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

[jsteiger]

Some good news: Finished building an LC25 today and it turned out perfect. Sounds amazing. Still trying to track down where my volume boost problem with the lc40 is, is there anything other than some misplaced resistors that would cause the jump in volume?

You could inject signal into the good working LC25 and note measurements at the Test Points. Then do the same with the LC40 and report here where things stop being the same.

 

[TransientAggressionSound]

You could inject signal into the good working LC25 and note measurements at the Test Points. Then do the same with the LC40 and report here where things stop being the same.

Any certain volume or frequency or just any audio?

 

[jsteiger]

Any certain volume or frequency or just any audio?

Anytime you are doing this we suggest a 400Hz sine wave. It can't be audio as the level would constantly be fluctuating.

 

[TransientAggressionSound]

You could inject signal into the good working LC25 and note measurements at the Test Points. Then do the same with the LC40 and report here where things stop being the same.

Anytime you are doing this we suggest a 400Hz sine wave. It can't be audio as the level would constantly be fluctuating.

Got it, forgive my ignorance but what am I measuring at the test points / what should I be setting my multimeter to?

 

[TransientAggressionSound]

Anytime you are doing this we suggest a 400Hz sine wave. It can't be audio as the level would constantly be fluctuating.

Hopefully these readings are of use.

DCV:
LC25: from TP1-4: -11.8, -12.2, -12.9, -1.2

LC40: -12.6, -13.7, -14.9, -1.2


Resistance: LC25: 3.7k, -1.9k, -2k, -0.2k

LC40: 3.6k, -2.2k, -2.4k, -0.1k

 

[jsteiger]

Hopefully these readings are of use.

DCV:
LC25: from TP1-4: -11.8, -12.2, -12.9, -1.2

LC40: -12.6, -13.7, -14.9, -1.2


Resistance: LC25: 3.7k, -1.9k, -2k, -0.2k

LC40: 3.6k, -2.2k, -2.4k, -0.1k

Negative. We are measuring the audio level not DCV. You must set your meter for ACV.

 

[TransientAggressionSound]

Negative. We are measuring the audio level not DCV. You must set your meter for ACV.

Alright, I’ve got some very different readings here haha.

LC25: -13.1, -13.5, -14.2, -1.3

LC40: -26.7, -27.7, -28.8, -1.5

Both sending a 400hz sine wive out at 0db and both modules set to 0 for each frequency.

 

[TransientAggressionSound]

Negative. We are measuring the audio level not DCV. You must set your meter for ACV.

How bad did I mess up here? Lol

 

[stylesforfree]

So, I am curious, I have a pair of CAPI BT50's and a pair of API 550b's...is there anything that a combination of the LC25 and LC40 will give me that the BT50's and 550b's won't?

Im of the understanding that the LC series are surgical and useful for carving and sculpting frequencies as opposed to the broad and deep colouration of the 550 EQ's.

 

[jsteiger]

So, I am curious, I have a pair of CAPI BT50's and a pair of API 550b's...is there anything that a combination of the LC25 and LC40 will give me that the BT50's and 550b's won't?

Im of the understanding that the LC series are surgical and useful for carving and sculpting frequencies as opposed to the broad and deep colouration of the 550 EQ's.

The LC's are not surgical. They are a 1 octave filter which is the same bandwidth as a BT50 or 550b. In some ways they are more flexible as you have control over 10 frequencies at once as opposed to the 3 or 4 of the others mentioned. I have had numerous folks tell me that they love running signal thru the LC's sometimes with no cut or boost just for the color of the module.

 

[stylesforfree]

Ah ok, thanks for clearing that up, I am also rocking a pair of the CAPI VC528's. Absolutely loving them running into the BT50's. I was worried that a pair of either the LC25 or LC40 eq's would be overstepping what I already had. Even grabbing one of each for summing drum mixes is very tempting, I guess I just need to try them out!