[florence88]

Hi, I'm not sure if I have done something wrong but channel 2 is far louder than channel 1 and the stereo signal appears to be panned pretty hard to the right.

So far I've tried turning T3 to adjust the balance but I ended up redoing the rebalancing with the DMM. It also appears that with the compressor off, the signal is slightly panned the same way, but significantly less (right channel louder).

Most of the measurements were correct, many were almost there, and a few were actually off. Here are the ones that were off:


(input signal = 3 VAC, makeup = 0, turn threshold +15 to -15)
TP4 = 0.026 to 0.23 VAC

(input signal = 3 VAC, threshold = -15, makeup = +20)
TP12 = 0.77 VAC

[JPK]

It also appears that with the compressor off, the signal is slightly panned the same way, but significantly less (right channel louder).
With the 3VAC input signal, do you get the correct 1.5VAC on TP1 and TP6?
Try again after removing U1 an U11.
Check the direction of BR1 and BR3.

[florence88]

TP1 and TP6 both get 1.47 VAC.
I will remove U1 and U11 now, then check the direction of BR1 and BR 3.

[florence88]

BR1 and BR3 are correctly oriented.

[florence88]

I tested TP6 with U11 removed. I couldn't get a voltage reading (V AC).
The chip leads got a bit bent while removing. Hope it's not a problem, I've manage to get it back into the holes.

I'm disassembling the module now to test PCB A. Might as well reflow now while I'm here.

[florence88]

I'm not sure if this has something to do with it, but the difference in the amount of gain required to get the first channel (left) up to 3 V AC on the Lindell box versus the amount for the second channel is huge. For the second channel, I am close to 0 dB gain and on the the first I need +24 dB (completely red).

I am about to run a test with the next two channels and see if the issue continues.

[florence88]

No, it's the CP4500

[JPK]

Hi, I'm not sure if I have done something wrong but channel 2 is far louder than channel 1 and the stereo signal appears to be panned pretty hard to the right.
With all settings like in channel1/step 6, what AC voltage do you get on output 1?
With all settings like in channel2/step 3, what AC voltage do you get on output 2?

I tested TP6 with U11 removed. I couldn't get a voltage reading (V AC).
Sorry, I meant: do you get the same smaller unbalance with the compressor off?

I'm not sure if this has something to do with it, but the difference in the amount of gain required to get the first channel (left) up to 3 V AC on the Lindell box versus the amount for the second channel is huge.
When you say "amount of gain", do you mean the makeup gain on the CP4500?

Do you confirm that the Voltages Checks in channel1/step 6 gives correct results, in particular TP2 @1.5VAC?

[florence88]

I am assuming that you mean the steps from "If your CP4500 is not working as expected":

The gain that I am talking about is the increase in volume that my DAW is sending to the interface then to the lunchbox. On channel 1 I am reducing by -4.59 dB to read 3 VAC on the output, and on channel 2 I am adding about +24 dB gain to get it to 2.93 VAC.

Channel 1 step 6: (input = 3 VAC, threshold = +15, makeup = 0) [-4.59 dB gain from DAW->interface]
    TP1 = 1.48 VAC
    TP2 = 1.46 
    TP3 = 1.48
    TP4 = 0.02

Channel 2 step 3: (input = 2.93 VAC, threshold = +15, makeup = 0) [+24 dB gain from DAW->interface]
    TP6 = 1.44 VAC
    TP7 = 1.44
    TP8 = 1.44
    TP9 = 0.02


I am going to take my time right now taking out U11 since it is difficult and fragile, then run the test. I will post results in a moment.

I hope that clears up what I meant about the gain. The gain is from the "external effect" plugin in ableton, it is what I am sending from the plugin through the interface into the lunchbox. I assume that the signal is clipping in the interface before reaching the chassis.

[florence88]

I just got the chip out, and the prongs have bent again. I don't think they can withstand another removal after this.

With U11 removed I first measured the output from channel 2 out of curiosity.
The output = 3.14 VAC now whereas before output = 2.93 VAC.
This is when the compressor is off by the way, when it is on the reading drops to 0.

Both when the compressor is on and off, with U11 removed TP6 = 0 VAC.

[JPK]

It looks like the compressor channel 2 input pulls down your source.
Can you do the following :
- adjust our source to 3VAC without the compressor being connected.
- then measure the source with the compressor connected, with and without U11.

[florence88]

So my lunchbox (Lindell 10 slot) doesn't give me any readings on the output when the CP4500's channel 1 isn't connected. I tested this out by connecting just channel 2 and fully disconnected. I can only read voltage when channel 1 is in. I'm not sure if this is a design issue with the box but I'm unable to run that test.

[JPK]

In this last test you must measure your source levels on the input XLR, where the signal comes in.

[florence88]

My bad for the late response, I suddenly got very busy. Okay so I just measured the output of my interface (using 10khz sine) and it looks like one of my cables puts out half the VAC that the other one does. I should have checked more rigorously. Ordering new cables now, I hope that was the source of the problem.

[florence88]

Yea it was the cable... My apologies for having wasted your time.