[grantnsw]

Hi Zyg,

I'm looking forward to see your f/b driver pics! I rang the NSW store yesterday, but the chap didn't know what was in the store-room.

I rang the Perth store after my initial question to you (a while ago) and received a PDF for the OLD model C2002. The response looks...

[zygadr]

BLOODY FANTASTIC grantnsw!!!!!..................brilliant find!.....thanks for that!

Yes, the response reflects on what I hear except that in general, there is a much better, more evident high frequency response than what is indicated in the old response curve.

The most important thing is that the top end will either miraculously dissapear or appear depending on whether you use a transconductance amp(SET or ZEN mosfet amp) or a voltage source, typical solid state.

The curve shown is more like what happens with your standard solid state amp, chip amp or whatever.
But!..................as soon as you go to alternate ''current amplification'', the top end rises VERY significantly.

Get a load of that QTS!!!! ..........is that a contender for Open Baffle or what????

Here are some pics of the new version. Note the difference in surround.

[grantnsw]

Hi Zyg,

Thanks for the driver pics! Very useful to aid in my possible? purchase. Yes, quoted Qts looks OB friendly. 

I'm glad the 'specs' for the old model C2002 are of use to you. Ross Williams Jnr, Purchasing Officer from the Perth store emailed it to me last March. The response to me looks scary with those huge peaks
and troughs but as you say maybe it was tested with a Solid state 'voltage' amp. Perhaps, that why the frequency response looks so ragged? 

Your comments on the quality of the NEW model are very interesting and indeed compelling to buy a pair. 
I guess 'we' need to get the latest specs for the new model!

Thanks for the Nelson Pass link. Very interesting but a lot of it went right over my head.

Regarding valve or SS amps, he says this at the end of page 4:

>> " Most of the examples we will examine do not require true current source amplifiers, only amplifiers of quite high output impedances. Most of these cases will be happy with an output impedance of approximately 47 ohms or so and prefer 47 ohms loaded in parallel with the output of a current source. That being the case, you can build a Thevenin Equivalent of such a current source by placing a large resistor (here later referred to as R0) in series with the
output of a high wattage voltage source amplifier and get similar results. " <<

I don't know much about amplifiers, but I have two. First is a 30yo? Technics SU-V8 with 140W per channel (into 4 ohms) Class A. Damping factor 30 and 60 for 4 and 8 ohms respectively. It draws 1kWatt! 

Second is an old Harmon Kardon HK6200 45W/channel with instant 30amps High current amp with damping factor 60 presumably into both its 8 and 4 ohm outputs.

I'm just wondering your thoughts please in view of Mr Pass' article? Amp O/P impedance is not 4 or 8?
cheers, Grant

[grantnsw]

forgot to mention that both my amps sadly are dead in one channel 

no doubt from my crossover attempts which must have been way too low Z.    Guess they'll cost a motza to repair

[zygadr]

Not sure either Grant...............it's all a bit ''iffy'' if you know what I mean

I recommend you email Nelson................he will eventually reply........he's a great guy and very approachable, but has a huge back log of emails from diy guys like us

Tonight I connected the drivers up to my high end Pioneer h.t. receiver and they sounded different again!!

There was reasonable high end(but I've heard better) and plenty of solid bass. Overall the sound sounded far more linear(less shout) and more listenable over long periods...........go figure?

Either way, I still prefer a simple single ended circuit with these units.............scary transparency, very real. Multi way jobs just don't cut the mustard no matter how perfect their set up and how brilliant their crossovers, they fudge their way through music hoping you won't realise their fake reconstruction of the frequency range

In regards to their rated sensitivity, I sadly suspect that the new driver is 90db or considerably less
I say this because I have some old 96 db drivers and 100db horns and these drivers need a considerable crank up on the volume pot to get near their output. It's not a great deal more that's required, but could be a deal breaker with 4 watt/channel amps etc