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Old 9th March 2005, 10:06 PM   #11
kaj2 is offline kaj2  Denmark
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Quote:
Originally posted by Blue
KAJ2:

There's more to modify on a QUAD 405 than simply fitting overpriced capacitors....


http://www.dc-daylight.ltd.uk/Valve-...-405-Mods.html


Never fit a bipolar capacitor when there is a dc voltage across it !


BLUE
Hallo Blue

As far as I can see there is more than overpriced capacitors to the NET-audio modification, as far as i can see they do more or less the same as in the dc-daylight link.
I do not know mutch about elektronic then. The good thing about NET-audio is that youcan send them the amp board and they do the modification.
Do you think that the amp will sound worse after the NET-audio modification?

Kaj
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Old 10th March 2005, 12:43 AM   #12
Blue is offline Blue  Cayman Islands
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Kaj

I think the Keith Snook mod to the front end and the correct placing of C8 in the bridge after upgrading the class A transistors is an original and cool move, also it looks like a hobby site, not commercial although proffessional.

As you say Net Audio will do the mod for you, that takes a lot because the amp could be in any state so they must be serious players.

I thought this was DIY? not let some company do it, I have done the Keith Snook mod to a MK2 and it is truley amazing and like him I have not done any thing to the current limiters yet as they have not been caught out to date.

I will not be posting much much more as I have had some bad feedback for expressing my opinions on other DIY Audio threads so good luck and..

ENJOY THE MUSIC

Blue
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Old 10th March 2005, 07:39 AM   #13
tvicol is offline tvicol  Romania
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Here is the schematic of my 405 clone.

Click the image to open in full size.
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Old 10th March 2005, 09:29 AM   #14
Blue is offline Blue  Cayman Islands
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A woman walks into a garage and asks how much to fix the brakes of her car, $400 says the man.

400 bucks to fix my brakes..... how much just to fix the horn.


Blue
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Old 10th March 2005, 09:59 AM   #15
tvicol is offline tvicol  Romania
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Blue,

Nice joke !

Here are further modifications, which I plan to implement some day.
Any suggestions, comments are appreciated.

Click the image to open in full size.
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Old 10th March 2005, 10:21 AM   #16
Zombie is offline Zombie  Sweden
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Do you still have the current limiting in? Seems like the CCD to the class A is a good idea...
Have you implemented your changes on a 405 original board or made your own?
Cheers
tom
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Old 10th March 2005, 10:46 AM   #17
tvicol is offline tvicol  Romania
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Quote:
Originally posted by Zombie
Do you still have the current limiting in? Seems like the CCD to the class A is a good idea...
Have you implemented your changes on a 405 original board or made your own?
Cheers
tom
I also think that a CCD for class A stage will improve sound quality.

All modifications have been made on an original board (copy). The amplifier is a clone.
With all modifications (see rev.2 picture), the amplifier is very stable and sounds excellent.

What do you think about a cascode stage after op. amp. ?

Cheers,
tibi
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Old 10th March 2005, 10:53 AM   #18
Zombie is offline Zombie  Sweden
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Hello!
What board have you cloned? I have the M12333 issue 10- the very latest I believe, a lot is stripped off compared to the 405.
Cheers
t
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Old 10th March 2005, 12:21 PM   #19
tvicol is offline tvicol  Romania
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Quote:
Originally posted by Zombie
Hello!
What board have you cloned? I have the M12333 issue 10- the very latest I believe, a lot is stripped off compared to the 405.
Cheers
t

My board is a M12368 issue 9 clone.
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Old 10th March 2005, 03:53 PM   #20
405man is offline 405man  Scotland
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In the article listed in the link below

http://home.jps.net/~shiloh/jaes.pdf

On page 12 in the 3rd paragraph reference is made to changing the construction of the bridge inductor from a single wire to one of many parallel strands and of the improvement in balance achieved. Has anyone tried replacing the inductor in the 405 with a parallel constructed one

Stuart
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