Author Topic: KT88 push-pull amplifier with integrated phono stage  (Read 2134 times)

Offline entropyagent

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #15 on: September 29, 2016, 05:12:39 PM »
Can you see this?:


I see what appears to be a mighty-purty-lookin' silver valve integrated. Thanks.

The only cosmetic issue that would concern me, is the risk of seeing my reflection.

Offline ghostinthemachine

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #16 on: October 11, 2016, 08:10:14 AM »
Very very handsome!
Let the music speak...

Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #17 on: October 13, 2016, 07:04:52 PM »
Yebo! I have a very nice output transformer design for the amplifier:

Power rating: 55 watt 
Copper losses:  less than 5%
Primary inductance: 114 Henry
EI96 core 50mm stack
Top roll off at 27kHz
Low end roll off at 42Hz at full power
0.4mm primary copper wire - DCR A-A - 53ohms
three parallel sections of 0.6mm copper secondary windings







Impedance measured with a 8.2ohm resistor:


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Offline Curlycat

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #18 on: October 13, 2016, 07:31:02 PM »
A truly beautiful looking amp!

Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #19 on: November 22, 2016, 04:30:03 PM »
After much to and 'fro, the PSU design is finalised:



Serious wiring to start!
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Offline fredeb

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #20 on: November 22, 2016, 04:48:47 PM »
Sjoe ! Lyk goed Karel .

Ari
“And those who were seen dancing were thought to be insane by those who could not hear the music.”
― Friedrich Nietzsche

Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #21 on: November 30, 2016, 06:06:55 AM »
Me soldering away:

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Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #22 on: November 30, 2016, 06:08:36 AM »
A few hours later:

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Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #23 on: November 30, 2016, 06:12:07 AM »
More hours later

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Offline iondb

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #24 on: November 30, 2016, 08:32:33 AM »
Very nice!! Makes me remember the time you helped me "solder-by-numbers" at the Indaba Lodge way back.....................and my amp is still working  :clap:

Offline fredeb

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #25 on: November 30, 2016, 09:51:39 AM »
Looking good ! I like the biasing setup - neat ! I also like the plates you have for the output tubes , helps keeping things cool .
“And those who were seen dancing were thought to be insane by those who could not hear the music.”
― Friedrich Nietzsche

Offline movershaker

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #26 on: November 30, 2016, 11:20:07 AM »
Fantastic looking amp. How much would an amp like this set me back?  :thumbs:
I've been too long too far away from music....

Offline kubusi

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #27 on: December 08, 2016, 07:52:34 AM »
Very very impressed with the workmanship and finish, I am only able to view one of the photos which was sufficient to see that quality. Many hours of work was done there, congratulations.

You state that you wanted to get the maximum power from those KT88 valves,  had you given any thought to using the TT21 or TT22 instead which is the identical valve with the anode connection to the top cap and consequently can handle a HT voltage of 1250. At the same time a pair will give up to 200 watts audio running in class AB1, not sure what you would get running ultra linear mode.
FIRST LAW OF VALVE AMPLIFIERS
Hot glass looks exactly the same as cold glass.

Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #28 on: December 12, 2016, 06:10:12 AM »
This amplifier would set you back about 30k and it takes about 6 months to build currently.

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Offline Mars

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Re: KT88 push-pull amplifier with integrated phono stage
« Reply #29 on: December 12, 2016, 06:13:20 AM »
Actually I have not considered the TT21 or TT22. Are they still available?

The KT88 has got sufficient power for what I think it needs. I might build 100W monoblocks if I go larger.
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