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SE 2 watt clean amp?

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johnr66

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Joined 2009
I'm new to tubes. I wonder how good a single ended amplifier can sound. I'm not after golden ear hi-fi performance, but want 2 watts per channel of output before clipping, 40Hz - 15 KHz with less than .5% THD.

The purpose of the amplifier would be to boost the output of headphone devices (Walkman) to drive speakers. Since the devices have their own volume control and other sound controls, The amplifier would not need need any controls, just a power switch.

I would think that a triode tube would have enough gain, but not sure if I have to add some negative feedback.

What do you think?
 
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piano3

Member
Joined 2010
Of the two suggestions so far, 6V6 will easily produce the power although EL84 has probably more linear triode curves. If you were to use a 5K transformer with EL84-ra~2k- you would have to swing 100V RMS. Is this easy? My 2 cents worth; how about very linear and cheap Russian 6N6P? I mean running both sections in parallel.
 
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piano3

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Joined 2010
Maybe possible operating point for 6N6P; 180V,25 mA per triode section 2.4k primary impedance. Comments anybody? Actually johnr, your requirement for less than 0.5% THD is a bit steep for SE at full power. A 300B would struggle to get this at 2 watts
 
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Eli Duttman

Member
Joined 2004
Of the two suggestions so far, 6V6 will easily produce the power although EL84 has probably more linear triode curves.
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The 6V6 family makes a better sounding triode than the 6BQ5/EL84. I'm not the only person who thinks that, ask Poindexter. The Russian 6П15П (6p15p), AKA SV83, makes a nice triode too.

Using a tube with a μ in the low 30s is (IMO) cutting things a bit too fine. The 5965 is high gm, low RP, linear, and its μ is in the 40s.

Check this thread out. Buy 1st class O/P "iron" and that kind of circuitry sings sweetly, indeed.
 
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Eli Duttman

Member
Joined 2004
johnr66 said:
Thanks for the replies. I take it a 140 volt supply and appropriate tube is out of the question? I happen to have a transformer plus doubler circuit. I look at the cost of the transformers and WOW:eek: is this expensive.
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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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piano3

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Joined 2010
I bought a big bunch of 6V6 for my Dad's small ampex amps which he uses with his computer. Merely looking at the triode curves did not inspire me to build him an SE. However,as there is no substitute for actually doing it, reading the opinions above means I shall need to think again!
 
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brucetassin

Member
Joined 2005
simple yet good sounding 6V6 SE.

You should check-out boozhound labs for a nice simple 6V6 SE. I just finished putting one together and it sounds very very good. The web site is easy to find, just google boozhound labs and look for "simple 6V6 SE Hi-Fi amp".
I had most of the parts on hand, only had to buy the SE OPT's. Got them from "tubesand more dot com" for $12 each. The project cost less then $50.
I used a cake pan from Krogers for a chassis.
 
Bigun

Bigun

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Joined 2009
diyaudio.com/community/threads/tgm8-an-amplifier-based-on-rod-elliot-p3a.245619/
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Eli Duttman said:
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.
Click to expand...

I'm using this OT and am very happy with the performance - at 2W you are well within its power rating which extends the freq. response.
 
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brucetassin

Member
Joined 2005
simple 6V6 SE amp

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.
My wife is still upset about the cake pan. I made it a stereo amp.
 

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azazello

azazello

Member
Joined 2008
brucetassin said:
You should check-out boozhound labs for a nice simple 6V6 SE. I just finished putting one together and it sounds very very good. The web site is easy to find, just google boozhound labs and look for "simple 6V6 SE Hi-Fi amp".
I had most of the parts on hand, only had to buy the SE OPT's. Got them from "tubesand more dot com" for $12 each. The project cost less then $50.
I used a cake pan from Krogers for a chassis.
Click to expand...
Sorry, but I doubt that cheep ampl with OT for 12$ 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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