EL34 Single-ended Class A tube amplifier KIT

[dmaxcy]

Hi All,

Recently I purchased Douk Audio’s EL34 Single-ended Class A tube amplifier kit: EL34 Single-ended Class A tube amplifier KIT for power stereo audio HIFI DIY | eBay. Not a bad buy with a sturdy and well thought out chassis.

However, it came win NO documentation of any kind. I can kind of figure out most things but I would really like to know the color coding of the transformer windings just to be sure.

Anyone know where I can access the documentation for this unit?

 

[316a]

Perhaps you should email the seller . It does not sound right to sell a kit with no schematic , instructions etc

316a

 

[dmaxcy]

Did last week. Doukshop in Germany.

 

[jazbo8]

Do you have this one?

 

[rayma]

I would really like to know the color coding of the transformer windings just to be sure.

If you can't be sure of the coding of the output transformer leads, don't connect the feedback resistor
and check the output polarity on a scope. If the input and output are the same polarity,
the connection is correct. If they are of opposite polarity, reverse the primary connections.
Then install the feedback resistor.

Or, out of circuit, you can drive the primary with a signal generator. Connect one lead
of the primary winding to ground, and the 0 Ohm tap of the secondary to ground.
Look at the polarity of the secondary output. Put a dot on the primary lead that gives
the same polarity on the output 8 Ohm winding as at the input.

 

[dmaxcy]

Possible wiring diagram

This is the closes thing that matches the component designators on the supplied pc board.

 

[hego]

Is not ultra-lineal ouput trafo?

This schema is a pentode connection.

 

[AleksGit]

Is not ultra-lineal ouput trafo?

This schema is a pentode connection.

No, this scheme ultralinear turn on tube.
Can be included in triode switch

 

[Koonw]

This amp has many brands, schematic could be similar to this one here: 2x6n9pj sections in parallel. ultra-linear and 5Z3P rectifier.

http://www.diyaudio.com/forums/tubes-valves/268969-boyuu-el34-a9-tube-amp-13.html

 

[pcan]

I have bought a very similar kit, but with a Point-to-Point wiring style. My output transformer wires are coded this way: red = plate, yellow = g2, Blue = b+. The secondary wires are: black = 0, yellow = 4 ohms, green = 8 ohms. Transformer weight is 1.2 Kg (seller claim was 1.5 Kg). I reduced to 33 uF each the filter capacitors before the choke. Supplied parts were 100uF each, way too much for a tube rectifier. I also reduced the value of the filter capacitors after the choke, they too were extremely and unnecessarily high - if the value stamped on the capacitor can is the real one. Exchanging the supplied 5Z3P with a GZ34 increased the B+ and improved the sound slightly.