1

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 19, 2023, 06:17:39 PM »

WOW! You are absolutely right!

It was a bad solder in one of the cable's pins!!

Many thanks, JP!!

Now works perfect!

2

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 18, 2023, 06:51:48 PM »

How many AC Volts do you have on the output transformer:
- on primary, between brown and yellow wires, 0.31VAC (With Gain 40, att -10, 9.9VAC)
- on secondary, between blue and violet wires ? 0.53VAC (With Gain 40, att -10, 16.8VAC)

Check that there is continuity between orange and red YES
and between green and black, when connected to the circuit. YES

3

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 17, 2023, 11:49:16 AM »

Good morning JP,

In the ADA8200 does not clip because the signal that arrives to the converter is very very weak with the gain at the minimun.

Could be the problem something in the output? I need to increase the gain of the ADA8200 input to equal the signal..

(Attached an small video that illustrates what's happens)

https://drive.google.com/file/d/1-KfmqLdMkBGRGOSQVwyDH-SCZggccnXV/view?usp=drive_link

4

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 15, 2023, 08:11:45 AM »

Good morning JP,

I'm sending 0.5 VAC (Measured between 8&10 pins in the extender)

I'm not sure how to check the sensitivity of the converters. For all the 500 modules I'm using inputs and outputs of a Behringer ADA8200.

5

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 13, 2023, 05:30:02 PM »

Hi again JP,

Following with tests (sound test in this case), I realized something very confusing.

The preamp starts the clipping at -40dB.

For example, if I insert a -18db sine signal from the DAW to the preamp, I have these results:

Gain 10 / Trim -10  -61dB
Gain 20 / Trim -10  -52dB
Gain 30 / Trim -10  -42dB (Clipping but green led)
Gain 40 / Trim -10  -35dB (Clipping but green led)
Gain 50 / Trim -10    -37dB (Clipping red led)
Gain 60 / Trim -10    -36dB (Clipping red led)

In the 3 last steps there's no gain increase...

6

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 12, 2023, 08:13:06 PM »

Hi again JP,

I realized that I had the MP573 chained with the EQ573II and the test was done with the EQ disconnected.

Now, with the EQ (or the jumper) the results are:

Sine signal 0.5VAC - 440 Hz -19dB (It's normal that the VAC increase to 0.8VAC when I switch off the PSU?)

TP2 - Input trafo pin 7 - 0.95VAC (Gain at 40) - 1.24VAC (Gain at 60)
TP2 - TP1 5.2VAC
TP2 - Output trafo yellow wire 10VAC

TP2 - R17 left 0VAC

7

MP573 Microphone preamplifier / Re: MP573 Distorted sound and malfunction

« on: December 12, 2023, 05:46:21 PM »

Hi JP,

The voltages are OK (except C but I think this is a bad measure).

Yes, the real measure was 22.6V

Check if you can trace the input signal on R17-left. It should be equal to Input trafo pin 7 when the gain is on 60.

Input trafo pin7 is 0.81VAC and R17-left is 0.81VAC

Apparently, the solder joints are quite good...

8

MP573 Microphone preamplifier / MP573 Distorted sound and malfunction

« on: December 11, 2023, 08:46:43 PM »

Hi JP,

After several months enjoying the amp, I detect very distorted sound when I increase the gain above 30.

I checked the voltages and resistances:

Set up Guide

1 Short circuit ( OK )
3 TP2 / V+ without Input Trafo 24,64 with Input Trafo 24,51V
4 3.020 V decreasing smoothly until 2.994 and counting in 10 minutes

A 2.6V
B 4.1V
C 2.6V
D 13.6V
E 2V
F 12.9V
G 0.9V
H 4.1V
I 0.35V
J 3.5V
K 22.8V
L 3V

Trace signal

Sine signal 0.5VAC - 3.300 Hz -13.5dB
TP2 - Input trafo pin 7 - 0.94VAC
TP2 - TP1 0VAC
TP2 - Output trafo yellow wire 0.13VAC

Transformers resistance
Output transformer
Yellow Orange 7.8 ohms
Red Brown 6.7 ohms
Blue Green 21 ohms
Violet Black 20.9 ohms

Input transformer
2-4 25 ohms
3-5 25 ohms
7-9 138
8-10 141


Following the signal, I detect a problem between TP1 and TP2 and so on.

What is your diagnosis?

Many thanks!!!

9

MP573 Microphone preamplifier / Re: Lunchbox Aux I/O vs MP573

« on: December 07, 2023, 10:07:39 AM »

Ohh, it what i was afraid for..

Many thanks, JP!

10

MP573 Microphone preamplifier / Lunchbox Aux I/O vs MP573

« on: December 06, 2023, 06:21:49 PM »

Hi Jean Paul and everybody,

I have a question. I would like to have my MP573 working for tracking voices (Input in the Lunchbox direct to a mic) and alao I wanna use the MP573 for mixing signals in the DAW.

So, the only way I think for doing this without plug and amplug cables in the rear of the lunchbox is using the auxiliar I/O that my MIDAS Legend L10 has.

But it doesn't work.

Do you know if it's compatible or if there's a way of doing without a patchbay?

Many thanks!

Paco

11

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: April 08, 2023, 12:08:06 PM »

Sure, I can do it.

Please tell me how?

Thanks JP!

12

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: April 04, 2023, 12:46:55 PM »

Ok, in that case, I don´t know what else to check...

13

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: April 01, 2023, 07:46:44 PM »

I detect continuity between pins 8, 10 and 12.

Should I desolder with care and solder again?

14

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: April 01, 2023, 11:26:09 AM »

I have checked visually the right orientation of RL1 and RL2

Also checked the joints of J2 and J5.

Checking with DMM, none of the pins has to have continuity, right?

15

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 31, 2023, 07:19:30 PM »

Is it normal to start to attenuate at 2K?
Yes, normal.

Do you confirm TP1 0.20 VAC instead of 1VAC?
What is the AC voltage on U1 pin1? It should be the same as TP1.
And what is the AC voltage on U1 pin1 in bypass?

Yes, TP1 is 0,20 VAC, same that U1 PIN1. in bypass, U1 PIN IS 0,985VAC (same than U2 pin4)

16

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 30, 2023, 06:50:00 PM »

Correct! It’s at minimum. Is it normal to start to attenuate at 2K?

This numbers are with 2VAC. There’s no signal attenuation in bypass

17

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 30, 2023, 01:32:51 PM »

Great, I was about to reply!

I Jean Pierre,

Solving all the problems of before, now I'm testing the EQ.

The HP Filter, Low and mid Shelf seems to work properly, but I feel not with the High Shelf.

The shelving in 10K seems to be excessive (Look at the pic)



Same in the other frequencies.

Can be related with this abnormal results checking the signal?

TP1 0.20 VAC
TP2 0.16 VAC
TP3 1.62 VAC

18

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 28, 2023, 06:01:42 PM »

JP,

Forget the last poat. Everything seems to work 100%. The problem is the slot of the lunchbox!!

Thank you for four patience!

19

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 28, 2023, 05:30:14 PM »

In bypass (OFF) mode, you should get half of the input voltage on U1 pin1 and U2 pin4.
With 2VAC you should get 1VAC.

Hi again Jean Pierre,

Sorry for bothering you again, but this makes me mad.

The current situation is:

- In Pre Mode everything is OK. The EQ works fine with the MP576
- In XLR there's no return signal from the EQ to the DAW



So, I can't trace the signal.
I don't know if the solution is to change U1 and U2, check the reles or how to check. The only problem is that it seems that in XLR mode goes to bypass

20

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 27, 2023, 06:12:11 PM »

When bypassed the signal path is really simple: U1 receiver followed by U driver.
Check that the relays are in the correct direction.
Check you didn't swap U1 & U2.
Did you do something that could have damaged U1 or U2?

The relays are well installed and the amps also well.

I don´t know how to check how to test if they are working right

21

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 26, 2023, 07:24:08 PM »

Not normal.
Do you also have an attenuation when the EQ is OFF ?
Check solder joints of R1 to R4, R10, R11, U1, U2.

yes, the attenuation is always, even if the EQ is ON or OFF

I have checked the joints you told me but nothing changes

22

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 24, 2023, 05:37:09 PM »

Looks good !

Trying to trace follow the signal (100Hz at 2VAC) the results are:

TP1 0.20 VAC
TP2 0.16 VAC
TP3 1.62 VAC

Are there normals numbers? in that case, I'm not sure why en XLR mode the signal drops more than 20dB

Many thanks, JP!!

23

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 23, 2023, 05:03:58 PM »

Yes you should replace them.
They were probably destroyed when you created these sparks.

Hi Jean Pierre,
I replace the resistors and finally every the parameters seems to go fine. (Except the point G, I'm not sure what resistor I have to measure)

*Read the second column, the first one was before the replacement.

A -2,1V    13,3V
B -14,6V  -13,3V
C -13,2V  -10,5V
D -13,8V  -11,1V
E -7,9V      -2,6V
F-5,6V        3,7V
G 
H -6,8V      2,5V
I -13,2V  -10,5V
J -13,8V  -11,1V
K -7,9V      -2,6V
L -5,6V      3,7V
M -6,1V      3,1V
N -6,8V      2,5V

I have just to test it and I verify that the signal drops more than 20 dB in XLR Mode

24

EQ573 Equaliser / Re: Problems checking the EQ573 II

« on: March 21, 2023, 09:11:20 PM »

I have to say that in the point A there's some sparks when I conect the O volts and the R48 resistor.
Normal, A is the positive supply rail for the circuit

Check V+ test pin (against 0V) : +16V
Check V- test pin (against 0V) : -16V
Check the solder joints of R48.
Check that R46 is still conducting.

V- gives -16V but V+ is -0,7V
I have checked ans resolder R48 and R46 is not conducting

Should I replace R46 and R48?

Thanks Jean Pierre!

25

EQ573 Equaliser / Problems checking the EQ573 II

« on: March 21, 2023, 10:42:37 AM »

Good morning Jean Pierre,

I have just to finish the EQ573II but I'm afraid there's something wrong with the assembly.

The checking figures are:

A -2,1V
B -14,6V
C -13,2V
D -11,1V
E -7,9V
F-5,6V
G  -0,7V
H -6,8V
I -13,2V
J -13,8V
K -7,9V
L -5,6V
M -6,1V
N -6,8V


I have to say that in the point A there's some sparks when I conect the O volts and the R48 resistor.

Could you guide me?

Thank you very much!