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Old 17th January 2014, 08:02 AM   #111
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Quote:
Originally Posted by trilbies View Post
I emailed you via your Form recently did you not get it? Might want to check your Form.
Never received your mail. Please, can-you copy-it in PM here ?
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Old 22nd January 2014, 09:35 PM   #112
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Originally Posted by nigelwright7557 View Post
I usually fix it with 100pf at the VAS stage across CB.
Sorry, my Electronics background is French I am not familiar with these terms, can you explain between which connections you put the 100pf?

Would anyone else recommend it?


Thanks
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Old 24th January 2014, 08:34 PM   #113
poluca is offline poluca  Italy
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hi, can you send me a copy?

g.lucap@alice.it
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Old 30th January 2014, 01:30 AM   #114
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Default discrepencies

Okay, just finished comparing the old design with the new one; little has changed, and Esperado, I am sorry to let you know that your PCB rewiring is incorrect Your PCB view connects the C19 and C20 capacitors (see schema below) on the other side of the R17 and R18.

Anyway the only unaccounted for elements that aren't on the original design are the ones circled in red below.

These two comps aren't present on the positive side.

Are these necessary just for the negative stage? or is that an error as I fail to understand what it does brings to this otherwise totally symmetrical schema


Thanks.
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Old 31st January 2014, 08:51 PM   #115
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Quote:
Originally Posted by trilbies View Post
Okay, just finished comparing the old design with the new one; little has changed, and Esperado, I am sorry to let you know that your PCB rewiring is incorrect Your PCB view connects the C19 and C20 capacitors (see schema below) on the other side of the R17 and R18.

Anyway the only unaccounted for elements that aren't on the original design are the ones circled in red below.

These two comps aren't present on the positive side.

Are these necessary just for the negative stage? or is that an error as I fail to understand what it does brings to this otherwise totally symmetrical schema


Thanks.
R17 and R18 was just a quick'n dirty little mod to adjust the DC offset 'on my amp'.
Positive OR negative side, depending the sens of the offset.
We could do better adjusting the current sources via R6 or r29. Forget R39/C21.
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Last edited by Esperado; 31st January 2014 at 08:58 PM.
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Old 1st February 2014, 06:33 PM   #116
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Default Update, it's going to be a mixed SMD/THT PCB

Have been in contact with Esperado. Chatting away, in French, he mentions SMD on a layout. Well, it's my expertise, so I'll get most of the passive comps as SMD where possible. That's all the Resistors and some Condos.

I estimate this design will be over 50% smaller on the length.

I think double sided, that goes without saying.

Stay tuned for the initial schematic with all mods I think should be on.

Last edited by trilbies; 1st February 2014 at 06:35 PM. Reason: addition for clarity
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Old 17th February 2014, 04:38 PM   #117
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Guys

Here is the V1a of the schematic. Comments please?
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Old 22nd February 2014, 04:13 PM   #118
paul301 is offline paul301  Zimbabwe
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Hi trilbies,
It has been 2 years since I upgrade my original "Crescendos" as per Esperando's fine design.
I am very very please with the results ans still enjoy listening to them on a daily basis. I used a small piggy back board on top of the Elektor design. I believe the stability of the amp is related to the input capacitance of the outputs fets used. With the increased bandwidth this becomes even more critical. I did not try the capacitor across the sources as per Elektor's suggestion for inductive resistors but found that a 270pf capacitor and a 390R resistor in series from the collector of the BF470 driver and positive supply rail solved the problem. In addition, I injected a small amount of DC (high impedance) into the input to correct DC offset. I stuck with the fuses in the power rails to the output stage and increased the capacitor to 2,200uf after the fuses. I also put 22K resistors on the outputs of the voltage amplifiers as per the Millennium edition. My bias presets have a 100uf across them.
The polarity of your C29 in your diagram is backwards.
Sorry this is a bit long but hope it helps.
Best regards,
Paul
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Old 12th March 2014, 02:45 PM   #119
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i have build it in 1998 and still play perfect!!!!
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Old 31st March 2014, 09:41 PM   #120
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Hi Guys, thanks for the feedback ! I will take these in consideration during development phase. I am planning to do a test board first before the final design. Just to make sure that all works.

I also need to get the overall design in 3D etc...


Cheers.
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