kevin gilmore

The only question is whether i spill the beans on the new headroom 2006 module, or let Tyll do the introductions... " **** are a girls best friends"

You want criticism, sure i can do that. Well one thing for sure, its a whole lot better than the italian built crap of 2 years ago. Real etched circuit boards. No more silver plated copper wire reinforcement to make up for hand etched boards. But it really is the same basic circuit which is a no feedback circuit with a single gain tube and a common emitter follower into a low impedance resistor. And 4 of these amplifiers, two for each channel when a a balanced input is used. Somewhere, and now deleted it said that the output impedance was virtually zero. I don't think so. Likely 5 to 10 ohms per amp, double that balanced. For low impedance phones its definitely an issue. It is not immediately apparent that you can actually get balanced output from an unbalanced input. Whats up with the hand made copper box around the output jacks. Where is the picture of the power supply box. How much noise does the fan make. Still i give rudi a B+ for the effort involved. This thing is not going to be cheap. There is $800 in pots alone. Probably $3500 to $5000 USD.

90 minute season finale. season 3 starts (for usa) in october.

jude told me over and over and over that it was not possible for moderators to read PM's. I loaded a copy of vbulletin and set up an entire board just to verify the statement. I can say for a fact that anyone with administrator privledge can in fact read any PM any time they want to. It is not an easy thing to do unless you are database aware. The only thing that is a bit tricky is getting a users password. That is more difficult. But not impossible. I guess after reading this post i should be more specific. administrators can read PM's moderators cannot.

Using the resources of headwize however IS acceptable. Many members there are also on head-fi. You may be able to contact people this way.

I've never measured the impedance of a power cord, i could see that the impedance could vary wildly between all the different kinds. May be as low as 25 ohms.

What a great episode. Looked like a series finale except that we all know that was not true. If its really a dream sequence, i'll be pissed. Sci Friday really is the best science fiction on tv at the moment. The new dr. who starts next week i think. I have already seen all of the new epsidodes and they are also fantastic. Too bad scifi is going to cut the hell out of them with all of the commercials. They really need to run as one continuous 44 minute segment.

You always need a resistor at the amp end. The value is the characteristic impedance of the cable.

Yep, that is correct... Just make sure you use 75 ohm cable.

When you have something right next to it to compare it to on the same exact set of headphones, then yes its pretty bad. Compared to everything else it is still pretty decent.

I'm the one in a private email that asked el grande enigma to add ray and rickcr42... I'll add one more. Tuberoller Really, i'm serious i always liked reading what he wrote. Other than the pure crap in the members lounge... Here are a few more sijosae, peranders, sft,dgardner

what problems are you referring to. I have 2 of them. Never had a problem with either. They sound like crap, but that is a different issue.

Sources and destinations for digital use are already properly terminated. Otherwise at those data rates, it would never work. spdif is 75 ohms, and aes/ebu is 110. Speakers are not a constant impedance by any means. The only cable out there that even approaches the impedance of a speaker are the goertz cables. And the capacitance of those cables is so high, it drives many amplifiers into distortion or oscillation. The best way is to have monoblock amplifiers absolutely close as possible to the speakers and then use the lowest impedance and shortest distance cable you can. As for headphone cables probably the same thing applies. I don't have a real solution for this other than to velcro a gilmore lite to the back of your head. 1/4 watt resistors are all you need. The quality of the resistors definitely make a difference. Figuring out the impedance of your source is not really so hard. You insert a resistor into the line and then a load to ground. Measure the voltage on both sides of the resistor and you can calculate the source impedance. Many manufacturers specify output impedance. All krell preamps and cd players are 10 ohms for example.

Of course it works balanced. Same deal except 2 resistors at each end.

non-commercial means NO MONEY. No paid ads, No sponsored threads... that kind of stuff. Its the rules for being a "not for profit" However if someone wants to donate another dual proc xeon machine stuffed with 2gb or more of memory and mirrored scsi drives, I'll find a way to accept it. I personally supplied the first one...

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.