• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Quicksilver KT88 mono 60watt amp schematic

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fdegrove

fdegrove

diyAudio Senior Member
Joined 2002
???

Hi Mitch,

BTW a very good tweak is putting IXYS hexFreds in various places on the rails.
Click to expand...

I can't even find hexfreds on Ixys site.

Any more detail on where and how you would insert these?

I can't see how these diodes are going to help anything but I keep an open mind.

Maybe you could use the circuitdaigram on pege to of this thread as a basis for your indication.

Thanx,;)
 
W

wheezer

Member
Joined 2002
Quicksilver Mods

It would go in-between the 330uf cap and the choke in the pi filter, on the LINE side of the choke.
If there is another Choke that feeds the OPT, before that one as well.
They help keep things stable when the tubes are looking for more current from the front end.
There are other places it can be used !!!

IXYS part is DSEI12-12A
IXYS DSEI12-12A

I also have DSEI08-06A??? Not sure why I have these.
DSEI08-06A


Digi-Key part #
 
B

Burnedfingers

Member
Joined 2002
Mystery part??????

Ok....

It has C

MP930

500

1%

E

The part is air hung(floating) one side of the two leads is attached to the 8ohm output terminal and the other lead goes thru a resistor to ground, at the point where it hits the resistor it also goes thru a resistor to the cathode (pin 3) of the input tube.

Scratching my head and reaching for a bottle of JD.


Joe
 
B

Burnedfingers

Member
Joined 2002
Frank

Enclosed is picture showing lead of caddock resistor, pot, and so forth.
 

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B

Burnedfingers

Member
Joined 2002
The rather blurred image shows one lead(left of screw)as caddock resistor lead. The gold lead is a hidden 18K resistor going to the cathode of tube #2. The resistor (horizontal ) measures as a 25ohm in circuit. The other lead at the junction of the 18K and the 25ohm resistor is a 233ohm going to pin3 of this tube.


Going for another drink.


Joe
 
fdegrove

fdegrove

diyAudio Senior Member
Joined 2002
TRANSCEDENT PSYCHES

Hi Joe,

It's a wild guess...this caddock resistor is connected to a split cathode resistor at the input tubes' cathode,sharing a fixed resistor (the coloured one,and then the little pot).

Now that pot would serve to set the input sensitivity of the input stage.(grid bias.)

It's just a guess,I may be off.

Mike Sanders is going to hate me for all that guesswork...

Cheers,
 
fdegrove

fdegrove

diyAudio Senior Member
Joined 2002
SUPER FRED

Hi,


I am not sure these interesting new rectifiers will make an audible difference in this particular amplifier though.

The 5AR4 should smoothe over any peaks from the diodes.
What could be audible is the lessened RFI of the diodes in the whole of the audio system.(less mains pollution)

All in all interesting info.
Thanx Mitch.

Joe,

How are the input tubes heated?AC?DC? And if DC how is it done?

Cheers,;)
 
W

wheezer

Member
Joined 2002
Quicksilver Mods

They are heated from the Tap of the PSU tranny. 6.3VAC. The days of rectifying for the heaters are gone for the most part. Too many issues. Diodes into the tubes So, yes they are AC heated.
The heater pin has a green wire going back to the PSU tranny.
 
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