kevin gilmore

What is to discuss. An opamp, and 2 transistors. Exact circuit published on headwize 2 years before ray built the piece of shit. I have discussed this plenty, do a search. And the Apache, you guessed it is 2 x hr2 in one box. Virtually identical to the circuitry in the headroom products circa 2000 or so. Nowhere near the beef necessary to truely drive low impedance headphones. Oodles and Gobs of feedback. Yuuch.

This is ray we are talking about here.... His stupidity is only matched by is arrogance... With a 12au7 the output impedance of the preamp section would be about 18k. With a 12ax7 it would be closer to 25k. Output impedance of the conrad johnson art preamp (act2) is specified as <500 ohms ct5 and ct6 are 800 ohms Ray's B52 is something in the range of 1500 to 1800 ohms.

well if the power amp has enough gain, and/or the source has a high enough output, then fine. that particular design is going to want to see a low impedance on the headphone output. So if you load it with say 150 ohms, it would be a lot better than running the thing with a wide open impedance. And if your amp is solid state, one mistake volume wise and the front end of said amplifier is going to turn to dust.

tell that to people that made the mistake of buying a stealth...

Don't have the pictures handy to see where the xlr preamp outputs are actually wired to. 1) if they are wired to the cathodes of the first tube, then its a simple cathode follower, however NO GAIN. As the pot is the first thing in the circuit followed by the cathode follower. 3) The only other place would be the same as the headphone output jack. Definitely not a really great place for a preamp output...

You may have a point there. aerius mode on... But you only need 2 wongs to make a wong junior...

No billy, you are wrong, wrong, just plain wrong. The stealth was even worse. On the stealth the front end gain tube was also used as an ultra high impedance preamp output. In other words it sucked bigtime. Could not even drive 3 feet of cable. So ray learned from his serious mistakes, and on the B52 added a simple cathode follower. A simple cathode follower does not a preamp make. Better yes, but still massively sucky. Anyone with brains should look at schematics of the audio research preamps, and the conrad johnson preamps to see it done right. Schematics of both available on the web. Hell ray still can't do an analog 12 volt fillament supply... Which is why he is using those $20 ultracrap ultranoisy switchers. Both on the Craptor and the B52. Can't wait to see what ray is going to use as the battery charger for the lithium battery in the predator. We should rename the predator, "the target of oportunity"

Of course it does. raptor not useful for anything <= 150 ohms

Well with your headphones this is clearly true. And of course a B52 is a (raptor) + (raptor) which means it (sucks)*(sucks) or in terms of money $1300+$1300 << $5300 A simple modification will allow the raptor to sound much better, but only with high impedance headphones (==300 ohms) There, I feel better now. A day without trashing my good friend ray is like a day without sunshine.

I just can't think of appropriate words that would allow me to respond to this. I'm just speechless...

Of course this is true. I get a cut directly from ray for all the extra stuff he sells because of my continued bashing of his junk. Ray is a dear and close friend and I have a lot of respect for him. Did i mention i have been drinking 100 year old scotch for most of the afternoon...

I would be more than happy to help my good friend ray shambles. Does everyone know that ray considers justin his son??? Go look at that thread, post # 289 The balls of this man are of phenominal size. Is this how all christian palestinian refugee's from the 1967 war act??? fact is that he has already done the circuit boards, and paid for the extrusion. unless he changes his big penis cap for something smaller, he won't have room for the required coupling cap size.

oops spelling errors... I prediciate that its gonna explode sending lithium and manganese schrapnel all over the place. I've been in the same room when an apple laptop battery exploded, definitely not a pretty sight. Also this... Ray is missing the REQUIRED cap on the VCOM pin of his pcm2704 implementation. Going to sound like shit without that cap. Distortion and noise thru the roof. Ray talking about noise levels. Highly entertaining.

Way over his head. Can't wait till we see how he really plans on charging the battery, as there is no charging circuitry on the predator itself. Predition, its gonna explode. On ray's website he says it is going to have less noise than all his other portables. Nothing is further from the truth. Because of the addition of a rail splitter compared to the tomahawk, its going to make at least 3db more noise... The religious zealots will eventually turn away. Its going to take one more really shitty product from ray to get that to happen.

Lets see, a one tube preamp. Yeah, great stuff. Gag me with a spoon. $5k+ for a one tube preamp with no remote control and no switching and a noisy switcher for the filament supply. Is that better...

You have the led "A" wired in upside down...

How to turn a ray shambles product into a singlepower product... Take a B52, make a set of unbalanced cables and tie them to an xlr with pin 2 and pin 3 connected together. Take the balanced outputs, and tie both Left channels together and both Right channels together. Viola two tubes in parallel top and bottom per channel. (with respect to ground)

old stuff and generally unobtainable... peerless of which i have significant stock. new stuff if you have lots of money.... audionote silverfoil transformers lets not forget the Mcintosh unity coupled transformers. But those are for push pull, not SE.

The sound of a single ended transformer output tube amp, and cathode follower amps are very different. Some like one version much more than the other. In either case you are probably going to have to find someone that is willing to do it right. For the transformer version, absolutely the best iron you can find coupled with a dht in to 30 to 40 watt range. Western electric 308's are absolutely the best at this, similar to the nagra amp that uses these, way out of your price range. For the otl version you probably want 6c33's running at full power as cathode followers. (zana is NOT cathode follower). This is also probably way out of your price range.

Constant impedance step attenuators are in fact available. Some of the goldpoint attenuators before mikhail bought the company were available this way. Requires twice as many resistors and twice as many rotary sections. And are basically twice the price.

I use my 7 digit agilent. Got to get it right down into the microvolts for best sound

Thats really not the right way to look at it. When i drop $35k for a pair of power amps, or $10k on a flatscreen, those products had better be absolutely perfect in every single way, and stay problem free for a very long time. It is the reason why wilson can get away with charging $150k for a pair of speakers.

If he went that far for the easy bias, i don't see any reason why he did not finish the job, and have a little single chip micro do the job automatically every 30 minutes, when there is a between the track silence. Servo bias with a 1 minute time constant is way easier and cheaper.

You have to adjust the dc output voltage for each of the 4 output tubes. Absolutely no difference between that and a he90 or aristaeus. My all tube amp uses self bias instead, and requires no output bias adjustment. Although there is a phase adjustment that is set basically once for the life of the amplifier. The blue hawaii has dc feedback, and for a range of different tubes the adjustment needs little to no adjustment.

I have personally only seen a picture of one such unit which clearly had pop-rivets holding the bottom on. I have a copy of that picture somewhere, and don't really want to look over 5 computers to try and find it. From a repair standpoint, pop-rivets are a really bad thing, as much of the time, drilling them out causes some damage to the paint.