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Old 14th November 2010, 02:55 PM   #1
el156 is offline el156  Portugal
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Default EL34 PP PROJECT

Here are so fotos of my latest project...

E88CC as input tube

ECC804 as phase splitter
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Old 14th November 2010, 03:09 PM   #2
M Gregg is offline M Gregg  United Kingdom
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el156,

Nice project!
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Old 14th November 2010, 08:27 PM   #3
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I love the curved front and the overall design.
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Old 15th November 2010, 07:57 AM   #4
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Youre lucky getting rid of the heat isn't an issue.
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Old 15th November 2010, 08:36 AM   #5
el156 is offline el156  Portugal
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Well, it is a newbie project,but i am not very happy with the sound ,it seems doesnt have enough power, but i will post the schematic to get your opinion about it, maybe i havesome mistake in there!
Thank you for your comments
EL156
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Old 15th November 2010, 10:58 AM   #6
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30W o/p with a pair of EL34's should be a breeze. Using 92dB/w LS sensitivity with good sized bass drivers should rock the room. This was a standard classic design of the 1960's and found amps of this everywhere in halls and theatres.

richy
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Old 15th November 2010, 12:53 PM   #7
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Quote:
it seems doesnt have enough power
Do you mean that the sensitivity is low, which means that your input signal can not give full output ?

Or do you mean that the output signal becomes distorted before the sufficient sound level is achieved ?

Can you show the chematic ?
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Old 15th November 2010, 01:25 PM   #8
el156 is offline el156  Portugal
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Quote:
Originally Posted by artosalo View Post
Do you mean that the sensitivity is low, which means that your input signal can not give full output ?

Or do you mean that the output signal becomes distorted before the sufficient sound level is achieved ?

Can you show the chematic ?
I think sensitivity is ok , the signal comes distorted before sufficient sound level is achieved, I have to draw the schematic first to post it later on or tpmorrow.
EL156
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Old 20th November 2010, 05:15 PM   #9
el156 is offline el156  Portugal
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Okay ! Here is my schematic ! Maybe someone can tell me what is wrong with this schematic !
EL156
Sorry for the bad quality of pic
Thanks
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Old 20th November 2010, 06:20 PM   #10
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Default EL34

Fair circuit so should work ok. I note there is no negative feedback so speaker impedance will have a big impact on the frequency respose (as per a typical guitar amp/combo) and matching the speaker impedance to the reflected output impedance will cosiderably affect power output. As a general rule you should load a typical 8ohm speaker to a 4 to 6 ohm tap to account for speaker impedance dips.
With the 380 volt supply I wouldn't expect much more than around 20 watts.
Here's another note for any other builders of ultralinear EL34 designs, you should never exceed a max of 420 for the HT, otherwise you will get flashovers between the screen grid and control grid, very nasty.
Incidentally this is my first posting on this site.
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