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Old 5th February 2018, 05:43 PM   #171
pserci is offline pserci  Italy
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IMHO The original PCB Layout of Crescendo is not so optimized, and prone to HF oscillations. Better employ a newer layout.
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Old 6th February 2018, 07:17 AM   #172
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by Kay Pirinha View Post
You know that the original ELEKTOR PCBs had 70µm copper layer?

Best regards!
Are you asking a question, or telling us a specification?
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Old 6th February 2018, 08:31 AM   #173
scafas is offline scafas  Italy
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Originally Posted by pserci View Post
IMHO The original PCB Layout of Crescendo is not so optimized, and prone to HF oscillations. Better employ a newer layout.
i read that the source resistor are the problem of oscillation
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Old 6th February 2018, 02:34 PM   #174
scafas is offline scafas  Italy
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Default board

this is the original board .
something to improve?
the pcb is 146x129mm.
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Old 6th February 2018, 02:40 PM   #175
schillg11 is online now schillg11  Germany
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Originally Posted by scafas View Post
this is the original board .
something to improve?
the pcb is 146x129mm.

Hi scafas,

google for 'ray's audio page' and see, what can be improved.
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Old 6th February 2018, 04:06 PM   #176
Kay Pirinha is online now Kay Pirinha  Germany
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Quote:
Originally Posted by AndrewT View Post
Are you asking a question, or telling us a specification?
I know for sure that Elektor sold their PCB's for this project exactly with this specs.

Best regards!
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"Bless you, Sister. May all your sons be bishops." (Brendan Behan)
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Old 7th February 2018, 04:44 PM   #177
scafas is offline scafas  Italy
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Originally Posted by schillg11 View Post
Hi scafas,

google for 'ray's audio page' and see, what can be improved.
i see , so i add some components on board to prevent oscillations..
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Old 7th February 2018, 08:55 PM   #178
schillg11 is online now schillg11  Germany
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hello scafas,

here is my modification done 2 years ago, according Rays page. Left side is the orignal , which was built 1985.
On the right side you see the modified board with Dale CMF 55 resistors and mica ,Panasonic FC, WIMA MKP and Frolyt bipolar capacitors. Also MJE350 and 340 as driver transistors and most important the source resistors as Metal Band resistor MPC 74, no wirewound resistors.

BR
Günni
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Old 8th February 2018, 05:10 AM   #179
scafas is offline scafas  Italy
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Quote:
Originally Posted by schillg11 View Post
hello scafas,

here is my modification done 2 years ago, according Rays page. Left side is the orignal , which was built 1985.
On the right side you see the modified board with Dale CMF 55 resistors and mica ,Panasonic FC, WIMA MKP and Frolyt bipolar capacitors. Also MJE350 and 340 as driver transistors and most important the source resistors as Metal Band resistor MPC 74, no wirewound resistors.

BR
Günni
other mod on Rays page:
- Use poor induction resistors for R27 to R30
- increases C16 from the Zobel network to 100nF and uses a MKP
- isolate T8 and T10 from the heat sink and connect them to zero
- Mount 22k load resistors for T8 and T10
- T8 and T10 may be needed. they are replaced by MJE340 and MJE350
- place a 100 nF capacitor on P1
- reduce the polystyrene from C2 to 100 pF
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Old 3rd April 2018, 11:22 AM   #180
scafas is offline scafas  Italy
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pcb are available , ask me in PM.
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