dsavitsk

I live on the top floor of a poorly insulated building in Chicago with southern and western exposure. Even when it is not that hot out, it is hot in here. Does anyone have personal experience, or access to reviews, to suggest brands and/or models of window AC units that are quiet above all else?

Even if the DIR9001 "sounds" better, I'm very doubtful it will make any difference in this particular DAC.

Sad, but have you seen the price on the 1704 lately? And you need 4 for a differential design? It looks like they will be available for the foreseeable future.

Happy birthday, Ari!

A reminder that I have a small number of DSHA-1 prototypes available. Circuit wise, these are virtually identical to the production version. The differences being that these run at about 75% the current of the production version, and they use the LL1544a input transformer rather than the LL1674. Both transformers are high quality, amorphous core Lundahls. The difference between them is that the 1544 is a 1:1 or 1:2 step up while the 1674 is a 1:2 or 1:4, and the level handling of the 1544 is a bit lower, so with a very hot source (Meridian), you can clip them in the extreme bass. That all means that the protos won't go quite as loud. Subjectively, they feel like they have a little less bass weight. However, they represent about 95% of the performance for much less money. They do quite well with both Grado and Sennheisers, and are what I use for general listening. These are $925 shipped in the US. Each comes with the AC wall wart power supply and a balanced to TRS adapter for using unbalanced headphones.

There are two different power supplies for the DSHA-1. One of them (the "ecp power supply") uses the same case as the L-2's power supply except that there are no venting holes cut in it. It is 8" x 4" x ~2.5". The other is an off the shelf AC wall wart (basically a transformer in a box).

Happy Birthday!

Soniccraft has many of the same caps, and tends to have the same sales. They list their specials at http://soniccraft.com/specials.htm

It's on Netflix streaming, too.

It isn't easy to get to via public transportation. But, it is worth the trip.

Getting in is kind of hit or miss. I was actually really underwhelmed when I went. But, the friend I went with who was also unimpressed, went back and said it was tremendous. So, we seem to have been there on an off night. It really is. There is nothing fancy about it, but I'd go every night if I could. The potato croquet appetizer is really good. They also often have a grilled eggplant special that is amazing -- and I don't generally like eggplant very much. Actually, my wife and I tend to order just about all of the appetizers. Between the two of us, it is hard to spend more than ~$30. Oh, and to celebrate their 25th anniversary, Charlie Trotter's is closing, so if you have any inclination to go, now is the time.

Where in Chicago will you be? I'd add Avec to your list. And Frontera Grill or Topolobampo, particularly if you are downtown. Personal favorites, all in Lincoln Square/Ravenswood/Andersonville Spacca Napoli, Los Nopales (both were some sort of James Beard honorable mentions, or something like that, and both are easy to get to on the Brown line), Sunshine Cafe (a hole in the wall, good, cheap, and very friendly, but not trendy -- bit of a neighborhood hangout -- walkable from the Red line.)

Does anyone have a part # or source for the caulk like goo used to stabilize parts on a PCB?

Tomb has the PCB and the transformer in hand. It is just a matter of finding some time to actually assemble the thing.

Happy Birthday!

ftfy

Seems to work here -- I clicked the media player icon.

Value of a life is generally higher than the sum of the parts in this chart, though it is surprisingly close:

His rhetoric is ridiculous, his claims are unfounded and without citations, and his designs are boring. But, really, he has to release his project as a kit for DIYers? I don't see where he owes kit builders of the world anything. Who cares if he makes a commercial design. If you don't like it, don't buy it. But why does this guy have so much power over the audio world?

I don't know as I've never measured them -- you'd have to ask the designers. But, I am not saying that they are necessarily or always overdamped -- I am saying that with certain headphones they might be. And that when people describe certain headphones as being bright, or shrill, this may be the reason. It is really a personal preference. But, there has been an emphasis on amps with a near 0 Zout for a while, and my experience says that it is not always the right choice. By the way, take a look at the Zout spec'd for the Apex Pinnacle http://viewer.zmags.com/publication/b0edde2a#/b0edde2a/2 ~12R for low Z and ~45R for high Z cans is where my experience says the sweet spot seems to be as well.

It isn't necessarily the case that the source is bright, or even that the amp is bright. Instead, it is often the case that the system of amp + headphones is overdamped leading to a bright sound. People describe this as being clinical, or neutral, and often think it is more accurate. Some people even like it. But, it is not necessarily "truer."

Ran across this while cleaning out a closet. Good stuff.

They are almost surely standard M6 lams with the E's on one side and the I's on the other -- it is a SE amp and the transformers need to be gapped.

To grossly oversimplify, there are a number of ways to do it. One, as Ryan suggests, is to just have tons of inductance (this is the Lundahl way). Downside is more windings, and possible loss of linearity. Or, you can put a resistor in parallel with the output. For instance, on the "16 ohm" winding, with a 20R resistor, Grados would appear as 12R, LCD's as 14, Senns as ~18. All of these are likely close enough (like everything, the lams in transformers have a big +/- to their specs and you would generally design for worst case.) The upside is that if the load has impedance peaks, this reduces that effect to an extent (though this is hardly the case with most headphones). The downsides are that, unlike with multiple taps, there is a different power rating into different phones, and like a OTL amp, in order to have the voltage swing for high Z phones, you'll have too much gain for low Z phones. It also often requires a bigger core*, which lowers the quality, and increases the cost of the OPT. * for a given core size, each wire loop can handle a certain voltage before saturation (audio transformers are rated in voltage swing, not wattage as is commonly used). So, as the voltage needs of the primary increases, the number of windings must increase. For example, to put 1W into 300R phones with a 5K:300 transformer requires a primary voltage swing of 70Vrms. However, to do the same with a 5K:16 transformer, assuming a parallel resistor, the primary voltage swing is ~300Vrms. Thus, not only a bigger transformer with more copper, but also much more stress on the tubes, and forcing them to operate in a less linear range. Or, you can have multiple taps. The down side to that is it costs more, and makes the winding more complicated, and if there are too many taps, you can start to lose linearity. Where that happens depends on the particulars. Every designer makes the tradeoffs they think are appropriate, so there is no "right" way to do this.

That does not sound very charming to me. Try Innerfidelity