SEWA - Seven Watt Amplifier

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BTW, I found a used Aleph 30 the other day (very rare here in Norway). I'm looking forward to getting my hands on a original :D
 

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:smash:
woow
this thread still alive!

Mad_K
I was with you in beginning of 'One Transistor amp' thread
and also a bit in this SEWA project, if you remember me.

http://www.diyaudio.com/forums/showthread.php?threadid=73598
OTA - One Transistor Amplifier

I while back I posted a amplifier design with only one transistor. I named it SEWA (Seven Watt Amplifier). It seems most people interested in the design actually wanted LESS power (power dissipation I guess). While the SEWA design has evolved into something different (coming later), I have renamed this design OTA - One Transistor Amplifier. Attached is the revised schematic. Enjoy! And please let me/us know if you decide to try it
http://www.diyaudio.com/forums/showthread.php?threadid=73598


I really like your work :cool:
And your way to go.
As 'audio father' Mr Pass did put it:
Keep it Simple, guys!
 
Mad_K said:
Hello again lineup ;) Thanks for the roses. Your presence is more than welcome.

A lot of guys here are interested in
tube preamps/drivers for SEWA,
maybe you can help?

My tube knowledge and practical experience is very limited
at least compared to those in TUBE & VALVES forum.

I really would like someone start a topic in Tubes,
about preamp project for SEWA.
As many TUBE Guys also reads Pass Labs forum,
several people with good Tube knowledge, alread may know about SEWA.


In Tubes Forum
Topic could be this ( or similiar ):

Tube Pre Amplifier for SEWA 7watt Class A MOSFET

okay, I go create this topic now, myself!
With such a title it may attract a few active posters ;)

See you.
 
Yup, the coupling caps are very important. I have had good results with Elna RJH (for low power version, 4700uF) Comparable to Panasonic FC, Sanyo MV-AX/WX etc. For higher power I liked the Evox Rifa PEH 200. In my next OTA build I am going to use a chassis mounted 10000uF 63V PEH 200 bypassed with a 250V 2u2 Rifa PHE426. It MAKES ;)
 
I don't want to be seen as a cap snob but have you tried things more exotic than RIFA? Like Hovland, Auricap or Mundorf? I would see something this quality critical on the input cap at least.

Also I wouldn't under-estimate the effect of that bias bypass cap nor the last power supply electro.

With very simple low parts count zero feedback designs like this, the catch is you must pay up for the absolutely best available parts if you want the most out of the design. I know YOU know this.

cheers,

Bart
 
Yes, I used to be fantaic about these things, but you know I am an engineer, so I guess that side of me keeps me from paying through my nose for any "audio" components. I use the best I can get from my electronic component supplier ( www.elfa.se ). For better sound, it is better to buy bigger/better trafo, supply caps, heatsinks, mosfets, voltage, current etc. IMHO. I know the passive components can significantly change/better the sound. I leave this to the individual tweaker ;)

BTW, there has been a lot of talk and little actual building to be seen in this thread. What we NEED is to see some pictures of some ratsnests acually making music. Come on gys, show us, show us! Someone must have buildt something :confused:
 
engineer accounts only for getting close to an approximation of good sound.

from there on in we can only trust our ears - admittedly subjective by personal bias but amazingly often agreed upon by large groups.

we pay larger sums for better parts hopefully only if these parts offer a worthwhile benefit / cost to our ears!

you cant get there merely as you say by bigger everything, sorry! you are wrong. in every place you mention, if correctly engineered, once quantity is adequate quality is everything.

look at the very best pre-amps from CAT and Conrad Johnson. This later refining very simple almost 30's designs for 30 years. They won't have an electrolytic capacitor ANYWHERE! both make their own caps.
 
I am with you and I completely agree/understand these things. Remeber that I said "bigger/better". What I said, counts for me, and my experiences. I'm really not into listening to sound, only the music matters to me. Let's not get into this parts debate in this thread, please ;)
 
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