Something stirs in the Undergrowth

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Andrew
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#1381

Post by Andrew »

What did they do on Basszilla? Could you copy?
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IslandPink
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#1382

Post by IslandPink »

It's a big ported box with Definimax 4015 on the standard Basszilla version.
There was an OB version, will dig out the info and have a look .
I'm just turning-over all the options again ... what I've given up in having the bass & mid/Hf bi-amped here, is the series cross between bass and mids that works so well on the Quasar . It gives you ( with the right drivers ) a really good blend, plus the extra 'Q' for the bass driver from the big choke , to get the bass response down lower .
Ah dear ... I wish James was here to chip in to the discussion.
I'll get the info as above , soon .
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IslandPink
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#1383

Post by IslandPink »

IslandPink wrote:There was an OB version, will dig out the info and have a look .
Ah yes, it uses the same 4015 driver but the amp is a Pass F2, which increases the system Q because of the high Zout . Hmm.. not convinced the F2 would be man enough to drive a 'sturdy' driver like that with dynamics , in the bass. I guess I could try with some series R after the F4 ... but the volume would be well down , might have to swap valves in the pre-amp to get a bit more gain .
I guess the first step is to listen to the 2515 without a crossover , driven from the F4, and convince myself ( or otherwise ) it can deliver tone without the equalisation & low-pass.
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chris661
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#1384

Post by chris661 »

Hmmmm...

To answer your earlier question about "mechanical inductance", I meant that, towards the higher frequencies, I think the mass of the cone increases the impedance compared to what you'd expect from a DC resistance plus inductance calculation.

IMHO, efficient speakers can be driven by anything - it doesn't know if your amplifier is on the verge of meltdown, or has another kilowatt spare. So long as the waveform is unclipped, what's the difference?
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#1385

Post by IslandPink »

I think I might have to build a transmission line and complete the set :roll: I can think of ways a TL could be packaged to be under an OB , so it's worth testing
So - I bought a single Audax PR240ZO from EBay today .
Looks like a nice driver spec for TL and TQWT . I can think of ways a TL could be packaged to be under an OB , so it's worth testing . Should get me down to low-30's Hz and I like the low Rms value of about 0.8 .
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BudP
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#1386 TL woofer

Post by BudP »

The opposing driver TL setup from Planet 10 is the first "box" woofer I have heard that can match the speed and texture that open baffle mids and upper bass require. I am sure that the XBL motors and ultra light weight cones aid in this. They are only 6" drivers, but the micro dynamics and astonishing texture, as in separating a bass viol section into individual instruments and properly placing them in the sound field, are not something I have found except in large open baffle bass setups with huge baffle panels and Gary Pimm's cardioid bass cabinets that use heavy damping to limit their open baffle expression. You might want to investigate Gary's structures by the way. I can send a number of pics your way. They are very very space efficient, though they do require large amounts of power and EQ to perform. The TL's from Dave just work brilliantly, are demure, efficient, attractive and hold off the bass resonance till below 20Hz.
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IslandPink
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#1387

Post by IslandPink »

Interesting stuff, Bud . I think I've seen a pic or two of Gary's set-up . Have you got a link for Dave's TL ?
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BudP
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#1388

Post by BudP »

I have attached a couple of pics of G Pimm's work and a basic plan for Dave's TL's. He has moved on from the drivers involved in this plan, but the concept has remained the same. You must go to him for current details. I cannot imagine they are worse performers than the stellar items I have on hand.
Attachments
The box and drivers
The box and drivers
Same view with cotton batting to enforce cardioid. Woofers are 15".
Same view with cotton batting to enforce cardioid. Woofers are 15".
FonkenWoofTL-0v8-map-120508.pdf
The TL sheet
(51.99 KiB) Downloaded 237 times
"You and I and every other thing are a dependent arising, empty of any inherent reality" Tsong Ko Pa
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IslandPink
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#1389

Post by IslandPink »

Thanks for the extra info . I did have a look through Dave's designs and picked out another more recent design by mistake , but you've set me straight on this now. This is a TQWT it would seem - very interesting . CSS SDX7 drivers .
So - what happens above say 150Hz where the sound starts to come out more directionally (sideways) from the cones ? - in your set-up , what was it interfacing to, above ? , & crossover frequency ?
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BudP
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#1390

Post by BudP »

You do need to be concerned about the upper range coming from driver direct drive. In my set up I am mating the subs to the Emminence Delt8 as an overlap. The Delta's are allowed to run down in frequency to wherever they like, they are there to protect the "long throw " Lowthers and are crossed over at 300 Hz using a simple series crossover.

The subs utilize plate amps with about 50 watts available. The controls are set to 60 degrees negative phase shift, appropriate amplitude and frequency cut starting at 180 Hz and rolling off at 6 db per octave. So, the Delta's provide the location cue for the upper range of the subs, the sub TL outlet matches the backside emissions of the Delta's in phase and the time alignment of everything blends into two columns of propagation.

With the EnABL process done for every resonance node on drivers and baffles there is no speaker specific location for the sounds you hear. The sound stage is literally wall edge to wall edge, floor to ceiling and about 200 feet deep, with the front edge seeming to be just a few inches forward of the wall, 24 inches back from the open baffle plane. There is a pic further back in the thread for this....monstrosity? Certainly Bauhaus ugly.
"You and I and every other thing are a dependent arising, empty of any inherent reality" Tsong Ko Pa
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IslandPink
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#1391

Post by IslandPink »

Sounds like what we all need !
I just realised the WoofTL you have is a TL, not a TQWT ! :)
I was wondering..."howcome the vent is at the small end".. then it twigged ! There's is a clue in the name, of course.
So, do you have the vent facing forward ?
( I've been struggling to find the picture of your set-up ) .
Dave suggests there's a fair bit of stuffing in there to get the response flat ?
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IslandPink
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#1392

Post by IslandPink »

Having looked at that design, simmed on Hornresp , and checked out also my first stab at a TL for the Audax PR240Z0 , I noticed something interesting . The WoofTl seems to use a very large start to vent area ratio, around 10:1 . This seems to extend the bass response lower - I could get to 20Hz with the Audax- admittedly with a sloping response . So, conversely you must be able to get equal bass response to a conventional TL in a shorter line, if that ratio is high . I was wondering how the apparently fairly short TL line you have there could give adequate ( eg. 40Hz ) bass extension .
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pre65
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#1393

Post by pre65 »

Mark, I had the opportunity to listen to a pair of these speakers tonight, driven by a HUGE pair of 833 monoblocks.

I think you might have liked them.:wink:

http://www.audiophilia.com/hardware/acapella.htm

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IslandPink
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#1394

Post by IslandPink »

Ooooh , those are interesting . Must be fairly local to you then ?
I wonder how the bass is done .... did you notice what sort of vent ( and where ) there was on the cabinets ?
Paul and Chris V would like the ion tweeter .
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pre65
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#1395

Post by pre65 »

IslandPink wrote:Ooooh , those are interesting . Must be fairly local to you then ?
I wonder how the bass is done .... did you notice what sort of vent ( and where ) there was on the cabinets ?
Paul and Chris V would like the ion tweeter .
Fairly local. :wink:

I could not get close enough to see the detail, but even in a sub optimal room (too small) they sounded exceedingly good. :)
The only thing necessary for the triumph of evil is for good men to do nothing.

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G-Popz THE easy listening connoisseur. (Philip)
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