dsavitsk

Everyone has pain, be it physical, emotional, or existential, and everyone does what they can to alleviate it. Every alleviation strategy has risks. Narcotics seem to be a poor choice for pain management, but then it is impossible to understand someone else's pain and what it might drive them to. I think the best we can do is hope that none of us are ever in such extraordinarily pain that something so risky seems like a viable option.

I'm glad somebody else said it I am thinking that the best option may be to offer the option of a clear top that would be in addition to the metal one. If someone liked it, they could order it and put it on.

You can't cut it in a laser cutter which makes getting it machined silly expensive.

The acrylic cases are, unfortunately, just not strong enough. I wish they were as it would give me an excuse to buy a laser cutter, but I just don't see it as a workable option. I looked into doing glass panels as I know the preference for see-through things, but it was going to be cost prohibitive to get done. If anyone else knows something about getting glass parts made, I am all ears.

Surface can cost less than $500, has MS Office, internet browsing, Skype, and a built-in camera.

Happy Birthday!

You might contact Tom - not sure if he has demos to loan out or not.

They should work. There are some CCS parts changes, different heater diodes, and heater diode snubbers to add. It is all pretty easy stuff. Also, depending upon who built your prototype, there is possibly a bias upgrade that makes a pretty big difference in the sound quality that they may not have included.

Nothing secret, just not really announced yet, which I guess makes it secret ... The next project will be a Black Diamond amplifier, based on this design: http://diy.ecpaudio.com/2012/11/black-diamond-headphone-amplifier-part-1.html http://diy.ecpaudio.com/2013/02/black-diamond-headphone-amplifier-part-2.html I have a final prototype mostly assembled sitting on the bench right now. I am awaiting delivery on the custom step up transformers which I am hopeful will arrive in the next week or two. Once they are here and I can verify that everything works as intended, I'll just need to have the various pieces machined, finished, and shipped to me. That process can take a surprisingly long time, but I am hopeful to have amps ready in late February/early March. As before, I'll do a small run of them, and when they sell out, I'll move on to something else. Not sure what that will be, yet.

Yes, there are a couple of cheap/easy mods that gets rid of just about all of it.

Baking. There are certain textures you can only get with shortening as it does not contain water like butter. But if you use all shortening, you lose the flavor from butter. It is an attempt to split the difference. And it is vegan and thus dairy free for those with allergies or dietary restrictions.

Happy Birthday, Frank!

Happy Birthday!

They are definitely noisy, and the impedance is surprisingly high -- upward of 300 Ohms. Where I have had OK luck with them is fed by a CCS and used as a bias for a pass transistor like an IRF810 or something. In that case, the impedance does not matter as the current across them is constant. However, they really are all for show as a zener still works more reliably, is quieter, and can be bypassed without creating an oscillator.

In a single feed amp, the point of transformer loading a tube is that it increases efficiency. That is, the power supply voltage represents the midpoint of the tube's possible plate voltage as it can swing above and below this point. This is as opposed to a resistor load where the power supply represents the limit of the tube's swing. This makes sense to do in a speaker amp where you need to squeeze all the power out of a tube you can. For instance, a 300B loaded with a transformer can put out around 15W of power with a 350V supply. In order to do the same with a resistor load would require a power supply over 600V with considerable heat lost across the load. This efficiency benefit comes at a cost which is that single feed transformers are necessarily compromised in quality. They must be gapped to avoid saturation, they must be made from non-exotic materials to avoid bass loss (and saturation), the core needs to be larger and the wire thicker to accommodate the DC both of which lower the fidelity, and they require more windings (to generate the necessary inductance) which increases winding capacitance, increases impedance, and further hurts quality. In a speaker amp where fidelity is not as sensitive as with headphones, these tradeoffs may well be worth it to keep amplifiers reasonable. However, in a headphone amp, this hardly seems to be the case. The power needed is easy to generate, and while they may be wildly inefficient, even inefficient headphone amps don't really use that much electricity. The two primary ways* to transformer couple and avoid compromised single feed iron are via parafeed and with push-pull. Indeed, push-pull actually maintains most of the benefits of the lower more efficient power supply, corrects most of the issues with single feed transformers, and adds the benefit of dropping into class B when necessary. And they sound better, too. So my objection here would be that is it just another amp that is just a scaled down power amp rather than being designed with headphones in mind. All that aside, even within the single feed paradigm, the above referenced amp does everything pretty badly -- poor quality power supply, poor loading of the driver, poor quality biasing methods, showy but noisy regulator, etc. So even if you think single feed amps are better in some way, this one is just not that good. * Intact winds DHT transformers with an additional winding which uses the filament current to counteract the B+ DC.

x2 I miss Chicago.

Happy Birthday!

Happy Birthday!

Oh my goodness. Get better, Ken!

It is not so much that they are discontinued, as that they were not recontinued. The idea is the come up with a design that I like, make a small run, sell them, and move on to something else. There are so many circuits to explore that doing the same thing over and over is just not that interesting. For what it's worth, I just ordered a run of transformers from Cinemag that should be here some time in late January. Hopefully completed amps will follow not too long after that.

Happy Birthdays!

Happy Birthday!

The Torpedo and Crack will teach you wildly different soldering skills. If you see yourself building one-off tube amps using point to point techniques, the Bottlehead is a good starting point. If you want to do primarily PCB based projects, the Torpedo is better. It is probably a good idea to get one project under your belt before jumping into future ones. Different people learn differently -if you are a book learner, Art of Electronics is excellent. If you are a hands on learner, start soldering working on other people's projects, and trying to trace what's going on. It is how a lot of us got into this stuff.