My_Ref Fremen Edition - Build thread and tutorial

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I am noticing some temperature related behavior that may be related to the Isa's and wondered if anyone else has noticed the same? When I first turn on the amp (cold start) it sounds a little bit harsh and, possibly, a bit louder. I don't want to overstate this, the effect is quite small. But after about 10 minutes, the sound is richer and smoother. For example, on the higher frequency notes of a piano, when cold there is a bit of an edge to the notes, as if harmonics were a little emphasized or a touch of distortion. After warming up, the harmonics are both smooth and warm.

I am only guessing that this could be the Isa's. I did have a problem with my balanced line receiver power supply which I fixed and it could be involved.

Jac

Jac: I’ve been playing with another type of chipamp lately and compare it back to my Evo A and I’m experiencing the same sort of warm-up effect here. I have neither of the new power resistors in place (the 1.8 boards have yet to built up), but whether it’s now the power of suggestion or some psycho-acoustic trick my mind is playing the amp does seem to open up a bit after a period of time.

Regards,

Pete
 
I may have tin ears.

Currently using another chip amp also. Uses LM3886 with a resonant mode power supply.
Neither it or several My-Ref amplifiers open up after 10 minutes. I very seldom listen for more than 2 hours straight, normal is most of a CD. They seem to “gell” much quicker to my ears.
They are hard on power up, but are fantastic after a minute or two. Before the first track has finished they play fantastic. If played at background levels for several hours it still sounds the same to me.
My 65 year old ears may be letting me down.
 
Did someone already found out what the best orientation of the Mundorf MREU30 resistor is on the R3 position?
 

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Hi there! Long time since I've jumped in the project but I'm still tuning/reworking the chassis arrangements . I started it using a big slim line 02/350 (435 x 350mm), but the WAF wasn't enough to have it in my living room. Now I'd like to get the EVO RevA mod and put in a smaller case .
So... any pics or practical advices about a very space constrained boxing? (measures and pics coming soon)
 
Hi, I used a Galaxy 388 (internal dimensions 310x280x80 mm).
From the photos you can see that everything fits with a little more space left. I used 20mm spacers, so LM3886 falls on the flat surface of the side heatsink, finding no grooves. This guarantees contact throughout the chip surface and perfect heat dissipation. In the hot Roman summer it only remains barely warm (I also have easy-to-drive speakers).
Ciao e buona musica
Giacinto
 

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Hi, I used a Galaxy 388 (internal dimensions 310x280x80 mm).
From the photos you can see that everything fits with a little more space left. I used 20mm spacers, so LM3886 falls on the flat surface of the side heatsink, finding no grooves. This guarantees contact throughout the chip surface and perfect heat dissipation. In the hot Roman summer it only remains barely warm (I also have easy-to-drive speakers).
Ciao e buona musica
Giacinto

You guys waste a lot of space space. Power transformers are in other chassis.

Thanks both! Absolutely inspirational!
I'm dealing with some strange problems with my car, I'll get to soldering as soon as possibile.

{ I know the hot Roman summer, I'll be there next WeekEnd! :eek: }
 
Hi, I used a Galaxy 388 (internal dimensions 310x280x80 mm).
From the photos you can see that everything fits with a little more space left. I used 20mm spacers, so LM3886 falls on the flat surface of the side heatsink, finding no grooves. This guarantees contact throughout the chip surface and perfect heat dissipation. In the hot Roman summer it only remains barely warm (I also have easy-to-drive speakers).
Ciao e buona musica
Giacinto

I use the same case but with inner chassis as it is more solid. The covers of this box are too flexible in combination with heavy transformers and put a force over Lm3886 terminals.
 
I use the same case but with inner chassis as it is more solid. The covers of this box are too flexible in combination with heavy transformers and put a force over Lm3886 terminals.

Yes, this is a problem. I mostly solved it by putting 9 rubber feet, but I was thinking how to put a stiffer plate on the bottom. How did you solve it? What is the inner chassis you talk about?
Thank you for the suggestion
Ciao!
Giacinto