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Old 16th July 2011, 05:56 PM   #211
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Probably not without a bit more investigation TBH.
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Old 17th July 2011, 02:01 AM   #212
wlowes is online now wlowes  Canada
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Default c227

OK..
So I went back and reviewed the c227 situation. I have been running for some time with it removed. Again, my set up is different as I am using the Arcam audio board as a dac fed by a usb to I2S feed. By killing that cap the analogue ground went to the tube output star ground and the digi ground went via my I2S ground ultimately out to the same earth ground. Pin 3 on the IEC.

I realized that I had gone overboard when pulling out excess parts associated with the original op amp output stage. I went in to put back some caps. C211, C215 went back in. I killed C8 and c108. I put in silver mica between -15 and ground and +15 and ground to fill in the c212 & c216 I had pulled by mistake some time ago.

In the experiment to connect pin 15 and 26 via a cap, I put a 47U BGN between 26 and the digital ground sid of c227. I killed it dead. Uncomfortable silence!! Have to go back and retrace my steps. Could be I broke a signal connection on the I2S or killed power some where.

Actually as I write this I think I screwed up and put the cap on pin 14! Opps.

at least 14 is digital ground, so I can't see how the cap did anything. Must have borken a wire somewhere. Bollocks as Andrew would say

Back to the drawing board. The tda1541 spec sheet indicates that 15 and 26 should each go to earth ground via a 100u cap. Interesting. I will keep you posted.. here is my happenstance cap attempt.
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Last edited by wlowes; 17th July 2011 at 02:03 AM.
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Old 17th July 2011, 02:57 AM   #213
wlowes is online now wlowes  Canada
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OK. Not so bad. Turns out I just forgot to connect power to the board.

I believe I actually got the BG in the right place as a functional equivalent to C227. At first I was not taken with the whole deal. After 15 mins, everything is smoothing out nicely. Must be new cap/wire settling. Think I'll leave the BG where it is for now and later tonight try the 15/26 with another cap.
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Old 17th July 2011, 06:12 AM   #214
wlowes is online now wlowes  Canada
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Default Cap in on -5 & -15

I did go back in and install a cap across the -5 %-15 pins. Also added some 24 guage copper wire to take analogue ground pin out to where I attach my ground wires to the tube output stage.

I have now been listening for about an hour, so all this new stuff has yet to fully settle.

At first I wondered if I liked it. There is a lot more bass. Enough that I realized I had turned down the volume. With less emphasis on the higher registers, there was alot less fireworks.

There is no less definition. Clearly a relaxed, liquid sound. I don't have a turntable, but I imagine this is very analogue. No hint of digital hash, or fatigue. That new range of crystal clear detail in the upper registers that came with the DEM reclocking is absolutely there. Its just very laid back and easy now.

Earlier in the evening when I thought I had toasted the Arcam, as part of my troubleshooting I put in my Sony CDP. It is sounding very good with Lampizator tube output and Russian PIO coupling caps. As a curiosity, I rolled out the 6n2p tubes and put in 6n6p. These are the so called magic tubes popularized by BAT. The sound stage went from a little over the top spacious to much more laid back. At first a little disappointing, and then in a few minutes it is the easy more real sound that you want to keep. This is the effect that all of the changes tonight have had on the ARCAM. Things are very detailed but relaxed. The sound stage is less spacy but very real. I am listening to my new reference which is YoYo Ma & Friends - Songs of Joy and Peace. It is very well laid down. His cello is very organic and real. The triangles and bells are very real. There is quite a range of vocals and instruments in this collection, and it is a good test of the system. This new Arcam presentation is standing up very well.

I'm going to give it a few days without any changes.

Oh BTW, the cap I put is was an old MCap aluminum/film 1u 250v. It is well broken in as it was the output coupling cap at first. Later pushed aside by Obligatos and Russian Teflon, so why not. forgive the blurry photo, but attached pic of my handy work.
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Old 17th July 2011, 11:06 AM   #215
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That's what I wanted to read !!
6N6P - direct off the DAC chip ?
How did you do i/v - resistor ?

Fikus told me to go straight off the op amp because the low gain of the valve would be insufficient.

You can see my state of readiness with the buffer ( ignore the test rect diodes mess - have newer solution already in place )
It'll be tested today between CD and volume as a straight buffer but once I'm happy that a....it works and.. b....I like it... I'm going to wire it as an output stage off the i/v opamps.
Unless of course you tell me it's OK straight off the DAC - that'll make my day.

On the Arcam - I'm glad you got it running and the mods are a gain. I need to think a bit more about what I'm doing before just adding caps - which I do sometimes without understanding why. The DEM reclocking has taken a bit of a hold since I heard the 250pf cap mod and I'll be in there again on Monday to do the whole thing again once my in5711 diodes arrive. I have a drawing I'll post once I'm certain it's OK and safe to share with you guys.
2 caps, a resistor and a diode and that's it for proper full on DEM reclocking.

It's all happening

Andrew
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Old 17th July 2011, 02:08 PM   #216
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Default 6n6p

H Andrew
You look like you are having fun. I hope the lampizator works well. I would start by following Lukas recommendations to the letter. In the Arcam I followed his schematic for the 6n2p. I followed all the mid point recommendations for resistor values for that tube.

My Sony has a pair of ad1860n dac chips. They have both I out and V out. On the voltage side they have an onboard opamp. I took the signal from the I out and used resistor values targeted for this range of chip and the 6n2p.
It works well with the 6n2p. Surprisingly, on this set up, I can put in the 6n6p without changing anything but the filament current. This tube clearly has less gain, so I pump up the volume a bit but no problem, my amp has too much gain anyways. I have no idea if he is right that it is not a good match for the tda1541a. I take his word for it. There is no way the filament current in my Arcam would light this tube anyways. You need a pretty decent transformer to get 6volts.
On the Sony, I can switch the tubes by bypassing the 2r resistor in the crc filter. I am going to put a little switch so I can toggle between the 2. I recommend you check that you can get enough current on the filament as the first check. I just clamp on my multimeter and switch on power. The volts rise fairly slowly so if its zooming up past 7v kill the power and add a resistor.

At the risk of sounding patronizing, please remember that all the power in tubes is lethal. (I have to remind myself every day). First thing after powering down is to discharge the high voltage caps. They stay lethal for days. Clip on ground first. I keep a resistor with aligator clips prominent on my bench as a reminder. Another tip from my tube guru Bruce Rozenblitz that is smart habit. If you have power on, keep one hand in your pocket. If you have shoes on and the chasis is grounded, its hard to kill yourself with one hand. Worse thing that could happen is you are holding all that metal with one hand and probing around with the other. Hand to hand straight thru the heart. My amp project its 500v which means your body will freeze until you die if you touch the wrong thing. It is very rewarding hobby. I just want us all to stay safe.
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Old 17th July 2011, 02:39 PM   #217
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And that, gentlemen, is why I'm too scared to touch vacuum tubes!
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Old 17th July 2011, 06:13 PM   #218
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Nearly done !

If you hear a BANG.......
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Old 17th July 2011, 11:40 PM   #219
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Default Nearly Done

Good luck with it. If you have some challenges feel free to ask for help. I might have encountered similar questions.
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Old 18th July 2011, 04:12 AM   #220
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I might take you up on that and maybe we should start a new thread soon too.
Didn't make it to the finish line due to domestic issues ( my wife telling me I had not cut the grass for 2 years - joke + telling me a few other un repeatable truth's
I kept telling her ' just another hour ' and I''ll be done.
She also reminded me my system is never finished and she was....correct

It doesn't stop does it ?

OK, tomorrow then and I'll be finished....erm...something at least.
Then DEM and then back to the amps and the external PS box for the CD player.

I blame you lot - particularly that Simon bloke
She knows all your names now - your in big trouble
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