kevin gilmore

But its way more fun to trash about $600k of instruments to salvage the connectors. Think of it as therapy In this case a micromass quatro 2 and a micromass maldi (now owned by waters). The qstar is next.... I now have 6 x 6 inch turbo pumps and controllers... And a pair of 12 inch pumps. Time to make some electron tubes by hand...

So you take a modern source with an output impedance of 50 to 200 ohms, add a tube buffer and the result is something with a minimum output impedance of 2200 ohms, and probably more. Yep sure is going to add that tube distortion and frequency response to what was a pretty clean signal.

I was going to keep it as a backup, but the difference is so great i don't see how i could use that old thing ever again. Of course I'm spoiled. Ebay they are going for about $1000, so the first offer of $800 or more gets it. Comes with 5 EXTREMELY USED batteries with no more than 25% capacity left. Would work great as a studio camera powered by the included brick. And you will need your own lenses. No compactflash cards or lenses included. Fully up to date firmware. Fully supported by photoshop cs2 or cs3 in raw mode. firewire connection very problematic from the very start. May work with an apple firewire connection.

hurry: The Black hatters still have a couple left in stock, doubt they will last the weekend. I was on the waiting list for 5 months... http://gilmore.chem.northwestern.edu/dsc_0011.jpg Same lenses i had from the other camera. That is the great thing about buying the right lenses the first time. And the second time and the 3rd time... 17-35 f2.8 ED-IF-AF-S 28-70 f2.8 ED-IF-AF-S 70-200 f2.8 ED-IF-AF-S-VR 105 f2.8 macro (the old one) 2X teleconverter Will buy the new PC lens once it is actually available. And probably the new ring flash setup, although my old ring flash actually does work in i-ttl mode with this camera, would not with the old camera which made it virtually impossible to use. I'm actually planning on making some money with this, just like i did with the last one, so its not really a toy.

Got my new Nikon D3 this morning. I just don't know how i lived with my old kodak slr/n for so long... Pictures tomorrow... 7 hours to charge the battery from empty...

The 727 is supposed to be a similar design to the 717 with the output stage dissipating about 3 times the power, therefore a more extended high frequency and low frequency response. If it really sounds much worse, there certainly could be a number of reasons, but i would be surprised if on a casual basis anyone could tell the difference between the two. Unless stax made some kind of horrible mistake.

As many of you know by now, i collect unusual, rare and expensive items. So have a look at these... http://gilmore.chem.northwestern.edu/fischers.jpg Anyone with any creative ideas what to do with them??

maybe, maybe not. If there is no relay in the output circuit then the off impedance is very high. If there is a relay in the circuit, then that could be where your ground loop is coming from.

see the problem is everyone is trying to fit new technologies into a name and a way of transmitting audio that is more than 40 years old. Back then, everything was pretty much tubes, which had a high output impedance, so all the professional stuff was designed to use input and output transformers to match everything. And so for long runs of cable, everything was balanced and 600 ohms. A lot of professional audio stuff is still done that way. Enter lots of present day audio gear that do balanced, except without any kind of isolation. And you get issues of whether or not the 3rd wire should be connected at both ends or not, and that ends up causing issues related to common mode voltages, and the ability of electronics to reject that. The fact is that for safety reasons, the ground wire of both unbalanced inputs and balanced inputs is referenced to power ground. So on some equipment if you connect both ends of a balanced cable to ground, you may still end up with an audible ground loop. As far as what we call balanced output these days, we really should use a different term entirely. And that term should be bridged output. Wadia had it right, although way to late and way to expensive. The inputs to our power amps should be seperated fiber optic digital running at 2.56 or 5.12 mhz with seperated clock and data. No more ground loops ever. Same thing for hdmi.

Do not under any circumstances remove the lemo like connector on the end of the headphone cable. You will need to get the matching connector. And then wire that connector to a stax male plug. You are not going to like the price of the lemo connector. (something like $75 if i remember right)

OK, here is a little more sillyness. You know those 3 channel amps with the active ground, How about this. Channel 1 is made up of R - L Channel 2 is made up of L + R Channel 3 is made up of L - R The left channel is channel 1 minus channel 2 == (r - l) - (l + r) == -2l The right channel is channel 3 minus channel 2 == (l - r) - (l + r) == -2r 3 wires, yet balanced...

If you have not figured out whether or not i am insane yet, nothing i can do will help you any further. You need ground cheaters because the center of that bridge amp is almost certainly connected to earth ground. Connecting the earth grounds of 2 amps together, and the minus terminals of the bridges together is going to result in lots of broken parts. OK, lets see if you can answer this one. You can buy those really big subwoofers generally for the automotive wars. Many of those drivers have dual voice coils. You can certainly wire the 2 coils in series, and now you would have what you would call a balanced dynamic driver. But you can also wire them in parallel, and what do you have. But really the difference is the same, the voice coil adds the forces from each coil together and turns that into a single force that moves the speaker cone. Does the speaker cone know whether it is being driven balanced or not, of course it does not. All that matters is the total electromotive force.

Here is a twist... Take 2 balanced output monoblocks (OK, don't do this unless you really know what you are doing) Tie the output minus terminals together and wire to 3 wire (as in common ground headphones). Make sure you use ground cheaters on the power cables. Now use 1:1 audio input isolation transformers at the inputs to the amplifiers. Is it balanced Sure is... It is just a matter of what you consider your reference to be.

There are lots of monoblocks that are not H bridge amplifiers. All of the older marantz and parasound amplifiers for example. There are monoblocks that have rca inputs only but are bridge output amplifiers. (crown, mackie et all) The easiest way to tell (with the power off) is measure the resistance between the rca ground and the minus terminal of the amplifier. If the resistance is very close to zero, then it is NOT a bridge output amplifier. All of my electrostatic amps are in fact H bridge amplifiers. Certainly not complementary but in fact dual push pull. If you replaced the heaphone with a large value resistor, (and eliminate the bias) it would look just like any other bridged amplifier, other than the very large voltage swing. Not counting the bias, electrostatic headphones are 4 wires just like dynamic headphones without a common ground. The fact that the resistance is almost pure reactive means little.

see you are mixing up words that mean nothing. unbalanced headphones are the same as balanced headphones with a common ground. The load (in this case the headphones) cannot possibly know how it is being driven. But if it is being driven from a balanced (really bridged source with no ground) then it has to be 4 wire.

OK, a phono cart is a 2 wire source. It does not know whether it is balanced or not, and does not care. What does make a big difference in this case due to the very low output voltages is how much noise and hum is added to the signal due to the cables and connectors. A 2 wire rca connector and standard coax references one side of the cart to ground, and does so thru the cable shield. Way better, an i know this for a fact is to use 3 wire coax, connect the 2 inside wires to the cart, then if you have to, at the rca end, connect one of the wires and the shield together. Way better, but still an unbalanced signal. Even better is to actually have a balanced input front end which in general requires twice as many parts, but can if done right get an additional noise level 3 to 6 db lower than a non balanced front end. Ray's piece of shit phono preamp does this. At the output ray uses a drv134 to convert the unbalanced signal to balanced. In fact this really does absolutely nothing. The 5 wire connect is clearly desirable, but really only usable with a true balanced phono section. Now balanced output is a similar yet completely different animal and for a different reason. Take a 200 watt rms amplifier into 8 ohms. Bridge the thing. Given enough heatsink and power supply you instantly have an 800 watt rms amplifier into 8 ohms. Plus you get absolutely matched rise and fall times. In fact you can take 2 lousy amplifiers (as in quasi complementary) and put them together this way and get something that sounds really excellent, as in the crown macro reference monsters. The reason krell et all do the balanced (as in bridged) output is because of the lack of quality pnp output transistors past about 135 volts. Its the only way to get huge amounts of power and retain the rest of the characteristics everyone desires.

Ray has sold more than 800 of them at $295 each. === $236k Thats the biggest and only plus point i can think of. Unity gain and less power than what you hook it up to...

Ray is one of those people that likes to count his chickens before they hatch. And he likes to sell at least 500 of a portable before he moves on to the next one. So if he could sell 500 @ 425 that would be $212K justin is eating into that at a rate of more than 50% so ray will be lucky to sell 200 @ 425 and that would be $85k. So ray is by the way he measures stuff at least $127k in the hole.

My guess is that one of those two vendors is not happy at all.

Yes the prototype is in the basement. But really it was so much easier to buy a pair of bigass krell monoblocks. The older i get, the less i build stuff especially if i can buy it instead. Which means justin owe's me at least 4 more amplifiers. (all electrostats)

Design of the B24 and my uberamp of about 6 years ago, virtually identical. Especially the cross coupled feedback with all the benefits from that. Uberamp scales very nice up to about 800 watts per channel into 8 ohms. With appropriate parts and +/-125 volt rails the B24 will do the same thing. Plan on many square feet of heatsink. And a power transformer that requires 2 people to lift it. As shown it is good for at least 100 real watts rms per channel into 8 ohms.

The least he can do is send me front and rear panels for the amp, and maybe a cardboard box for the power supply...

Here is one for you, that you might not expect It is the only DAC/amp combo that i have tested (and i have tested a number of them including a couple of 2704 versions) that works with a SunBlade 1500 and Solaris 10. Which is very convenient for me... Not sure why the others don't work.

No i have not said anything to Ti about this. He either should know about it, or will soon. Ti ==== Ti Khan. TI ==== texas instruments There was a very long thread on the nelson pass forum at diyaudio.com which i'm sure is still there about how TI desperately tried to stear clear of nelson's patents on a particular chip, but were unable to do so and ultimately licenced nelson's patents. I think that nelson is a reasonable person, and for diy like things (as in virtually no commercial potential) he is likely to give his permission. I have seen him do so in the past. But if you don't ask first, well....

Yes it is sweet. However it absolutely violates Nelson Pass's SuSY patent. (in fact so does my Uberamp) So if he wants to sell boards, he had better talk to the man and get permission first. TI ended up paying nelson big bucks to buy his intellectual property on this issue. I still think i can show prior art and that nelson's patent is null and void, but that is a legal battle i would never want to fight.