Rubik's Cube (DIY speakers??)

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

Unread post by TheRealAleman »

Series Wired?? I can see a bit of an issue with what I'm planning then. Obviously with the Cubix, and the Cubix Pro each section is powered by a separate amplifier, either buit in or external. With my design each speaker will have 5 drivers (Three 12" Kenford SBX3040 8 Ohm Bass drivers, One QTX QXW6 6.5'' 8 Ohm Mid Bass, and one Visaton G20-SC 8 Ohm tweeter) in series that's a total of 40 Ohms. The Sub's are/were available in 4 Ohm, but really difficult to find.

I suppose I could Bi Amp them, with the Bass wired 2 in series and 1 in parallel to give a 5.3 Ohm load. Impedance isn't the "Be All and End All" but I don't want to subject the S300 to an "Impossible load". Once you start throwing another pair of S-300's into the mix, to drive each section this project really starts to price itself out of my league :( :cry: :cry: :cry:

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

Unread post by savvypaul »

If I were going to DIY, I would start with something a little more straightforward. Make a cube in floor grade chipboard, line with steel plate, dope drivers, experiment with resistor values. Use with your existing NVA amp. See if you like the semi-omni presentation.

The CubixPro are a wall of sound; exceptionally powerful. My view is that you need a larger than average room to really appreciate what they can do. A 12" cube with 8" driver will fill an average size room very well.
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TheRealAleman (Sat Jan 28, 2023 8:35 pm) • CycleCoach (Sat Feb 04, 2023 9:42 am)
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Re: Rubik's Cube (DIY speakers??)

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savvypaul wrote: Sat Jan 28, 2023 7:26 pm A 12" cube with 8" driver will fill an average size room very well.
I must admit as I work through the idea in my head there is a lot of sense in what you are saying.

I think a 10" doped bass driver, 5" mid and the visaton is possibly the way to go, for me. I try and follow the KISS principal, but just love to complicate it.

Being very cheeky here, but what are/were the dimensions of the Cubix sections?

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

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TheRealAleman wrote: Sat Jan 28, 2023 8:49 pm Being very cheeky here, but what are/were the dimensions of the Cubix sections?
Well, development. I "accidentally" :whistle: ;) ordered a pair of Kenford SBX2530 10" 4 Ohm drivers Yesterday, which have now been sent, so this project is officially Off the Ground :dance: :dance: :dance: And I have a pair of Visaton G20-SC Tweeters sitting in my CPC basket (local to me so I can collect them in store).

The 300mm cabinets will be built from plywood, which will be reinforced internally with more plywood panels, and then steel lined. I'm going to get both plywood and steel laser cut to size. 5mm thick steel for sides and top, and 20mm for the base sound like a good idea?

Now onto the Crossover components. :geek: As I understand it a 3.3 uF capacitor, and 12 Ohm resistor in series with the tweeter is all that is required. However, as "The Doc" drummed into us on many occasions, there are components and then there are Components. Capacitor wise in the past "The Doc" has suggested these Russian Military K75-10 Hybrid Paper In Oil 3.3uF 500V Audio Capacitors which I can get, "nudge, nudge, wink wink", from a "guy" in Bulgaria :naughty: :naughty: (*). In the intervening years did "The Doc" use anything else??

Resistor wise , there is "bog standard" "common or garden" wire wound, at 20p each :o Should I go a bit more "upmarket" and try either "cement" resistors (£1.40) or Panel mounted Heatsinked resistors at £1.83? I'm leaning toward the cement resistors as they are sold as For use in Crossover Networks in PA and Hi-Fi . Options??

I cannot believe the price CPC want for 16SWG tinned copper wire ... Off to the Bay of E

Is there a thread on doping cones ... with pictures ?? :think: :pray: :pray:
















(*) Assuming I don't break any trade embargoes :pray: , or have a visit from the men :shifty: :shifty: driving blacked out black Range Rovers :o :o
Last edited by TheRealAleman on Wed Feb 01, 2023 11:55 am, edited 2 times in total.

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

Unread post by savvypaul »

A couple of things that jump out, initially.

If you put 20mm steel in the base, I doubt you'll be able to lift the speaker.

Richard put an 8" driver in a 30cm cube.

Lots in the archive from others that have done Doc Mods...
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TheRealAleman (Wed Feb 01, 2023 12:14 pm)
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Re: Rubik's Cube (DIY speakers??)

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savvypaul wrote: Wed Feb 01, 2023 11:45 am If you put 20mm steel in the base, I doubt you'll be able to lift the speaker.
:geek: :geek: Square mild steel plate of 246mm which is 20mm thick would add about 9.5Kg to the build, plus another 6.75Kg from the 5mm plates, :shock: :( well not impossible to move, but not something to drop on your foot either. Slight rethink coming up, especially as 20mm plate adds £170 to the build :doh: :doh: ... I'm not sure 246mm interior cube will be big enough for the components anyway.
savvypaul wrote: Wed Feb 01, 2023 11:45 am Richard put an 8" driver in a 30cm cube.
:think: :think: Did he ever build anything with the 12" drivers? I know from looking at the archive, that he put prices up for the 10" and 12" Cubix Pro, just not sure if they were ever built. ... Can see this becoming a 330 or 350mm cube. If I double up the thickness of the ply plates with a 300mm outer cube I only have a 246mm interior cube to play with, 10mm less with 5mm steel plate ... 230mm baffle cut out required for the 10" driver
savvypaul wrote: Wed Feb 01, 2023 11:45 am Lots in the archive from others that have done Doc Mods...
Don't I know It :cry: :cry: It's taking ages to browse all the threads ... I'd love to know what's in the Richard Dunn Archive forum that is locked :grin: :grin: :grin:

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

Unread post by Fretless »

RD said that 5 or 6 mm steel plate was sufficient. I have just been revisiting my own Doc-Mod thread to look back at what I did. Glued an assortment of steel linkage plates from the DIY store in 2 layers in the lower 3/4 of a speaker cabinet. Certainly made a huge difference to the performance!.

Here is my voyage of discovery and the accompanying commentary from RD on the Audiolab Minax speakers.

https://hifisubjectivist.org/viewtopic. ... ilit=minax

An example of clumsiness and learning. :doh:
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TheRealAleman (Wed Feb 01, 2023 1:56 pm)

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

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Ok As the 10" Drivers are on the way , it's time to look at what's involved in doping. Luckily Karate Stu managed to get images working on around page 100 ish of his epic loudspeaker mod thread/blog, so I've seen the after effects of Doc's doping on 5.5" cones. Also from that I've seen some instructions along the lines of pour a line around the edge of the cone, and allow it to run down to the dust cap, then add about the same amount on the top of the dust cap and let that flow down. It reduces in volume as it dries so repeat as necessary to get the amount of attenuation you require. As it's HF i'm trying to reduce then its mostly required around the dust cap.(???)

Product wise is the the correct "Bison Kit"?

Image

and is this the correct "plastidip" ... ISTR "The Doc" saying he used a spray rather than a brush.

Image

Cabinet wise I've found a CNC company that supplies 19mm Ebony veneered MDF panels for the same cost as 25mm Marine Ply ... Which makes the marine ply pretty good value. So I'm thinking go with the mdf and line with the 18mm plywood that I have "lying around" from other projects. ... Then 5/6mm steel over that. As the tweeter is self contained I can completely hide it within that 37mm of MDF and Ply with the 5mm thick steel serving to hold any required packing piece.

As the intention is to eventually go for a pair of 10" bass drivers in isobaric configuration, and add a side firing 5" mid driver, I'm wondering if going for a 30 by 30 by 60 cabinet from the beginning with the lower "half" blocked off with a solid baffle is a good idea. It certainly is more cost effective, as it's 136 quid for the panels for a 30cm cube and 225 for the bigger cabinet (Material cost only, machining will be extra :o)

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

Unread post by karatestu »

Yeah, that's the right bison kit. You don't need that much though :grin: I never poured it round the outer edge, juef over thd dustcap. Make sure everything is level and add small amounts at a time and listen. My 6.5" drivers i got about right. The 5" had too much added because i had an ear problem at the time which was unknown to me which made certain high frequencies annoying.

The plastidip is correct although I've never used the glossy- might show up the imperfections too much ? Doc used to spray it on the rubber surround as well but I never thought that was a good idea as it increases the drivers resonant frequency (less bass). I masked the surrounds off.

I don't use bison kit anymore, evil headache inducing stuff. I use black gutter sealant from wickes which I find to be better. It is butyl rubber and never goes completely hard and can be removed later if needed. You can even sand it :lol: It does require a whole different application technique though as it is not as viscous as Bison kit (comes out the cartridge like silicon sealant. Once bison kit is on you'll never get it off.
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TheRealAleman (Fri Feb 03, 2023 8:09 am)
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Re: Rubik's Cube (DIY speakers??)

Unread post by NSNO2021 »

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.
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TheRealAleman (Fri Feb 03, 2023 5:40 pm)
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