[Build] CAPI LC25-LC40, 500 Series Rotary Graphic EQ's, Official Support Thread

[geardude]

thanks for clarifying, had a feeling that's what you meant when applied to the gainstaging.

Per the specs of my RME FF802 from the site/manual:

For my line out Output level at 0 dBFS @ +4 dBu: +13 dBu

I usually gun for around -18dbfs when recording so I'll repeat the test again and dial it in at the proper level which I guess according to the data above should be -13dbfs!

 

[jsteiger]

You can easily measure it with your DMM. Touch your probes between the RME's output cable's XLR pin 2 and 3.

0dBu = 775mV AC

From what you posted my guess is -17dBfs will be 0dBu which is 775mV AC.

 

[kante1603]

Hi,


do you have a link to this snackbox?Built in psu or external?
The more I follow your posts the more I don't trust it.
You might also want to update your profile and add your location.
Maybe someone in your area has a "good" 500 or 51x rack to test them in?
This way you could at least get your rack out of the equation.


Just an idea,


Udo.

 

[jsteiger]

I am with Udo at this point. I wonder about the rack. Unless oddly the exact same error was made maybe on the DTO5 board or something.

 

[jsteiger]

Do you have a way to "listen" to the audio at the Test Points to see if the hum or buzz is present from the start? TP1 is right after the DTO5 amp.

 

[jsteiger]

I think that will work. Just watch the volume so you don't blow a speaker.

 

[jsteiger]

Alright so using the probe method described above and I do get the hum at Tp1 & throughout the rest of them

OK next try the same probe listening method at either end of RR2 which is 1k. Then try both ends of RR4 which is 160Ω.

 

[geardude]

OK next try the same probe listening method at either end of RR2 which is 1k. Then try both ends of RR4 which is 160Ω.

RR2 and the hum is there, can't reach RR4 at the moment; trying to get creative with alligator clips but they bridge  to RR5 when connected...with the tiny space and the fact that it's hiding behind the 2622 its tricky to say the least Let me fiddle around and see if I can pull it off

 

[geardude]

Ok so I added on some whisker's to both sides of RR4 and probing I'm getting the noise as well.

 

[jsteiger]

OK. RR2 is between the 2622 and the DTO5 so problems here tell me its likely not the DTO5.

RR4 is before the 2622 and basically right at the card's input so problems here tell me it is not even on the EQ card.

 

[jsteiger]

Thanks Jeff for the long winding troubleshooting! The box was indeed a suspicion. I'll be upgrading my box and testing this out in the meantime to fully confirm this as well!

Well, the LC25-LC40 cards are 100% fully VPR compatible. I will be interested to see what you find. It should be not much different than passing line signal thru a VP28 though.

 

[kante1603]

Thanks Jeff for the long winding troubleshooting! The box was indeed a suspicion. I'll be upgrading my box and testing this out in the meantime to fully confirm this as well!

Now I'm really curious how this works out.....
What do you mean by "upgrading my box"?
I still recommend to test the eq in a "trustworthy" rack,preferably from a well-known brand or the ones around here.Have never had any problems like this over all the years,I run eight racks with around 50 modules here.
Still looks to me like the problem is outside of your eq.


Best,


Udo.


Addendum:I tried to open the link on a mac running safari,did not work.Then on my ipad,worked but I can't seem to zoom in deep enough.
At least a "psu" is visible,looks like it is ac!
I wouldn't trust it,,maybe there's a supercheap smps board inside the rack.
The mains plug doesn't seem to have a safety gnd,right?
Also seems to have various link switches and insert points on (unbalanced?) jacks.
From this point on I seriously doubt the complete grounding scheme of your snackbox.

 

[3nity]

Just about to start my LC eq...really looking forward to!
By the way Jeff...what an awesome job you doing|! everything is topnotch!

By the way im using a Collective case 1U rack 3 space module...hope it meets all the requirements!
Thanks.

 

[jsteiger]

Just about to start my LC eq...really looking forward to!
By the way Jeff...what an awesome job you doing|! everything is topnotch!

By the way im using a Collective case 1U rack 3 space module...hope it meets all the requirements!
Thanks.

Thanks 3nity    Dan's rack will work perfectly.

 

[geardude]

Now I'm really curious how this works out.....
What do you mean by "upgrading my box"?
I still recommend to test the eq in a "trustworthy" rack,preferably from a well-known brand or the ones around here.Have never had any problems like this over all the years,I run eight racks with around 50 modules here.
Still looks to me like the problem is outside of your eq.


Best,


Udo.

Well, the LC25-LC40 cards are 100% fully VPR compatible. I will be interested to see what you find. It should be not much different than passing line signal thru a VP28 though.

Addendum:I tried to open the link on a mac running safari,did not work.Then on my ipad,worked but I can't seem to zoom in deep enough.
At least a "psu" is visible,looks like it is ac!
I wouldn't trust it,,maybe there's a supercheap smps board inside the rack.
The mains plug doesn't seem to have a safety gnd,right?
Also seems to have various link switches and insert points on (unbalanced?) jacks.
From this point on I seriously doubt the complete grounding scheme of your snackbox.

Well it the problem was indeed the 3 slot "NoS snackbox" . Hooked both units into an API HC 6 slot and no problems. Talk about chasing your tail in circles when you got it right

Thanks for the patience and help! I'm going to delete some of my posts as to not clog up this help forum. But lesson learned, don't skimp out on a cheap lunchbox alternative. 

 

[kante1603]

Hi,


glad it's solved now.....and I can still trust my stomach,hahaha!


Now have fun (and get yourself a good rack.....or build one,it's easy!).


Cheers,


Udo.

 

[geardude]

Hi,


glad it's solved now.....and I can still trust my stomach,hahaha!


Now have fun (and get yourself a good rack.....or build one,it's easy!).

Thanks brother, Indeed I shall. I scooped up this high current 6 rack used but down the line plan to build out a CAPI PSU & Rack. Till then this will do!  8)

 

[jsteiger]

Well it the problem was indeed the 3 slot "NoS snackbox" . Hooked both units into an API HC 6 slot and no problems. Talk about chasing your tail in circles when you got it right

Excellent news! Glad you got it sorted. Congrats on nailing the builds out of the gate after all 

 

[Wiz]

I have a LC25 that I finished.... I could have sworn I checked everything was working by running sweeps.... but maybe I missed one.

My 12.8Khz band doesn't boost or cut.

Everything else works...

I have been over the board.. I am pretty sure everything is where it should be.

Any thoughts... 

cheers

Wiz

 

[jsteiger]

Hey Wiz, if all other bands are working fine then it must be the wiper/gyrator of the 12.8k switch.

So, on the switch PCB, it starts at the wiper of SW11 and goes to the pin JP2-5.

From there onto the Main PCB entering JP2-5.

Thru the series resistor GR30. The rest is the gyrator which is pins 1-3 of A5 as well as GR27 & 28 and caps GC19 & 20.