I have made them by reading the last pages of this thread. Sorry, I'm not prepared to make a description... But it's all here 🙂
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According to me the problem of dam1021 is the output buffer is not suitable for a rest of the card. With this configuration, the sound has improved a lot: I connected to a raw buffer circuit valves see link, without potentiometer, I only improved the anode supply by replacing the resistor with inductance and increased the capacity of the power supply capacitors and coupling the output - voltage stabilized filaments, resulting all very quiet. Then I added a potentiometer to the dam set at -14, I did last firmware update, filter F4. I compared the dam1021 with Lector Digicode 704, see link: mechanical Teac cd VRSD10 connected to dam1021 (SPDIF), the digital source connected to the Popcorn hour c200 Lector Digicode 704 (SPDIF), Spectral dmc12 preamplifier, amplifier Spectral dma80, speakers MTD MUSIC. TEST THE BLIND AND SWITCHED FROM LECTOR DAM IN REAL TIME, WITH HELP OF A FRIEND OWNER LECTOR. Result: timbre, spaciousness and three-dimensionality INCREDIBLY EQUAL, I REPEAT THE SOUND WAS UGUAE. I do not have a premise in a technical, do not ask measures or graphics, the result of this all depends on what I have described above. Congratulations to Soekris.
P.S. sorry translation
The Simpre 88 SR, un preamplificatore a valvole minimale
http://www.lector-audio.it/Digicode-704/Digicode_704.pdf
https://photos.google.com/search/_tra_/photo/AF1QipPtWAoz8if0pJRI4aG2L3KKmhb6MUcaoYnhWxPR
https://photos.google.com/search/_tra_/photo/AF1QipOEje5PNZqCsbfh5ypH0yowi0DbgUwTOj88c3c_
https://photos.google.com/search/_tra_/photo/AF1QipPoS2wztdW6EVzKkuttkgqXpNrlzBGa2wvojpht
P.S. sorry translation
The Simpre 88 SR, un preamplificatore a valvole minimale
http://www.lector-audio.it/Digicode-704/Digicode_704.pdf
An externally hosted image should be here but it was not working when we last tested it.
https://photos.google.com/search/_tra_/photo/AF1QipMHO2yAGK23-y5gGhl2NtF8MLIbJ-LpMUOG02Lihttps://photos.google.com/search/_tra_/photo/AF1QipPtWAoz8if0pJRI4aG2L3KKmhb6MUcaoYnhWxPR
https://photos.google.com/search/_tra_/photo/AF1QipOEje5PNZqCsbfh5ypH0yowi0DbgUwTOj88c3c_
https://photos.google.com/search/_tra_/photo/AF1QipPoS2wztdW6EVzKkuttkgqXpNrlzBGa2wvojpht
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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TNT,
What are the loops of wire I think I see on your board? I could understand for the cap jumper but I think I see them at the resistor position, also.
Hate to have to say it but those styroflex caps are not very good for anything. Maybe you can get away with them. Certainly they have the advantage of being very light in weight.
They are renowned for their gritty sound. Excuse the rhyme.
When I FINALLY get around to it I have got some Russian teflons which will be difficult to use but should work very well.
Nonetheless, congratulations on making the mods and thanks for your picture. I am ginning up the courage to go and finally do them this afternoon.
Take care,
What are the loops of wire I think I see on your board? I could understand for the cap jumper but I think I see them at the resistor position, also.
Hate to have to say it but those styroflex caps are not very good for anything. Maybe you can get away with them. Certainly they have the advantage of being very light in weight.
They are renowned for their gritty sound. Excuse the rhyme.
When I FINALLY get around to it I have got some Russian teflons which will be difficult to use but should work very well.
Nonetheless, congratulations on making the mods and thanks for your picture. I am ginning up the courage to go and finally do them this afternoon.
Take care,
The loops are the parts of the "factory mod". One takes away the cap, the other was to set the output resistance to 0,1ohm but I went for 0. Styroflex is the ultimate capacitor dielectric. I wanted specifically a capacitor made out of this. Maybe will aslo try some other make of styroflex.
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GIAN, we cant see your pictures. Maybe your tube output stages took away all the differences and made the 2 DAC equal sounding?
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Try attaching your pictures to the forum 🙂
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it forward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that.
Polystyrene is an excellent dielectric but its presence is not enough to make a cap "good".
I did not realize you were using jumpers all of the way. From what Paukl/moredamfilters found with his tests is this low value requires, at least, 1000uf additional to have a reasonably flat impedance.
Using those jumpers might be easier than using those damned resistors! After losing two in a glob of solder I threw my hands up in frustration. I hope I can get them back down to try again with jumpers. Much cheaper ...
Aha... so maybe I should get a bit larger caps then - thanks!
rickmcinnis, would you advocate against my choise for the styroflex output caps?
Yes, I took the "chicken" path and shorted them. If not only for having an escape route if I didn't like it. The sound is really special. Its really intense. I think I have discovered some resonances in my speakers that I have not been aware of before. The sound is so extremely detached from the speakers but also so stable that anything not associated with the music immediately sticks out. Remains some questions in the upper midrange but I 'm glancing at those dome tweeters..
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rickmcinnis, would you advocate against my choise for the styroflex output caps?
Yes, I took the "chicken" path and shorted them. If not only for having an escape route if I didn't like it. The sound is really special. Its really intense. I think I have discovered some resonances in my speakers that I have not been aware of before. The sound is so extremely detached from the speakers but also so stable that anything not associated with the music immediately sticks out. Remains some questions in the upper midrange but I 'm glancing at those dome tweeters..
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