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Old 17th November 2006, 02:09 PM   #21
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Yeah .. cool stuff.. I'm motivated to set up an LCD screen above my bed so I can read it all....

Check out this related thread

Question about DIY EL34PP amp
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Old 17th November 2006, 02:41 PM   #22
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Quote:
Originally posted by peritus307
Yeah .. cool stuff.. I'm motivated to set up an LCD screen above my bed so I can read it all....

Check out this related thread

Question about DIY EL34PP amp
well it seems that we are building similar projects

I will make some modifications to the schematic of that PDF. I wont use a pentode for the first stage, will be something like this:

first stage: 12AX7 diff-amp with a solid-state current source
driver: 12AU7
output: 2xKT88
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Old 20th November 2006, 04:28 PM   #23
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Power supply:

the 500v supply:
8x220uF 400V caps for the power supply
2x 0.47uF 630V
4xBY228 fast diodes (1.5KV / 2A)
And the bias power supply (bridge diodes + 470uF)

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Phantom load for measurement (6 ohm)
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Old 26th January 2007, 10:45 PM   #24
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Long time ago since my last post.

The project is going well. I have to make some adjustments (Feedback, etc)

some pictures:

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In this next picture, look just below the PSU transformer. It's the 10H 250ma choke good support for the PSU trans.

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What do you think? isn't beautifull??
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Old 26th January 2007, 10:48 PM   #25
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Just out of curiosity....
I thought that it was always 'best' to place the PT 90 degrees from the OPTs to prevent coupling ? Furthermore, I thought it was best to mount the power choke out of phase as well...Perhaps I am mistaken ?

Regards,
Steve
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Old 26th January 2007, 10:54 PM   #26
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I didn't know about that. I hope you're wrong

By the way, it only has a little hum that I still have to fix.
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Old 26th January 2007, 11:41 PM   #27
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Quote:
Originally posted by zafira1981
I didn't know about that. I hope you're wrong

By the way, it only has a little hum that I still have to fix.
No, actually he is right, but in this instance you may get away with it. (or not) In your next project though you definitely want to mount the output transformers at right angles to the power transformer.

How about some pictures of the underside of your amplifier? May help some of us identify other potential sources of hum in your amplifier.
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Old 27th January 2007, 12:18 AM   #28
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It will be simplier to rotate output transformers, it seems to me the power tranny rotated will not fit...
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Old 27th January 2007, 02:58 AM   #29
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rotating the two output transformers will be boring and annoying but can be made simply. In fact, i think i could use the same holes.



Here is a pic of the connection side.

It's not finished. I'm making a little bit of order. When I used the amp for the first time it was a mess , really a mess of cables & stuff.

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Old 27th January 2007, 09:39 AM   #30
Jaap is offline Jaap  Netherlands
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Default twist

all heaterwires should be twisted, perhaps better not to hop from tube to tube but all heaterconnections to central startingpoint.

make sure there is only 1 earth point connected to the chassis.

shielded wire from inputplug to first tube.

use gridstoppers everywhere
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