kevin gilmore

Dac's both powered from the usb port. Both units run from batteries to avoid any possible ground loops. Same intel based computer used for both. I think i know what all the IMD crap is on the predator, but until i get some time to test and verify, i won't say anything. Lets not forget that jude absolutely loves the predator. Can anyone continue to trust jude's recommendations at this point? Slightly biased maybe, no never... I think it is the same problem where the predator makes lots of hiss on some laptops... All i have to say is Induced Harmonic Compensation. Yeah, that's it... Ray is copying Rudistor. Truely classic.

Actually this is exactly what you would expect from a tle2426 (or compatible) rail splitter that has to fight a low impedance load. Ray decided to seriously lower the values of all the feedback resistors on the opamp such that at medium and high gain positions each channel puts about 120 ohms of internal load to ground. That is 60 ohms that the rail splitter has to drive before you actually add any headpones. So without any tantalum low impedance caps on the output of the rail splitter where they would actually do some good, the output of the rail splitter is going to sap up some of that seperation.

Done by a 3rd party who happens to own both units. Someone I trust who has no hammer to pound with. I see no reason not to post this, as it should be clearly duplicatable by just about anyone. http://gilmore.chem.northwestern.edu/picovspredator.htm

I'm not done yet, more sillyness to follow. Since i have a NC lathe at my disposal i was thinking of making some bells to ring with the hammer. Turns out the science for making bells is very complicated.

Got to start watching those cut and paste's... Actually with the glass shop at northwestern university shut down, i have stashed one of the 3 glass lathes. So i do in fact have the necessary stuff including bakeout ovens and turbo pump down systems to actually build tubes. Even have a 50 year old RF generator suitable for flashing the getters. The nichrome wire and the rest of the stuff is easy except if i want to do thoriated filaments or indirect cathodes. The cathode material is nasty. Getting new getters probably not so easy either. The bug and butterfly were cloisene'd enamel.

with that video of a home made tube going round these days... (and it turns out that guy was someone i worked with back in the midwest hifi days 30 years ago) I figured i would show a picture of a tube i made by hand in 1976 (at zenith) Has a couple of bugs in it. (actually a bug and a butterfly) http://gilmore.chem.northwestern.edu/tube1.jpg http://gilmore.chem.northwestern.edu/tube2.jpg Proving without a doubt that i was nuttier, longer than just about anyone. (made from picture tube necks)

I managed to get one of those hd-dvd players at wallmart for $99. Did not even have to wait in line. Just for chuckles i bought it. Filled with software bugs like i've never seen before. Won't even play one of the startrek remasters (which are glorious by the way) all the way thru, you have to go back to the menu and play it title by title. Think the blu-ray players are any better, think again. Go to avsforum and look at all the titles that various players won't play, or do stupid things with. Its not the price for me, i want something that works right out of the box and not have to install firmware every week for the next year. Plus some of the firmware fixes allow some disks to play, and then break others. So if you want to watch disk A you need this rev of firmware, and this disk you need a different rev... But evidently you can't go backwards in revisions on most of the players. The only player that works perfectly is the PS3. Very sad. By the middle of this year you will see lots of blu-ray players for $299 or less. In fact you can buy a blu-ray computer drive for that now...

I started counting headphones in that picture, came up with at least 21, probably more like 30. Then i started counting everything in my house, dynamic and electrostatic, and can come up with almost that many. What i'm obviously sorely lacking is enough closet space to do that. I would have to throw out half my wardrobe (ahem) to pull that off. Damm

Thanks billy, It really means a lot to me. Maybe I'll let you play with my new hammer. (i just got a couple of miniature pumpkins) http://gilmore.chem.northwestern.edu/hammer3.jpg

Does 19 pair of electrostatic heaphones and a pair of esl 63's qualify as an electrostatic fanboy??

My opinion is that all the meridian cd players i have seen are mediocre sounding units with a fancy front panel and a price 3 or 4 times what they are worth. What did you expect from tuberoller's massive pitch for them at the time. Still has not worn off. And lets not forget the $50 computer cdrom drive as the transport. There is to this day no fully complementary silicon process. You cannot make perfect npn transistors AND pnp transistors on the same piece of silicon at the same time. One has to be lateral, and the other vertical. So most opamps are virtually 90% npn transistors. No matter how hard you try you are not going to get identical slew rates for rising and falling edges. If you are in the fully differential, fully balanced, fully complementary camp as I clearly am, then opamps are not going to cut it for the seriously high end stuff.

From the duracell and prismatic web sites... duracell alkaline 9 volt battery internal impedance 1.7 ohm duracell aa alkaline .12 ohm duracel aaa alkaline .25 ohm have not found the numbers for the carbon zinc versions, but it has to be much worse. lithium ion prismatic .06 ohm Now to find the ESR of that 15000 uf cap...

Certainly not compared to lithium batteries.

hornet does not have any output capacitors. Neither does the tomahawk or sr71. raptor and b52 have output caps. 50 to 100uf. electrolytics. all of mikhail's tube amps have output caps. He typically goes much bigger. 470uf.electrolytics. the zana deux has a 50uf output cap (i think) Bigass film cap.

Both true and meaningless in this context at the same time. If the capacitor was an audio output cap, or coupling cap, then the change in the dielectric might be audible. Across a battery with a relatively low output impedance none of this applies.

Of course the numbers are doctored. I've yet to test a rudistor amp that comes within 30% of rated specifications. Same thing with the complete bullshit numbers on the apache. >120db signal to noise ratio. Absolutely impossible with an amplifier with a gain of 65db. Fact is even under the best conditions, johnson noise will bring the signal to noise ratio down to about 108db. Unless of course you plan on running the thing in a bath of liquid nitrogen. 2hz. Again absolute bullshit. Those chassis are what about 1.5 inches thick. Output caps big enough to give 2 hz frequency response would be bigger around than the chassis depth. Or really shitty electrolytic caps. How about that power supply. Anyone see any chokes on the top of that supply. They sure aren't going to fit inside the case. Which means that if the supply is actually regulated, then it is solid state that is doing the regulation. Completely ass backwards. You might want solid state rectification, but you want a pass tube for the power supply if what you are after is the tube power supply sound. Rudi's opamp unbalanced/balanced to balanced input stage has a gain of 13db. At least the version in his latest dynamic amp does. All the voltage gain in that amp is all in the cheap opamps. It may be built better (because its actually built in the UK) than the old junk, but it is still a piece of shit. A very expensive piece of shit. Somebody will buy one sooner or later, then we will get pictures of the insides. If rudi is not showing pictures of the insides like he has done with some of his other units, you know there is a reason.

I'll add that it can't meet the gain and distortion numbers if it is only the 2 tubes in the audio circuit. At most you are going to get a voltage gain of 100, and you really need a minimum of 500, and really 60db which is 1000.

here is my opinion on that OTHER site. Wonder how long it will last. Actually my take on this amplifier is a bit different given hints from rudi's website. If you believe the distortion numbers rudi quotes then clearly there is significant feedback in the amplifier. Therefore each of the 4 output sections is likely to be a composite amplifier with 1 section of a 12ax7 triode connected to a el34 wired as a triode with feedback around this section. Then the input is rudi's unbalanced to balanced autoswitching balanced to balanced input stage which is all opamps. If you look at the amp chassis however, there is no indications of any external heatsinks. If you run the el34's at their sweet spot of about 10 watts each, then somewhere there is going to be plate resistors or constant current sources that dissipate 40 additional watts. If that is inside the chassis as it certainly has to be the thing is going to get very hot. Probably the best thing rudi has done to date. Certainly the most expensive. There were a few burmeister electrostatic amps built, they were $25k each. Evidently they were worth it. __________________ Quando Omni Flunkus Moritati Now the stuff that would be deleted over there... No more box of boxes, i'm disapointed. limited to 400vrms HOW??? And why would you anyway. And if it can do 700vrms is that stator to stator, or stator to ground. Notice the low frequency cutoff is 2 hz. Yeah bullshit, and it also means its a capacitively coupled output. Back to that correct spectral harmonic compensation thing (politically correct version 3)

a bit more work http://gilmore.chem.northwestern.edu/hammer3.jpg

my serial number is better than yours... Ask justin

Yep and then the arm twisting behind the scenes to get wakeride74 to change his opinion. Yes the spin is working overtime.

Wonder when ray is going to go back to his nasty old trick of shipping his product to some of justin's pre-orders. Just like he did back in the amp wars days when he sent his amplifiers on eval to anyone interested in a singlepower.

Buy the 900 volt parts. Really. You should not run them at more than 50ma each. You can try the 450v parts, I have not tried this. Getting 3 of them in series to correctly voltage share might be tricky. If you raise the voltage rails past +/-400 you have to change out the 2sa1156 with a 2sa1486. Then you can probably go to +/-550. Everything else references the two rails, so there should be no other changes.

Well its a new year, and it is certainly starting with a bang. I do like flashbak's quote that the dac in the pico was superior to the one in the predator, and then ray's fanboys jump all over him. Great stuff. For portable amplifiers that use 9 volt batteries (sr71,hornet and a whole bunch of others) and are not class A (none are) the impedance of the battery is an issue because 9 volt batteries are a high impedance. So you slap a cap (4 for the sr71) across the battery to lower the impedance so that the audio does not modulate the power supply. But lithium batteries are anything but a high impedance. In fact the lithium battery inside ray's predator has a lower output impedance than that big honking electrolytic cap that is in parallel with it. A huge waste of realestate. So he perpetuates the myth that the cap makes all the difference, and the cap takes 600 hours to charge. And then he puts in an ultra crapo and in my opinion dangerous lithium battery charging circuit. I'd post the necessary equations to show that a 15000 uf cap takes less than 2 seconds to charge from a 9 volt battery, and much less than that for a lithium battery, but i'm just a touch hung over, and about to start the new years festivities. Ray really has lost it on this one.

You would put 2 of them in parallel, not in series. In parallel with suitable heatsinking you can get to about 100ma. You could put 2 in series to get twice the voltage swing (say 1800 volts) but then there are going to be voltage breakdown issues and they have to be heatsinked very carefully and probably with berylliumoxide insulating washers. (which are toxic if not handled right)