This is one of the simplest (and nicest) project i've ever made. I suggest it to all the first-time DiYers
In my opinion, Its main advantages  are:

• low price and good quality
• components easy to find
• easy costruction
• (above all) lot of fun in changing parts or experimenting new tubes or changing bias point or driving tubes or... (see modification section in this page)..

http://www.nuovaelettronica.it
The kit number is LX.1240 KIT
The issue number is               182
Description:   FINALE classe A a VALVOLA
Price:    185.000 lit. (ca. 100U$)

This little monster delivers about 8+8w using a pair of EL34 SE in ultralinear mode.
The output thansformer is rated 2300ohm and can be used to build a lot of project using famous tubes, like 2A3 and 300B. Or with a couple of EL84 in parallel SE.
Also the supply with its 330V dc of output can be used to power a lot of different tubes.

MODIFICATIONS

Here comes the funny parts..... ;), i've I've changed almost everithing, i suggest you try it to... you can experiment a lot  using this kit end learn much more too...

EASY/LOW COST MOD.

• TUBES I've tryed several types, but, leaving back the different suppiers (svetlana, chinese..) one of the best and easyest improvements is using a tetrode/triode instead of a penthode.   What you loose in bass power and amplification you gain in clarity and smoothness of music. Changing to tetrode is very simple: the tetrode version of the EL34 is the 6CA7
• By changin the heater connection of the ECC82 (cut the shotcircuit of pins 4-5 and connect them to 6,3V, leave pin n°9 floating) you can experiment a broad range of other tubes, including 6CG7 (the noval version of 6SN7) and ECC88/6DJ8, ECC83 etc.. this is a nice way to taste the different "voice of tubes".
• You can also experiment EL34/6Ca7 in triode connection: Simply remove R12 from the ultralinear tap of the output trasformer and connect it (trough the resistror R12) to pin 3 (anode) of the EL34.
• you can also try  to take away the feedback by cutting the loop or taking away the RC network R11-C8. To avoid ringing/oscillating is better to use low-amplification factor tubes when doing this mode. I've tryed this with the 2A3 and it was one of the best discover: no feedback gives "life" to music.

• Double the power supply. This is necessary to improve channel separation and bass response. To tell the truth I've do it in firrst place, before any other mod.
• With separate supply trasformers you can do the last improvement:substitute output tubes with 2A3. What you need are only tubes, sockets and a couple of resistors do decrease heater voltage to 2,5V. (unless you use the 6,3V version of 2A3).

The power supply should be changed as follows

The resistor RF should be calculate with ohm's law, allowing for some loss if you use long wires for the heather. I used 1ohm resistor each.
The bias poit of the 2A3 can be choose from the sheets. I used a bias point published in another project, this used Rk=820/2W. For CK you can use any low-z cap. Value must be 100-470uF. At the end I choose a network of 10X5,6uF mylar capacitor.
I've also paralleled the supply caps with 30uF paper-oil... just to get the taste..

LISTENING IMPRESSION 

Not much to say... after building it and the first series of (low cost mods) me/myfriends  began to belive that valves had a good chance to be the right device for sound...  after I put the 2A3 and took away the feedback we had no doubt... tube were the winners...
From then on,  we think that building DIY amplifiers with tube  was the right direction.... that lead me to "Francesca" and the 572-10....  and my friends to "The Triodino" and 300B........ but this is another story....   :).
 

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