Two items I would recommend all hobbyists to have in the soldering arsenal is products like solder-wick and chip-quik. Chip-quick, or it’s equivalents, are special solders that have a very low melting point and hence stay in a liquid state much longer than regular solder. After removing excess normal solder from the part you want to remove you just add some chip-quik to the soldering pad/inserted lead, heat it up slightly, work the assembly gently and the part can be easily removed. Some heavier parts just fall out on their own. The downside is you need to use more solder-wick to get rid of the chip-quik on the PCB and the components you just removed. One has to learn to be frugal with the stuff.
You’ll save lots of PCB solder pads from lifting off/getting ripped off.
Cheers,
Pete
Would putting a 10K Alps pot on the line in and using a DAC like a Topping D30 as a source be fine with this amp?
Or should there really be a preamp between the two?
That’s my normal amp test setup (modified Topping D30 + Alps 50K instead) and it works well. You need the Alps if you can’t control the input signal into the DAC.
Pete
@Kokanee
Are you using Lead Free Solder by any chance? Use the one with 3% Ag if you want to use lead free solder .I am personally horrible at soldering. My Granny recommended me to use Pine Rosin as Solder Flux , it works man. My solder now looks clean not dry like before. My experience is very little. Good soldering station is also very important.
Before getting pine rosin like this
https://www.amazon.com/1-Lb-Pine-Gu...eywords=Pine+Rosin&qid=1615048238&sr=8-3&th=1
I would like other experts to comment , whether it is fine to use Rosin now a days. Use a smoke extractor/absorber , Most people cut cost on it but important as smokes of rosin can harm your lungs, most solder wire comes with rosin core so flux will only be helpful for de soldering.
Are you using Lead Free Solder by any chance? Use the one with 3% Ag if you want to use lead free solder .I am personally horrible at soldering. My Granny recommended me to use Pine Rosin as Solder Flux , it works man. My solder now looks clean not dry like before. My experience is very little. Good soldering station is also very important.
Before getting pine rosin like this
https://www.amazon.com/1-Lb-Pine-Gu...eywords=Pine+Rosin&qid=1615048238&sr=8-3&th=1
I would like other experts to comment , whether it is fine to use Rosin now a days. Use a smoke extractor/absorber , Most people cut cost on it but important as smokes of rosin can harm your lungs, most solder wire comes with rosin core so flux will only be helpful for de soldering.
Well, here’s my final setup of the amp with only minor changes to the stock BOM and I’m very pleased with the sound and I believe I’ve found the "sparkle" I had reported I was missing with the stock parts. What I hear is based on my speakers, my DAC my room acoustics and my old, R&R era impaired hearing. ;>)
For those with smaller desktop/bookshelf speakers may find the stock build comfortably warm and sufficient in the upper end since you sit right in front of them.
C201 - WIMA 4.7uF
C127 - WIMA 1uF
R1,2,3,4,15,20 - all Vishay Dale RN55s (0.1%). Tight fit on R1&3
C28 - changed to a silver mica 47pF
R11&R14 (either matched pairs of stock KOA Speers or 0.1% Dale’s)
C10 - changed to 680pF
10pF C0G across R1 leads (I can’t say I hear a difference but the guy with the scope data said it was needed)
C18 changed to a Vishay-Roderstein MKP1837 (had to be mounted underneath the board and leads slightly bent to keep away from 7293 leads)
R9 - changed to Mundorf M-resist 5W metal oxide (I had them laying around from a speaker cross-over rebuild). This probably really extreme since the main audio frequencies should go though the coil. The designers can correct me on that.
Zobel network components (R8 & C4) changed to R8=4.7R and C4=220nF to push possible RFI interference further down to around 154kHz from around the lower 500kHz area. This may be completely unnecessary but it’s just values I’m used to using. Similar to the reason that the recommendation to change C10 to 680pF was made as I remember.
Finally, because I installed a DIP8 socket at U4 I compared op amps TL071BCP to it’s supposed upgraded form in the TLE2071ACP. I prefer the more clean upper end on the 2071 but unless the designers, or someone else with a scope, can check for instabilities (I don’t feel any component overheating nor has the 7293 shut down during long listening sessions) blindly rolling op amps is always a crap shoot.
Kudos to the designers as this is a dead quiet, wonderfully sounding amp built with simplicity and the ability for personal changes in mind. See my previous post for my PS info. I think I documented everything....
Cheers,
Pete
For those with smaller desktop/bookshelf speakers may find the stock build comfortably warm and sufficient in the upper end since you sit right in front of them.
C201 - WIMA 4.7uF
C127 - WIMA 1uF
R1,2,3,4,15,20 - all Vishay Dale RN55s (0.1%). Tight fit on R1&3
C28 - changed to a silver mica 47pF
R11&R14 (either matched pairs of stock KOA Speers or 0.1% Dale’s)
C10 - changed to 680pF
10pF C0G across R1 leads (I can’t say I hear a difference but the guy with the scope data said it was needed)
C18 changed to a Vishay-Roderstein MKP1837 (had to be mounted underneath the board and leads slightly bent to keep away from 7293 leads)
R9 - changed to Mundorf M-resist 5W metal oxide (I had them laying around from a speaker cross-over rebuild). This probably really extreme since the main audio frequencies should go though the coil. The designers can correct me on that.
Zobel network components (R8 & C4) changed to R8=4.7R and C4=220nF to push possible RFI interference further down to around 154kHz from around the lower 500kHz area. This may be completely unnecessary but it’s just values I’m used to using. Similar to the reason that the recommendation to change C10 to 680pF was made as I remember.
Finally, because I installed a DIP8 socket at U4 I compared op amps TL071BCP to it’s supposed upgraded form in the TLE2071ACP. I prefer the more clean upper end on the 2071 but unless the designers, or someone else with a scope, can check for instabilities (I don’t feel any component overheating nor has the 7293 shut down during long listening sessions) blindly rolling op amps is always a crap shoot.
Kudos to the designers as this is a dead quiet, wonderfully sounding amp built with simplicity and the ability for personal changes in mind. See my previous post for my PS info. I think I documented everything....
Cheers,
Pete
Those were indeed tricky! I have 0.4mm solder, a fine conical tip and #2or3 solder-wick to clean up bridges if they occur. The small diameter solder helps a lot. My soldering iron tip holder is pencil-like as well making fine work easier.
Pete
Your grandmother solders electronics? Really? ;>)
I use these little tubes of No-Clean paste flux from CHIPQUIK (#SMD291)
and have a little desk fan that blows ant flux vapor away from me out into the room (the fan doesn’t blow onto what I’m soldering at the moment).
Pete
Pete,
Thanks very much for you assessment of performance. Glad you found the “sparkle”. I’mcurious if you have a sense of which change(s) are responsible.
And thanks especially for taking the time to document and share the tweeks you have applied. They are just in time for my Mouser order.
Francois.