First Watt power amp builders might want to consider "breathing LEDs" which produce the effect shown in this video (WITHOUT an Arduino)
Here is a store who appears to sell them at very low prices.
Disclaimer: I've never bought from them and don't know whether their products are excellent or garbage. However the cost to find out appears to be low.
Here is a store who appears to sell them at very low prices.
Disclaimer: I've never bought from them and don't know whether their products are excellent or garbage. However the cost to find out appears to be low.
Hi Meper,
Sounds like you may have a differential input that is inadvertently grounded on one end. That will cause high distortion measurements. Or you may have the gain on the input set too high and it’s clipping. More tips in this thread:
Howto - Distortion Measurements with REW
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Thank you!
I got a hint in the other forum. I had Window set to "Rectangular" which is wrong. I just tried setting it to "Blackman - Harris 7" and this was much better. By playing with Sine generator output level I got down to 0.0034 % Noise and THD+N = 0.0035 % in a loop back test. Think this is on par with Arta. Will see if this is low enough for distortion measurements on M2X. I need to make the physical interface from banana to RCA and a divider as you show in the "HowTo" link.
I got a hint in the other forum. I had Window set to "Rectangular" which is wrong. I just tried setting it to "Blackman - Harris 7" and this was much better. By playing with Sine generator output level I got down to 0.0034 % Noise and THD+N = 0.0035 % in a loop back test. Think this is on par with Arta. Will see if this is low enough for distortion measurements on M2X. I need to make the physical interface from banana to RCA and a divider as you show in the "HowTo" link.
Now that I've finished my M2X build (except for the front panel blue light 
) I have just a couple notes to share:
) I have just a couple notes to share:- The flameproof resistors (R13 & R14) should be mounted ~4mm above the circuit board since they get hot. I know that's obvious to many but it probably should be in the guide for the benefit of new builders.
- Additional shielding for the Edcor audio transformers doesn't appear to be needed in my amp with the SLB PSU and the power transformer mounted vertically ~15 cm. from the Edcors.
- If you decide to mount the PSU transformer vertically the L bracket from toroid.com seems like a good solution. I wanted to go with the DIY option so I made an L bracket from some 0.063" sheet aluminum I happened to have. It was a bit too springy so I made a U bracket from the same material. One thing I didn't anticipate with the U bracket was that the through bolt needs to be insulated from the bracket (I used some nylon bushings). When the bolt was in electrical contact with the bracket it got very hot from induced currents.
If the thermistor is a "CL-60 like" you can use it for both small and large transformers.
The other question may have some answers…..but two trafoes (one for each channel) on same IEC then the fuse has to be larger than if you only have one trafo (half VA size) for one channel on the IEC. Primary fuse is often dictated by in-rush current which can be very large if you don't have any in-rush limiter but with CL-60 you should be able to rate the fuse after how much power (current) you pull from trafos during operation......and then add some to have a safety margin…..and remember to use slow fuses in primary.
Ok just for an example, say you have a trafo that is 225va and using on a US grid would need ~2A slow blow fuse (which is the bar min. if you double up on that trafo on one IEC it would need at least a 4A but given the safety margin a 6A slow blow would be cool? This is also assuming using a CL 60 type.
Depends on what your local voltage really is, and the rating should be max, not min,
225VA/120V = 1.875A
225VA/110V = 2.045A
2A is a bit too high if you have 120V mains. The issue with this scenario is the transformer is under-rated for stereo though fine for mono.
in my case
400VA/120V = 3.333A, I use a 3.1A slow blow, and a C-60 current limiter.
Cool thanks. Thinking about building something for my pops and was just going over some ideas.
Maybe someone who knows code can address this, but I am pretty sure this is not OK.
I believe each transformer would need to be individually fused at the correct rating. A single 4A fuse could allow one transformer to overheat badly before blowing the fuse.
My area runs hot so I get 120 w an occasional drop to 117 during summer or winter. Weather here in TX is all over the place so the grid can be all over the place. Thanks for the insight
Geez ok. I guess i'll read what other say to get a handle on the proper approach to this.
