In general... no
You'll find them spreaded in various threads.
The My_Ref original PCB and schematic did not include those caps since the original designer (Mauro Penasa) didn't think they were necessary at all in his circuit.
They were later added by Russ White of Twisted Pear Audio on request since some people on this thread thought they were necessary.
If you're referring to my BOM for the original TP boards I didn't include them for two reasons:
- I trust the original designer
- The amp IMHO sounds better without.
Thanks ClaveFremen!
And yes, I was referring to your 2.0 BOM.
I have made some boards from this Russ White eagle .brd adjusting the size to fit 10cm x 10cm limitation and pay the lowest price in these Chinese board makers. hehe
I'm planing to enter in your ref FE group buy sometime in the next year
And yes, I was referring to your 2.0 BOM.
I have made some boards from this Russ White eagle .brd adjusting the size to fit 10cm x 10cm limitation and pay the lowest price in these Chinese board makers. hehe
I'm planing to enter in your ref FE group buy sometime in the next year
Has anyone tested this amp out yet and if so how does it compare to a solid non-opamp design? Has anyone attempted this design with any other OPAMPS and what was the reasoning for picking this one as opposed to the large number of others? I have been trying to make a SS amp with a OPAMP front end however the voltage swing was supposedly an issue where I would have to play around with the drawing to get the voltage swing to work with the 45v rails on the SS portion - does this layout have issues with the V swing and if not can I use something similar going into a SS driver and output topology?
"Has anyone tested this amp"
"Has anyone tested this amp out yet and if so how does it compare to a solid non-opamp design?"
Compares favorably , measures well and sounds good.
You can see other designs with the LM3886 which uses other than the LM318, the reason why Mauro chose the LM318 is described in early in the thread.
I don't think the amp has any voltage swing issues ,since the LM3886 is a complete audio amplifier and the LM318 doesn't providing the voltage swing here, but the gain for the higher negative feedback.
The IC's you should investigate for your amp is the LME498** family drivers, which I believe are now out of production, but probably still available from somewhere.
"Has anyone tested this amp out yet and if so how does it compare to a solid non-opamp design?"
Compares favorably , measures well and sounds good.
You can see other designs with the LM3886 which uses other than the LM318, the reason why Mauro chose the LM318 is described in early in the thread.
I don't think the amp has any voltage swing issues ,since the LM3886 is a complete audio amplifier and the LM318 doesn't providing the voltage swing here, but the gain for the higher negative feedback.
The IC's you should investigate for your amp is the LME498** family drivers, which I believe are now out of production, but probably still available from somewhere.
Thanks. I would like to try this one hopefully I can find the PCB files easy in the thread.
Why is it desirable to have higher negative feedback with lm3886? Sorry if it is a novice question- trying to learn as much as possible.
Lme498*** and fam is discontinued. I found an IC that can handle higher voltage then standard 15+- that should be a solid fit. also want to try another 15v one to see if a particular opamp is worth dealing w the hassles of stabilizing it and getting it to work in a high power application before I spin my wheels and ask a ton of questions.
Thanks in advance.
AFAIK, the original PCBs are no longer available since a long, long time now (you can make one yourself, though).
But you can find PCBs for an updated, improved version of the "myRef", the "Fremen Edition":
http://www.diyaudio.com/forums/chip-amps/234032-my_ref-fremen-edition-build-thread-tutorial.html
If you follow exactly the recommended BOMs, you'll get a technically excellent & extremely well sounding amp...
I also recommend MyRef Fremen if you are not afraid of smd parts.
If you need i can search in my old computer for the files of the original one wich is great and the retrofit of shunts for the Lm318 made MyRef even better.
It's a very nice project and not so complicated.
Regards,
Adrian
I can get used to SMD - matter of time before I have to do it anyway. I found the PDFs in the google drive. Is there Gerbers available so that I can order completed PCBs?
Gerbers are not available.
I organize 2-3 Group Buys during the year, the 10th one is closed.
Since I'm going to evaluate a Chinese PCB manifacturer, in the next weeks I could order a small batch, if you're interested let me know by PM.
Please help.
It was time to put my MR in a case. While testing one channel, the amp suddenly hummed. I quickly turned it off then upon powering it on again, the DC protect just stays on "protect mode"
Any tips on how to determine whether the LM3886 (or the LM318) chip has died? The LM318 PS is still at ~14v and the Main PS is correct at 32V. I did not use a socket for the LM318 and the last time I tried unsoldering one, I ruined the double sided PCB.
It was time to put my MR in a case. While testing one channel, the amp suddenly hummed. I quickly turned it off then upon powering it on again, the DC protect just stays on "protect mode"
Any tips on how to determine whether the LM3886 (or the LM318) chip has died? The LM318 PS is still at ~14v and the Main PS is correct at 32V. I did not use a socket for the LM318 and the last time I tried unsoldering one, I ruined the double sided PCB.
Mark : It was the 1R input resistor indeed. I noticed one of the main cap was hot. Turns out I switched the center tap with one of the secondary wires. The boards connect to the transformer via a terminal strip and that's wher I made the mistake. I did not pay attention to the connection since the othe board was working using the same psu. Now that working board has a leaking cap .
Thanks again for the help. Both board are still working after changing only the resistor and the leaking cap.
Thanks again for the help. Both board are still working after changing only the resistor and the leaking cap.
I purchased these boards a few months ago second-hand and will be starting my build shortly.
Is it possible to test the board, prior to installing the LM3886? To make sure I have the correct voltages and the PSU is performing correctly so I don't destroy the LM3886. I have a Light-bulb tester and will certainly use it, but trying to be as careful as possible.
Is there a better way to test the PSU and other voltages are correct? Or just build it and use the LBT with one-hand on the off switch?
Is it possible to test the board, prior to installing the LM3886? To make sure I have the correct voltages and the PSU is performing correctly so I don't destroy the LM3886. I have a Light-bulb tester and will certainly use it, but trying to be as careful as possible.
Is there a better way to test the PSU and other voltages are correct? Or just build it and use the LBT with one-hand on the off switch?
bulb test the Transformer first. That checks the transformer wiring is correct.
Add on the PSU and bulb test that assembly. That checks the PSU wiring is correct.
At this stage you can check you have the expected voltages on the smoothing capacitors.
add on the amp PCB without the chipamp and test via the bulb.
This allows you to check the voltages sent to the opamp power pins and the voltages sent to the chipamp power pins.
Now you can add in the chipamp and bulb test.
Then check the mVac and mVdc at the output of the amplifier BEFORE you connect any test load.
Remember to resistor discharge the capacitors after each power ON test.
Add on the PSU and bulb test that assembly. That checks the PSU wiring is correct.
At this stage you can check you have the expected voltages on the smoothing capacitors.
add on the amp PCB without the chipamp and test via the bulb.
This allows you to check the voltages sent to the opamp power pins and the voltages sent to the chipamp power pins.
Now you can add in the chipamp and bulb test.
Then check the mVac and mVdc at the output of the amplifier BEFORE you connect any test load.
Remember to resistor discharge the capacitors after each power ON test.