I don't know, but surely not SOTA parts (there are two of them--one goes to ~96 kHz and is 24 bit, the other to ~230 kHz and 16 bit (IIRC)). The slower is good to measure down to -110 dB, for -120 dB/-130 dB you need the analog notch filter in front of it.
Samuel
yes, that is correct -- all stock with no crutches... see what they look like in the nude. I am OK (for now) to get clean data without spurious junk along with it.
I have the unit open now, I can look at the adc p/n. probably will go to 32 bit in future if that can help a little more. Next, I'll power up the Vicktor osc and see what it reads on the A-P.... if anything.
Just doing a bunch of comparisons between adc's at the moment.
Thx-RNMarsh
I have the unit open now, I can look at the adc p/n. probably will go to 32 bit in future if that can help a little more. Next, I'll power up the Vicktor osc and see what it reads on the A-P.... if anything.
Just doing a bunch of comparisons between adc's at the moment.
Thx-RNMarsh
The ADC is buried somewhere.... there are three stacked pcb layers on the left and three on the right side.
I see a lot of AD parts..... like AD797 opa's.
[ If curious - The analog section uses thru hole parts -- mf resistors and caps. While the digital uses sm parts.]
-THx RNMarsh
I see a lot of AD parts..... like AD797 opa's.
[ If curious - The analog section uses thru hole parts -- mf resistors and caps. While the digital uses sm parts.]
-THx RNMarsh
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Richard- it seems the ADC in the AP may leave a lot to be desired. If you follow this http://www.diyaudio.com/forums/lounge/200865-sound-quality-vs-measurements-1053.html#post3656059 you will see that the ADC is definitely not up to the needs for current DAC chips, at least without the notch in front to help. Its an indication of the trade out between bandwidth and resolution, and that technology marches on.
Been real busy with other things occupying my time... Like getting last minute house repairs done before winter sets in.
Well, I found the hardware parts to the IM pcb-kit. Now I can put that IM feature in it next. button it up and get back to the WIN8 and A-P software issues... going to try it on my old XP next and see if it works better/normal. Then, I'll get back to A-P on improving the performance of the A-P, if possible. Looking forward to doing multi-tone tests on whole system and IM tests etc
THx-RNMarsh
Well, I found the hardware parts to the IM pcb-kit. Now I can put that IM feature in it next. button it up and get back to the WIN8 and A-P software issues... going to try it on my old XP next and see if it works better/normal. Then, I'll get back to A-P on improving the performance of the A-P, if possible. Looking forward to doing multi-tone tests on whole system and IM tests etc
THx-RNMarsh
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I have no indication that there would be any significant hum induction from the mains transformer, so I'm not sure why this modification should do any good..?
Samuel
Well, we got 10..15dB reduction of mains components in the noise floor with our company's 2722 when we were assessing the perfomance of a Jung style super regulator. I think this will be somewhat different among units as stray fields are highly dependant on the exact winding geometry. Of course the mod will void warranty so it's at your own risk to do it. AP confirmed that they are aware of that issue and admitted that the noise floor might (and often will) be improved.
We recently undid the change as the unit needs to be transportable and for most measurement tasks the improvement is insignifcant, but I'll be using the cable assembly for my personal 2322, hoping to see a similar reduction. Will try to post before/after measurements when I get to it.
We recently undid the change as the unit needs to be transportable and for most measurement tasks the improvement is insignifcant, but I'll be using the cable assembly for my personal 2322, hoping to see a similar reduction. Will try to post before/after measurements when I get to it.
I had to 'outboard' the mains transformer also on my AWA F242A D&N set.
I thought I had an internal psu fault until I moved the transformer.
I found a null position but not practical to mount the transformer in that physical orientation, so outboard it went.
This gave me about 12dB lower noise floor.
Dan.
I thought I had an internal psu fault until I moved the transformer.
I found a null position but not practical to mount the transformer in that physical orientation, so outboard it went.
This gave me about 12dB lower noise floor.
Dan.
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If one is going to the trouble of out-boarding the power transformer of an AP, I wonder if out-boarding the rectifiers and supply caps might also be worthwhile - to eliminate charging current pulses from within the chassis. Essentially then, one would bring in clean DC from an outboard supply to the AP. It might be easier to leave the original raw DC supply components inside the AP, intact but disconnected. Then bring in clean DC from outside supplies. I'd have to look at the schematics to be sure about feasibility. In my home workshop I have a SYS-2322 among other sensitive test equipment items. Being a stickler for adequate work space lighting, I use several very intense fluorescent lighting fixtures above the workspace and also under the first shelf above the bench top. The ballasts radiate enough EMI that I can hear buzzing in FM tuners on the workbench. So I shut off all these lights, opting for some dim incandescents, when making precise noise or distortion measurements. The AP seems refreshingly immune to this EMI, but, just to be sure...
In the case of the AWA, I thought about it also.
In practice, the residual now is only broadband noise, with no hum/supply intrusion.
Dan.
Yes, I just found some photos I had taken inside my AP and I see that there are more secondary windings and associated raw DC supplies than I had recalled. As you say, the transformer connectors are a "snap" but the diodes and caps are numerous and soldered in place. I'll have a look at the similar SYS-1 PS schematics (SYS-2 schematics not being released yet) to see what's there.
Old But Good....
I could not understand why I could not get specified distortion measurement from my USB soundcard.
When I shorted the DNM input and listened to the residual output port all was revealed.
The power transformer was mounted to the side panel, near the back corner.
It turns out this transformer position was about the worst possible, and moving/rotating it changed but did not cure the problem.
This investigation lasted for about a minute before the 'outboard' decision was made.
I had bought this 25yo ex military (barely used, if at all except for calibration days) only two days beforehand, so I was relieved when I was able effect a simple cure to what I thought was a board fault.
My father has the same test set, and I think his has the same built-in 'fault'.
This auto-nulling test set measures down to -80db/0.01%/0.1mV fullscale range, so not the best possible but still quite useful.
The huge winner is the fast auto-nulling and the big VU meter
.
Dan.
It's a lot to me also.
I could not understand why I could not get specified distortion measurement from my USB soundcard.
When I shorted the DNM input and listened to the residual output port all was revealed.
The power transformer was mounted to the side panel, near the back corner.
It turns out this transformer position was about the worst possible, and moving/rotating it changed but did not cure the problem.
This investigation lasted for about a minute before the 'outboard' decision was made.
I had bought this 25yo ex military (barely used, if at all except for calibration days) only two days beforehand, so I was relieved when I was able effect a simple cure to what I thought was a board fault.
My father has the same test set, and I think his has the same built-in 'fault'.
This auto-nulling test set measures down to -80db/0.01%/0.1mV fullscale range, so not the best possible but still quite useful.
The huge winner is the fast auto-nulling and the big VU meter
.Dan.