kevin gilmore

Remember that if its going to be at headwize, it absolutely must remain completely non-commercial. Otherwise i get in serious trouble. Bandwidth is certainly not an issue with an unlimited gigabit link, but at some point i have to start throwing more computers at it...

Those aren't batteries! This kind of stuff reminds me of stuff i used to do 40 years ago.

You are close. At the destination you put a resistor to ground in parallel with the output that goes to the amplifier. The numbers are as follows. I have yet to see a cable that is less than 45 ohms impedance. I have yet to see a cable that is more than 150 ohms. (300 ohm tv twinline, but i've never seen someone use that for audio) The stuff i use is 50 ohm pure silver very constant impedance over length cable made by gore cable. There are a bunch of good 75 ohm cables. High quality shielding is still mandatory for low noise. Typical solid state preamp output impedance 10 ohms. Typical tube preamp output impedance as little as 30 ohms (conrad johnson ART) to several hundred ohms (audio research)

Another one of those things that makes much of the industry really pissed at me. All cables when improperly used act as filters. You cannot possibly ever say that one is better than the other, all you can say is that you like the sound of this one over the sound of another one. Pick a cable, any cable, there are only two ways to use it. The right way, and NOT the right way. The right way is to terminate the source and destination ends in the characteristic impedance of the cable. Termination to ground at the destination end, and a value at the source end that when added to the impedance of the preamp adds to the characteristic impedance. There is only one real way to measure the characteristic impedance and that is with a time domain reflectometer. Of which I have a few including the latest that can resolve time to 25 pico seconds. Take any 2 of the most different sounding cables and let me measure and terminate them correctly. I then challenge anyone to listen to and tell the difference between them. Not even weeks of listening will give a definitive answer. Some of the fancy twisted and other geometry cables in fact show significant differences in impedance down the length of the cable. These should be avoided at all cost. Many preamplifiers with tube output stages present a significant problem as their output impedance is already to high, sometimes way to high. In which case a passive attenuator must be used to correctly terminate the cable. This can result in a loss of up to 10db.

2 bose wave radios. Really... One in the bedroom to wake me up every morning, and one on top of the fridge in the kitchen. I should say that i got both of them for free. I would never ever think of paying even half price for bose.

philodox: Lets see, output impedance of no less than 500 ohms. No Bass. Non existant damping factor. Bottom half of a wcf without the top half. All pull and no push. I could beat you up further, but you get the idea. Ray the Engineer must have designed this

A 6h30 is useful for only one thing. A cathode follower. Or a preamp output. Definitely not as a gain tube. And certainly not as part of an output stage that drives headphones. Sacd Lover, don't cheap out. Go full balanced. Might as well do it now, or you might hate yourself later. Which means you need 8 x 6c33

Mikhail just called me and told me what the schematic is. It is certainly NOT a T2 as that is a solid state/tube hybrid. The BH is much more like a T2 in this respect. Mikhail's amplifier is a single tube differential amplifier, with the second tube as a direct coupled cathode follower, which is ac coupled to the output tubes. The output tubes are directly coupled to the load. I assume there is some feedback. Multiple plate resistors and lots of standing power for the output section. Something like 15 watts per tube. Similar to the BH in power consumption. (i.e. great for cold winter nights) So in this respect its more like a SRA3S except with a drive tube in the middle. As far as the woo audio amp, who can argue with quality like this. At that price it is a bargain. Edit: not the sra3s, as that is also a solid state/tube hybrid. More like this http://www.bonavolta.ch/hobby/en/audio/hdgsta.htm

Time for my 2 cents. The SR-007 does in fact go to dc. But the sound is severly limited by the choice of output tube, you can tube roll the thing night and day and you still can't get away from the fact that a 450 volt (max) tube is being pushed to 700 volts. The Rp of the tube limits what it can do at low frequencys. Coming some time in the future is the KGST which has 6s4 output tubes which have about half the impedance of 6cg7's. And are rated for the voltage. Fully DC coupled. The ES-1 and BH share the same output tubes. About 4 times the power of a sr-007. The ES1 is based on my ac coupled design. The BH is fully dc coupled. They sound much more similar than you might think. No one is currently making BH's. So if you want one, you would either have to build it, which is a significant amount of work, or pry one out of someone who already has one. I should also mention that i own an aristaeus, and i very much like the sound of that too.