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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#46

Post by IslandPink »

OK Finally .... we had some trouble with a shifted magnet on 0007 which GPA were able to rectify quite quickly . Now I have a pair playing, and they are very impressive - if you choose the music appropriately !
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IslandPink
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#47

Post by IslandPink »

They are big beautiful beasties :
Note special Hi-tech mounting platforms .
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#48

Post by Andrew »

So tell us more about the sound....

-- Andrew
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#49

Post by IslandPink »

Difficult to assess some areas given the limited band ( about 700-8500Hz ) , however with choice of material ( guitar, piano ) you can get some impressions .

Hugely sensitive ( should be around 109dB/w) and you can well believe that .
Dynamics to spare : Effortless at normal to highish volumes .
Tonal colour excellent allowing for the limited band - you pick up tonal subtleties you never heard on all sorts of things.
Detailed , very detailed and edges crisp as well , more than you'd expect given the 8.5k roll-off .
Fast fast fast . Len Edwards was here last night and we listened to various including Michael Hedges 'Ariel Boundaries' . Len said something like 'fast isn't the word ! ' .
So, lots of fun . I just spend a bit of time selecting suitable LPs .

MJ
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steve s
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#50

Post by steve s »

Hi Mark, they look very impressive,

the boxes look like a lot of hard work though...
i have wondered myself of building something big (as in boxes !)... but the bass i'm getting from OB would take some beating, but its at the expence of an extra pair of big drivers for the lower bass.

i'm on a similar route with a pair of vintage vitavox horns being swapped in and out in place of the lowthers, in many ways they are very close.. but my minds not made up.. the intergration is very good, with a very balanced sound that seems to play everything well..so far

cheers
steve
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IslandPink
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#51

Post by IslandPink »

Yes indeed Steve. This set-up is going to be big and heavy but also pretty cool I would like to think !
For ref those just joining the boxes for the bass units will be as per the Jensen box shown :
http://www.supravox.fr/anglais/kits.htm#Jensen
for 285GMF , about 1m tall and 500x550 mm footprint, about 7cuft .... big .

As for the top end, I now have a first-cut plan for the crossover forming :
Autoformer the Horn drivers down to around 100-102dB ; leave natural rolloff of horns in place at about 8.5k ; then add in Aurum Cantus G3 ribbons above ; 2nd-order high-pass at 8.5k ( cap & air-core coil ) . I need to calc the values now and see if anyone has some spare air-cores ... or wind my own . Probably less than 0.2mH I'm guessing .

Meanwhile the wood for the bass boxes is lining the sides of the hall - amazing how many pieces ! I had a semi-pro friend cut all the pieces to near-net size, but the remaining tasks, eg. bevelling-off some of the front pieces , are not trivial with very hard 25mm birch . Ho hum . I suppose people have spent 20 years making scales models of the Cutty Sark from matchsticks , could be worse .

MJ
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#52

Post by IslandPink »

Dave Slagle is working-up some autoformers for me :
http://www.intactaudio.com/forum/viewtopic.php?t=900

:D
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#53 Finally......

Post by IslandPink »

Behold : A honking-great Onken !!
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ed
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#54

Post by ed »

woots

I didn't realise how quickly time passes...is it your annual post Mark? :D
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#55

Post by Andrew »

Oh, yes look at the dates, Ed's right, almost to the day.

Well done Mark, those Onken styles boxes are not the easiest to build, lets hope it doesn't actually honk ;)
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#56

Post by IslandPink »

Oh yes - that's weird isn't it ?
Yes, project proceeds in slow motion , like some glacier slowly grinding its way downhill , slow, but unstoppable . I have also nearly finished the Pass labs F4 , but that's another story .

Let me see if there's another worthwhile photo ....
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#57

Post by IslandPink »

I was just looking for a picture of the autoformers but it's still on the camera , will have to download in a few days .

Going to be a bit busy in next week or two -
New Teres 'Verus' motor pod arriving tomorrow , then on holiday in Austria for a week from Friday .
Give me a year or so and I will reply to any questions.

ILPS
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Ray P
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#58

Post by Ray P »

Hi Mark, good to chat at Eggborough today and I can hear potential in your mid horns, but, I think you now owe us a full update on the status of your project....

Ray
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#59

Post by Ray P »

Mark, you might have started something....

After Eggborough yesterday I've been looking at the AzuraHorn website and found the prospect of a push/pull design utilising my Lowther EX4s tempting. Main problem would be getting any Azurahorns shipped over as they're over the size accepted by AusPost.

I've also been checking out some of the stuff you mentioned, along with Bert Doppenberg's latest DIY stuff.

If I do anything I'll start anothe thread.

Ray
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#60

Post by IslandPink »

Hi Ray
well..
Status of the (speaker) project...
Onken bass speakers , one unit almost done. Needs top panel fitting and some felt and wool damping ( not too much ) applied to interior . I have the materials now. I also have started varnishing the exterior, which is a good sign .
2nd speaker has most of the parts made & ready for biscuit-jointing together, but I need to psych myself up for that stressful exercise.

If I can finish the first one of those, I might apply myself to making the sort of L-shaped support for the horns and ribbons which is going to sit on top of these bass beasties. that would give me the opportunity to try to get a first-pass idea of the crossover from horn to ribbon sorted out during the winter . I have autoformers, but need to get parts to get something like a 2nd-order high-pass for the ribbon , and invite someone like Nick down to test some things .

Of course there is also the Pass F4 Amp project which is nearly done. these will be driving the bass cabinets . It's just the final scary drilling of holes that's stopping me :shock: Then of course I need to make some sort of pre-amp , as they don't have any gain ..aaarg !!

Martin Seddon is a very nice guy. Do you have his E-mail ?
Have a chat with him .
The Azura AH-425's that I have were about the limit of air-mail shipping apparently .

Mark
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