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Old 4th February 2005, 08:18 PM   #281
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The strange wiring of the bridges and the 0.1-ohm resistors is just for current sharing between parallel rectifiers. There IS a more intuitive way to draw it. I shouldn’t draw these things at 2:00 AM. I will post a better schematic soon.

-Casey Walsh
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Old 5th February 2005, 01:10 AM   #282
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You do not have an idea yet on the 0.1 resistors, given the question marks ?

i have 5000va toroids, at 2.6 times your values that could pose a problem for me.
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Old 5th February 2005, 06:33 AM   #283
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Quote:
Originally posted by SmarmyDog


Jacco: But you are a nut! Regarding the leftover thousands of transistors, I thought the "Kilowatt Brothers" would use them for mass production of these babies. (Just kidding Mr. Pass).

-Casey Walsh
Well Casey the building of said monsters would have to be under liscence from Pass Labs Of course!

Im sure with enough bottles of negotiations we could work out something now couldnt we? hahahahahha

Things are progressing along slowly here. much slower than i had hoped but we now have some preliminary data on the big inductors and believe me there BIG. in fact, there going to as big if not bigger than the transformers! all in the name of low loss, and low noise.

I may get the company thats custom making these inductors to make up 2 of the FAT air coils for comparison.

Zc
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Old 6th February 2005, 09:07 PM   #284
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Front end update:
As I said, +-80V (which I think of as 160Vp-p), is trivial. Nailed that. For a tube critter, that's a big Duh. Remember, when you want volts, tubes are your friends (it's current that makes tube folks want to run and hide). Got two details I want to nail down before going on to the follower stage.
Power supply is still a 100VA EI isolation transformer into a voltage doubler. Don't see any need to change that at this time. Have not made up my mind whether to regulate or go CRC to get the rail. Right now it's CRC.
As usual, my main enemy is time. I'll try to steal a few more hours in the near future. May have to order in some parts. We'll see.

Grey
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Old 7th February 2005, 08:55 AM   #285
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Buddy Grey,

if you have chosen the supply voltage and know how many mA have to be delivered, undoubtebly you must have narrowed down a range of tubes.

What is five minutes of extra sleep compared to the joy you can bring us ?
The front end is magic, you're the magician, show us your tricks !
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Old 1st March 2005, 02:29 AM   #286
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Progress report.
Almost none, unfortunately. My daughter got sick. Those who have dealt with small children will know what I mean when I say that a two year-old can deliver a blast of germs that would qualify as a Weapon of Mass Infection. They turn, give you a pitiful look, and sneeze right in your face. Okay, that put me down for most of the past two weeks. Couple that with the need to get the dual headphone amp out the door (done...yea! now all I need to do is get paid for it...) and the line stage (circuit done, PCBs etched and populated, now I've got to get it into a chassis and try to get it out the door, too), and I'm still wishing I had more hours in the day.
(Had to stop and write a story, too...)
I got interested in trying different combinations of tubes in the differential cascode, so what time I've been able to apply to the Monster Front End has been spent in that direction. A little tweaking here, a little fiddling there, then back to bed as it's not wise for sick folks to hang out in cold basements too much.
Incidentally, someone posted earlier (in this thread, I think) that their basement was around 60 degrees. I wish! Mine runs between 52 and 58 degrees, depending on the outside temperature. In another month or two, that will begin to creep up, but until then the forecast for the basement is chilly.

Grey
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Old 1st March 2005, 03:24 PM   #287
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Maybe you just need a nice sound system with a Class A
amplifier in your basement.

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Old 1st March 2005, 05:17 PM   #288
MikeW is offline MikeW  United States
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Or a nice pair of slippers.
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Old 1st March 2005, 09:10 PM   #289
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Nelson,
All the heavy iron is already in the basement, but in another room. The cumulative square footage of the basement is enough that it would be prohibitive to try to actually heat it, per se, so I try to make everything do double-duty. In this case, that means music and heat.
Mike,
I'm putting together another Mini-A (on your board layout) that will be the first time that I've actually had decent cound in the area where I do the electronic stuff. Not that a Mini-A is all that great as a space heater, but before all is said and done I may decide to biamp or something.
(thanks for the boards, by the way...)

Grey
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Old 5th March 2005, 11:41 PM   #290
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Default Update

Hi All:

Here's a quick update of where I am with these puppies.

The mechanical configuration hasn't changed much other than the tedious details of the bottom chassis. Here is a SolidWorks rendering:

Click the image to open in full size.

Here is a link to a higher resolution picture: http://photonlogic.com/PicServe/PM/2005-03-05/PM2.jpg

The bottom plates are in the queue at the CNC shop. While I’m waiting for them I’m going to set up some test equipment to start matching the output stage FET’s.

If you have the eDrawings viewer on your computer you can download the 3D model from here. The viewer will let you manipulate the model freely in space. It’s quite cool.


-Casey Walsh
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