MPP

......
 

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Frans, for me that looks like an ancient plate found in Nazca.

Jeaaa, cool, ain't it ... lots of work though, my second major board design in ... (as long as I live). Should be good for +/- 70 VDc bridged into 4 Ohm. If, and only if, the final build sounds VERRY good to me (and my friends with the golden ears), only then I will publish all, but in the meantime it would be nice to have an experienced amplifier builder than wants to beta it :) One version sits here singing any song with no problem, but it is running of +/- 35 VDc. These are exciting times ...

The board design is unconventional, it uses an third ‘external’ layer in the form of an copper plate that will be mounted on the PCB with 7 copper screws, this serves as the ground plane. The high current circuit is designed with jumpers, these will be 6 mm2 and all power and audio large signals will travel these copper jumpers. The series inductance is wound from 6 mm2 copper, 25 turns, about 2 cm diameter for 6 to 7 uH, the series resistance of this thing is a few mOhm’s only.
 
Prety nice tool, although time consuming. The shape of the curves looks very similar, so simple Hfe matching whould work too, at least for this batch of Fairchilds.
I am surprised how high the Hfe is anyway. BC550C and BC560C are not better in that sense.

Dat sheet for BC33740 show HFE from 250 to 680
from the first bunch of 50 tested I shuld be able to get quite a few sets of 18 with hfe matched in the + - 5 range

I will use the closest match possible for same part of circuit hfe + - 2

Range of Hfe for 337 is 100 to 250 for type 16
160 to 400 25
250 to 630 40
What is the best hfe for Paradise ?
 
it would be nice to have an experienced amplifier builder than wants to beta it :) One version sits here singing any song with no problem, but it is running of +/- 35 VDc. These are exciting times ...

QUOTE]
Beta buld me me me :D



I like unconventional boards
I used same principle on my old LT1028 balanced MC
2 PCB a couple of mm apart
one board for componnents and second board as ground plane and suply.

The connection was made troug the pins of the decoupling capacitors.

Not big deal to solder first time with long terminals but after that it was labor of love to get them apart and make changes
 
Bksabath, the original Paradise could show signs of oscillation if Hfe went too high.
Unfortunately me and others thought it is better to use as high Hfe as possible and that was one of the reasons we got in trouble. That was solved by local ground and generous decoupling.
The New Pardise is much less sensitive so you can use high Hfe if you wish.
Hfe of 400 should be on the other hand be enough to let it work well.
 
I just looooove the paradise....playing vinyl on my Rig is just phenomenal..I use a version that is just the middle between the "old" paradise and the new version...to be honest there's just myriads of small tiny details and a crispness that I have never ever heard before..Base is solid and well spaced, small in size but very concentrated and tight in energy. The concept is surely very very strong.. sounds is natural and very very dynamic and lively....I'm in Looove....(with music)
 
Got sore thumbs ploughing in the first 250 BC33740

The bulk of the batch seems to be between Hfe of 520 and 560

Once the bins are full I can start to fine sort again

I will populate boards with same (as close as possible) Hfe and select similar values between the left and right channels.

For now I am going to give it a rest and listen to a few tracks.
 

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Dreams come true

This is what I came up with (I do not want to start a new thread on this, but still I want to show the 'thing', so here it is), I guess I am spending to much time at the ATL :)

What about this, I can do 70 Watt class A in 4 Ohm (or 150 Watt class A in 8 Ohm bridged). The amplifier has 14 components (and that includes the loudspeaker). The simulation FFT shows first harmonic at -100 dB or better (that is at clipping and at 10 Khz). There is no global feedback. There are no capacitors in the circuit.

So that is what I get when I cannot sleep. Maybe now I get some sleep ... :)
 

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