It's not as it seems. What the plot shows is that the noise in each FFT bin is at about -158db. The noise in all the FFT bins has to be summed up to get the total noise level. The -158dB is the FFT noise density, not the total noise.
While I do think the the performance is good 
, it does not have a THD+N of -121dB. The THD can be, with the right settings, but not the THD+N.
So I think there is something wrong with the settings in the MI Pro. Perhaps the noise is not included correctly or only for a very narrow bandwith?
Anyway, this is perhaps a bit OT for this thread.
, it does not have a THD+N of -121dB. The THD can be, with the right settings, but not the THD+N.So I think there is something wrong with the settings in the MI Pro. Perhaps the noise is not included correctly or only for a very narrow bandwith?
Anyway, this is perhaps a bit OT for this thread.
Hi Frex,
The 1kHz version I built is working great. Like gtose I used thin film SMT resistors mostly from the ERA-8A line. The +/-16VDC power is from a stack of Li Ion 16340 batteries, and comes into the chassis via a mini-XLR jack.
Distortion is lower than the resolution of my measurement system.
Thanks Frex!
Miq
The 1kHz version I built is working great. Like gtose I used thin film SMT resistors mostly from the ERA-8A line. The +/-16VDC power is from a stack of Li Ion 16340 batteries, and comes into the chassis via a mini-XLR jack.
Distortion is lower than the resolution of my measurement system.
Thanks Frex!
Miq
An externally hosted image should be here but it was not working when we last tested it.
Hi Frex,
The 1kHz version I built is working great. Like gtose I used thin film SMT resistors mostly from the ERA-8A line. The +/-16VDC power is from a stack of Li Ion 16340 batteries, and comes into the chassis via a mini-XLR jack.
Distortion is lower than the resolution of my measurement system.
Thanks Frex!
Miq
Why not a switchable version with 1 kHz and 10 kHz?
Thanks for the information guys,
just got an email from Frex and sent a payment - looking forward to having a play. First time with surface mounts - so another adventure
Gulp! I suspect you might struggle with this a little if it’s your first bash at SMD soldering - there are some very tricky bits. Might be best to get comfortable on some less valuable PCBs.
However, don’t let me deter you - I highly suggest using solder paste and hot air rather than hand-soldering those smaller components. The resistors are easy - those tiny ICs are the problem. But good luck!
PCB (almost!) complete! Managed to get through the bulk of it on Saturday. The caps for C10, C17, C42 and C43 were missing from my Mouser order, however... so I'll have to wait until they arrive before finishing up.
Next weekend I'll put the case together. Detailed pictures, complete build and testing to follow.
Next weekend I'll put the case together. Detailed pictures, complete build and testing to follow.
Attachments
interesting to see the result. As far as this is not a cheap project justifies the costs ...
