Something stirs in the Undergrowth

Dedicated to those large boxes at one end of the room
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IslandPink
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#2266 Re: Something stirs in the Undergrowth

Post by IslandPink »

Wow - are these the answer to the AER conundrum for Quasars ?
Look like the biz , these ones are expensive but a fair bit less than the current AER's or Voxativ's.
https://www.hificollective.co.uk/drive- ... agnus.html
I find the comments on spider design and the Qm values of 15 particularly interesting.
https://www.hificollective.co.uk/drive- ... o-fc8.html
Actually I need to check whether they are prices for a pair or individual ( even though you have to buy a pair ! )
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chris661
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#2267 Re: Something stirs in the Undergrowth

Post by chris661 »

Looks to me like that's price per pair.
I still don't really get the Qms thing for a couple of reasons, but if you've decided that's your criteria, then I wish you the best with it.

FWIW, Cube Audio also do finished speakers, which are reviewed online. Might be worth a bit of reading around to see what people think.

Chris
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#2268 Re: Something stirs in the Undergrowth

Post by IslandPink »

I'm already sorted with the FX120's, but those are going out of production so something else will be required. It would be necessary to hear them, at that price. Maybe Nick needs an upgrade for his OB's :D

Meanwhile I got a pair of 56uF Mundorf EVO Oil caps and after trying one for two hours now in the functioning OB, this is the best value(uF) yet in terms of integration and probably tone. So the combo looks like this , there might be one minor edit to this (perhaps the trimming R for the 285's ) once I get the pair working.
Quasar_FX120_cross.jpg
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#2269 Re: Something stirs in the Undergrowth

Post by IslandPink »

chris661 wrote: Wed Dec 12, 2018 3:50 pm FWIW, Cube Audio also do finished speakers, which are reviewed online. Might be worth a bit of reading around to see what people think.
I was just going to say, I'm not sure whose ears I could trust, however :
Cube_Nelson.JPG
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#2270 Re: Something stirs in the Undergrowth

Post by IslandPink »

I like wooden choke-holding boxes from EBay . Only £32 for these :
Cross_boxes.JPG
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#2271 Re: Something stirs in the Undergrowth

Post by IslandPink »

Meanwhile I tried a driver-swap on the folded horn Mk.5 ( cockroach) to check something. Stuff I'd been reading in a couple of areas, but particularly Horst Moeller's site ( Moreart ) suggested with compromised horns, using drivers with a rather higher-Q than the traditional ( Q ~ 0.2 or 0.25 ) could have benefit at the lower end of the working range. I mean phase more than amplitude.
So I tried the Faital 8FE200 in place of the FE208Ez, it has Q = 0.40
Sound was indeed a bit better, a little bit more extension and tone in the lower-mids.
Phase plots are here, it's does seem the phase response graph is the more useful way of judging what's good or better/worst with horns in this area. The solid curve is the 8FE200, the grey curve the FE208Ez. I'm looking generally at the area 70 to 600Hz , and specifically at the difference in phase between 100Hz and 400Hz for this comparison.
Phase_PMVO55cm_208Ez_8FE200.JPG
This is more or less the last thing I'll do with this construction. It seems clear the horn needs to be longer and slower-expansion to get loading below 100Hz , so there will be more developments to come, but the OB's and amp take priority for now.
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#2272 Re: Something stirs in the Undergrowth

Post by IslandPink »

Ooh look, a pair of lickle houses for chokes .
Also somewhere for a capacitor to hide.
Cross_Boxes2.JPG
Choke boxes with reinforced corners now, with M4 socket nuts to mount to wing of OB. Slightly different plan for the cap side, will become clear as I labour towards the finish.
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#2273 Re: Something stirs in the Undergrowth

Post by IslandPink »

For Nick's benefit, I managed to find the same binding post pair that Maplin used to sell, on EBay :
https://www.ebay.co.uk/itm/Dual-Twin-Go ... Sw0kRbtz2S
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Nick
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#2274 Re: Something stirs in the Undergrowth

Post by Nick »

:-)
Whenever an honest man discovers that he's mistaken, he will either cease to be mistaken or he will cease to be honest.
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#2275 Re: Something stirs in the Undergrowth

Post by IslandPink »

This job is getting very intricate :confused3:
At least I've worked out all the details now.
Cross_boxes3.JPG
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#2276 Re: Something stirs in the Undergrowth

Post by IslandPink »

A bit of recent entertainment in the horn world, I mentioned to Nick, Simon etc :
https://www.diyaudio.com/forums/multi-w ... condo.html
then :
http://www.goodsoundclub.com/Forums/Sho ... 5249#25249
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vinylnvalves
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#2277 Re: Something stirs in the Undergrowth

Post by vinylnvalves »

Read that with interest and amusement. Following Romys ideas set be back in my pursuits. Having all you horns horizontal not pointing to a point source is a good example....
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#2278 Choke & blu-tack

Post by IslandPink »

Some painstaking progress today. I knew the drilling and fitting of the crossover boxes to the OB was going to be tricky.
Choke-mounting drillings - the choke first has to be placed under the box ( cover ) while the box is moved to exactly the right location, with its edge near-flush with the baffle rear edge ; then the cover is lifted off without disturbing the choke - and the holes marked.
OB_chokefit.JPG
Then the trickiest bit - how to mark & drill the holes that fit the cover over the choke ? - the M4 sockets are already installed into the corners of the box. I spent a barely finite amount of time thinking about this, then decided, after a brief trial on suitable pens, to use little blobs of blu-tack pushed into each M4 socket ; then used the chosen red pen to scribble ink on the very middle of each blob of blu-tack , then I could bring the box down over the choke and onto the baffle, the red blu-tack marking the drilling locations. You can see the blu-tack in situ on the box inserts, and small red marks on the wood near the choke -
OB_choke_stamping.JPG
This just about worked, with a little enlargement of the clearance hole for the screws afterwards.
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#2279 Re: Something stirs in the Undergrowth

Post by IslandPink »

With the choke fitted and the cover on, I could work on the other side, which houses the cap, tag-board and speaker connectors.
Here is the insert piece fitted, after careful adjustment of position and marking of screw positions (3). Cap show in-situ with its clamp.
OB_cross_half.JPG
And with the final cover fitted, a mock-up of the finished job (below).
Tomorrow I need to make final decisions on the type of wire to use from crossover to bass driver and mid drivers, and make some little notches to let the wires out of the bigger box, then try & wire-up & fit everything together - with the front baffle back in place with the drive units.
OB_Cross_Mock.JPG
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#2280 Re: Something stirs in the Undergrowth

Post by IslandPink »

One other piece of progress .
I got the other Fostex FX120 down from upstairs, removed it from the 30L sealed box, and fitted to the wooden baffle with the other FX120. In the process also managed to punch a hole through the foam surround of the other FX120. I have decided to ignore this, as it's not visible unless you go really close and know where to look.
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