Originally Posted by arnaud
The 007 is much more tolerant of music genres and listening habits while, apparently, giving very little away to the 009 when properly fed.
I think this sums it up nicely. To add to it though, behavior at higher volume level is the true test of any component. With amps this tests the circuit and power supply far more than whisper levels. Clipping would be the most extreme case but the ability to maintain the full voltage swing into any load is what all amps should strive for. When Tyll did his comparison of electrostatic amplifiers he dropped me a line asking for how I test 'stat amps. My first port of call is always how they perform with hard to drive sets (Sigma's, 007Mk1) at high volume levels so that's what I told him, push them and push them hard.
This is a far bigger issue with transducers, they need to work harder to produce higher SPL and this will cause issues with the housing, diaphragm and even the stators. Excess energy needs to be dissipated, both as vibration and as heat, which will trip up the designs. Take any of the Lambdas and push them hard. The driver structure is well designed but the interface with the baffle and the baffle material is not ideal as it can't transmit the extra energy as efficiently. Same problem with the SR-Omega, the plastic skeleton that the driver rests in does the sound no favors.
Now these structural issues have been dealt with in the 009 but Stax did design them to have a sound and the Stax amps are supposed to counter that and make for a nice combination. This are the same design choices we make when designing amps, this stage has a bit more second harmonic distortion to keep the higher orders in check and all that. There is also one aspect of the recent Stax models that has been overlooked, why did they change to the new diaphragm material? Now that we know what it is I can only think of one reason, even higher tensile strength that mylar.
Originally Posted by georgep
Hi Mike, was the mod only the feedback change or was it more drastic (replacing transistor)? Been thinking of having something like this done with mine.
Only one amp I know of has had the transistor swap but I for one don't understand why anybody would do that. The 2SC5466 that Stax use is perfect for the role and is only outclassed if you need a part that handles more voltage. All but impossible to raise the rail voltages within the 727 chassis....
Originally Posted by DefQon
I'm pretty sure the original BH or KGBH is also available as diy as evidently the schematics can be found on the headwize projects page.
Don't forget there is the Megatron as well if you like stats and tubes.
There are a few dozen DIY Blue Hawaii's out there so yes.