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Topics - JPK

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1
Discussions about the products / MOVED: CP554 and Matching
« on: January 13, 2024, 11:41:27 AM »
This topic has been moved to CP554 Diode bridge compressor.

https://www.soundskulptor.com/forum/index.php?topic=439.0

2
Discussions about the products / MOVED: MP599 preamp phantom problem
« on: January 02, 2024, 04:51:12 PM »
This topic has been moved to MP599 Microphone preamplifier.

https://www.soundskulptor.com/forum/index.php?topic=431.0

3
CP554 Diode bridge compressor / In case your CP554 doesn't work as expected
« on: August 18, 2023, 11:49:03 AM »
Check the usual suspects:
Forgotten solder joint,
Bad solder joint (reflow suspicious joints),
Reversed components (transformer,s electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
Flipped IC's or transistors,
Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.


Check the DC voltages:
Check the supply voltages as described in the setup guide.

Check the side chain:
Set the compressor as described in step 9 of the setup guide.
Remove the jumper on JMP1.
Inject a 1VAC sine signal into the input.

Threshold switch position     TP4 & TP5 AC voltage    JMP1 pin1 DC voltage
+6dB    0.11V    0.14V
  0dB    0.22V    3V
-6dB    0.45V    10.8V
-21dB    2.4V    15V



4
Discussions about the products / MOVED: MP AB528
« on: July 08, 2023, 06:41:22 PM »
This topic has been moved to AB528 Microphone preamplifier.

https://www.soundskulptor.com/forum/index.php?topic=383.0

5
CP554 Diode bridge compressor / Modification on CP554 for stereo work
« on: May 04, 2023, 07:04:42 PM »
We have made a modification to the CP554 which we recommend that you also do.

In the current version, it is the channel with the lowest level that controls the sidechain.
To restore a more standard mode, simply cut off diode D12 on the right PCB and leave the spot empty.
This will make the loudest channel control the sidechain which is preferable.
No need to recalibrate.
The modification is recommended for mono use also.


Dans la version actuelle, c'est le canal avec le niveau le plus faible qui contrôle la sidechain.
Pour rétablir un fonctionnement plus standard, il suffit de couper la diode D12 sur le PCB droit et laisser l'emplacement vide.
Cela fera en sorte que le canal le plus fort contrôle la sidechain, ce qui est préférable.
Pas besoin de recalibrer.
La modification est aussi recommandée en mono.

6
MU524 Vari-Mu Tube Compressor / In case your MU524 doesn't work as expected
« on: February 20, 2023, 11:55:28 AM »
Check the usual suspects:
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.
  • Make sure that resistors R1, R3 do not touch the transformer daughterboard pins.
  • Make sure that capacitor C12 do not touch the transformer daughterboard pins. It is very close and if the pins can pierce the insulation the circuit will oscillate.


Voltages checks: +/-20%

Initial conditions:
IN pot @ max
OUT pot @ min
REC pot @ max
Bypass toggle @IN
All Push buttons @UP
Input signal: Sinus 1kHz, 1VAC
Jumper JMP1: removed

Results:
TP1 = TP2 = 30VDC (black probe on 0V)
TP1 = TP2 = 1.25VAC
TP3 = TP4 = 1.8VAC
Output: 3.5VAC (between XLR pins 2&3)

Changed conditions:
Jumper JMP1: on 1-2
Input signal: Sinus 1kHz, 0.3VAC
OUT pot @ max

Results:
TP3: 0.26VAC (black probe on 0V)
TP4: 3.1VAC
TP5: 2.9VAC
TP6: -3.5VDC
Output: 6.1VAC (between XLR pins 2&3)
Meter: -6dB

7
First Aid / MOVED: AB528 question
« on: February 20, 2023, 11:38:40 AM »
This topic has been moved to AB528 Microphone preamplifier.

https://www.soundskulptor.com/forum/index.php?topic=330.0

8
First Aid / MOVED: VARI-mu build
« on: February 20, 2023, 11:35:02 AM »
This topic has been moved to MU524 Vari-Mu Tube Compressor.

https://www.soundskulptor.com/forum/index.php?topic=341.0

9
MC624 Monitor Controller / MC624 Serial Communication Protocol
« on: February 18, 2023, 12:10:51 PM »
For those interested, this is the communication protocol used by the MC624.
The data are sent via the USB connector pair at the back of the unit.

It is possible to drive the MC624 from the usb connector. We use an USB connector for convenience but the signal going through is actually a standard serial asynchronous RS232, 8 bits, 9600 Bds, port interfaced to RS485.
When the unit is set to master, the serial link is an output.
When the unit is set to slave, the serial link is an input.


MC624 Protocol :
There are 3 commands made of one byte each:


Volume command:

Bit 7 bit 6 = 00
The volume is binary coded from 0 (00000) to 63 (11111)


Input/Output select command:

Bit 7 bit 6 = 01
The SUB state is coded in bit 5. 0 = OFF, 1 = ON
The output channel is binary coded in bits 3 & 4, from 00 (channel 1) to 11 (channel 4)
The input channel is binary coded in bits 0, 1 & 2, from 000 (channel 1) to 101 (channel 6)
You must send both the IN and OUT numbers in each command.


Functions command:

Bit 7 bit 6 = 10
The MUTE Left state is coded in bit 5. 0 = OFF, 1 = Mute left
The MUTE Right state is coded in bit 4. 0 = OFF, 1 = Mute Right
The MONO state is coded in bit 3. 0 = Stereo, 1 = Mono
The DIFF state is coded in bit 2. 0 = Normal, 1 = Diff
The DIM state is coded in bit 0. 0 = Normal, 1 = Dim
Bit 1 is not used.
You must send all the 5 states in each function command.




10
MP566 Tube microphone preamplifier / In case your MP566 doesn't work as expected
« on: January 19, 2022, 09:38:56 AM »
Check the usual suspects:
  • Check you didn't leave the polarity switch on the center position (=mute),
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.

Check the DI input
If the DI input works then the issue may be in the switching between DI and XLR. Check Q1 (2N7000) . This component is sensitive to static electricity and is better handled without your shoes on (body grounded).


Try to follow the signal
Send a constant 0.5VAC sine signal to the input. It must be measured between pins 2&3 of the input XLR or pins 8 & 10 of the extender. Check the level with the preamp connected because the input impedance of the preamp may pull the signal down.
Connect the voltmeter black probe to the 0V pin.
  • Set Pot IN to 10, Pot OUT to 0, Gain switch to MID:
    you should read 3VAC on TP1.
  • Set Pot IN to 10, Pot OUT to 10, Gain switch to LOW:
    you should read 2.25VAC on TP3 and 7.2VAC on TP4.


11
EQ573 Equaliser / WARNING : Error on C8 in EQ573-II (PCB REV 2.3)
« on: October 25, 2021, 09:43:34 AM »
The (+) PCB marking for C8 is wrong on PCB REV 2.3.
The plus side of this capacitor should go to the left, near the inductor L2.
This is an issue only in the case where the EQ is linked to a MP573 with the link cable.
In such a case, the capacitor will fail rapidly because it is reverse polarized.

This error is corrected on PCB REV 2.3B.

12
LA502 Optical Compressor / Meter LED's low brightness
« on: August 28, 2021, 09:42:04 AM »
If you purchased your kit in 2021 summer and your meter is working normally but the LED's seems too dark, then you may have received a bad LM317LZ component for U10.
Indeed, we have received a batch of LM317LZ with about 14% of bad parts.
If this is your case, please send us a message on https://www.soundskulptor.com/en/contact.php and we will send you a new part.
I am sorry for the inconvenience.

13
TS500 Tape Simulator / Meter LED's low brightness
« on: August 28, 2021, 09:38:42 AM »
If you purchased your kit in 2021 summer and your meter is working normally but one (or both) row of 8 LED's seems too dark, then you may have received a bad LM317LZ component for U5 or U6 (or both).
Indeed, we have received a batch of LM317LZ with about 14% of bad parts.
If this is your case, please send us a message on https://www.soundskulptor.com/en/contact.php and we will send you a new part.
I am sorry for the inconvenience.

14
CP5176 FET compressor / Meter LED's low brightness
« on: August 28, 2021, 09:33:21 AM »
If you purchased your kit in 2021 summer and your meter is working normally but one (or both) row of 8 LED's seems too dark, then you may have received a bad LM317LZ component for U5 or U6 (or both).
Indeed, we have received a batch of LM317LZ with about 14% of bad parts.
If this is your case, please send us a message on https://www.soundskulptor.com/en/contact.php and we will send you a new part.
I am sorry for the inconvenience.

15
DI503J Triple DI and Re-Amp / Error in capacitors C3, C7, C8 (ceramic instead of film)
« on: August 25, 2021, 11:07:11 AM »
Some early kits received by mistake ceramic capacitors instead of WIMA film for C3, C7 & C8.
Please let us know if it is your case and we will send you the correct 1uF film.

16
TS500 Tape Simulator / Testing your TS500
« on: March 25, 2021, 05:49:56 PM »
You can check that your TS500 is functioning correctly by doing these measurements.
The result values are approximate, depending on the quality of your meter, in particular when measuring a 10kHz signal.

ConditionsSwitch position              Output voltage (VAC)
input signal = sine 1kHz, 0.4VAC    TAPE SAT on left9.2V
(on input XLR between pins 2&3)TAPE SAT on center7.4V
BIAS on rightTAPE SAT on right7.1V
TS500 ON
Both pots on 10

ConditionsSwitch position              Output voltage (VAC)
Input signal = sine 40 Hz – 0.25VAC  SPEED on 7.5'9.4V
TAPE SAT on leftSPEED on 15' 8.5V
BIAS on centerSPEED on 30'7.5V
Both pots on 10

ConditionsSwitch position              Output voltage (VAC)
Input signal = sine 60 Hz – 0.25VAC  SPEED on 7.5'7.5V
TAPE SAT on leftSPEED on 15' 9.3V
BIAS on centerSPEED on 30'8.7V
Both pots on 10

ConditionsSwitch position              Output voltage (VAC)
Input signal = sine 80 Hz – 0.25VAC  SPEED on 7.5'5.4V
TAPE SAT on leftSPEED on 15' 7.9V
BIAS on centerSPEED on 30'9.3V
Both pots on 10BIAS on right6.1V

ConditionsSwitch position              Output voltage (VAC)
Input signal = sine 10kHz – 0.25VAC  SPEED on 7.5'2.5V
TAPE SAT on leftSPEED on 15' 4.1V
BIAS on leftSPEED on 30'5.1V
Both pots on 10SPEED on 7.5' and BIAS on right 5.1V

17
MP566 Tube microphone preamplifier / Output transformer check
« on: February 04, 2021, 05:49:31 PM »
This is how you can check the output transformer by measuring the coils DC resistances
The POL switch must be in the center position.

7  8  9  10 11 12
o  o  o  o  o  o


o  o  o  o  o o
6  5  4  3  2 1

pin1-pin3 : 106 ?
pin4-pin6 : 101 ?
pin9-pin11 : 102 ?

18
XT500 Lunchbox connector extender / Extender pins description
« on: January 31, 2021, 06:26:10 PM »
Pin   Name                                          Description
1Chassis groundLunchbox chassis
2Output +4dB HotOutput XLR pin 2
3Output -2dB HotLow level output (not used)
4Output +4dB ColdOutput XLR pin3
5Analog groundInput and output XLR pin 1
6Stereo linkConnects the side chains of 2 adjacent compressors
7Input -2dB coldLow level input cold (not used)
8Input +4dB coldInput XLR pin 3
9Input -2dB HotLow level input hot (not used)
10Input +4dB HotInput XLR pin 2
11Gain AdjustBuss feed on Radial lunchboxes
12+16VDCPositive power supply
13Power groundConnected to the Analog ground in the lunchbox
14-16VDCNegative power supply
15+48VDC PhantomMicrophone phantom power supply

19
News and updates / Modules availability
« on: January 13, 2021, 04:42:04 PM »
Some of our products are out of stock today. This situation is due to a disruption in the supply of some transformers and integrated circuits, caused by the lock-downs in several countries.

12/01/2020 : EQP501 and 501 are back in stock.
19/01/2020 : TS500 (8.), LA502 (4), CP4500 (5) back in stock
27/01/2021 : CP5176, MP566, MP573, MP599 back in stock
19/01/2021 : MP573 back in stock
05/03/2021 : All our products except the CP4500 are back in stock. The CP4500 should be back in April.

20
EQ573 Equaliser / In case your EQ573 doesn't work as expected
« on: January 09, 2021, 09:34:48 AM »
Check the usual suspects:
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.
Check the DC voltages:
Next, without any input signal, connect the voltmeter black probe to 0V (TP4 for EQ573) and note the DC voltages you get at the points shown on the picture below. Compare with the expected results (more or less 10%).
EQ573-II:


EQ573:


Try to follow the signal
Send a good constant sine signal on input, like 100Hz - 2VAC measured between pins 2&3 of the input XLR.
All controls on OFF, source switch on XLR.
Connect the voltmeter black probe to TP4 and trace the signal on:
-  TP1: 0.53VAC
-  TP2: 0.46VAC
-  TP3: 0.30 VAC
The reading should follow the input signal level.
The place where the signal drops will give you hints on where to look for.

21
501 Single Host / Connecting the auxiliary jack
« on: January 06, 2021, 11:33:00 AM »
Jumper settings
- To connect the auxiliary jack to the module output:
T   R
o o o
o-o o Out+
o o o
o o-o Out-
o o o
o o o
o o o
o o o
o o o
o o o

- To connect the auxiliary jack to the module input:
T   R
o o o
o o o
o o o
o o o
o o o
o o o
o o-o In-
o o o
o-o o In+
o o o

22
EQP501 Passive Equalizer / In case your EQP501 doesn't work as expected
« on: January 06, 2021, 08:31:16 AM »
Check the usual suspects:
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.
Check the DC voltages:
First check the supply voltages as described in the setup guide.
Next, without any input signal, connect the voltmeter black probe to 0V and check you get no DC voltages on TP2. Any DC voltage higher than a few millivolts shows that the DOA is the issue.

Try to follow the signal
With all pots at 0, Send a constant 100Hz - 2 VAC sine signal on the input, measured between pins 2&3 of the input XLR.
Connect the voltmeter black probe to 0V and trace the signal.
- On TP1 you should get about 1.3 VAC- On TP2 you should get about 1.15 VAC
The reading should follow the input signal level.
The place where the signal drops will give you hints on where to look for.

23
LA502 Optical Compressor / In case your LA502 doesn't work as expected
« on: January 04, 2021, 07:38:24 PM »
1. Check the usual suspects:

  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.
2. Check the DC voltages:
First check the supply voltages as described in the setup guide.
Check you get no DC volts on TP1. Any DC above a few millivolts here shows that there is an issue.

3. Try to follow the signal

Send a good constant sine signal on input, like 1VAC measured between pins 2&3 of the input XLR. PEAK at 0.
Connect the voltmeter black probe to 0V and trace the signal on:
- R2 right pin: Should be at 0.7VACand follow the input voltage.
- REV1.3: R5 low pin should be at 0.5V when GAIN is on 100.
- REV1.4: R5 right pin should be at 0.5V.
- TP1: should go above 10V when GAIN is at 100.

Check the input transformer coils resistance

1    3    5
o  .  o  .  o

              BOTTOM VIEW

o  .  .  o  o
10      7  6

1-5  ? 2 kohms
6-10  ? 2 kohms

Check the output transformer coils resistance

1    3  5  5  6    8
o  .  o  o  o  o  .  o  PRIMARY

      BOTTOM VIEW

o  o  .  o  o  .  o  o  SECONDARY
16 15    13 12    10 9

1-3  ? 10 ohms (5 ohms if in circuit)
6-8  ? 10 ohms (5 ohms if in circuit)
9-12 ? 12 ohms
13-16 ? 12 ohms

24
News and updates / Welcome to the Sound Skulptor forums
« on: December 29, 2020, 11:15:29 AM »
Here we can find help on build issues, share experiences and discuss products.

25
MP512 Microphone preamplifier / In case your MP512 doesn't work as expected
« on: December 29, 2020, 08:32:23 AM »
Check the usual suspects:
  • Check you didn't leave the polarity switch on the center position (=mute),
  • Forgotten solder joint,
  • Bad solder joint (reflow suspicious joints),
  • Reversed components (electrolytics, diodes, transistors, IC's). In case of IC's, probably destroyed, better replace,
  • Flipped IC's or transistors,
  • Trim all the component leads and test pins as short as possible. Nothing must touch the chassis plate.
Check the DC voltages:
First check the supply voltages as described in the setup guide.
Next, without any input signal, connect the voltmeter black probe to 0V and check you get no DC voltages on TP2. Any DC voltage higher than a few millivolts shows that the DOA is the issue.

Check the DI input
Check you didn't forget to remove the JMP1 jumper.
Check you didn't swap the 2 transistors on the DI board.
If the DI input works then the issue may be in the switching between DI and XLR. Check the 2N7000 on the DI board. This component is sensitive to static electricity and is better handled without your shoes on (body grounded).

Try to follow the signal
Send a constant 100Hz - 100mVAC sine signal on the input, measured between pins 2&3 of the input XLR.
Check the level with the preamp connected because the input impedance of the preamp may pull the signal down.
Connect the voltmeter black probe to 0V and trace the signal.
On TP1 you should get about 750mVACOn TP2 you should get more than 10VAC, depending on the position of the gain potentiometer.
The reading should follow the input signal level.
The place where the signal drops will give you hints on where to look for.

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