A film cap could work well, but remember you are tying the output of two active regulators together with it - so really high Q /low-ESR isn't good and will promote ringing on either or both supplies (hence my note on damping). Small film cap with a series reisstor could be worth a try, say 1ohm. But a small oscon seems to work OK generally, esp if you have largish caps on the 1541 pins already (eg 47uF).
Definitely something to play with that works better if you can drive a 'scope!
Definitely something to play with that works better if you can drive a 'scope!
Actually I think there is - seems more lively but my mind is on this .....g D flip flop thing I've got myself embroiled in - sorry.
I'll be firing it ( DEM ) up again soon then I'll report back on both things with something a bit more coherent
btw...It's on the alpha 5 - tonight it'll be on the alpha because.... it works and is stable.
Have you got any 10 uf oscons spare ?
You can have one if not
Andrew
I'll be firing it ( DEM ) up again soon then I'll report back on both things with something a bit more coherent
btw...It's on the alpha 5 - tonight it'll be on the alpha because.... it works and is stable.
Have you got any 10 uf oscons spare ?
You can have one if not
Andrew
Yes Simon - it's a winner - go ahead
It's another step - not huge but there's more to the edges of percussion and it feels like the attack speed is just more lively - as I reported on the ' 5 '.
I wish I could describe this stuff better - apologies.
I also wish I understood better why these little tweaks work.
Yes I can read the explanations by you and Martin and others too but it's just grasping it that ' does me in '
DEM method is aborted and I'm implementing this instead ( attachment )
Flip flop's are now officially for holidays not CD Players.
Anyway, once I get this running I'll post pics
Martin - thank you - it's a nice one
Andrew
It's another step - not huge but there's more to the edges of percussion and it feels like the attack speed is just more lively - as I reported on the ' 5 '.
I wish I could describe this stuff better - apologies.
I also wish I understood better why these little tweaks work.
Yes I can read the explanations by you and Martin and others too but it's just grasping it that ' does me in '
DEM method is aborted and I'm implementing this instead ( attachment )
Flip flop's are now officially for holidays not CD Players.
Anyway, once I get this running I'll post pics
Martin - thank you - it's a nice one
Andrew
Attachments
Ok - now for a head scratcher... does C227 not already do this?
-5 @ pin 26 goes to digital ground via c221,c222
-15 @pin 15 goes to analogue ground via c224,c225
digi and ana ground are tied together via c227. Basically we are adding caps to c227
I think I actually killed that one some time ago thinking it would be good to have digital ground not send very high frequency over to analogue ground. I thought at the time it was good. I have a couple of options in my used cap drawer. There is a BGN 47U at one extreme. At the other end are my newly aquired 1500pf silver mica russian military looking for a use. perhaps its time to experiment. Thoughts?
Had a look at the schematic now - no, this extra cap i suggest is doing something quite different.
C227 is odd to me - most other implementations (and the quietest way of doing things) would be to have just one ground plane and the analogue and digital grounds going into it. The only reason these have different pins on dacs is to keep the current loops inside the chip separate - sharing one tiny internal bond wire for all digital and analogue 0v return current would badly degrade performance by crosstalk.
C227 is odd to me - most other implementations (and the quietest way of doing things) would be to have just one ground plane and the analogue and digital grounds going into it. The only reason these have different pins on dacs is to keep the current loops inside the chip separate - sharing one tiny internal bond wire for all digital and analogue 0v return current would badly degrade performance by crosstalk.
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.
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.
Attachments
Last edited:
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.
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.
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.
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.
Attachments
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
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
Attachments
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.
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.
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
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
Attachments
- Status
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