SEWA - Seven Watt Amplifier

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#181
There is an error in the gate bias circuit. The 47K that connects to the 330U cap should be connected to 0V where you have connected it to the cap. The 330u cap should be connected at the junction between the 12K and the 47K. Other than that, it looks fine. I would have designed it much denser though 😉 I recommend to have holes for standoffs/pcb mounting in the front corners also.
 

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#184
Hi,

This is a rough idea about SEWA with a Jfet. I think that this circuit will not work as is, Jfet is not biased properly...

I kindly ask more knowledgeable guys to have a look at this and suggest neccessary corrections. The main idea is to merge good sides of both ZEN V8 and Sewa, which would resuld in an amp with zero voltage gain, 5-10 w power, and excellent sound...

Regards,

Vix
 

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#185
If you could find a JFET that can take as much heat as a MOSFET, you can simply pop it in the SEWA circuit with a minor adjustment of the bias voltage divider to account for the different VGS. However, since such a device is not yet avaliable, you'd have to get smart and utilize some tricks like cascode operation to get the dissipation down. Sounds like a fun project 😉 Read up un Nelson's cascode article; it shows cascoding of a follower. Compare this to the ZV9 and you can start connecting the dots. 😉
 
#186
Vix said:

. . . suggest neccessary corrections.
Click to expand...

As far as I understand, why LU1014D is for the kind of like a triode at its small signal and low Vds level. Therefore, the signal voltage swing might have to be kept low inside the narrow triode area, unless the kind like a triode is given up.

Regards
 
#187
jh6you said:


As far as I understand, why LU1014D is for the kind of like a triode at its small signal and low Vds level. Therefore, the signal voltage swing might have to be kept low inside the narrow triode area, unless the kind like a triode is given up.

Regards
Click to expand...


Then, it seems that it doesn't make much sense build a follower with LU1014D, since the most benefit is extracted in the common source mode?

:xeye:

Anyway, it would be interesting to compare SEWA and Zen V8 or V9...

In my ZEN V8 I have experimented with the amount of feedback, and decided to run it with feeback. It looses some "air" and "magic" but sounds more balanced and the bass gets better too...

Nevertheless, it is similar to a triode-like sound, midrange is very sweet and soft, highs are good but could be better, bass, uhmm...honestly, not to my liking. This is its only serious drawback. But Iam going to build ZEN V9. With an Aleph current source , it must be much better.

By the way, did anyone compare ZEN V9 with an Aleph3?

Regards,

Vix
 
#197
mad_K
Can you check my pcb layout for Sewa R2
I will send to your email
Buy PCB from other country i Will cost Whole Amps 😡
Beause shipping cost is very expensive 😡
I Only Build for my self with hand drawing pcb ........ :xeye:
Can you pm your email, because i can send picture to you using this forum email.
 
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