Rubik's Cube (DIY speakers??)

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savvypaul
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Re: Rubik's Cube (DIY speakers??)

Unread post by savvypaul »

NSNO2021 wrote: Fri Feb 03, 2023 1:23 pm At the risk of being labelled a heretic, I always viewed doping as a way of compensating for deficiencies in the driver. When I redesigned and rebuilt my Cubix I wanted to avoid doping at all costs which I have done with pleasing results. As always its "horses for courses" and theres no absolute right or wrong to this. Re resistors and capacitors I would get the very best your budget allows, I have yet to hear a cheap capacitor that I have liked.
What qualities do you look for in a capacitor?
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Re: Rubik's Cube (DIY speakers??)

Unread post by Daniel Quinn »

Doping is a lessor evil , far less harm than a capacitor or inductor . My opinion of course .

In my three way , I have a 12 inch bass driver which isn't doped but as 8 lines of doping from outer to dust cap , each line 9mm wide .

I've discarded the capacitor and inductor on the 5inch midrange and simply run it full signal .
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TheRealAleman (Fri Feb 03, 2023 5:40 pm) • CycleCoach (Sat Feb 04, 2023 9:49 am)

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Re: Rubik's Cube (DIY speakers??)

Unread post by NSNO2021 »

"What qualities do you look for in a capacitor?"

Paul thats a good and very difficult question to answer when you take into account the cost and effort required to A/B test capacitors.

The first thing to make clear is I am new to building speakers (messing around is nearer the mark). In my case I started by working out the values I required and then read everything I could find , filtering out the noise as best I could. I then outlined what I was hoping to do to a few experienced people on forums, asking them which they would choose out of my short list and why.

I then bought 3 different capacitors for the forward firing tweeter and 2 for the two side facing omni directional tweeters and fitted these to the outside of the rear face of my Cubix so that changing them out was simple.

They all need a month or more before they "settled down". I ended up selecting Jantzen Alumen Z Caps & Audyn True Copper Max.

And finally to answer your original question, neutrality is what I like, no over emphasis across the range of voices and instruments.
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TheRealAleman (Fri Feb 03, 2023 9:11 pm)
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Re: Rubik's Cube (DIY speakers??)

Unread post by karatestu »

The best capacitor is no capacitor :grin:

Ime there is no one size fits all. The best capacitor for a speaker level filter will not necessarily be good for power supply, signal coupling , decoupling, feedback etc.

I think different capacitors can sound different and i would personally pay more for one that is well built and is designed to last a long time without me having to change it every 10 years :grin: Look at the data sheets and there are a whole bunch of specs which can become a bit overwhelming. The easy way is to get a consensus from as wide a user base as possible and try the ones which people like. Can get expensive though especially for 10,000uf psu caps and boutique xover caps. Say you were crossing a woofer over to a mid at speaker level at 200Hz - the size of the components required (caps and coils) gets ridiculous and the cost rockets.

There is another way and that is a passive line level xover. The down side though is you need an amp channel per speaker driver (like active xover) but then many biamp anyway with speaker level filters so already have the required number of amplifier channels. Doing it this way you get to use very small value film capacitors ( say 470pf for a tweeter high pass) which are available in polystyrene. You also don't have to worry about the reactance of the component interacting with the driver and playing silly games.
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TheRealAleman (Sat Feb 04, 2023 9:12 am)
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Re: Rubik's Cube (DIY speakers??)

Unread post by karatestu »

As regards doping I agree with DQ that it is a necessary and lesser evil. The ultimate though is finding a driver that is well enough behaved in its roll off that it can be run fully open with no doping (as some have already done). Cheap drivers are not well known for their smooth roll off so out comes the dope. There are a few that are well behaved (especially if not used point & squirt) but they are mostly not cheap.

Personally I have been trying to hold off from buying expensive drivers mainly due to trying to use what i have available and with all my amateur electronics the fear of blowing up something expensive is always in the back of my mind.
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CycleCoach (Sat Feb 04, 2023 9:41 am) • SteveTheShadow (Sun Feb 05, 2023 10:46 am)
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Re: Rubik's Cube (DIY speakers??)

Unread post by TheRealAleman »

I think I can see where everyone is coming from.

Crossovers are the work of the devil
Doping "cheaper" drivers and minimal HQ electronics is better than Crossovers,
And HQ speaker drivers that can be driven fully open or with the minimum of HQ electronics is the best of all.

I think Savvy is coming down the latter route with the new Cubes. The issue there is if you are trying to build to a price point where can you draw the line on cost. It does, however, remove the need for "The Docs" golden ears and years of doping experience. Of course, if you had someone with those abilities then you would have the additional cost of wages and build time, So more expensive HQ drivers makes sense.

If I had Stu's space and materials then I probably would go through a few iterations of design with different drivers and components, but I don't, so I am going to try and stick to accepted practice (more or less), and go along a well worn path with some, hopefully minor, diversions.

Keep the suggestions coming though. All experience and knowledge is ultimately useful 👍👍

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Re: Rubik's Cube (DIY speakers??)

Unread post by TheRealAleman »

Reading all 194 :shock: pages of Stu's Epic speaker mod adventure in three days :shock: :shock: was possibly not my brightest idea!! :angry-steamingears: I now seem to be channeling my inner KarateStu :o

First off, and I am amazed that no one has already pointed this out! Using solid core tinned copper wire in a steel lined enclosure is probably not my mind thinking in a logical pattern. Yes, you can do it, with care, in an NVA amp because the things are acrylic!!! Anyway further perusal of the DIY forum has given me Doc's answer ... Some sort of good quality stranded wire is all that's required... Just make sure that you run single lengths.

I know I was thinking about using veneered MDF and ply for my cabinets but in true Stu style what about translaminated marine ply? Extortionately expensive, but the interior could be say 250mm square column, and the outside have rounded over edges. It could be left as a simple Column, or even going with something organic, even Daliesque 😱. The feet could be made out of the central cut outs ... The only ouch would be the cost of "FIFTY" (!!!!) 310mm squares of marine ply, then add the cost of CNC machining. While I think they would look fantastic, and be incredibly stiff with 50 to 60mm thick walls, again, I think the cost Vs a steel lined mdf and ply cabinet needs carefully consideration.

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Re: Rubik's Cube (DIY speakers??)

Unread post by karatestu »

You need something flexible to connect to the speaker drivers . Multi stranded is good for flexing whereas solid core isn't unless you go thin and that is not the best idea imo.
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TheRealAleman (Sun Feb 05, 2023 6:47 pm)
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Re: Rubik's Cube (DIY speakers??)

Unread post by Daniel Quinn »

The doc didn't have golden ears , he had years of experience.

Additionally the solid core tinned wire did of course have a dielectric .
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TheRealAleman (Mon Feb 06, 2023 11:58 am)

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Re: Rubik's Cube (DIY speakers??)

Unread post by TheRealAleman »

savvypaul wrote: Wed Feb 01, 2023 11:45 am Richard put an 8" driver in a 30cm cube.
I'm not trying to duplicate the Cubix/Cubix Pro design or setup, but build a speaker based on the principles. Am I right in thinking that each section of of a cubix has a single bass/mid unit (upfiring) and a single visaton tweeter ... Front (then inside and outside firing for the additional sections)?

I'm planning a floor stander upward firing bass-mid (2 In isobaric Push-Push config), with 2 visaton G20Sc tweeters firing to the front and side (Inside or outside by swapping the complete speaker over)

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