Thanks for the reply guys.
Mouser now stock Silmic II at a fraction of the cost of some places - but the nonROHS ones. I may go with these or an NG as a inexpensive starting point. (It feels like a weird conspiracy - realised my Miopia/Dislexia had crippled my search for AMTRANS AMGR, despite being sure I cut and paste, eventually found more stuff on esoteric parts, while also realising that perhaps ordering caps from the Ukraine right now is of question …)
My intentions are building 4 amps as monoblocks to bi amp, and eventually look at matched parallel sets for the bass drivers - this will replace my triamp gain clone set up. Ill start with standard value caps as a base line - with the idea of eventually looking at tuning the each amp via C13 or even C12 and omitting the corresponding parallel inductor or capacitor in the crossover network … etc etc . ( this may never happen…..)
As of now I simply wish to attenuate the input 6dB, playing with the gain is clearly a no no. Halving R13 and adding an identical series MK132 will work - but a series 47k seems a bit big. Or am I missing something?
Mouser now stock Silmic II at a fraction of the cost of some places - but the nonROHS ones. I may go with these or an NG as a inexpensive starting point. (It feels like a weird conspiracy - realised my Miopia/Dislexia had crippled my search for AMTRANS AMGR, despite being sure I cut and paste, eventually found more stuff on esoteric parts, while also realising that perhaps ordering caps from the Ukraine right now is of question …)
My intentions are building 4 amps as monoblocks to bi amp, and eventually look at matched parallel sets for the bass drivers - this will replace my triamp gain clone set up. Ill start with standard value caps as a base line - with the idea of eventually looking at tuning the each amp via C13 or even C12 and omitting the corresponding parallel inductor or capacitor in the crossover network … etc etc . ( this may never happen…..)
As of now I simply wish to attenuate the input 6dB, playing with the gain is clearly a no no. Halving R13 and adding an identical series MK132 will work - but a series 47k seems a bit big. Or am I missing something?
Hi Guys
Got my amp boards through from Mario, firstly.. Quality is excellent!
Popping on holiday next week but I want to order the parts to start when I get back.
Is there any recommendations for the build if working with 6 ohm speakers?
Thanks
Seb
Got my amp boards through from Mario, firstly.. Quality is excellent!
Popping on holiday next week but I want to order the parts to start when I get back.
Is there any recommendations for the build if working with 6 ohm speakers?
Thanks
Seb
Only thing I came across was the working voltage, I used 22v transformers for use with my 6 ohm speakers. You could go a bit lower but don't go higher. Good luck with your build.
Mario? Who's Mario?
Dario, maybe? 😉
😀
Yes, as already posted use 21-22V secondaries
Man have i stuffed my board??
The idiot i am, wasnt concentrating and soldered caps directly where it was marked not to use 😱
So while unsoldering the caps i scratched the board and exposed copper which is now covered with solder!
Can someone advise on what to do next.
Much appreciated
Ryan
The idiot i am, wasnt concentrating and soldered caps directly where it was marked not to use 😱
So while unsoldering the caps i scratched the board and exposed copper which is now covered with solder!
Can someone advise on what to do next.
Much appreciated
Ryan
Hi Ryan,
I can't see any damage, the exposed copper is on the groundplane and on ground pads, so no problem.
R6 soldering seem suspect, reflow it.
Dario is too fast for me. I was drawing a little pic showing traces to ground plane (blue) and isolation space (yellow). Note there are four traces in those two pads. I suspect even if you lost one the others would be enough.
The bubbling on the mask looks like too much heat was used. Solder wick (copper braid) really helps in a situation like this. I apply some extra Chip-Quick flux on the braid and watch carefully as the solder is transferred off the pin/pad. It is much easier to tell when to remove the heat. Done carefully and slowly from a couple angles the TH parts can actually fall off the board on their own.
Last weekend I had to remove 24 three pin pieces from a different project and learned how well the braid functions if one slows down and watches the action with a good magnifying lens.
Now taking student applications for "Bob's Braid Academy" 😀😀
The bubbling on the mask looks like too much heat was used. Solder wick (copper braid) really helps in a situation like this. I apply some extra Chip-Quick flux on the braid and watch carefully as the solder is transferred off the pin/pad. It is much easier to tell when to remove the heat. Done carefully and slowly from a couple angles the TH parts can actually fall off the board on their own.
Last weekend I had to remove 24 three pin pieces from a different project and learned how well the braid functions if one slows down and watches the action with a good magnifying lens.
Now taking student applications for "Bob's Braid Academy" 😀😀
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phew!
That bubbling is the flux residue. So i am all good there. While inspecting the board i found a couple MK132 resistors going the wrong way. So i desoldered them and reversed them.
Is there any way to test the resistors to see if i damaged them while i was getting them out and back in?
That bubbling is the flux residue. So i am all good there. While inspecting the board i found a couple MK132 resistors going the wrong way. So i desoldered them and reversed them.
Is there any way to test the resistors to see if i damaged them while i was getting them out and back in?
Glad to hear that. The academy does offer a class for flux removal, but it's full this semester - sorry. 😉
man i would love a course like that.
Do you have a common sense course too? 😀
Actually while we are on the topic of board cleaning, can i just bathe a board in pcb cleaner? Will this be covered in flux removal course or common sense course
Do you have a common sense course too? 😀
Actually while we are on the topic of board cleaning, can i just bathe a board in pcb cleaner? Will this be covered in flux removal course or common sense course
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Just to clear things up on my pondering (and I appreciate I’m possibly opening abit of a messy can)
I'm questioning using R13 as a shunt in an equal voltage divider - and the use of some 47K series input resistance - and appropriate shrinking of C12 to some 20 pico for a similar filter product.
I realise a bulk film 20k pair as a voltage divider up wind of the original circuit would suffice being the same as a passive stepped volume (and one could still question the filter change).
BUT - theoretically -
One - at 47k is series resistance noise a big question? , the bulk film being best (I actually thought the MK132 was bulk) - if no is tantalum or thick film caddock? (I’m not good with analogue noise)
Two - the filter – has a 12 fold or so smaller cap differing parasitics/or considerations? Even if I use the same package / make. ?? esotericism aside - is this an issue?
It’s the first time I’ve really had to pay attention to the moving filter of a passive set up – I use a 24 bit digital set up - and have no fear of digital attenuation for the first 40dB of a 16 bit source, but I’m matching amps here ……
Apologies for long post about stuff that too little knowledge of is dangerous. I’m not worried about getting de-facto answers here lads ‘n lasses - I can make my own blunders – but I’d like your musing on such tomfoolery…..
I'm questioning using R13 as a shunt in an equal voltage divider - and the use of some 47K series input resistance - and appropriate shrinking of C12 to some 20 pico for a similar filter product.
I realise a bulk film 20k pair as a voltage divider up wind of the original circuit would suffice being the same as a passive stepped volume (and one could still question the filter change).
BUT - theoretically -
One - at 47k is series resistance noise a big question? , the bulk film being best (I actually thought the MK132 was bulk) - if no is tantalum or thick film caddock? (I’m not good with analogue noise)
Two - the filter – has a 12 fold or so smaller cap differing parasitics/or considerations? Even if I use the same package / make. ?? esotericism aside - is this an issue?
It’s the first time I’ve really had to pay attention to the moving filter of a passive set up – I use a 24 bit digital set up - and have no fear of digital attenuation for the first 40dB of a 16 bit source, but I’m matching amps here ……
Apologies for long post about stuff that too little knowledge of is dangerous. I’m not worried about getting de-facto answers here lads ‘n lasses - I can make my own blunders – but I’d like your musing on such tomfoolery…..
Thanks Davym,
What transformers did you end up sourcing? Seem to be quite a few people using R-core.
Will taste, and do not want to start any controversy, but I still prefer the sound given by laminated transformers, as long as they are constructive of high quality.
At least in my case, and I repeat will taste or feelings, I find it more airy sound between instruments.
I have tested my My_Ref with 300VA toroidal transformers and then return to the lamellar at the expense of construction problems that have given me, but honestly I appreciate more the sound.
They will feel, but the music should be enjoyed by as you appreciate more, talk a little audiophile but realistic.
Good day to all
At least in my case, and I repeat will taste or feelings, I find it more airy sound between instruments.
I have tested my My_Ref with 300VA toroidal transformers and then return to the lamellar at the expense of construction problems that have given me, but honestly I appreciate more the sound.
They will feel, but the music should be enjoyed by as you appreciate more, talk a little audiophile but realistic.
Good day to all
Hi sebbyp. I used 22v 300VA toroidal transformers from airlink but they do hum a little bit. I only notice it when it's really quiet in the house and no music playing, usually at night. I intend to change them at some point for potted versions or R-core but I have other priority's at present and the amps sound brilliant as they are.
Just received my amtrans resistors from parts connexions. I am struggling to decipher the markings on the parts.
I have 221J, 102J and 151J. Can anyone tell what each of these markings equal.
I have 221J, 102J and 151J. Can anyone tell what each of these markings equal.
Just Google "numerical resistor codes" and you will find enough info to make you an overnight expert. 🙂
Mmh...
Are you sure they're not Amtrans capacitors?
221J = 220pF
102J = 1000pF
151J = 150pF