3D Nite EQ in 500 Format

[mihi_fuchs]

I transferred the designs to the 500 format. Works perfectly and does what it is supposed to.

Hardest part was sourcing the C500K potentiometers. Initially I went for these
https://www.conrad.at/de/p/alpha-rd...entiometer-mono-0-05-w-50-k-1-st-2358971.html

However, they are C50K, not center detent, and limited in quantity.
So I only used them for prototyping and ordered a small production line of 150 pieces by my own. They are center detent and C500K and what you can see below and in the dropbox link.

Compared to the original build, Bands and the gain level of all bands as well as the overall gain can be adjusted.

For my builds I have tried to find potentiometer with similar/matching values, as they are 20% accurate to what is given, that takes a bit of quality control.

However, I'm very happy with the Build, and thanks a lot to members KHstudio and PeterC, who started the project here.

Here are some pics and the link to the building documentation:
https://www.dropbox.com/scl/fo/egry...ey=7g4nl8e68fyflrtjbdc9zi8ht&st=9r5webtk&dl=0



Best regards

 

[john12ax7]

Looks nice. Where did you order the small production run of pots from?

 

[mihi_fuchs]

Looks nice. Where did you order the small production run of pots from?

YU WAH (H K) LIMITED. I think was via Alibaba. But as far as I remember minimum was 150 pots.

I still have a few left - C500K and C50K. In case you need just contact via PM.

BR
Michael

 

[Whoops]

Here are some pics and the link to the building documentation:
https://www.conrad.at/de/p/alpha-rd...entiometer-mono-0-05-w-50-k-1-st-2358971.html

Hi, great build, congrats.
it would be great to see the link to the building documentation,
you copied the wrong link to your post. It shows the Pots and not the build docs

Thanks

 

[mihi_fuchs]

Hi, great build, congrats.
it would be great to see the link to the building documentation,
you copied the wrong link to your post. It shows the Pots and not the build docs

Thanks

Hey,
my apologies. Just edited the original post. Here it is again:
https://www.dropbox.com/scl/fo/egry...ey=7g4nl8e68fyflrtjbdc9zi8ht&st=9r5webtk&dl=0
Frontpaneldesigner file will be added in the upcoming days to the files.

Best regards,
Michael

 

[mihi_fuchs]

Frontpaneldesigner file and Potentiometer calculation sheet (based on Harpo's XLS file from this Thread) have been uploaded.

I got 20 PCBs left. They go to the Black Market. Potentiometers are included and pre-measured roughly to give you a set of compatible values.

The frontpaneldesign file has never been produced - I drilled my own one. Make sure it fits the PCB before ordering (maybe print a paper dummy panel and check before ordering).

Offer is valid as long as I can find matching potentiometers (everything has to be measured by hand beforehand).

Link to the Black Market thread is posted here:
https://groupdiy.com/threads/3d-nite-eq-in-500-format-pcbs-potentiometers-20-pieces-available.88439/

Best regards,
Michael

 

[Whoops]

Hello Michael,
nice work and thanks for the project

One think I don't understand is why the use of the huge Wima capacitors?

You used 19 very big Wima capacitors when there's already not a lot of space in a 500 series unit, I don't see any technical reason to use such big capacitors

Thanks

 

[mihi_fuchs]

Hello Michael,
nice work and thanks for the project

One think I don't understand is why the use of the huge Wima capacitors?

You used 19 very big Wima capacitors when there's already not a lot of space in a 500 series unit, I don't see any technical reason to use such big capacitors

Thanks

Hi whoops,

I guess the point maybe was that these had the better specs back in the days.
Spacewise it’s not the big of a deal - but actually small wimas are cheaper … and the big red is one of the most expensive parts here.
As a consequence - you can also build it with small ones. The footprint is included and i can post the mouser no. Later here.

I guess the big red maybe historically origined as they may have had the better specs back in the days - all 5%. But that’s only a hunch …

BR
Michael

 

[mihi_fuchs]

smaller wimas - possible alternative (footprints are included in pcb):

https://www.mouser.at/ProductDetail/505-MKS41-50-10
https://www.mouser.at/ProductDetail/505-MKS4C032202BKSSD
https://www.mouser.at/ProductDetail/505-MKS4.47-100-10

 

[Script]

I guess the big red maybe historically origined as they may have had the better specs back in the days - all 5%. But that’s only a hunch …

Peculiarly, when I build the rack version I found that less precise caps with more deviation from ideal value by up to 10%), yields better tuning results of octaves, gain and attenuators. This required measuring all caps and reiterating all calculations with various cap selections.

Caps plus resistors define the octaves, while those resistors also define gain, which has to be compensated for (using the spreadsheet), which then affects the max gain and/or mid position of the pots (as for rotaries with fixed resistor values close to impossible to match across L and R).

So working backwards kind of seemed better to me. The reason being too much interaction, double/triple role of components.

Not tested but my hunch is this 'problem' could be fixed by introducing an additional gain stage after octave filter and before the pots/rotaries to get equal gains before attenuators. Also, then rotaries make sense.

 

[mihi_fuchs]

Peculiarly, when I build the rack version I found that less precise caps with more deviation from ideal value by up to 10%), yields better tuning results of octaves, gain and attenuators. This required measuring all caps and reiterating all calculations with various cap selections.

Caps plus resistors define the octaves, while those resistors also define gain, which has to be compensated for (using the spreadsheet), which then affects the max gain and/or mid position of the pots (as for rotaries with fixed resistor values close to impossible to match across L and R).

So working backwards kind of seemed better to me. The reason being too much interaction, double/triple role of components.

Not tested but my hunch is this 'problem' could be fixed by introducing an additional gain stage after octave filter and before the pots/rotaries to get equal gains before attenuators. Also, then rotaries make sense.

Yes, exactly.

However - as the potentiometers' center comes with +/-1% max deviation for the center value and max. +/-5% for the max deviation, you can actually achieve two units with highly similar gain - therefore the extra quality control for the pots regarding stereo functionality. And therefore it was necessary to order actually the big batch.

By the optional potentiometers you have full control over gain of a band and frequency of a band. You can adjust by calculating beforehand or by measurement. Additionally you have extra options for potentiometers for unity gain with eq in (RV30) and bypass (RV48).

I think by all these requirements you get two quite good matching eq.s if measurement, calculations and adjustment is done right.

By the extra quality control of the pots you should maybe have the best posibility to get to stereo.

But that is the theory - in practice and to my ears I can work on a stereo image with my set of eq.s.

Hope that explained a bit my way to approach the matter. Of course, as you did, I really think you get the same result. However, the PCBs allow to work your way either and accept the for sure cheaper smaller caps.

Best regards,
Michael

 

[Script]

Thanks for explaining. Yes.

I too matched pots, as best as I could -- or let's say as required, cos band (octave) position of pot too makes a difference (in spreadsheet calculation).

Closest to ideal pot for lowest or highest band first (forgot which), then adjacent bands with gradually less ideal pots -- but same degree of deviation per pot across L & R.and same order of 'pot-deviation to band'.

If I were to build another unit, I'd be happy to PM you about pots...

 

[mihi_fuchs]

I just uploaed an updated Building Guide and BOM (V2_1). This includes now the data for the switches, the LED and the LED holeder and their sources.

Additionally the typo regarding the fully adjustable gain has been corrected to fully adjustable fequency bands.

More information is given on the onboard potentiometers in the building guide.

But in addition, you can find it here too:

RV6, 9, 12, 15,18 and 21 adjust the frequency you are adjusting by the pot. These are optional and allow fine tuning of the frequency band by f.e. measurments.

These values of following RVs you adjust according to the calculation sheet:
- RV35, 37 39, 41, 43 and 45 adjust the gain.
- RV30 adjusts the general level of the eq.
- RV48 adjusts the general level of the bypass (RV48 has the same value as RV30).

Clipping circuit:
RV201 adjusts the clipping LED. Adjust to 20k. If you see you clip earlier you can adjust with RV201.

Hope that helps with the builds.

If you have any more questions just let me know.

Best regards,
Michael