Evolution Amplifier by Mauro Penasa

[Panelhead]

I liked the My_Reference Ver A and C. Built several versions, finally ended up with a four chassis version that mirrored the ASR Emitter II amp.
Bought a new set of speakers and decided that the 40 watt or so My_Ref was going to be a little light. So put together Mauro's latest design.
It is sold direct with the LM318 opamps, on board voltage regs, and feedback nets installed with surface mount components. The design evolved, the nets are dialed in a little better, the SIP rectifiers replaced with discrete bridges, and the often criticised zener supply replaced with 3 pin regs at a higher voltage. The output protection relays are doubled up so each channel has its own dual relay and the relay is moved to the output instead of ground side.
For additional flexibility, the design is set up to allow either single LM3886 current pumps, or 2 paralleled LM3886 current pumps for higher current delivery and lower output impedance. Each current pump has its own discrete diode bridge and pair of 10,000 ufd caps for filteration.
This is Mauro new design in a nutshell.

[Panelhead]

This is the amp

[Panelhead]

Four LM3886, 8 10k CAPS, 16 MBR20100 diodes. 400 va, +/- 23 volt transformer. Chassis from Parmetals.

[Panelhead]

Compared to a My_Ref the sound is even smoother. Mauro recommends building the single chip, "base" model first to hear how sweet it is compared to his My_Ref. The measured performance is better at low levels with the sinlge LM3886.
I do not follow directions very well and built the "full" version to start with. Could not wait to get the power and control for my new speakers.
The small heatsinks seen are included with the circuit board. I tapped them to allow adding larger hangoffs to cool the amp. For testing I just ran these. Even driving my power hungry speakers these little sinks only got warm. At idle I could not feel any heat I will add the larger sinks once the amp is installed permantly at home.
The amp is very quiet, and offset measured 11 mv and one channel and 13 on the other. Suspect matching of LM3886 would get it lower.
In a direct comparison, the Evolution damped the woofers much better and tightened up the low end. Also the mids and highs also improved over the My_Ref.
Looks like another homerun design from Mauro. The cost when I purchased mine was around 160.00 with shipping from Roma. Total cost was as seen ran around 350.00.

George

[DcibeL]

Yet another amplifier I want to build...I think I need to build some more speakers, I have 3 amps now (2 complete, 1 nearing completion) and still only one set of speakers. If I build this one then I will have 4 amps...What to do with all this?

[Nordic]

Its a shame that one has to buy preassembled boards.... totaly against my principles, I could just as well walk into the shop and buy an amp...

[Andypairo]

Originally posted by Nordic
Its a shame that one has to buy preassembled boards.... totaly against my principles, I could just as well walk into the shop and buy an amp...

Just some comments:
1-Mauro has released *freely* the MyRef, and were made lots (and I mean lots) of boards (with his permission, ok) from which he gained nothing (AFAIK).

2-It seems normal to me that he now is reluctant to completely share another work without even covering expenses.

3-Since the final result heavily depends on the layout (the compensation techniques to achieve such results are critical to parasistic components generated from a sub-optimal layout) he preferred to take control over the most critical parts, hence the pre-assembled smd part.

Cheers

Andrea

[Nordic]

I fully understand it, and am greatfull for my my_ref C.

I hope he get very rich while listening to his nice amp, by himself...

Sorry, I grew up in a house with a dad as a drummer.... music was something we made for other people to provide happiness and SHARE in it...

I suppose you could take 2 people with a million dollars, one would donate alot to welfare, the other would keep it all to themselves... both fair choices, but both revealing in a way.

I don't realy see if he sold the PCB's instead how one could make much off a mess.... afterall you just have to solder components to their pads... Maybe I'm just sour because I am perpetualy broke

[Andypairo]

AFAIK he pre-assembles only the critical parts (i.e. smd).

Cheers

Andrea

[Panelhead]

Mauro choose to sell assembled board for commercial reasons. I have no problem with that. He is doing this to make a living.
I too would have preferred a blank board. And all through hole assembly. That way I could comment that such and such resistor, cap worked better. Selling them with all the feedback loop components and voltage regs takes half the fun out.
All I have left to do now is the other half, listen to music. Which is hopefully why I build all this stuff in the first place.

George