SE 2 watt clean amp?

[johnr66]

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?

 

[planet10]

SE EL84 would fill the bill.

dave

 

[Eli Duttman]

John,

Triode wired 6V6 family tubes will yield 2 VERY nice WPC. A 5965 will be excellent as the voltage amplifier.

You really don't need NFB, if you use good O/P trafos, as the bulk of the HD will be euphonic 2nd order.

 

[piano3]

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.

 

[piano3]

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

 

[Eli Duttman]

Of the two suggestions so far, 6V6 will easily produce the power although EL84 has probably more linear triode curves.

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 R_P, 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.

 

[azazello]

6V6/triod mode/ & 12AT7
Picasa Web Albums - Nikola Nikolov - amplifiers

6V6 buy from Tube List range 6K4 - 6ZY5G
12AT7 buy from Tube List range 12A - 12Z5
All transformers and chassis buy from Angela.com

 

[Cassiel]

The 6V6 family makes a better sounding triode than the 6BQ5/EL84. I'm not the only person who thinks that,

Having listened to both tubes in triode mode I can say that I'm another person that thinks like you on this matter.

 

[Pano]

I've listened to both and may have to agree. (Poinz's amp among them). 6V6 is nice. But neither are bad. Really nice, in fact. And I have some 6П15П that will be put to use soon. Should be interesting.

 

[johnr66]

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 is this expensive.

 

[Eli Duttman]

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 is this expensive.

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.

 

[piano3]

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!

 

[mashaffer]

6EM7 would get you close to 2W and would be true SET.

 

[brucetassin]

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.

 

[VictoriaGuy]

Bruce-
I had a quick look at Boozhound and found this:
Boozhound Laboratories
Is this what you are talking about?
If not, can you please post a link? Sounds like an interesting project.
John

 

[Bigun]

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.

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.

 

[brucetassin]

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.

 

[Tom Bavis]

Nice job! But I hope you bought her another cake pan...

 

[burgunder]

If I understood any of this I would look at this too http://www.diyaudio.com/forums/tubes-valves/178363-super-cheap-triode-amplifier.html

 

[azazello]

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.

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.