dsavitsk

300B is hard to drive well. How about putting a follower between the driver and the 300B. Jack has done such things. I think you can do a better circuit than the opamp as driver, but it is a quick and easy solution. The biggest hurdle is the step up transformer as it will need a sizable core (or a ton of windings) to deal with the voltage swing. Something like a Lundahl LL1689 would work. The 119DA might. If Hammond's rating is to be believed it should swing 80V or so. The voltage gain is low, so maybe pair it with a 1:4 step up before the driver circuit.

+1

I have no idea what's going on here, but I miss Chicago

For people who like OTL amps: http://www.mouser.com/ds/2/440/WIMA_DC_Link_MKP_5-1184.pdf

Happy Birthday!

Sorry I missed this, and very sorry to hear about your kitty. A good resource for all things CKD http://www.felinecrf.org/

Indeed! At least for now, the plan is to do a small run of Black Diamonds. I am just investigating some machining issues right now, so hopefully they'll be ready this fall. Work has also started on a DSHA-2, but I haven't even prototyped it yet, so it is probably a winter or spring thing, if it works at all.

Depending on the material, you can get a pack of 100 of these from McMaster for as low as $1.49. Unless I am missing something. I am sure I have piles of them, but they are still in boxes. If nobody else has some, I'll send some in a few days.

It's like telling an F1 driver who has a very small track with insufficient room for an F1 that when he has to practice on that track, to practice driving a Toyota Yaris. As an alternative, our house has 8" thick plaster walls and cement layers in the floors and ceilings. It blocks sound really well, so you could do that.

Practice with one of these

Are you sure that it isn't one side of the amp that's noisy?

The Cinemags are very nice, but you'll lose a little resolution. The Jensens are essentially identical but they cost more. The Lundahl LL1592s are a little more expensive, but resolve enough better to make them worth the difference to me. The Lundahl LL1690s are more expensive still, but are absolutely transparent. They are what I used in the L-2 by default.

Input transformer is never overkill ...

glad to hear she is doing better. lots of good advice. for food, lots of cats love baby food. just make sure there is no onion or garlic in it - pureed chicken and turkey go over well here. also, strong smells sometimes work. our old vet used 9 Lives tuna for getting post operative cats to eat. truly the nastiest food on earth.

happy birthday!

very sorry for your loss.

Refenestration?

HBOGo via a Roku? Or a cable from a laptop to the TV, or Google's new Chromecast, or some other screen sharing technology. The first few seasons of The Wire are low def, so the delivery method does not really matter that much.

I stayed in a hotel in Italy where the toilet was in the shower. Nice scooter, Steve. I spent the day doing trigonometry.

The Z out on both the L-2 and DSHA-1 on the high setting is ~40 Ohms. On the low setting, it is lower, ~10 Ohms for each. Much of this comes from the copper resistance in the transformers. Adding series resistance on the low setting will make both sound worse. This is because the transformers only have so much inductance. Beyond a certain point, the load has too high of an impedance for this inductance. Adding the series resistance will create a mismatch and you'll lose bass, and just muck thing up.

It's a little weird. I could see converting to digital and doing the RIAA using DSP, but as is it makes no sense.

I tend to think it is the opposite. With complicated crossovers, a non-zero Zout will lead to the crossovers operating at a different point than they are designed for. It is likely part of the reason that high Z out is not that detrimental to headphones -- they are more like single driver speakers in this regard. Again, I'd think the opposite: if the drivers are not damped, then you would want a lot of electrical damping. As it is, since high damping factor seems to over damp things, that suggests that the drivers themselves are reasonably well damped. On the other hand, output impedance may well be a red herring here. If the drivers are not damped, then they would kick back lots of back emf, and it could be that they don't play well with amps with lots of feedback due to this. So perhaps they need some electrical damping (and 300/50 = 6 is actually a reasonably high damping factor) and that you want enough, but want to avoid doing it via feedback to keep from generating high order harmonics. Here's the L-2's THD which, if nothing else, is free from high order distortion. DSHA-1 is sold out, if that makes things easier Adapters are not included, but I end up supplying a lot of them. Part is Neutrik NA2MPMF.

You'll probably need some voltage gain. I was working on such a thing before everything went into storage, so look for it this fall/winter ...