The Quest for >2000 Vppss

[kevin gilmore]

q12 is the current limit. so if the amp board shorts, at least the power supply will not explode.

what do you want me to replace the pzta part with?  remember 20+ma

Edited October 28 by kevin gilmore

[simmconn]

I was just pointing out, as how Q12 is connected today, it’s not doing what it is supposed to do. The output should be connected to gate instead.

I remember last time you recommended TTC004B as a replacement for the PZTA42 (different package). We just need something with a flat hfe-Ic curve to, say >100ma at VCE=10V.

[JoaMat]

Seems simmconn reads shematics. Regarding Q12, schematics and gerbers don't match, I think.

[kevin gilmore]

power supply schematic updated. amp board updated.

circlotronpsupdated.pdf

 

kgsshvcarbonv6.1c3cs - CADCAM.ZIP

Edited October 29 by kevin gilmore

[Michelag]

Wow!

But just for my understanding, this is the limit after which damage to earspeakers can occur, right? 

I mean, so much power is really needed to drive the most demanding e-stats? 

Or is it thought as an exercise of pushing it to the boundaries ?

 

[kevin gilmore]

max voltage swing is 4 x bias.  so 580 x 4.  the amp does loose about 20 volts of voltage swing, so 600 is a nice number. same voltage the koss uses. also the rating on the pnp transistor.  could cut the voltage to 550v for a bit more margin.

 

[psyduck]

Though running it close to max bias will probably damage your hearing.

[kevin gilmore]

surprisingly on something like a 727, the peaks are already clipped at moderate volumes.  so this will let all the wonderful dynamics thru.

and damaging you hearing, definitely.

[15lyl]

Such high voltage is too close to the head, will it affect the brain? say cancer.

[spritzer]

No.  Given the simple physics that the force of an electrostatic field falls with the square of the distance, it quickly vanishes into background noise before even reaching the skin.  An amp like this would never be run at full tilt, not into Stax compatible drivers at least.  Well past 120dB so permanent hearing damage until they simply burn up.  That means the field is even weaker than that in reality.  

Ideally you'd never want to run the headphones above say 1200-1400Vppss (which is already crazy loud) as depending on the air parameters around you, is could destroy the headphone drivers.  Now there are a lot of variables at play here but a rule of thumb says insulation of air is 3kV/mm and we are running at 0.5mm spacing so 1500V.  I go a bit lower as humidity is a huge factor here and the new Stax drivers appear to be anything but stable so I'd err on the side of caution with them.  I've noticed some very alarming behavior from the X9000 and the 007S so yeah... Stax will never side with you if you have driver damage.  

[15lyl]

Thank you for your explanation, Spritzer.