kevin gilmore

are you completely out of your mind, that would take me a week. ok, here is something quick that gives you the idea 4 x lm741 at different gain levels why it looks like crap and the background is not black, not sure and resulting phase

and a pair of matched and isolated digital voltmeters, very hard to do with one

a graph is in order here so that people would better understand whats going on. unfortunately I can't think of generating a quick way to do this, I took 6 of the kgsshv schematic at different levels and tried to sim at the same time but the software hung. may be able to look at this again late tomorrow. if someone else can do it so much the better. because I think that most people are not going to understand without a picture.

the psaudio is still referenced to safety ground. So its not going to protect you from line voltage induced death. A whack from 220V is still nasty. the capacitors in the power supply will still be able to kill you. No question about that. So if you don't understand how to set the currents and then adjust the offset voltages, some extra reading/looking at the board pictures might be a good idea.

I posted this over there, will post here. if I had time I would find to do a way to do the graph that shows frequency response relative to output voltage, maybe in a few days if people don't get it so here is how this works Required Slew Rate = 2 x π x Frequency x Peak Voltage x K we can argue about K later, different people have different ideas about the value.The load is a capacitor and it takes a particular amount of current to charge/discharge the capacitor at a particular frequency and voltage. Lets reference the maximum peak to peak output voltage of the amplifier at 1khz as 0db. Now lets calculate what amount of current is needed to do 20khz at 0db at the same peak to peak voltage into one standard headphone load, 120pf Now lets figure out (and this part gets complicated) how much more current is needed to guarantee .01% thd at 20khz at 0db. taking into account the open loop gain. Its clear that some of my earlier amplifiers with output currents in the range of 5ma to 10ma cannot do full voltage swing at 20khz. But will do a full flat frequency response at less than full voltage swing. So the question is how loud do you listen and how much actual audio content is at 20khz relative to 1khz. It is my opinion that 20ma however is enough to do full voltage swing even with 500V power supplies. 2sc4686,2sc3675,2sc5466 etc, cannot do more than about 10ma before they eventually blow up. Even with lots of heatsinking. And ixta3n120 has so much output capacitance that even with impossible current numbers it could never get there from here. Cree C2m1000 however can run at at least 30ma at 500V power supplies, is ultra low output capacitance etc. So is the current flavor of the decade output device, till something better comes along. A couple of people think that the carbon is a bit bright at 20ma, and have turned their units down to 18ma. This is one way that the amplifier can be tuned. The performance of an el34 at 20ma begins to effect the lifetime of the tube. Significantly. emission labs 20B work fine at 20ma, but have a stupid price and questionable long term reliability. There is no free lunch.

Seriously.... WHY? lipstick on a pig is far more appropriate.

I've talked to a couple of people on this and their answers were pretty much the same. If you are doing fluids and trying to do laminar flow, then great. For audio, pretty much a gooseegg. It probably does sound a bit different, but not for those reasons.

dan wants the male stax plugs, which are slightly more work. And printable with a $800 3D printer. any machine shop will happily make them for you out of teflon.

yes you can modify any of the power supplies to do that.

First 4 relays are opposite polarity from the second 4 on the max4820 boards. Yes all 4 of them in series, so 32 bits to write all relays.

not a fully balanced fully differential fully discrete one that i know of.

it is not illegal to own more than one amp. however it may damage the universe if one person owns more than 50 amplifiers (electrostatic,dynamic,speaker amps...) I think I am one amplifier away from that. And the ssdynalomini should put me over the top.

of course its hand solderable. you just have to find the right set of hands. preferably robotic.

fine, cram the new digital attenuator in there. should be enough room.

birgir has a large pile of the 10k alpha parts

my guess is that the amp is non linear at high gain with high impedance headphones. probably voltage clipping

i would not use the amphenol/wpi connectors i am also out of male connectors although hopefully in the next couple of weeks i will make a batch out of ebony (i predict lots of cracking) ask chinsettawong

Sure looks like 4 input wires and 2 output wires to the transformer, but what do I know. parallel dual single ended output stage sounds like push pull to me.

latest board

I read some of what you have written elsewhere, and its becoming clear you don't have any idea what you are talking about. The apex amplifier linked to above is a single ended amplifier, that is there is a single output tube driving an gapped output transformer that carries the full dc of the power supply. The rise time and fall time of the output signal is not the same. The eddie current tube amp pictured above is a push pull amplifier with 2 output tubes per channel. The output transformer is not gapped, and there is no dc in the transformer. The rise and fall time of the output signal is the same. In fact with both input and output transformers, that amplifier can be considered as fully balanced, and fully differential. Big difference in the kind of sounds that these amplifiers make. Now, since a couple have sent me emails about the black widow, here is my explanation of whats wrong with the picture above. Now maybe in the 2 box version the board had to be that size, and was obviously stuffed into a box of a specific size. But designing that way is stupid. In the single box there is all sorts of room to make the board bigger and do a much higher quality layout with better and bigger heatsinks, and having the left and right channels be absolutely identical. The worst offender of differences in left and right channel layout was the melos, but the liquid fire, liquid lightning and especially the liquid glass are in the running. The power supply board is obviously new, full ground plane on top, suitably sized heatsinks secured to the board etc, why use an amplifier from 2007. The stax mafia can (and probably should) do a much better layout with larger heatsinks, identical channels etc. There is absolutely nothing unique about the circuit design. If its going to be eye candy on the outside, it really needs to be eye candy on the inside if its going to command a premium price.

I would carefully check all the solder joints on the pzta parts I have been known to miss a couple

This is typical of all power amps with unregulated power rails. There is a solution (see uberamp2) which requires a lot more of a lot of stuff. You can mess with the filter settings in audio precision to make much of that appear to dissapear. Still 100db down is better than .01% thd, 3rd harmonic invisible, typical of bipolar outputs done that way. About the best you can do without feedback or lots and lots of current mirrors reducing distortions in circuits is not an easy thing, best to start with something decent to begin with.

You know that there IS a solution for that problem. But it's a slippery slope looking at the board now, its an astounding job. and its only 2 layers. infinitely better than the "professional" crap

There are other gerber viewers that work with the latest files. soon I will upgrade to the newest version that does the X2 version of Gerbers with full polygonal and contour support and that will probably make a mess with many of the viewers

want a pair of them real bad. (office/home)