jcx

I'm curious what people do about the lead spacing creepage/clearance - TO-220 only has ~0.028" min spacing at the lead entrance to the package - not enough to meet any consumer safety standard without coating obviously lots of stuff gets built without extra coating, sleeving, lead forming but not so much at 450 Vdc the TO-247 package has more reasonable lead spacing, ~2 mm but still dosen't work with the 0.6 mm+0.005 mm * Vpk IPC-9592 formula I once found but have since lost a reference to kV blocking sub 100mA fuses - not real common and why is my font so small?

iPods will drive the LCD-2 to 100 dB SPL - so why so much discussion in this thread about amps?

do I have to go into dynamic peak headroom details here too? - the other place I've come to expect such inanity

using 50 Ohm, 91 dB/mW requires +/-10 V, +/- 200 mA peaks to reach 120 dB SPL some people may be happy at 1/2 the I,V for "only" 114 dB SPL peak at clipping - as push-pull Class A which can deliver up to 2x the bias currrent the DynaLo and M3 should manage this lower power the M3 "3-channel" active ground can't sink both R,L channel peak current in Class A, but a properly set up 36-40 V supply M3 should be able to drive the LCD-2 to 120 dB SPL as long as you don't mind the idea of the output gnd channel Mosfets running Class AB on (rare) peaks do remember that the stadard AD8610 op amp in the M3 can't take higher supply V and should be swapped to opa604

biasing back-to-back electros is a very old recommendation - past its "use by" date Bateman's "Capacitor Sound" articles showed lower measured distortion from bi-polar Al electros which have full thickness oxide grown on both foils ploarizing V will increase microphonics - just like a condenser microphone

err - that N*Ac number would be 90,000, not 900,000

my comments were general - how hard it appears to me to make an appropriate xfmr for for sub 100 pF es headphone loads for the full audio bandwidth I was playing with the numbers for Koss esp950 - since the K90 uses +/-600V H-bridge drive a similar drive V from the xmfr will require ~800 Vrms stuff 800 Vrms, 20 Hz, 10,000 gauss Bmax into the Faraday relation and I get ~900,000 N*Ac at 10,000 turns that's 9 cm^2 9 cm^2 effective core area looks very big to this engineer with very little xfmr design experience - when I only need a (few?) W of circulating pwr max in the headphone Cload the parasitic capacitance is just a "guesstimate" from some tube power output xfmr resonance peak #, a old Magnetics catalog, and measurements of toroid pwr xfmr similar to those suggested as "poor-man's" push-pull tube amp output xfmr

very curious about es headphone xfmr design - when I looked at the numbers inter and intra-winding capacitances were several times the headphone's load C - and the Iron cross section is stupidly huge to get down to 20 Hz

very dynamic music peaks may be ~25 dB above average levels, 95 dB pk spl from the senns would require < 1 mWrms if this is truly your listening scenario then you really don't need an amp - at worst just modify your source line out stage with a ccs load of ~4mA and any reasonable quality audio op amp will happily drive your cans with inaudible distortion in Class A I wouldn't expect anyone to be able to make fine distinctions at such low average listening levels - certainly little recorded music would "sound live" simply due to the Fletcher-Munson loudness effect changing the perceived frequency balance You do need to keep the level far below most live presentations for extended ”background music” listening of hours a day but I want an amp to drive my cans to near live levels if only for a