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JimL

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About JimL

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  1. The Headcase Stax thread

    Apparently according to a post on HF, the Jr. will list at $4k for the headphones alone.
  2. The Headcase Stax thread

    I asked about transformers and the Woo guy said no, but he may have thought I was only asking about output transformers.
  3. The Headcase Stax thread

    I can confirm that the Shangri-La was not working. Someone at the HFM table said it's been shipped around a lot and I just said, "uh-huh," in my best John Wick imitation. the Shangri-La Jr. was working, but the person at the table didn't even know what output tubes it was using, and the HFM literature was just pictures with no text. Also, they had a second HFM stat headphone sitting on the table unplugged and when I started to plug it in to the Jr. amp a person at the table stopped me and said, only one headphone at a time, even though the Jr. amp had two output jacks. OK, whatever.
  4. The Headcase Stax thread

    So, a little more on the new Woo amp. One 6SN7 per side, two 300B outputs, "proprietary output technology." The Woo person refused to say any more about that, except he said the GES was output plate resistor and the WES was output chokes - common knowledge, and implied that this wasn't either of those. My BS sensors were on at that point. I asked about how they got enough gain and he was not forthcoming about that either. Forgot to ask if they are still using passive power supplies. Also, didn't notice at the time, but although it looks like the amp is the upper chassis, the headphone jack looks like it is coming out of the lower chassis, where the power button is. Don't know what that is about.
  5. CanJam in NYC Feb 17-18

    Will be at CanJam tomorrow AM, but leaving to meet friends at around 1 PM.
  6. KGSSHV Carbon Build Thread

    Not really. If the parts are fake and you solder them in, what you save in money you lose in time with a broken circuit. And then, you have to spend more time and money removing the bad parts and buying and installing real parts. Not worth it IMHO.
  7. The analog thread.

    A look on the VInylEngine cartridge database failed to turn up any Apogee. Perhaps a look at that website will refresh your memory: https://www.vinylengine.com/cartridge_database.php
  8. The analog thread.

    Perhaps you're thinking of one of the Adcom HO MC cartridges. They had a line of them for a few years, got good reviews in Stereophile by Anthony Cordesman IIRC.
  9. krell ksa5 klone

    Depends on what its function is. As Kevin Gilmore points out, for a servo, an op amp with virtually no offset current (JFET rather than bipolar) and low temperature drift, that is slow (since the servo is monitoring for DC offset and is deliberately slowed down anyway), is good. OTOH may sound like crap as an amplifier, where the requirements for "good" are significantly different.
  10. The analog thread.

    I would go with MM for a poor man's rig. MC tend to have lower output which puts more demands on the phono stage - higher amplification plus lower noise, or need for input transformer = more complication = more money.
  11. Blue Hawaii BJT Build thread

    Nice! BTW, probably the reason the BH is running cooler is that you've got 70+ watts sitting outside the case (those 4 EL34s at 9 watts filament power plus 9 watts plate dissipation per tube).
  12. The Headcase Stax thread

    Partly that, but by all reports it sounds like Dan is a nice guy, so that likely rubs off on his headphones. OTOH if he was an SOB...
  13. Blue Hawaii BJT Build thread

    I like to run my filament 5% low, which is 6 volts. I believe David Berning, who designs for long tube life, likes to run his 12.6 volt tubes at 11.5 volts, and his 6.3 volt tubes at 5.7 volts, which is close to 10% low.
  14. KGSSHV Carbon Build Thread

    So, here's where a little math beforehand would have helped out. Now, the 10M90S is specified as having a thermal resistance of 80K/W junction to ambient (K = Kelvin, so 0 degrees Kelvin is absolute zero, each degree Kelvin = 1 degree centigrade), and the C2M10000170D is specified as having a thermal resistance of 40K/W junction to ambient. As these devices are rated to run below 150 degrees centigrade, what this means is that the 10M90S without heatsink is rated for less than 2 watts, and the C2M is rated for less than 4 watts. The 10M90S split the PS voltage between them (for as long as they were functioning), so 400 volts each at 20 mA = 8 watts. Running a transistor at 2 and 4 times their rated power dissipation will blow them in short order. If you've ever seen the actual size of the transistor inside its case you will understand why they can get fried quickly by being overstressed. Therefore, you need to replace ALL the C2Ms,all the constant current source 10M90S, and all the DN2540s as well, unless you're absolutely confident that the other devices protected them like a fuse. Which I doubt. Murphy's Law: a transistor protected by a fuse will blow first, protecting the fuse.
  15. The Headcase Stax thread

    Probably because it's the cheapest amp around.
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