Sourcing of parts
Hello fellow Xmas amp builders. After a couple of weeks I received my Mouser order of my parts. When I ordered the specified capacitor for C16 was in stock, but by picking time they were sold out; who knows when they will actually restock them. See:
UKZ1H101MHM Nichicon | Mouser
My question: How important is the specified cap for overall performance, and could it be replaced with another part? I thought the ome below, but perhaps there are other, better ones.
UPM1J101MHD6AA Nichicon | Mouser
Hello fellow Xmas amp builders. After a couple of weeks I received my Mouser order of my parts. When I ordered the specified capacitor for C16 was in stock, but by picking time they were sold out; who knows when they will actually restock them. See:
UKZ1H101MHM Nichicon | Mouser
My question: How important is the specified cap for overall performance, and could it be replaced with another part? I thought the ome below, but perhaps there are other, better ones.
UPM1J101MHD6AA Nichicon | Mouser
Hi Francois, I've found that your choice of cap, at that position, will effect the overall sound. The MUZE series tends to warm the overall sound but IMHO tends to mask the delicacy of the high frequency response. Im currently evaluating (all Nichicon) UFW, UFG, and UKWs. I had to get them from either Newark Electronics or Digikey since Mouser seems to be out of everything.
I personally wouldn't get UPM but UPWs might be OK.
Just my two cents,
Pete
I personally wouldn't get UPM but UPWs might be OK.
Just my two cents,
Pete
Getting ready to populate my boards and after goin through this thread again I have a question.
I noticed Pete left the capacitor out of C2 and used a jumper with a reference to the servo circuit.
I am at a loss as to the advantages/disadvantages of doing this, all ears for someone who wants to throw me a bone..
Thanks, Greg
I noticed Pete left the capacitor out of C2 and used a jumper with a reference to the servo circuit.
I am at a loss as to the advantages/disadvantages of doing this, all ears for someone who wants to throw me a bone..
Thanks, Greg
This has to do with getting rid of C2 “feedback shunt capacitor”. This cap ties the feedback to ground via AC coupling so that we don’t have large DC drifts. If we short the cap, there is a possibility that the amp can have DC drift. This is where the DC servo function cones in: to control this drift and keep it close to zero. The idea is that with a DC coupled feedback network, the sound is more immediate and no cap to spoil the phase. Better stereo imaging and better bass extension, so we think. Hope that helps. One can also live dangerously and skip the cap and skip the DC servo. If you have SSR DC offset protection, this is fine.
L1 inductor
I'm having a play about with this before I send some magnet wire to a fellow member.
I searched for the diameter and turns but alas I didn't find that information.
I have 1mm diameter wire and initially I did about 10 tight turns on an AA battery (14mm diameter) . This yielded bear to 3uH and by the time I started unwinding it O got it down to 2usomethingH I could tell it wasn't going to work.
So I tried a pencil as the 'dowel'. Approx 10mm diameter. About 12 turns and I had 2.5uH but again by the time I unwound it to lower I could tell there wasn't going to be many turns left at all. Stretching out the few turns I had left to meet the through holes helped.lower the inductance but something doesn't seem right as I had open coils and looked nothing like what I have seen here!
My LCR seems OK.
Any advice?
I've tried online calculators but they seemed hard work for some reason.
Maybe I was having an off day!
I'm having a play about with this before I send some magnet wire to a fellow member.
I searched for the diameter and turns but alas I didn't find that information.
I have 1mm diameter wire and initially I did about 10 tight turns on an AA battery (14mm diameter) . This yielded bear to 3uH and by the time I started unwinding it O got it down to 2usomethingH I could tell it wasn't going to work.
So I tried a pencil as the 'dowel'. Approx 10mm diameter. About 12 turns and I had 2.5uH but again by the time I unwound it to lower I could tell there wasn't going to be many turns left at all. Stretching out the few turns I had left to meet the through holes helped.lower the inductance but something doesn't seem right as I had open coils and looked nothing like what I have seen here!
My LCR seems OK.
Any advice?
I've tried online calculators but they seemed hard work for some reason.
Maybe I was having an off day!
I’ve always used this calculator but I can’t say I’ve actually measured (in uH) if the result is as it’s supposed to be .
Pronine Electronics Design - Single-Layer Air Coil Calculator
Cheers,
Pete
Just FYI...
I built a set completely w/o any of the components for the servo. I wanted to hear the chip w/o any influence from the opamp. I upped C2 to 330uF, C10 to 680pF, C1/C101/C201 to 2.2uF and by-passed the 220uF Panasonics with 440nF WIMAs. Other build components were changed but I have to create an orderly list (if anyone wants it) and it’s better you all build what is recommended first. DC offset was near zero. This little amp sounds fantastic! Bass & mid-bass are satisfying, with my pre-amp tone controls set almost to flat (I had to tweak the treble up a tad) I have wonderful airiness & soundstage. This is a great little lyrical chip-amp on par with any of the simpler LM3886 builds I’ve done. Dibya’s layout is well done. 7293 only slightly warms the heatsink (at my listening levels).
How’s everyone else’s builds going?
Cheers,
Pete
I built a set completely w/o any of the components for the servo. I wanted to hear the chip w/o any influence from the opamp. I upped C2 to 330uF, C10 to 680pF, C1/C101/C201 to 2.2uF and by-passed the 220uF Panasonics with 440nF WIMAs. Other build components were changed but I have to create an orderly list (if anyone wants it) and it’s better you all build what is recommended first. DC offset was near zero. This little amp sounds fantastic! Bass & mid-bass are satisfying, with my pre-amp tone controls set almost to flat (I had to tweak the treble up a tad) I have wonderful airiness & soundstage. This is a great little lyrical chip-amp on par with any of the simpler LM3886 builds I’ve done. Dibya’s layout is well done. 7293 only slightly warms the heatsink (at my listening levels).
How’s everyone else’s builds going?
Cheers,
Pete
How critical is it to surround R9 with the magnetic field of L1? I mounted all my resistors first and then noticed everyone has R9 going through the middle of L1. The leads on R9 have already been clipped, but I can always replace them.
If being in the middle of the field is not important, does the direction of the field have any effect? Do I need to try a clockwise vs counterclockwise coil orientation?
If being in the middle of the field is not important, does the direction of the field have any effect? Do I need to try a clockwise vs counterclockwise coil orientation?
Claude.. I think in blind testing one would be hard pressed to say they added to the upper end, or airiness but I'll disconnect them and see how things change. I was hoping, by their addition, I wouldn't have to engage the preamp's tone controls but that was not the case.
Pete
I mounted my resistor underneath the board and all works fine. My impression from my readings is that putting it through the middle just is a convenience.
Im not even gonna touch the winding direction question. .
Pete
The 100V 680pF has the same physical dimensions and pin spacing as the 400V one. Unless Dibya mentions something about the 63/100V type sounding inferior (in his experimentation) to the 400V type, it’s only handing an input signal so it should be fine.
...and I mean "tweak"...I barely moved the dial... There is a PRP resistor in the input position currently. I have a naked z-foil I can put in that position but I have a feeling that’s not the fix. I’m also going to examine a T-shaped negative feedback Dibya mentioned in another forum long ago.
It’s fun..and all these build changes actually helped me find the occasional ground loop problem I had in my DAC to amp problem. Win Win!
Pete