Helps/opinions needed before renewing my old Mini Crescendo amp

[Cruzs]

Hi all,

I'm a beginner and using this Mini Crescendo amp for 8 yrs 'till now. Some days ago, I've just found my 2 pairs 2SK135/2SJ50 extra below my bed and for some reasons I'm planning
to renew/upgrade my old Mini Crescendo amp (2x70W version) with them. So, I need some answers/opinions before I start to work for it.

I have 2 different schematics that I believe they were originally
published by Elektor in the 80's, and the schematics are:

A. Mini-Crescendo 70W/ch (with a pair of 2SK135/2SJ50)
hxxp://www.audiofanatic.it/Schemi/Tipo/Stato_solido/finali/pic_finaliSS/70W_MOS_2SK135_2SJ50

(please change the "hxxp" with "http", coz the pic is too big..sorry)

B. Crescendo 140W/ch (with 2 pairs of 2SK135/2SJ50)
hxxp://www.solaris.no/electronics/power_amp/elektor_cresc/cresc_1280.gif

(again..the pic's still too big, please change the "hxxp")


My questions:

1. Can I use schematic-B (140W) with all of its components value but only use a pair of 2SK/2SJ on the output stage to make a 70W version ?
Remarks :
- PSU voltage = +50V/0/-50V
- Quiescent Current = 100mA

2. Can I use schematic-A (70W) with all of its components value and add another pair of 2SK/2SJ on the output stage to make a 140W version ?

Remarks :
- PSU voltage = +70V/0/-70V
- Quiescent Current = 200mA

3. What if I use some branded components (R, C) that are famously used in tube amps like Beyschlag, Riken, Holco, Dale, AB, etc (for R), ELNA (Tonerex, Cerafine, Silmic), Black Gate, Solen, Jensen, etc (for C). Will it dramatically improve the sound?

4. Can I replace a 35A/200V Bridge Diode with 4xMUR860 diodes ?

I have an idea. If the answers for the question (1) & (2) are YES, I'm planning to make PCB that can be used for both schematics.
Firstly, maybe I'd like to make the mini version before upgrade it into 2x140 version (add another pair of 2SK/2SJ and change the PSU).


I would really appreciate for some answers/opinions/helps.
Thanks.

[lineup]

hard to say if you can get more power/supply voltage
generally it is not to recommend

the other way, to use less supply for less power can work better

Point 3.
Will it dramatically improve the sound?

Nooooo!!!!!
Actually most components changes will not change sound at all.
Except for changing components in your speakers = sound producers.

There are people that tell they can hear a difference after changing only one supply cap from one brand to another.
But if they did not know and compared before/after, they would fail to verify what is before/after.

It is so easy to say: I changed this and now I hear difference.
Because 'hear one thing' does not mean you ears did send this signal to your mind.

There are limits to what details ampifiers/speakers can produce.
There are also limits to what human ears can catch.
But there are no limits to what humans can imagine.
/Lineup 2008

The problem is that we do not actually hear what our ears catch
the sound impression is a mixed image produced by our brain.
A mix from memories, expectations, associations, visual sensory information, smell and skin sensing signals.
There is no way to separately extract only signals from one sense into final brain image = perception image.

Besides, our hearing has so many illusory tricks functions,
that we can easily be fooled.

Same way is with signals from our eyes.
Like through any camera lense, the received image is upside down.
But our mind will process it and turn it back the 'wrong way' so that floor is down and ceiling is up.

If you wear special glasses that will project the floor down-ceiling up into your eyes,
you will first get the impression world is upside down.
But after a while you will get used and your brain will learn howto see the world correctly again.
----------

About Auditory Perception & Illusions there is one leading woman: Diana Deutsch
This article gives a summary introduction to how human hearing mechanisms works:
THE PSYCHOLOGY OF HEARING - Diana Deutsch

[Cruzs]

Sorry, just to make it clear for me.
So, it's not to recommend to implement my question no #2 even if I use approriate PSU and Elco for the 140W version?

Thanks.

[gain]

Cruzs,

my advise in such matters is the old saying, "if it ain't broke don't try and fix it." if you are not satisfied with your current power amp, build one that will satisfy you.

Lineup,

your post is money. pure money. false expectations and/or misinformation make people think they hear a difference when in fact it is their brains mixing information coming from their imaginations into the signals from their eardrums, hence creating a biased perception of reality.

marketing personell are well aware of that aspect of human nature you so eloquently described in your post, and take advantage of it constantly to sell overpriced and/or unnecessary audio products to unsuspecting consumers who "swear" they hear a difference.