Tube Pre Amplifier for SEWA 7 Watt ClassA MOSFET

[Mad_K]

The point is to wire the bridge to get two diodes in antiparalell...

 

[Tyimo]

Yes. Thanks!

Greets:

Tyimo

 

[lineup]

How are you doing with your SEWA, Tyimo?

I wonder among other things, what you use for preamplifier.
What did you endup with as 'best' pre for SEVEN Watt Class A single stage SEWA?

 

[Tyimo]

Hi Lineup!
Since I built my own choke loaded mosfet follower amp I am not anymore a SEWA user. Except that my amp is also a follower, but has much more power than 7 watt.... A kind of "TWEWA"... It is absolutely noise less!! Only music!!
I use now an EF86 (in triode mode) grounded cathode preamp.
It is even better than the E88CC Mu follower!
Very soon I will try a 6N6P WOT, or better to write WIT (With Interstage Transformer) preamp. I will post the result.

Greets:

Tyimo

 

[lineup]

Thanks for your answer.

I will go search for your Choke loaded TWElve WAtt amplifier schematic.
Maybe you recall on which page it is?
Anyhow, your TWEWA is a very unusual amp.
We can count those with a Coil in output stage on 5 fingers!

yours lineup

 

[lineup]

I still havent found your amplifier TWEWA (12 watt)
Can you help me find the schematic, Tyimo?
thanks
/Linie

 

[Tyimo]

Hi Lineup!

Here is:
http://www.diyaudio.com/forums/showthread.php?postid=1173182#post1173182

but it is 15W!
Now I use a 30W version...


greets:

Tyimo

 

[Geek]

How you guys get the thing to handle the heat?

I have all four transistors on a 12" x 6" x 1" sink with a shrouded fan and it still trips the thermal breaker at 75C. in 5 minutes or so

Cheers!

 

[Tyimo]

Hi Geek!

Mine is not so warm. I use full aluminium case and heatsink.
Here is my old SEWA.


Greets:
Tyimo

 

[Tyimo]

Here is my choke loaded 30W amp:

P.S.How can I put more picture in one post?!?

 

[lineup]

Hi Lineup!
Here is:
http://www.diyaudio.com/forums/showthread.php?postid=1173182#post1173182

but it is 15W!
Now I use a 30W version...
greets:
Tyimo

Here is my choke loaded 30W amp:
P.S.How can I put more picture in one post?!?

Thanks very much, Tyimo.
You are a true friend.

Nice pictures. I have a look at svhematic and download it now.

See you

 

[Tyimo]

Thanks very much, Tyimo.

You are wellcome anytime my friend!

Nice pictures.

Unfortunately, not. Made by a mobil phone cam. I will try to make a better one.

Tyimo

 

[Geek]

Hi Tyimo,

P.S.How can I put more picture in one post?!?

You can't

My heatsink is the same cm^2 as your first one about and the same schematic.

Iq is correct, I wonder why it cooks?

Dang sand!!!


Cheers!

 

[Tyimo]

Hi Geek!
My first pics is the original SEWA with CCS and 30Vdc.
The heatshinks are ca. 50C., but my whole case is made from 5mm aluminium. So the case itself a big heatsinks.
Do you have some oscillations??

Tyimo

 

[Geek]

Hi Tyimo,
No oscillations, but didn't take into account the case. That would likely do the trick.

I just need a bigger sink then, because I was going to make the SEWA into a piece of furniture with hardwood fretwork and little exposed metal

Cheers!

 

[Tyimo]

Hi Geek!
I think that will be the solution.

Greets:

Tyimo

 

[meanman1964]

Here is my choke loaded 30W amp:

P.S.How can I put more picture in one post?!?

Hi Tyimo,

Do you have a schematic of the 30Watts version?

 

[Tyimo]

Hi meanman1964!

First you have to finish your tubepre and Choke loaded amp and write here your listening impressions.
After we can speak about it...

Greets:

Tyimo

 

[meanman1964]

Yes, I know

 

[meanman1964]

How much is the output voltage of this pre amp ?