My "audiophile" LM3886 approach

Nordic said:
, I do have some 0.47ufd caps that look realy nice and some 2.2ufd bipolar ones, is there ANY risk testing them out over the weekend (in place of the 1ufd) or would this impact too much on the amp's range?


Hi Nordic

the .47 will work OK but cut the bass to some extend. the 2.2 will also work and you will have much more bass. not as tight but you might prefer it. but the downside is that the bipolar is a bad choice for good sonics.

I would suggest that you go to Mantech and get the 1uf Wima MKP they are very big 250 or 600 v but VERY GOOD quality. and use them on them after the RCA input. they should have them in stock down in CT

I have tried my system without the CAP but as the others have noted , you should measure if there is any DC comming from your source. I have a pair of 1.5uf Wima MKP10 in my DAC's output so i do not have a DC problem

Rudi
 
Got my Kits today..

Well after 1 and a half hours I have one board done; not bad considering I had three boys watching and asking 1,000 questions on what I was doing, and what all those pieces of things were, and what is this all for :)


Hpe to have things into a case and testing by the end of the weekend.


Nicely put together kit!

Jonathan
 
Changed feedback cap

Hi there ! An hour ago I changed my Panasonic FC feedback caps for Sanyo Oscon 220 µF /10V. The change in sound is dramatical ! First impression is that the highs have an much wider open end, much more clearity in voices. Alison´s voice (Goldfrapp) is soooo sweet ... :wiz:

Got to listen - bye !
 
I glanced at the schmatics this morning and think something as simple as lowering C29 and raising C27 would involk a simple high pass function on the amp and NOT affect anything IN the actual amp.

As I mentioned previously, the slope and freq. are not THAT big of a concern since the low pass can be adjusted to blend. The drivers are 6.5" mids to 10" woofers so the the mid can go quite low, and the woofer (Aluminum cone) can go up as high as 400 -600 Hz easily.



EDIT:

"I changed my Panasonic FC feedback caps for Sanyo Oscon 220 µF /10V"

I did not see a 220uF in the feedabck path. May I ask the componet number of that cap?
 
mark_titano said:
I think the caps that SmellOfPoo has changed are C9 and C24. The voltage rating of that caps in the original components list is >35V... I'm not sure but I think that 10V could be too low

I changed C9 (?) only, it´s the elytic closest to the input cap. Before changing it I missed to measure the voltage going through it, but on the levels I listen the amp never puts out more than 3 V (measured with a true rms voltmeter on different freq.) and so I think 10 V are enough.

An externally hosted image should be here but it was not working when we last tested it.
 
SonOfPoo


You've got the single board version, haven't you? i seem to remember you posting that you split ypur board down the middle.

Thenyou would not have the 100nF 100v Wima Polyester (C21) bypassing the 220uF, as in the Mono boards, Rev_C_2_1a.

There likely would be a lesser benefit with a cap upgrade on the later Mono board.

Audie.
 
SmellOfPoo said:


I changed C9 (?) only, it´s the elytic closest to the input cap. Before changing it I missed to measure the voltage going through it, but on the levels I listen the amp never puts out more than 3 V (measured with a true rms voltmeter on different freq.) and so I think 10 V are enough.

An externally hosted image should be here but it was not working when we last tested it.

I named C9 and C24 because I've used the original Penasa's layout for my_My_ref...
You can see here the original schematic:

http://www.audiofaidate.it/materiale/My_ref_A_SCH.pdf

Even if I've not still tried them, I think that the Rubycon ZA could be another good solution in that position

http://www.farnell.com/datasheets/101.pdf

in this way you'll be able to put in a 220uF/35V that fit the original ratings ;)

Mark
 
Got new input caps today, could not get WIMA's though, but these look nice enough, Have to wait till Wednesday for the DIY shop to complete cutting the pannels for my case (i'll probably get impatient and test them somewhere before then).

Was going to stick a bunch of these boards into a big box, but was diffirently inspired by the heatsinks I eventualy got... going for miniature layout now.