need help in building tube amplifier 10 watter

[milen007]

hi guys.
i would like to build and SE tube amp. i need schematic for amplifier tubes that might be simple (less part count) to build for newbie. high voltage is not a problem.

i am after around output of 10 watt or more.

read bout 300B. they have 9 watt. any other choice?

and how to determine output transformer?

regards, Erwin

[kevinkr]

The difference between 9W and 10W is small fractions of a dB, and you won't hear the difference. 18W would be just a 3dB difference and is just enough to be a noticeable increase in an otherwise ideal amplifier.

You haven't mentioned your budget, and powers in excess of 10W in SE amplifiers usually come at the expense of increased complexity and cost. The bigger transformers and output tubes required quickly get expensive.

How much power do you really need, what kind of speakers are you driving, how efficient are they, how large is your room, and how loud do you like your music.

There are tons of 300B and other amplifier designs on the web, you just need to search.

I would recommend tubelab's products here: http://www.tubelab.com/

[rdf]

Originally posted by kevinkr
...powers in excess of 10W in SE amplifiers usually come at the expense of increased complexity and cost. .../[/url]

A good middle option might be a high grunt driver for some A2 action.

[milen007]

ops forgot to mention the budget is around $1000 excluding casing

my speaker should be around 87db. i have try using cheap t-amp 10 watt and it could drive the speaker to the listening volume with ease hence i assume the SE with just do the same with my 2 way diy speaker.

my room is around W3.5mxL5mxH2.7m

hi rdf

i lose you. whats A2 action? thx for the inputs

[Geek]

Hi,

Originally posted by milen007
...any other choice?

Yes. SE a 6550 or KT88. Gorgeous sound.
(...and no witchdoctor blessings needed )

Typical 6550 in SE:
Class A Amplifier
Plate Voltage ................................. 250 V
Grid No. 2 Voltage ............................ 250 V
Grid No. 1 Voltage ............................ -14 V
Plate Current (Zero Signal) ................... 140 mA
Plate Current (Maximum Signal) ................ 150 mA
Grid No. 2 Current (Zero Signal) .............. 12 mA
Grid No. 2 Current (Maximum Signal) ........... 28 mA
Load Resistance ............................... 1500 Ω
Power Output (approx) ......................... 12.5 W
Total Harmonic Distortion ..................... 7 %

Cheers!

[ray_moth]

An SE amp has to operate in Class A, i.e. the OP tube is always conducting and never cuts off even at maximum power. It's normally in Class A1, which means the grid never goes positive and grid current never flows.

However, if you use a suitable output tube that can stand grid current without distorting or melting the grid, and can provide a low impedance driver that can supply current to the grid, then you can allow the grid to go positive. That is known as Class A2 and will give you more power.

[milen007]

hi Geek

any schem? total newbie cant get the info from your description. thx

hi ray_moth

any schem as well?

regards,
Erwin

[Geek]

Hi,

Here's a couple I found first page on Google:

http://www.single-ended.com/como-armar.htm
http://www.tubebuilder.com/images/sc.../kt88_se2a.gif

Cheers!

[rdf]

Choke follower output driver on the first. I like.

[milen007]

Hi Geek

yep thats alot in google. but i do not have the knowledge to judge which is better and which has flaw. need some expertise on determining that.

how to know which has low Zout?