m.

 

I am sure I could build a round horn that size.  I am also sure I could design and build triangular horns into the peak of the cathedral ceiling or a triangular/pentagonal horn snuggled up against the side walls.  It is just a question of whether I really want to do that, and whether my wife would make me wear that old frying pan in the shed so the aliens stop whispering things in the mind.  Or I could try to curve or fold the Midbass Horn.  Whichever way I go I will need to get all of the other horns embedded in the room in the best way and then think about designing the midbass horn.

 

Regarding filters, the system will be fully active with passive line level crossovers...so 6 amplifiers per side and with filtering happening before the amplification stage.  Compared to a standard passive crossover network between the amplification and the transducers the filter component sizes will be much smaller and much less expensive.  I would rather spend the dollars on matching the amplifier to the frequency range rather than investing in too many Duelunds or the like. 

 

 

  • One luxury of a channel only running up to 100hz  (assuming a reasonable slope LPF) is you can place this channel anywhere in the room

 

Yes.  This also means that I can leave the design of this horn until after rest of the horns have been positioned in the room.  There is good leeway in that regard.  I will do what I can to ensure physical time alignment, but I am not sure it will be possible, especially after the listening position has been determined and the speakers placed in the room.

 

 

  • Which driver do you have coming?     How will you go about designing a horn for it? ....  what about building that horn?

 

 

Vitavox K15/40 15" 15ohm alnico magnet.  They are still made today but are hideously expensive for a pair.  Hornresp will be used after I measure the T/S parameters, but I will be surprised if the horn I end up with is not quarter-mouth Exponential or similar.  I will look at plenty of options here though.  This will be the most difficult horn to design and construct properly.  My lathe should be able to turn the quarter-mouth radius of 60-70cm if I end up going round and straight (which I doubt) otherwise I think I will draw it up in AutoCAD and get it CNC'd.  

 

 

  • A tapped horn which can reach below 40hz is also enormous.... but can be made a lot smaller than a FLH.    Although with the luxury of (I assume) not being limited to a pre-determined driver.... then you can choose an already hatched TH or FLH design (there are quite a few) and get that built to spec.   Easy.

 

Yes, the tapped horn I may be able to hide in the corners of the room or in the floor.  A relatively inexpensive driver and a proven design is definitely the way to go here. Plus with such a narrow operating frequency range I may just be able to get away without room correction.

Edited by acg
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Sounds good.   You sound like you have the scope to build basically whatever you like, and place it however you like.

 

The profile and mouth shape will matter surprisingly little for frequencies < 100 hz .... but that obviously depends on your crossover slope.

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Sounds good.   You sound like you have the scope to build basically whatever you like, and place it however you like.

 

The profile and mouth shape will matter surprisingly little for frequencies < 100 hz .... but that obviously depends on your crossover slope.

 

I do have a lot of scope with the room...it is basically "mine"...whatever that really means.

 

Regarding crossover slopes, I would like to think that with three horns covering the bass region 20Hz - 600Hz that I will be able to get away with the shallow first order slopes.  I am least sure about the crossover between the tapped horn and the midbass horn...perhaps the tapped horn will require a steeper slope.

 

 

Talking about straight, quarter-mouth circa 45Hz horns...

 

 

EbayBassHorn1.jpgEbayBassHorn3.jpg

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Thats nothing.

 

800px-Large_horn_loudspeaker.jpg

 

I am trying to find some pics of a system I saw a few years back which had the horns going into this guys backyard. Were about 10-15m long with the mouths cut into his listening room. Anyone seen these?

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Thats nothing.

 

800px-Large_horn_loudspeaker.jpg

 

I am trying to find some pics of a system I saw a few years back which had the horns going into this guys backyard. Were about 10-15m long with the mouths cut into his listening room. Anyone seen these?

 

That is a probably something like a full-mouth 20Hz horn.

 

And yes, I think I have seen those photos.

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