BTW, LT8330 with small schematic modes can solve the problem if supply voltage is over 15V. Just need larger cap on pin 5 and feedback divider readjustment since it's reference is 1.6V not 1.225V.
I looked at the data sheets, so using the LT8330 and adjusting R17 and R144 then using the 9volt ac to ac adapter is a non issue then?
Alex
Alex
The larger cap would be 1uf on pin 5, from datasheet?
Reason I ask is i dont usually go into this area!! Not my strongpoint...
:>)
Alex
Reason I ask is i dont usually go into this area!! Not my strongpoint...
:>)
Alex
yep, ~1uF on pin 5.
R44 should be around 33kOhm
All input caps at least 25V rated (C159 C68 C102 C156 C47 C33 C179)
You can go even to 12Vac (or what you got left from O2)
Although, it is not a tested solution, may require a bit of a "tuning".
R44 should be around 33kOhm
All input caps at least 25V rated (C159 C68 C102 C156 C47 C33 C179)
You can go even to 12Vac (or what you got left from O2)
Although, it is not a tested solution, may require a bit of a "tuning".
Great, that makes me feel a whole lot better!! At least I read the datasheet correctly!! Its been a long time for ohms law stuff for me!! Ha! You mean R144?
Thanks Sergey!
Alex
Thanks Sergey!
Alex
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Correct, R144 🙂
BTW, C50 C63 are also have to be 25V at least. You can step down in values a bit if you struggle sourcing 4.7uF.
BTW, C50 C63 are also have to be 25V at least. You can step down in values a bit if you struggle sourcing 4.7uF.
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Ok thanks....on the "may require" some tuning....I looked at the many examples in the data sheet and see the inductor values and of course the zener values change. So when using 9 volts the zener in your bom is ok, but did you mean that these inductors might need changing? I guess there is a formula for these and any other parts that might need this type of tuning...
I dont have an real equipment here to look at signals etc, just a simple voltmeter..so I get a little paranoid with this stuff...
Alex
I dont have an real equipment here to look at signals etc, just a simple voltmeter..so I get a little paranoid with this stuff...
Alex
I meant more like freq compensation. To tune the feedback cap. Also I do not expect it to be significantly different from 3467. Even if it will be a bit off it is unlikely will have a significant impact on anything.
Can say there is a big chance it will be OK. Just don't forget to solder it the right way 🙂
Can say there is a big chance it will be OK. Just don't forget to solder it the right way 🙂
Just in case, will duplicate it here.
To give a rough power consumption idea.
The amp, being loaded with 100 Ohms on each channel and driving around 2Vrms both consumes around 1W from 6Vdc. ~1.2W is achieved at 2.5Vrms.
To give a rough power consumption idea.
The amp, being loaded with 100 Ohms on each channel and driving around 2Vrms both consumes around 1W from 6Vdc. ~1.2W is achieved at 2.5Vrms.
Hey Sergey,
FYI, I am still alive and finally finished Chris's head amp and now can concentrate of your Alligator, I will read thru all my notes and the thread and start getting a order ready to start the build!
Alex
FYI, I am still alive and finally finished Chris's head amp and now can concentrate of your Alligator, I will read thru all my notes and the thread and start getting a order ready to start the build!
Alex
Done! 😀 I just shipped Alex my bag of Crocodile parts that has been sitting here probably a year.
I can see that I'm still just not going to get time to do any soldering anywhere in the near future, so much better these parts get used to build a Crocodile! Alex has the hot air soldering thing figured out now too from the AmpCasq project and he does great reviews.
All the parts should be there, including those special order coils.
Enjoy! 🙂
I cant thank you enough AGDR!!
I am looking over the schematic and reading all the thread posts once again!
I know Sergey designed this tiny amp without any I/O on the board to keep it small!
I will want to add all the normal I/O stuff eventually and get it into a nice small box. So any suggestions on the volume pot, any additional parts and wiring it in. I think Sergey mentioned to me that a linear 10K pot and adding 22-47pf caps to ground for emi protection on the inputs as well.
Looking at the board compared to Chris's amp, even though its smaller in overall physical size, the pads for most of the stuff dont look that hard to be able to solder paste etc...
Dont get me wrong they are still very tiny compared to most of the stuff we work with!
The chip density is high, I think I can most likely get many parts tacked down with paste and hot air a bunch of parts all at once, maybe in 2-3 passes..this way we keep the heat on the overall parts and board down to less heat cycles?
Looking forward to this challenge!
Alex
I am looking over the schematic and reading all the thread posts once again!
I know Sergey designed this tiny amp without any I/O on the board to keep it small!
I will want to add all the normal I/O stuff eventually and get it into a nice small box. So any suggestions on the volume pot, any additional parts and wiring it in. I think Sergey mentioned to me that a linear 10K pot and adding 22-47pf caps to ground for emi protection on the inputs as well.
Looking at the board compared to Chris's amp, even though its smaller in overall physical size, the pads for most of the stuff dont look that hard to be able to solder paste etc...
Dont get me wrong they are still very tiny compared to most of the stuff we work with!
The chip density is high, I think I can most likely get many parts tacked down with paste and hot air a bunch of parts all at once, maybe in 2-3 passes..this way we keep the heat on the overall parts and board down to less heat cycles?
Looking forward to this challenge!
Alex
Sergey,
Back in the updates you mention that R146 and R147 could be reduced to 22-33 ohm t make it repeatable?
In the schematic R146 and R147 = 220R.
So are you saying these can be reduced both the 22-33R value?
Thanks
Alex
Back in the updates you mention that R146 and R147 could be reduced to 22-33 ohm t make it repeatable?
In the schematic R146 and R147 = 220R.
So are you saying these can be reduced both the 22-33R value?
Thanks
Alex
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I ordered a 12vdc regulated adapter from Jameco and will use it for this project. So all the stuff about using an LT 8330 is not needed and upgrading all the caps etc..
Alex
Alex
adydula, good to see that you are alive and kicking 🙂
R146 and R147 change to 22-33Ohm was to reduce noise during powering up. With new values it was almost inaudible. Yes, you need to change both of them together.
See if it works in your case because I do not have a large enough sample to call it a "statistic" 🙂
R146 and R147 change to 22-33Ohm was to reduce noise during powering up. With new values it was almost inaudible. Yes, you need to change both of them together.
See if it works in your case because I do not have a large enough sample to call it a "statistic" 🙂
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Yes I am alive an will be 68 years young next month!!
I got my hot air gun working, completed Chris's amp and it worked first time, so I got the SMD small parts soldered with solder paste ok....wasn't that hard at all...but doing something new for the first time is harder just to get over the unknowns!! Ha!
AGDR is sending me his parts and I am ready to start on your crocodile!!
Good to hear from you again down under!
Alex
I got my hot air gun working, completed Chris's amp and it worked first time, so I got the SMD small parts soldered with solder paste ok....wasn't that hard at all...but doing something new for the first time is harder just to get over the unknowns!! Ha!
AGDR is sending me his parts and I am ready to start on your crocodile!!
Good to hear from you again down under!
Alex
It is good to try something new. Although fiddling with a heat gun not what people usually mean 🙂
Just to make you feel better - retirement age in Australia is pretty much 67 😀
Can suggest to soled the PSU section first and make sure it is running OK. As an option - to do not load, on the begging, those resistors that connect amp to the PSU.
Just to make you feel better - retirement age in Australia is pretty much 67 😀
Can suggest to soled the PSU section first and make sure it is running OK. As an option - to do not load, on the begging, those resistors that connect amp to the PSU.
Good idea! Chris suggested the same thing to me for his amp, which I did not do!! and lucky for me or my great soldering skills (lol) it worked first time!!
I will start with the PSU stuff and proceed.
My tact is to place as many parts in an area down with the solder paste and heat them all up vs one at a time and heat and reheat etc....this helps reduce the number of times I get the pcb and parts "hot"....
I will start with the PSU stuff and proceed.
My tact is to place as many parts in an area down with the solder paste and heat them all up vs one at a time and heat and reheat etc....this helps reduce the number of times I get the pcb and parts "hot"....
It seems like components don't mind heating that much, as far it is gradual and even, to avoid mechanical stress. Hot plate under the PCB helps a lot with this.
Too bad this amplifier uses so many SMDs. That really limits the number of people that can build and try it.
I don't mind soldering SOICs, but all those tiny resistors and caps aren't worth the hassle.
Seems the trend lately is "to see how small we can make the PCB for this project", hopefully 50mm x 50mm, so it qualifies for one of the Chinese board house's 5cm x 5cm special pricing offers.
This design could easily be put on a 10cm x 10cm board using thru-hole components including the LM6172s, which are still available in a DIP-8 package even though the OPA1611/1612 isn't.
Nowadays, 10cm x 10cm boards don't cost much more than the boards half their size.
I don't mind soldering SOICs, but all those tiny resistors and caps aren't worth the hassle.
Seems the trend lately is "to see how small we can make the PCB for this project", hopefully 50mm x 50mm, so it qualifies for one of the Chinese board house's 5cm x 5cm special pricing offers.
This design could easily be put on a 10cm x 10cm board using thru-hole components including the LM6172s, which are still available in a DIP-8 package even though the OPA1611/1612 isn't.
Nowadays, 10cm x 10cm boards don't cost much more than the boards half their size.