Recent content by bobkatz

Direct coupled versus transformer coupled: the sonics. I am sad to report that my Estat amp build using a Pascal 80 watt amp and a high quality toroidal output transformer is a bit too colored at least for my taste. It sounded very pleasant with either the Stax 007 mk2 or the Audeze CRBN1...

Dear Aokman: You're truly giving to the community! Many thanks. It's encouraging to learn that the XP power has output protection modes. That's worth a lot. In my past builds I used an amazing Bertan regulated DC-DC converter with 2 mv ripple! But it's very expensive, as is the Emco. I wish we...

I agree that UHV has no experience dealing with English-speaking clients. But I've been down that road before and at least they give an output voltage and current. Personally I'd prefer a regulated supply to keep the ripple down. An unregulated DC-DC converter can be rather noisy. I'll let you...

I've seen the video and thank WCGR for the leads! I bought the 600 volt regulated module that Kevin found. The overvoltage circuit that WCGR developed is on the 5 volt side of the module, so it won't protect from catastrophic issues AFTER the DC-DC converter.

Thanks, Kevin. It protects the phones, that's the cool thing. If you come up with something more complicated with, perhaps a warning light that the bias failed, I'd love to see your invention!

I'm a big fan of using equalization to finalize or polish even an already-excellent headphone. I use the RME ADI-2 FS to accomplish this... it has like 20 equalization slots that you can use for each of your headphones. I have both the 007 Mk2 and two Audeze CRBNs. The 007 is modded with...

Now for the sonics! With the 5k load, the sound is much less "transformery" and more transparent. It's a win win for me, the transformer has begun to disappear. Most people would not be able to tell anymore that this is a transforrmer-based energizer. This thing can be built with $500 in parts...

Bump. If anyone has a 600 V overvoltage protection circuit for bias I would love to see it.

Progress report on terminating the 15 watt transformer. I got some 5k 100 watt resistors from Digikey. These are designed to go on heatsinks. But jeez, they get VERY hot with sine wave testing. I burned one out (down to about 300 ohms) with testing at "only" about 500 volts RMS at 1 kHz sine ---...

Wow! Keep on keeping on, Kevin.

Good point about the lack of overvoltage protection in these modules. What would be a good overvoltage protection circuit for 580 V DC? If anyone has one I'd be grateful. Thanks.

More discoveries: Linearity of frequency response of my transformer-based amp, which uses a 15 watt toroidal transformer. I have reported in this thread that there is a rising HF response at the secondary. The response is -0.5 dB at 20 Hz, flat by 50 Hz or so, flat at 1k until it's +0.25 at 10k...

OK, thanks. So the source impedance is going to be hopefully less than 25k so a 10 Meg TVM will not meaningfully load down the measurement. Well done! I will steal those values from you!

I was just worried that for a low value resistor divider, the wattage resistors required would be very high, and for a high value resistor divider, then you run into precisely measuring the actual voltage even with a high impedance VM or a 10X probe. The higher the value of resistors in the...

BIAS supply questions. Again, if my design question belongs in another thread, please alert me and I'll repost. Thanks. The questions are: 1) Regulated bias supply or unregulated? • Advantage Regulated: The UHV-power regulated supply module, model USA24600S-4, available from lcsc.com, is...