Hi Mark! This converted SRS005 set is now in operation. Punchy bass, decent mids and clean highs excellent. The notch filter in the CS4344 DAC (3.9 mH-SMCC + 180pF mica) reduces 4fs peak (176kHz) to remarkable 12dB and reduced overall even the noise spectrum of the Jensen transformer...

Maybe the JVC RX900 ? I remember that the specs of both indicates that they have the same driver (64ohm, 3000mW,Bandwidth) The RX900 is just semi closed, but this may leads to a larger soundstage.

The switching frequency of the HV generation circuit seems to be 72 kHz (with C33=C_T=10nF and R33=R_T=1.8kOhm, see SG3524 datasheet). The bandwidth of the amplifier should end way below 72kHz, but reducing the gain will increase the power bandwidth, so I don't recommend my feetback mod...

The quit noise measurements of my modified SRM252 (Tantals+HighCaps+x250gain) shows slightly more spikes below 3kHz and less above (same for left channel):     The rectangular response shows no significant difference between the unmodified (252rec_r) and the modified version...

Here are two more measurements of the quiet noise at the amp output with another linear 12v power supply.  (unmodified (500xgain) SRM252 unit, input poti at minimum, driving SR003). Worse peaks even between 3 and 4.5 kHz. Shows a relative big influence of the wallwart psu at the amp...

Quote:   Yes, 22uF/250V. I measured the silent noise of the SRM252 (with a silent track from CD) driving the SR003. It shows significant spikes that could come from the HV generation circuit.    

Quote:   If the HV capacitors (220uF/250V(?)) are loaded via R23, R24, reducing their values could have unwanted effects (increasing/reducing/deforming the loading impulse etc.). I can try some measurements with my digital osco (hope it will survive this), at least to find out if...

Quote:   The induction pulses could decrease the sound quality by modulating the ground connection (resistive coupling). Reducing the ground resistance by soldering a wire above it may help.

Can you post the schematics of the internal psu (with these 750ohm resistors) ? The HV generation via induction pulses will surely limit the available energy. May the current be with us. Happy new year!

Quote:   Ok. I didn't take the limited current capability of the SRM252 into account. Nice that I heard an improvement (maybe self-biased, or the volume wasn't loud enough to hear the amp aching;).   So, with the original 300k feetback resistor and with 130kOhm load (SR202 at 10kHz)...

vanishing

Quote: Give it Kevin Gilmour (60Hz!).    

Probably just some parasitic charges on the diaphragm are responsibel for this seeming dismishing failure, by shielding the bias loads, so that the SPL decreases, effectively reducing the bias voltage (?), so that the diaphragm could bounce against a stator, maybe even stick, and binding...

Apart from the bad bias connection Spritzer mentioned to be the problem, and the less tension Wachara mentioned, there could also happen the following scenario: The Sr009 collects dust (maybe more than usual, maybe just when it's new) that forms an electrical connection between the...

Quote:   Quote:     Probably, if the diaphragm bounces the electrode, the high impedance bias can't dominate against the low impedance output (at least at the bouncing spot) and it'll be over with the bias loads. But then polarisation of the diaphragm (in the...

Even the diaphragm don't move like a piston, if the diaphragm looses tension, this would allow more excursion and thereby increase the sound pressure level (if not electrically damaged), or  ?   Did the failure also occurs with the SRM323 ? I saw Kevin Gilmours SRM323 psu schematics...

Regards to you, Wachara! Sry for my unawareness . Tenson, hmm... So, a diaphragm under normal tension/biased can't reach/stick to the electrodes ? Seems, the SR009 hasn't got a vent like the SR007. Is it possible that the diaphragm bounces a stator when setting the headphone on (with...

Seems to fit, Currawong! So, loads on the electrodes binds the microscopic dust Stax said.  

If the diaphragm sticks on a stator, like Currawongs experience with this kind of problem indicates, this could be a result of the new multilayer stators, which "have been completed through the unification of metal plates" (like Stax write in their SR009 brochure). When they use different...

Seems that Manfred Mann also praised the HARX700 in their lyrics:   You are the moment Martha's madman came out of darkness, You are the eyeglass of the nearly, nearly blind, You are the footprint in the sand of Easter island, You are the fusion in the furnace of the sun. You are the...

You can buy RX900 earpads for about 30$/pair at:   http://store.jvc.com/product.asp?Model=J48247-001 http://bluetin.com/catalog/victor-jvc_victor-jvc-rx-900-j48247-001-earpads-pair-for-ha-rx900-hp-rx900.html   http://global.rakuten.com/en/store/e-earphone/item/1052/

The data you posted shows that lifetime of electrolytics doubles with every 10°C.   I'm focussed on lifetime vs temperature here without regarding other parameters/effects/types etc.   Laws of nature don't require real data to be right, even reality is typically complex by use.   If...

Quote: The speed of chemical reactions doubles when the temperature is increased by 10 degrees celsius (Arrhenius Law), so the lifetime doubles with every 10 degrees less working temperature (thereby, just for example,  105°C caps will live four times longer than 85°C caps (at 85°C))...

Do the SR007 and the SR003S also have the new SEP (super engineering plastic) membrane ? One post of Spritzer seems to indicate that for the 007 (...MK2.5...) since autumn 2010 (serial no 3xxxx) and www.stax.co.jp listed the SR003 under the 'new lambda series'. What about the thickness or...

Seems there exist 22uF HV caps that will fit (height 20mm, diameter 10mm) and have a higher voltage (350V instead  250V) than the original ones. Maybe they have a lower ESR and/or will last longer.   By comparing the modded 252a with an unmodded one (serial number 1 apart), the modded...