Pass "DeLite" Amp from BAF

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Variac

Variac

diyAudio Editor
Joined 2001
BurningAmp.org
Paid Member
We have to give Jason (the diyAudio founder) almost all the credit on the design. He has really worked hard on that section. I just complained when I didn't think it was good enough. The new forums were more my area..... We work together on most stuff though..

It is really great to have two people working on improving the place, otherwise its pretty overwhelming.
 
E

Ejam

Member
Joined 2004
DeLite with a Current Source

Paul Hynes built the attached depletion mosfet follower some time ago. http://i700.photobucket.com/albums/ww7/paulhynes/SE1.jpg

I was thinking of flipping it with the current source on top and the gain stage on the bottom with the output taken from the drain of the bottom fet. Firstly will this work? Secondly, with the dual power supply arrangement is an output coupling cap necessary? Thirdly is a source degeneration resistor needed on the current source?

Regards

Ejam
 
Nelson Pass

Nelson Pass

The one and only
Joined 2001
Paid Member
I was thinking of flipping it with the current source on top and
the gain stage on the bottom with the output taken from the
drain of the bottom fet.

I have several examples - it works

Secondly, with the dual power supply arrangement is an
output coupling cap necessary?

No, but you have to match the parts or trim the resistors
to get low DC offset. Also, you have to drive the Gate of
negative device referenced to the (-) supply, not ground.

Thirdly is a source degeneration resistor needed on the
current source?

Probably.

:cool:
 
I

infotrad

Member
Joined 2004
semantech.com
Why the teo 300-watts light bulbs?

I am a novice at DIY, i.e., I've never built any electronic circuit, and wonder what the 300-watt light bulbs do. From the schematic, I can only infer that they are some sort of resistance, but consuming 600 watts of electricity seems rather like a waste tome. So my questionis: What purpose do these two light bubls have in the amp?
 
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Amp_Nut

Member
Joined 2006
Lovely, elegant design that not only put a smile on my face, but also brought back nostalgic memories of a similar amp I put together about 35 years ago, using a Germanium power transistor salvaged from a flash gun. ( It used a couple more resistors), The speaker was a Phillips full range, placed on the mouth of an earthen ware pot. The source a portable cassette player.

Since that was powered at approx 12 VDC, I used a saucer full of water ( topped up daily!) as the heatsink.. the transistor head was partly submerged in the water..

I am curious to know if substituting the Grossly Non Linear load of the light bulb with a fixed resistor, would improve distortion ?

Thanks again.
 
V

VladimirK

Member
Joined 2007
Amp_Nut said:
Lovely, elegant design that not only put a smile on my face, but also brought back nostalgic memories of a similar amp I put together about 35 years ago, using a Germanium power transistor salvaged from a flash gun. ( It used a couple more resistors), The speaker was a Phillips full range, placed on the mouth of an earthen ware pot. The source a portable cassette player.

Since that was powered at approx 12 VDC, I used a saucer full of water ( topped up daily!) as the heatsink.. the transistor head was partly submerged in the water..

I am curious to know if substituting the Grossly Non Linear load of the light bulb with a fixed resistor, would improve distortion ?

Thanks again.
Click to expand...

In simple designs, quality of every component affect not only measurable distortions, but also subjective sound quality. So, further modifications to this disign could be predicted - decent resistors in TO-247 case, heatsinks, shunty power supply, CCS load, modulated CCS, input buffer stage, some NFB ...
 
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