dsavitsk

Travel mugs on Woot (12/02/2011): http://www.woot.com/

I saw a little kid use a floor model toilet at Sears once.

Happy Birthday, Pavel!

Happy Birthday!

I am pleased to announce two new headphone amplifiers from ecp audio: the DSHA-1 and the L-2. The DSHA-1 is a fully differential (balanced) solid-state headphone amplifier. Designed for exceptional synergy with Grado headphones, it is an excellent choice with other dynamics as well. It is extremely clean, clear, and detailed yet tube-like in its warmth. The unique differential topology uses Lundahl amorphous core input transformers to provide noise free voltage gain (selectable to 6dB or 12dB) and high CMRR (better than 120dB at 60Hz), and MOSFET source followers for output power. The output is transformer coupled: eliminating capacitors from the signal path and allowing the DSHA-1 to work equally well with balanced and single ended headphones. Further, the differential nature of the DSHA-1’s circuitry isolates the signal from the power supply. In addition to an exceedingly quiet amplifier, this means that bass transients are not powered from large capacitor banks, and mids and highs do not pass through noisy electrolytic capacitors. The L-2 is a single ended “spud” parafeed tube headphone amplifier for dynamic headphones developed out of the L’espressivo line of DIY projects. As a single ended tube amplifier utilizing a single 6S45pi tube for both voltage and current gain, the L-2 has the musicality and liquid clear midrange tubes are known for. However, because of the novel shunt-regulated biasing arrangement, the high performance plate load, the short signal path, and the extremely high quality parts used throughout, the L-2 surpasses the usual limitations of the SET topology. It excels in dealing with complex musical passages and heavy bass notes. Further, the L-2 is so quiet that even with sensitive headphones, you cannot tell whether it is on. There is no hiss, no hum, just quiet. The L-2 uses Lundahl input transformers, V-Cap parafeed capacitors, and custom designed, nickel-core, Electra-Print output transformers with both low (32 Ohm) and high (300 Ohm) impedance taps. All of our amplifiers are craft made in small batches and hand assembled in Chicago. The woodwork is hand made from sustainable stock at Pickett Furniture in Brooklyn, NY, and the metalwork is machined and finished in California. The DSHA-1 is available from $1995 shipped in the USA, while the L-2 starts at $2495. For questions, please email [contact at ecpaudio.com], or use the contact form at www.ecpaudio.com. More information is available from www.ecpaudio.com

Sounds like something in the heater supply came loose during shipping. Since both sides of the tubes failed together, my best guess would be that it is likely a wire connecting to the regulator. If you know a decent tech, it may be something that can easily be repaired.

All reasonable points. The person who asked me to design something requested tubes. And, I'll take the Allen Wright position that tubes sound better, even as followers. I'm not sure I believe this, but I'll say it anyway. But, as for comparing against triodes, the issue there is that as the tubes age, or as a different tube is used, rp changes which influences the riaa acuracy. You can use a large output resistor, but unless it is really large, tube changes can still matter. With a cascode, or pentode for that matter, since the Zout is almost completely governed by the load, the filter is much more tightly controlled even as tubes die. And I've built an all triode phono stage. Seemed like something different might be interesting, and my ear prefers pentodes to triodes these days The irony is that the person also needs a line stage, and for that I basically copied SY's Heretical line stage, but I did so with all sand parts.

Happy Birthday

A friend asked me to come up with a phono stage that is of reasonable quality but not too over the top. Here's my first go. Basically, it is a hybrid cascode gain stage followed by a passive RIAA filter and a cathode follower. The idea is that the single gain stage should not only provide enough gain, but it should be reasonably quiet. The Zout is also governed by the plate resistor which keeps the filter stable even as tubes age. In a sense, it is much like Pete's pentode phono, other than that the cascode should be a bit quieter than a pentode. That's a lot of should's, so it remains to be seen whether it actually works. The only really tricky part I anticipate is selecting the JFET for having the right current with the right gain resistor. A negative supply such as Vacuum State uses with a similar (though differential) set up would alleviate this issue, but I am trying to keep it as simple as possible and I do not want to add another PS, or a virtual ground on the bias supply if I don't have to. For the power supply, in order to keep things as simple as possible, I wanted to use an off the shelf power transformer. Antek has a bunch of toroids with a HT winding and a couple of 6.3V windings. So, for the heater, I just used schottky diodes and a LDO reg. Their windings are generally spec'd at 2A or something, so there should be a bit of voltage headroom. For the bias which needs ~10-12V, I used a voltage doubler follower by a LDO linear reg, followed by the shunt reg shown in the schematic. B+ is a CLC or CRC followed by a simple shunt reg (CCS and a mosfet biased by some zeners).

A day of reflection. I didn't mean to stir so much up, and I definitely stepped in it. I apologize to KG directly, and to everyone else. So, I'll sit on my hands for a while.

I don't understand why they would?

That's exactly what I was saying, that the arbitrary application of law erodes trust in institutions. Sorry if I did not make it clear.

Oh my. When I posted the initial post that started this whole mess, I did not think I was accusing anyone of fraud -- I really thought KG was bragging that he had done it willfully. I like KG, I was just calling him out and giving him a hard time. (The second post is, admittedly, a little more serious.) With the clarification, it is certainly a different story. And, one I am quite sympathetic to. So, can we call it a misunderstanding and let it go? If you think my argument is weak, you should say so. I don't take it as a personal attack. I don't agree, but that's OK. I have made plenty of weak arguments in my life. I have quiet support? It is, ironically, one of the best arguments for why fraud is such a social problem. It erodes trust in public institutions that are necessary for the maintenance of functioning societies.

I can't speak to the Icelandic law. I was simply reacting to the statement suggesting that duties were lower than they should have been due to "creativity in shipping." If I overreacted to that statement, then it is my mistake. As for filling out the customs form incorrectly, if that os indeed what happened, how about http://www.law.cornell.edu/uscode/18/1001.html

Where exactly is the line between fraud that is fraud, and fraud that you don't think is fraud? Simply calling my argument ludicrous does not refute it.

Was fraud the cause of the bankruptcy? Yes. How much was this worth? $1000? What if they posted that they found some random guy on the street, grabbed $1000 out of his pocket, and ran? Or stole his CC number and charged this much to it? Would that be OK to call them out on? Or $500 each from 2 guys? How many people does the cost need to be split over before we no longer care? There are ~300,000 people in Iceland, so if it was $1000 this cost them $0.03 each. The total cost of street crime is less per year in the US than the amount of revenue lost to just tax evasion, which is close to $400 billion. Split that over all 300 million people and that's $1300 each we pay to subsidize this. Something like 50% of farm income, and 40% of business income is not reported. Fraud adds another $800 billion or so. And this is all outside of the financial crisis, which costs trillions. I have no tolerance for white collar crime. So yes I really posted that. I can't believe they bragged about what they did, frankly.

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Happy Birthday!

I bet they play better than this Thurston Moore album I have ...

For the very cheap, Pioneer SP-BS41-LR Bookshelf Loudspeakers @ woot for $100 http://www.stereophile.com/content/pioneer-sp-bs41-lr-loudspeaker

Happy Birthday, Al!

20 If in fact UE is not going to use the patent, it probably just means that someone will have to pay a licensing fee. 20 years is a long time in technology terms.

You seem to, which is fine. But, to be clear, what you seem to care about is the commercialization of the amp, not "about it." I don't know if you care about it, and I don't care whether you do. I don't actually care if you care about commercialization either, other than to say I am confused about the whole thing. Apparently not. But, you have not posted anything I have seen to illuminate your point. I am not going to debate the designer's disposition. My understanding is that he claimed that a certain amp did not meet its published specs. Seems like a fair thing to post, and not an attack. I don't actually know if it does or not, but that is the sort of thing that can be settled reasonably easily. What basics are wrong. He designed an amp that meets its specs. The PCB may be sloppy, but it seems to be good enough for what it needs to do. What else do you not like? Not sure whom this is a swipe at. But, as I say, I just want to know what the actual objections are. Anyhow, this is like movie censors that drive up audiences by being outraged. If people had just ignored this guy, there would not be hundreds of these in the works.

A. Who cares, B. The only such rumors I have seen have been from you, and C. The ground plane on the PCB is indeed a little messy, and there appear to be traces to nowhere. However, it seems really unlikely that any of that will actually influence performance negatively. Perhaps it reflects badly on the designer as someone who is not particularly detail oriented, but all empirical evidence seems to indicate that the amplifier operates as advertised.

Best thing I've learned is to farm out casework to professionals whenever I can It is broken pretty flush to the case. But, there is a little wiggle, and the tap tip is fluted, so I may be able to stick some thin metal bits down these channels and turn it just enough to expose enough to grab with some small pliers. Maybe some vibration would cause it to extract itself? I could put it on a UPS truck for an afternoon.