kevin gilmore

Well after working on this for a bit, and Ti can certainly prove that i'm wrong... The opamp servo is in fact a common mode servo. The differential stuff comes from the susy. So i think that the balanced dynahi and balanced dynafet are correct as is. But i ran into something last night i have to warn everyone about. I got to playing with one of these new all discrete I/V converters. The thing has 100mv of DC output. Why is that a bad thing, for a differential amplifier like these two, with a voltage gain of 10 (differential voltage gain of 20) that 100mv of dc turns into up to +1 volt of output at one of the terminals and -1 volt of output at the other terminal. So 2 volts DC across the headphones. While no big deal for electrostatics, and this is something the stax mafia have known for years, this is REAL BAD. Think AMB's protection circuit will protect you. Think again. His circuit adds +L and -L and +R and -R together. In this case it would be +1 volt plus -1 volt. Result is zero, so the protection circuit is happy. But there is still 2 volts of DC on the output ready to destroy your headphones. Gets even worse if you are making an amplifier with a voltage gain of 40. Think about it for a minute, what the gain has to be to be able to do 160 volts peak to peak on the output. power supply board in progress http://gilmore.chem.northwestern.edu/dynahips.jpg edit: i finally see what Ti was talking about. So i added a single 1M resistor.

Those are the same as the krell heatsinks from the ksa series, anodized black, in 9 inch lengths, and turned sideways.

Ti wanted me to add a common mode servo. Which i did to the board. Will test circuit later. I don't think its necesary, but what the hell do i know. Have the design for the power supply. The main difference between the dynahi and dynafet is whether you like the sound of bipolar as outputs vs fets as outputs. And a slight difference in the cost of all the additional parts. The safety circuit really is a great idea, but no easy way to get the output wires to a corner of the board. Will look at that later.

dynafet a bit more because of the extra parts, but the bias is adjustable. Say 20 watts per channel. Dynahi is about 18 watts per channel.

This is possible, but need to find the absolutely smallest latching DPDT relay that run on 5 or 12 volts. With the current relays, the board would be 7.4 x 2.6 inches and you would need 2 of them.

first rev of both done. someone needs to do some serious checking on these. Both boards identical size with identical mounting holes and compatible with the T2 power supply angle brackets. http://gilmore.chem.northwestern.edu/dynahibal1.zip http://gilmore.chem.northwestern.edu/dynahifetrbal.zip

dynahifet in progress http://gilmore.chem.northwestern.edu/dynahifetbal.jpg because of all the power supply stuff all over the place, this might end up as a 4 layer board.

I suppose i could yank that part out and do it as a seperate board.

They would work just fine. But i want something that is compatible with my stack of machined brackets. getting close now. http://gilmore.chem.northwestern.edu/dynahibal1.zip trying to figure out which one of the 14 or so dynafets is the one i want to start with OH.. and this

Well the patent for super symmetry has run out, so i don't have to even ask nelson for permission... (not that i think that was ever a valid patent to begin with) Current board size 9.12 x 5.22 target board size 9 x 5 People really want to use HE6's as room speakers and dump 60 watts RMS into them, this will do the job for sure. The only right way i know of to do unbalanced to balanced, and balanced to balanced at the same time. opamps, bah humbug. If you go with the opa445 as the servo, you don't need the +/-15 volt regulators. Anyone want to suggest additional power supply capacitor sizes. I have plenty of room left.

much closer now. Since its now supersymmetry, with 10k input impedance, some things have had to change. Will send to ti for comments. You can certainly reduce the gain now by changing the 200k feedback resistors and increasing the compensation caps. Obviously a 10k resistor in series with both inputs at all times. Same name, same place, for the board picture balanced schematic http://gilmore.chem.northwestern.edu/dynahiver2a.pdf

Well you clearly know there's an app for that So i've been working on stuffing the house with lutron RA2. And there is in fact an ipad app for it. But its too combersome. So i wrote my own. Runs native on a HP slate 500, or any windows box. And even on an ipad inside firefox with my local web server box with ASP. http://gilmore.chem.northwestern.edu/lutronapp.jpg Next week i'm going to automate the 3 bathrooms Full up macro capabilities... Then integrate in the TV's, dvd players, music server... This could go on forever. The preamp app will be just as easy. Source code for this thing (all of my new things) will be available, and for the usual and customary price.

working on the balanced board now. Its a low impedance input with nelson pass's supersymmetry. True balanced, and balanced or unbalanced input. here is the balanced version as a work in progress. I wonder what other case this will fit into http://gilmore.chem.northwestern.edu/dynahibal.jpg Ater that, i'll do up the dynafet boards. I'm once again on a roll, and maybe the wonderful crema out of my new coffee machine might have something to do with it. Slightly jittery though Need some more of blubliss's hand roasted bean...

The digital attenuator part is similar to, but drives different from AMB's thing. Its still an 8 bit relay thing, with latching relays. I used AMB's calculator for the resistor values. My version drives twice as fast as linuxworks thing. I originally was going to use AMB/Linuxworks thing as is, and give credit but linuxworks turned into such a jerk... And they still have not actually released the thing. Mine may be out before theirs The version with no front panel, i was thinking an ipad app. wifi... infrared? that is SO last century...

Not too many companies want to make EI power supply transformers these days. Actually it seems that these days, no one wants to make anything unless they can make a million of them. And then not even then (semicoductors i like) Torroids are much more efficient and smaller for the same amount of power delivered. Torroids radiate much less magnetic field. Torroids buzz less. (well some of them anyway) It may also have to do with the fact that for power torroid transformers, you can wind the primary on one area of the transformer, and the secondaries on the other side and avoid the hastle with interwinding capacitances and other stuff that seems to get UL in a tizzy. There are some things about the good old days i would rather have back. The fast recovery diodes are at least 10 times (probably more like 25) faster than the old high voltage diodes. Once again, trying to find 1kv to 2kv diodes is getting harder and harder and harder. So i use what i can get my hands on, with lead times of less than a year. The SiC things might be really good. i'll let you know once i get some. Fact is that if you build stuff the good old way with the good old parts, you are nowhere near the ultra low noise levels that i can get now. sucks don't it.

Lil knight among others have asked for an updated dynahi board. Here it is. http://gilmore.chem.northwestern.edu/dynahi8.zip changes, remove 2sk389,2sj109, add lsk389,lsj109 2sk170,2sj74 you can use opa445 instead of op27 and then you don't need the 7815 and 7915. 2sa1349,2sc3381 can be replaced with the single versions. I need to check this a few more times. unbalanced input, balanced output version coming soon.

bom errors fixed except for the transformer description which i will have to dig up.

Just noticed that if you are using the lsk389, you have to solder it in to the bottom of the board... The 2sK170's are fine. I'll fix the board layout quick.

I'm cleaning up the BOM now... I only found one error (C9---C10) If others know of any errors, post/PM/email please. http://gilmore.chem.northwestern.edu/kgsshv.xlsx

i thought we already had the schematic for the sra14s... will look soon.

Its time to get back to work on this, now that the other 2 major projects are completed. I've been told to stay away from OLED's because power supply failures can cause burned up lines. So unless someone has a better idea, i'm going to go with this one. http://www.4dsystems.com.au/prod.php?id=114 I want a touch screen, and i want the embedded proc to be able to do i2s to drive the switching etc. Edit: screw it, i ordered both the oled and lcd versions. Also ordered enough stuff to make the thing programmable from wifi. You could do a version with no touchpanel or knobs at all.

This gets into the discussion of which values of film resistors (varies by manufacturer) is the least inductive. If you are careful, you definitely can get metal film resistors that match the carbon comps. Or buy those non-inductive bulk carbon film on ceramic things which are very temperature stable.

If anyone knows of a portable gps unit that actually displays time in seconds, i would really like to know about it.

Yes i have tried a few versions of that too. That was the one time i got my ass kicked, first time in a while. For some reason getting hit with voltages like that does not have the same effect it used to... I'm going to have to try again.

Yeah team... I'm getting REALLY TIRED of the fake parts... There has to be something we can do about this. Maybe massive group buys directly from the manufacturer. The fake 2sk389's are not a surprise. Hey linear systems, get off your fucking ass and finally release the lsj109's please (after 3+ years) I'll have to clean up the bom one of these days.