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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

SE 2 watt clean amp?

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SemperFi

Member
Joined 2002
azazello said:
Sorry, but I doubt that cheep ampl with OT for 12$ will sound good. 6V6 needs 8-10 sq cm iron for very good sounding. Than if You will change OT-s to bigger, You
will sense very big difference. I think, IMO, 24$ are money to wind. Sorry for off...but, IMO, cheep amplifier = cheep sound.
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Sorry for you:( You don't know what you're missing :D I don't know which OTs he got from 'tubesandmore', but the cheapest Edcors are great! Less than 20dollar bliss:)
 
azazello

azazello

Member
Joined 2008
Sorry, guys, but I don't like good sounding amplifiers, ....I like very, very good sounding..../IMO/
/When I made my first ampl, I think that is the top of Ice cream....now when I listen it - EL84,
I think how it sound is terrible....maybe the time and skill are guilty/.
 
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johnr66

Member
Joined 2009
Eli Duttman said:
What sort of transformer do you have? What are its spec's?

A 140 VRMS rectifier winding would make a nice B+ rail, when rectified by a Greinacher ("full wave") voltage doubler. TANSTAAFL applies and the DC draw is limited to 1/4 the RMS current rating.

If you glanced at the thread I linked earlier, you'll have noticed the mention of the Hammond 125ESE. That O/P trafo is quite affordable and is not hopeless.
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The transformer is from an old solid state Kenwood receiver. It has a 70 volt center tapped secondary (used for the 40 volt single supply to the power output stage). It has a 6.3 volt winding for pilot lights, probably 2A max (might be an issue). It is sounding like I need a higher voltage if I want to do this right.

Is the cathode resistor to allow the grid to be more negative? Why is the screen fed through a relatively low value resistor from the supply or a tap on the primary OPT? I thought it should be fed a fixed voltage of about 1/2 of the plate.

PS. love the "cake pan" amp:)
 
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Eli Duttman

Member
Joined 2004
The transformer is from an old solid state Kenwood receiver. It has a 70 volt center tapped secondary (used for the 40 volt single supply to the power output stage). It has a 6.3 volt winding for pilot lights, probably 2A max (might be an issue). It is sounding like I need a higher voltage if I want to do this right.
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Depending on its current capability, that Kenwood trafo could be suitable, as multi-stage voltage multipliers are available. However, the cost of the caps. needed to make such a multiplier work well is high.

IMO, you will be better off using a set of "iron" known to work well. A full set of power magnetics for "El Cheapo" can be purchased from Allied Electronics, at reasonable cost. $25.82 buys stock # 967-2343, which is the Triad N-77U main B+ trafo. $17.31 buys stock # 967-8019, which is a Triad VPS24-1800 that supplies "12" V. heater power and B+ boost. $13.41 buys stock # 227-0034, which is Allied's own 6K27VF that energizes the B- supply and 12AT7 heaters. Finally, $7.74 buys stock # 967-1004, which is the B+ filter choke (Triad C-24X).
 
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VictoriaGuy

Member
Joined 2008
brucetassin said:
Hi John, yes thats it. It cant get any less expensive than this and still put out something worth listening to. Here are a few pictures of my project.
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Thanks, Bruce. I was 'led astray' by the pics of the 'dual mono' version on the Boozhound webpage - double PTs, double chokes, etc....

Another good-sounding and simple amp is the RH84 by Alex Kitic - I built one a couple of years ago.

John
 
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