Bias set to 20mV! Running fine with music. Sounds very good. The hum is not audible >2ft away. With no input, there’s 40mVAC at the outputs. 1mV with input shorted.
I’ll have to experiment with different setups for DC protection and delay to stay safe.
If I’m lucky I will conquer the likely grounding hum, but I could live with it at this level.
I’ll have to experiment with different setups for DC protection and delay to stay safe.
If I’m lucky I will conquer the likely grounding hum, but I could live with it at this level.
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I was just looking at your connection diagram PDF. GND1 should connect directly to the power supply, not through the wire to the input end of the board. Speaker returns should also go directly to the power supply. The input end should either connect to the output end of the board or the power supply directly, one or the other but not both.
Grounding is very important to eliminate hum. It can be tricky to get right.
Grounding is very important to eliminate hum. It can be tricky to get right.
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Thanks for the extra picture and this point. I will experiment with lifting the PE connection, too.
I also have MicroAudio (Cresnet) SMPS-600 supplies to test with the amp.
Many variables.
Yet another PCB...
Happy new year to all of you guys
I started to prepare for a "Full Enchilada"-Build - TubSuMo + NS-OPS. The PCBs provided so far are a masterpiece of layout work - anyway I need to redraw them to fit some of my requirements. I started with TubSuMo IPS, which I wanted to be designed in a way that you can watch illuminated tubes through the enclosure's front panel In addition, I took the chance to give some options for the caps - I plan to assemble cheap SMD caps for first test and replace them with Nichicon KZs and Silver Micas for the final setup. Here's a screenshot of how my idea looks like - still a lot of checking and refinement to do:
I take the chance to thank Valery, Jeff and all the other guys to lead a great idea to an idiot-proof design. Once I finished IPS I'm going to start NS-OPS sim + layout with 4 pairs of 2SC3263/2SA1294 - it seems to be quite impossible to catch 2SC2922/2SA1216 these days
Will keep you up to date with my progress (as long as sbd. is interested and has some patience)...
Prost!
Holgi
Happy new year to all of you guys
I started to prepare for a "Full Enchilada"-Build - TubSuMo + NS-OPS. The PCBs provided so far are a masterpiece of layout work - anyway I need to redraw them to fit some of my requirements. I started with TubSuMo IPS, which I wanted to be designed in a way that you can watch illuminated tubes through the enclosure's front panel
In addition, I took the chance to give some options for the caps - I plan to assemble cheap SMD caps for first test and replace them with Nichicon KZs and Silver Micas for the final setup. Here's a screenshot of how my idea looks like - still a lot of checking and refinement to do:
I take the chance to thank Valery, Jeff and all the other guys to lead a great idea to an idiot-proof design. Once I finished IPS I'm going to start NS-OPS sim + layout with 4 pairs of 2SC3263/2SA1294 - it seems to be quite impossible to catch 2SC2922/2SA1216 these days
Will keep you up to date with my progress (as long as sbd. is interested and has some patience)...
Prost!
Holgi
- it seems to be quite impossible to catch 2SC2922/2SA1216 these days
Prost!
Holgi
Maybe I can help?
FS: NOS Sanken MT200
Thanks, Jeff Yep, I noticed the change to the Onsemi devices, but I'm curious about the impact on sound signature - did anyone ever compare the well-known smooth/warm Sanken sound to the Onsemis? I will try to find out and maybe I build both versions for 1:1 comparison with my sources and speakers - at least for me that's what counts
Same applies for the tube selection, I have some old 12AU7 at hand and ordered some matched/selected for comparison. This is going to be fun!
By the way: Is there a condign SMT replacement for A992/C1845 available? I found SOT-23 variants (MMBT) for some MPSA TO-92 devices, but nothing for the Fairchild semis...
Prost!
Holgi
Yep, I noticed the change to the Onsemi devices, but I'm curious about the impact on sound signature - did anyone ever compare the well-known smooth/warm Sanken sound to the Onsemis? I will try to find out and maybe I build both versions for 1:1 comparison with my sources and speakers - at least for me that's what counts Same applies for the tube selection, I have some old 12AU7 at hand and ordered some matched/selected for comparison. This is going to be fun!
By the way: Is there a condign SMT replacement for A992/C1845 available? I found SOT-23 variants (MMBT) for some MPSA TO-92 devices, but nothing for the Fairchild semis...
Prost!
Holgi
I've never heard any difference between the On Semi or the Sanken output devices, the distortion is so low in these amps it would be hard to hear any difference in output stages. You need to pay attention when first warming up the On Semi output devices though. They will blow if you let them run away, while the Sankens would just blow the fuse.
We've been using the FJV versions of 992/3324 as Rick suggests.
We've been using the FJV versions of 992/3324 as Rick suggests.