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Old 28th July 2011, 11:41 AM   #301
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by nad View Post
What about the double insulated stuff with no IEC mains earth pin?
Double insulated equipment designed and built and tested and warranted to meet to ClassII standards are in a different category to our home built, untested ClassI devices.
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Old 28th July 2011, 04:20 PM   #302
wlowes is offline wlowes  Canada
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Default scares the heck out of me

every time I hear someone talk about not grounding a case. Particularly around tubes. I read somewhere about all the people who died because they tried to fix 'double insulated' radios at home by plugging in some kind of power cord while the device was open. the cord was called a widow maker
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Old 28th July 2011, 05:49 PM   #303
AndrewT is offline AndrewT  Scotland
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Tell your household insurance company that you opened and slightly modified a ClassII product and listen to their response when you make a claim for accidental damage.
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Old 28th July 2011, 06:52 PM   #304
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Walter - what have I done ?

We've got some real heavyweights contributing to the Alpha thread that has shifted it's way to valves, earth arrangements and now insurance claims ( made by our wives just before our funerals )

Actually I need to respond to something AndrewT mentioned last week and this has reminded me to get on with it.
I need to plan and word my question very carefully however - Andrew... are you reading this ?

Bad news re the Bursons - thought they were drop in units and required just a small mod ? see atached pic
I'm fairly sure they are good for up to 250ma

I'll contact Lucas direct re buffer - his lampizator drawings and comment can be a bit short of fine detail ( well, for me anyway )
He'll not be too impressed I've stuck with 6N6P's either....

Friend of Peter Daniels ? - what a cool friend to have - any freebies ?

Good luck with the ' re work '

Andrew
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File Type: jpg BURSON.jpg (89.1 KB, 128 views)
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Old 28th July 2011, 06:56 PM   #305
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Hey, I'll bet Simon knows the answer - he has super regs all over his machine and on his dac board - as you know already.
He's been quiet here lately......
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Old 29th July 2011, 01:16 AM   #306
wlowes is offline wlowes  Canada
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I got the first generation Bursons on a clearance sale. They are only 80ma. could be it is just too much for the -15v one to drive its consumer and the other -5v reg and it's consumers. I am going to take my time and rewire without the cascade. Each reg will be fed off the 24v rail independently. I am also going to mount them right at the tda1541 consummer with point to point twisted pair back to the rail. They are a bit bulky for this application. They do add quite a lump to the Arcam.

We do have a some notworthy members helping us sort this all out.

I meant to ask you what cap values you are using on your buffer? Feel free to PM if preferred. I have worked my way through Lukas stuff and may be able to help figure it out.
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Old 29th July 2011, 02:07 AM   #307
wlowes is offline wlowes  Canada
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Quote:
Originally Posted by AndrewGM View Post

I'll contact Lucas direct re buffer - his lampizator drawings and comment can be a bit short of fine detail ( well, for me anyway )
He'll not be too impressed I've stuck with 6N6P's either....

Andrew
In case it helps, here is a picture of the lampizator output stage on my backup machine. It is playing while the Arcam goes back to the drawing board. It is running 6np6 tubes right off the I output of ad1860N dac chips btw and it sounds quite sublime.

I build the tube stage across the back panel. RCA output right beside the tubes which are close as possible to dac. The mains comes in on the left side. B+ power is the first pair of caps on the left. after the bridge, 2x100u 250v with 1k resistor linking the positive. Filtered power goes across the back with red/black twisted pair feeding via another 1k resistor another 100u cap for each tube. (so separate power supply to each & double filtered as Lukas recommends. The ground is as follows. Larger white wires take ground from rca neg to negative side of the first filter caps. Then another heavy wire takes it right back to the earth lead on the mains socket. There is very close to the mains a wire to a bolt in the chassis to ground the box . At each tube I use the neg RCA tab as my first star point for collecting ground. Pin 9, the dac neg lead, and the neg side of the last crc filter all go there and then from there back as described. So there are multiple star points but they all allow current to flow away from the signal source to the mains. Similarly with the filter supply, the power comes from the mains to that second CRC filter. Here it is 2x10k u 25v caps separated by a 1r 5w resistor. In fact to get enough current for the hungry 6n6p I even bypass the 1 ohm resistor so its actually just a bridge followed by 20ku caps. I take the filtered DC on twisted pair to pins 4,5 of each tube. The neg side of the filter is grounded back (nuther white 18gauge wire) to the earth ground at left.

So it is not neat. I am using dirt cheap caps from a surplus store and penny resistors. It is dead silent and sounds quite good. The arcam has all cool caps and more of them, chokes, and Kiwame resistors and sounds quite nice. I add this as a concrete example. This one did sound bad at first and I swaped out a pair of suspect caps.

Hope this helps.

Last edited by wlowes; 29th July 2011 at 02:15 AM. Reason: forgot picture
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Old 29th July 2011, 02:18 AM   #308
wlowes is offline wlowes  Canada
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Default Missing Picture

Here is the picture refered in last post
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File Type: jpg Sony Lampizator 6n6p 001.JPG (162.0 KB, 128 views)
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Old 29th July 2011, 04:51 AM   #309
wlowes is offline wlowes  Canada
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Default Burson shunts in!

Whew! In a mad soldering marathon I rewired and have Burson regs on -15v and -5v. As I suspected, there just was not enough power capacity in the -15 reg to power the rest. As soon as I removed the -5v LM337, the voltage shot up to 14.85 on pin 15. I then went point to point picking power right off the rail. Turns out I have 26.5v on the rail which is a bit scary as the BGN caps are only 25V rated. Seems they have a little buffer. Wired the -5v reg close to pin 26.

Board now looking even more like a mad scientist creation.

Checked voltage output on the reg. It was -5.00 spot on. I proceeded to wire it to the Oscon at pin 26. Voltage saged a bit under load. One thing that is cool about the regs is they are adjustable. With a little jeweler's screw driver I adjusted the voltages to be exactly -15.00v and -5.00. Plugged it into the system and music happened.

It's late, my wife calling me to come to bed, so only a couple of samples. I must say it is worth the effort. Not as dramatic as the DEM but same league. First impressions confirm the Burson marketing pitch. Yet more realistic sound stage. More 3d and very relaxed. Seems like some more detail. Need to do some serious listening on the weekend.

Thanks Simon for encouraging this step.
Walter
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Old 30th July 2011, 01:57 AM   #310
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Worth it then - way to go ?
I don't doubt Simon for a moment but he did his s' regs early on in his development - he swapped them from another tweaked machine right at the start.
I may be in a position to buy come September but I'd like to think it's a real step in relation to the investment needed - it won't be cheap compared to some of the things we've done lately -

I took a feed off the i/v op amps straight to the buffer tonight using my spare alpha dac board - result !!
No odd sounds and even less hum ....
Don't care why - it's just sublime considering the original state of the dac board. ( well, apart from the dem mod I tried on it )
So tomorrow I'll be ' at it again ' and will mod the good dac board and do the changes more neatly - I can then hear the buffer properly in the main system - minus all the other unwanted dac board components.

Still considering dc regulated heater supplies before I bolt it down properly though - it may completely silence it ( the hum now becomes audible well outside sensible listening volume settings ) wow !!

Let us know what happens when you've had a good listen to the Bursons - very interested in your progress with this.

Oh, one more thing....we've got to do something with i2S to get the max benefit from DEM - looking into this now and will flag it all up as soon as I understand it.
erm...that'll be December then

Best Wishes

Andrew
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