1

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: January 19, 2024, 10:06:01 PM »

The new VCA chips fixed the issue. Thanks JPK 🙏🏻

2

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 29, 2023, 01:39:26 PM »

I realized that the issue with not being able to trim the channel to correct volt has moved from  board 1 to board 2 since we started. I have also moved all VCAs form 1  to 2, so i took a new test switching out all VCAs from 1 to 2 again, and i found out that it is one of the That 2180A VCAs that are malfunctioning.

I'll send you an email to get this sorted.

3

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 27, 2023, 05:04:06 PM »

Usual causes for this kind of issues:
- Bad solder joint,
- Forgotten solder joint,
- Components leads cut not short enough and touching something they shouldn't,
- Conductive solder flux creating unwanted connections on the PCB.

So i have gotten a new T2 now, but still one issue remains.

Firstly:

- Bad solder joint, = reflowed all now
- Forgotten solder joint = No
- Components leads cut not short enough and touching something they shouldn't = Not an issue
- Conductive solder flux creating unwanted connections on the PCB. = both boards Cleaned with isopropanol



Board 1 is now ok, but i am left with one issue i also had at the start of this thread, which i think is the cause of the unbalance.
With 3 VAC measured when bypassed, i can only get around 2.7 VAC max with IN button activated and T2 is turned all the way up to 1K

Tests come out ok, except this:

2.3
input signal = 3VAC
Threshold on +15
Makeup on 0
Signal level (VAC) on

• TP6=1.5VAC,
• TP7=1.3VAC
• TP8=1.5VAC,
• TP9=0.06VAC

This leaves me with the original unbalance i had.  Any idea about this?

4

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 21, 2023, 07:38:46 PM »

I have added a value on 2 of the tests:
Can you check them:
Step 1.5
When Threshold goes from +15 to -15, TP5 goes from +0.35VDC to -1.2VDC

Step 2.4
DC voltage (VDC) on TP10=-1.2VDC

1.5 = 0.35 -> -1.178
2.4= 0.36 -> -1.14

But, suddenly board 1 is working now, It has been laying still since last time i measured. Weird.  The only thing "out of the ordinary" that happened, was that i touched one of the other testpins on board 2 while testing 2.4. This made the needle go all the way down to the right. After this it is ok!

Sadly no real explenation on the issue, but as with all lucky accidents i've now managed to wreck the T2 trimmer. It does simply not work anymore. I must have overturned it to maye times. New one is allready ordered

5

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 20, 2023, 09:09:38 PM »

Does the behaviour of channel 1 tell you anything about what this can be?
Sorry, no.

Threshold mutes the audio in a very steep fashion, instad of compressing it.
The signal on TP12 is the side chain signal which  directly controls the VCA's. So we need to know what is going on TP11 and TP12.

TP11 and TP12 works as they should as described in 1.5
Sorry if i was not clear enough on this. After measuring in VDC instead of wrongly setting my DDM to VAC, they checked out.

So as i said, the unit passes all tests on the "In case your CP4500 doesn't work as expected" list

1.5
Input signal = 3VAC
(measured between output XLR pins 2&3
with compressor bypassed)
Makeup on 0
Threshold goes from +15 to -15
• TP4 goes from 0.060VAC to 0.190VAC
• TP5 goes from +0.35VDC to a negative value
• TP11 goes from 0VDC to -3.5VDC
• TP12 goes from 0VDC to +3.5VDC

6

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 19, 2023, 07:08:01 PM »

My bad, these values checks out on VDC too.
Meaning the unit is passing all tests, and there is no real reason it should not work as excpected?

I don't think so:
TP11 goes from 0VDC to -3.5VDC
TP12 goes from 0VDC to +3.5VDC
This should happen when the threshold changes from +15 to -15. Is that the case?

Could it be that the trimmer is gone bad on T3?
Possible. You can check it by measuring the resistance between the 2 side pins. It should vary from 0 to 200 ohms (remove U22 before checking)3

Ok, i will check.

But could you give a feedback on what you see in the video i linked?

Does the behaviour of channel 1 tell you anything about what this can be?  Threshold mutes the audio in a very steep fashion, instad of compressing it. 
This also happens when only board 1 is active, is that normal?  If not, the chances are slim that T3 is the culoprit, as is it not even installed in the unit when testing board 1 alone.

(Edit: checked all trimmers, and they respond ok)

7

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 18, 2023, 11:02:43 PM »

When testing TP11 and TP12, my meter starts meassuring around 0.5 VAC and the meter starts decreasing in value unbtil it hits 0 VAC. Thishappen both with Threshold on -15 and +15
Here we are measuring DC voltage, not AC.

You always have the option to send us your your unit for a check. In this case, please contact us here.

My bad, these values checks out on VDC too.
Meaning the unit is passing all tests, and there is no real reason it should not work as excpected?

Not to keen on spending $$ sending the unit to France. If we can't fix this one remotley, it will sadly be discarded and put in a dusty corner. To bad, as i really really like this one.
I've buildt over 20 pc. of 500 units from various brands, only the SS TS 500 Tape module has been the one i/we gave up on.

As i said, this one worked well until i adjusted T1, T2, T3 and T4 to get it back in perfect stereo balance, then it started fritzing. Could it be that one of the trimmers have gone bad?

I tried adjusting T3 with a sine going through, and when my screwdriver touched the metal trimmerhead the audio slightly changed volume. I tried wiggelig a little and at one point the wiggeling actualy seemed to improve the issue. Both channeles now responded almost the same when adjusting threshold.
So i desoldered the T3 and inspected it. Looked fine!... and then resoldered it again = the main issue still persists, but the audio is now stable when my screwdriver hits the trimmer, and wiggeling does not help. This is all to confusing. Could it be that the trimmer is gone bad on T3? This is the trimmer i adjustet very first in the process.

I made a new video showing the issue in stereo:

https://www.dropbox.com/s/aa10nuih14c7ysq/IMG_6421.MOV?dl=0

8

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 18, 2023, 10:53:49 PM »

When testing TP11 and TP12, my meter starts meassuring around 0.5 VAC and the meter starts decreasing in value unbtil it hits 0 VAC. Thishappen both with Threshold on -15 and +15
Here we are measuring DC voltage, not AC.

You always have the option to send us your your unit for a check. In this case, please contact us here.

My bad, these values checks out on VDC too.

Meaning the unit is paasing all tests, and there is no real reason it should not work as excpected?

Not to keen on spending $$ sending the unit to France. If we can
I've buildt over 20 pc. of 500 units from various brands, only the SS TS 500 Tape module has been the one i/we gave up on.
As i said, this one worked well until i adjusted T1, T2, T3 and T4 to get it back in perfect stereo balance, then it started fritzing. Could it be that one of the trimmers have gone bad? Did you watch the video i linked?

9

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 16, 2023, 09:10:16 PM »

99% of the reported issues are caused by bad solder joints.
I would recommend starting by reviewing all you solder joints and reflowing all suspect looking ones.
Don't be shy on heating until the solder flows nicely, as long as your iron is thermally regulated.

The unit has worked fine since i buildt it, as i said something happened when i started adjusting the balance that was off-
I have looked over the olders joints, they all look ace but i did reflow any mildly suspicious ones and i did redo the ones around the trimmers though, as these are the only parts i touched when this all started to happen, but there was nothing visiblywrong with these joints.
I do not beleive this is caused by any bad soldering.

I have also Switched all socketed parts from Board 2 into board 1 with same result.

So i have backtracked to the measuring tests and found something (green is ok, red is not, blue is not sure)



1.1
Mix = 100%
Ratio = 10
Attack = 0.1
Release =1.2
IN button pressed
HF lift, 100Hz, 50Hz buttons released
Negative meter probe on 0V

• V+ =+15 to +16VDC,
• V-  =-15 to -16VDC),
• +12V = +11.1 to +12.9VDC,
• -12V  = -11.1 to -12.9VDC



1.2
Step 1 conditions plus:
Input signal = 0V
Threshold on +15
Makeup on 0
TP1, TP2, TP3, TP4, TP11, TP12 = 0VDC



1.3
Step 1 conditions plus:
Input signal = 0V
Threshold on +15
Rotate Makeup from 0 to +20
TP12 goes from 0 to -2.3VDC



1.4
Input signal = 0V
Makeup on 0
Rotate Threshold from -15 to +15
TP13 goes from -1.8V to +2.8VDC



1.5
Input signal = 3VAC
(measured between output XLR pins 2&3
with compressor bypassed)
Makeup on 0
Threshold goes from +15 to -15
• TP4 goes from 0.060VAC to 0.190VAC
• TP5 goes from +0.35VDC to a negative value
• TP11 goes from 0VDC to -3.5VDC
• TP12 goes from 0VDC to +3.5VDC

When testing TP11 and TP12, my meter starts meassuring around 0.5 VAC and the meter starts decreasing in value unbtil it hits 0 VAC. Thishappen both with Threshold on -15 and +15

1.6
input signal = 3VAC
Threshold on +15
Makeup on 0
Signal level (VAC) on
• TP1=1.5VAC,
• TP2=1.5VAC,
• TP3=1.5VAC,
• TP4=0.06VAC
DC voltage (VDC) on
• pin 1 of U6 (white dot) = 0V.


1.7
input signal = 3VAC
Threshold on -15
Makeup on +20
Signal level (VAC) on

• TP1=1.5VAC
• TP2=0.4VAC = 0,26
• TP3=1.5VAC,
• TP4=0.2VAC

DC voltage (VDC) on
• TP11=-3.5VDC,
• TP12=+1.2VDC,
• TP13=+1.7VDC

10

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 12, 2023, 03:59:18 PM »

Do you mean U2, U3, U4, U5?
Yes

So, no 0,75 VAC reduction
Were you configured as in step 4 of the setup guide?

All VCA say 3,75 VAC except one of them which only give 1.875 VAC
This is possible.
Does the result depends on the slot? If true the issue could be the slot.
Do you get good results if you replace the suspect VCA by one from the other board?

Were you configured as in step 4 of the setup guide? = Yes

Does the result depends on the slot? If true the issue could be the slot. = No, result does not seem to depend on slot.

But, today the following happened:

As i told, i replaced all OPAs with some others i had laying around, same brand and model. 
The CP4500 was laying on top of my 19" rack, connected to my luchbox via the extender. Powered on.
When i reached to pick it up, i only touched the corner of the front plate.. and BOOM! I saw the small fire in the electrical blast between my finger and the unit.
One of the OPAs blew so hard a piece of the plastic is gone.

So put all the the original opas back now, just in case i bought a bad batch...

When tunring on, it works as before. Samme issues, no more no less.

So..


Good idea crossswapping VCAs:

What i did was to put all the VCAs from board 2 into board 1. And this actually seemed to work, at least the threshold went smoother again, i just visualized on the meter and heard if the sine diaapears quickly.

So i started changing one after an other to see if any of the board 1 VCA was the culprit. And i actually experienced one VCA working from board ione and the rest not, but when i started round 2 and testet the first working VCA again, suddenly it did not work. So i have a hard time recreating anything, as the issue seem to be random.

I then checked all...
...the board 1 VCAs in Board 2 = did not work - Nor same issuen tho. I have a constant sine that does not get affected by the threshold
...The board 2 VCA on Board 1 = did not work - Same issue as before
...the board 1 VCAs in board 1 = did not work - Same same
back in ...the bord 2 VCA back in Board 2= works fine

This again seem to confirm that there might be something with both board 1 VCAs and something else on board 1.

The funny thing is, the unit worked fine. I only had maybe 1-2dB unbalance on one channel, but all this trouble started the moment i tried readjusting the balance.

11

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 11, 2023, 12:50:56 PM »

i can not get T1 on channel one to match the 3.0 VAC
With board 1 only, try removing the VCA's, one at a time. It should reduce the output level by 0.75V. If one of the VCA's doesn't reduce the output, it can be a defective VCA or a bad slot.

Do you mean U2, U3, U4, U5?

• With 3.75 VAC on output: 
• When Removing U5, reduces output to 1.875 VAC,
• Then Removing U2 = 1.875 VAC.
• Then Removing  U3 = 1.880 VAC
• Removing U4 =  Silence

So, no 0,75 VAC reduction


But, i tried the follwing to, to try to identify if one is acting weird:

• 1 VCA always in slot U5
• the other 3 VCA put in U2 one by one 
• All VCA say 3,75 VAC except one of them which only give 1.875 VAC

So, can we conclude one of them is gone bad?



 

12

CP4500 Stereo Bus Compressor / Re: Unbalanced channels + + +

« on: December 07, 2023, 11:07:34 PM »

So, something has really happened to this unit now.

Watch this video, thisn is not normal. This is only happening on left ch. (pcb A)
https://www.dropbox.com/s/zk0808316bocxha/IMG_6345.MOV?dl=0

When hooking it up with both pcbs the right ch. does not loose the sound like this.

any ideas?

13

CP4500 Stereo Bus Compressor / Unbalanced channels + + +

« on: December 07, 2023, 09:49:24 PM »

-----------------------------------------------------------------------------------------------------
So, this is a continuation of thread: https://www.soundskulptor.com/forum/index.php?topic=419.msg2349#msg2349
Just to politely not weddingcrash the other users questions.

So:
I have unbalanced output after a couple of years.

My issue is that whn i start calibrating the unit from start, i can not get T1 on channel one to match the 3.0 VAC signal that is present when i standby. T1 only manages to increase the voltage to 2.595 VAC.

Edit: and on channel two board i can't get T2 og T3 down to 2.595.

-----------------------------------------------------------------------------------------------------

@Dolbah
Do you get TP1=1.5VAC with 3VAC at the input?
Are the VCA's socketed or SMC?

@JPK



3.0 VAC source signal gives me 1,492 VAC on TP1.

With T1 turn on max, it gives me  2.709 VAC on the unit output.


My VCAs are in sockets

EDIT:
I realized now, that when testing with only board 1 powered, i get the above results. As soon as i power both boards, board/channel 1 suddenly gets a bump and is suddenly outputting 2.95 VAC
When removing board 2, it goes down to 2.7 VAC.

EDIt 2:
I had a bunch of OPA2134PAs laying around, so startet switching them. When replacing U21, i finally was able to match the bypass and active signal. But i have no chance of getting T4 to trimm the meter to 12 dB attenuation (worked yesterday).
Also noen of the trimmers on board 2 is reacting. And i feel the threshold is very sensitiv.

14

CP4500 Stereo Bus Compressor / Re: Channels keep becoming unbalanced

« on: December 07, 2023, 07:47:03 PM »

@Dolbah
Do you get TP1=1.5VAC with 3VAC at the input?
Are the VCA's socketed or SMC?

@JPK



3.0 VAC source signal gives me 1,492 VAC on TP1.

With T1 turn on max, it gives me  2.709 VAC on the unit output.


My VCAs are in sockets

EDIT:
I realized now, that when testing with only board 1 powered, i get the above results. As soon as i power both boards, board/channel 1 suddenly gets a bump and is suddenly outputting 2.95 VAC
When removing board 2, it goes down to 2.7 VAC.

EDIt 2:
I had a bunch of OPA2134PAs laying around, so startet switching them. When replacing U212, i finally was able to match the bypass and active signal. But i have no chance of getting T4 to trimm the meter to 12 dB attenuation (worked yesterday).
Also noen of the trimmers on board 2 is reacting. And i feel the threshold is very sensitiv. Lets close my apperance in this thread, and start a new one. --> https://www.soundskulptor.com/forum/index.php?topic=422.msg2350#msg2350

15

CP4500 Stereo Bus Compressor / Re: Channels keep becoming unbalanced

« on: December 05, 2023, 10:28:27 PM »

This is funny, i buildt mine a couple of years ago and today i realized it is now ublanaced. First post i see in here is this +1
My issue is that whn i start calibrating the unit from start, i can not get T1 on channel one to match the 3.0 VAC signal that is present when i standby. T1 only manages to increase the voltage to 2.595 VAC.

Edit: and on channel two board i can't get T2 og T3 down to 2.595.

Sorry, did'nt mean to hijack this tread, but since we are in the same boat, lets see what JP says

16

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 19, 2022, 05:49:46 PM »

R19 3K296
R20 180K
R21 21K99
R22 14K94
R23 9K99
R24 8K18

C19 WIMA 0.022 100-
C20 WIMA 0.01 100-
C21 WIMA 4700 100-
C22 WIMA 2200 100-


HD1 = 2043, P is downwards

30" + BIAS to the right = no change when listening to TP3 to TP5

Solder joint looks good, and have been reflowed earlier (did them all)

17

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 19, 2022, 05:46:41 PM »

R19 3K296
R20 180K
R21 21K99
R22 14K94
R23 9K99
R24 8K18

C19 WIMA 0.022 100-
C20 WIMA 0.01 100-
C21 WIMA 4700 100-
C22 WIMA 2200 100-


HD1 = 2043, P is downwards

30" + BIAS to the right = no change when listening to TP3 to TP5

18

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 18, 2022, 07:04:41 PM »

I get it, but mine still doesent sound correct. I found a good way to test this by using this YT video:

TS500 demo - YT

I made a audiofile of it, and put the DRY signal from the video into my TS500 and recorded the result with identical settings:



Here is my result:
https://www.dropbox.com/s/lwvb4o8v2wqsqlz/TS500%20YT%20test.wav?dl=0

If you compare this with the wet signal from the video, you hear a clear difference.


I am listening my way through the NAB pre-emphasis stage and can hear the high pass driving the highs louder, all the way to R13 and it decreases a bit, then at R25 it decreases even more until i get to R35 and U11 again  and i'm back at the de-emphasis and everything gets pulled down to the point that i can recognize it as the level that is outputet from the module.
I have Drive at zero and saturation set to minus, and levels are on green all the time.

Any pointer in the correct direction would be appreciated

19

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 17, 2022, 07:28:18 PM »

The change on high frequencies occurs after R35
This is normal because U11a does the NAB de-emphasis (low pass filter).
Maybe the corresponding initial pre-emphasis (high pass filter) made in U2a is not working. Check the value and solder joints of R7, R8, C4, C5.

R7 = 0,997 Ohm
R8 = 5K605 Ohm

Not sure how to read caps with my DDM without removing them, but:
C5 = 221/K1J
C4 = Wima 0.01 100-

Reflowed my joint but same results. All looks good visually. Replaced U2 just in case, no luck.


But the spectrum analyzer in my previous post shows clearly a low-pass situation going on or at least at that side of the spectrum, how would this be affected by a high-pass filter?
Do you have any frequency response charts for the unit, so i can compare?

20

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 15, 2022, 09:19:42 PM »

Check component value, direction and solder joints on:
R33, R34, C35 to C38, U10, U6.
Try removing U6 and listen if it makes a change.

Sorry for bumping this old post, but I seem to have the same issue.

• I have gone over all joints.
• Replaced U3
• Checked R33,R35 and C35, C38 + Replaced U10.
• Removed U6 = Same result, no audible change in sound.
  

Left picturer is a Pink Noise without TS500, the right is the same Pink Noise with TS500 set at:
- 30"
- Tape Sat at middle
- Bias/EQ to the right


I listened to the TPs and it starts after TP5

Honestly, i thought this was normal until i started checking out sound demos online with nice clear Highs, and then i saw this post. 

UPDATE:

I've located the point on the PCB. The change on high frequencies occurs after R35, when i listen to R35. it sounds nice and clear but on R36 and Pin 1 on U11, the highs have been pulled down. The same on C39, C40 and C41.
 
I've changed U11 with several other OPA2134 frm other SS gear i have, same results. Is it supposed to be like this? I dont get the impression from listening to any demos.

When removing the OPA, i can listen in to PIN 1 and 2, and i get a normal high freq sound, with out any loss.

21

TS500 Tape Simulator / Re: Everything works but high frequencies are getting lost somewhere

« on: May 15, 2022, 01:30:58 AM »

Check component value, direction and solder joints on:
R33, R34, C35 to C38, U10, U6.
Try removing U6 and listen if it makes a change.

Sorry for bumping this old post, but I seem to have the same issue.

• I have gone over all joints.
• Replaced U3
• Checked R33,R35 and C35, C38 + Replaced U10.
• Removed U6 = Same result, no audible change in sound.
  

Left picturer is a Pink Noise without TS500, the right is the same Pink Noise with TS500 set at:
- 30"
- Tape Sat at middle
- Bias/EQ to the right


I listened to the TPs and it starts after TP5

Honestly, i thought this was normal until i started checking out sound demos online with nice clear Highs, and then i saw this post. 

22

Discussions about the products / Re: SS CP554 Diode bridge compressor

« on: April 01, 2022, 07:29:19 PM »

But i look inside, and see many of the same componenets. Same transformers etc.
It belongs to the same family and for sure shares some similarities, soundwise.
I would say that if you like the Neve sound, the compressor will allow you to add some more to your tracks.
Also the side chain is completely different from the CP4500. It has its own character.

Cool! Are you close to launching them?

23

Discussions about the products / SS CP554 Diode bridge compressor

« on: March 31, 2022, 05:48:47 PM »

So! SS CP554 Diode bridge compressor is announced.

I allready have 2xMP573 with EQ573 Mk2 and CP4500

So, of course the CP554 looks very tempting! But i look inside, and see many of the same componenets. Same transformers etc.


Would i gain anything new with the diode bridge type compression in compared to running the 573s and CP4500?


I also have a pair of JLM LA500 comps, and a API529, but my GAS is feeling the urge to collect all the various types of compression into my setup. (And also i love the build process)

But i am haveing a feeling that i'll not gain that much new sonic terrain with the CP554..

Change my mind!!

Thanks

24

EQ573 Equaliser / Re: WARNING : Error on C8 in EQ573-II

« on: October 25, 2021, 05:20:14 PM »

Will you send out replacements? i've a pair of these and i've had mine in for months now, linked to MP573. I do have small issues, like often they both will start making a pulsating lo-freq sound, that goes on forever. It vanished if i turn it frem PRE to XLR , back and forth a couple of times.
But there are no visible meltdowns that i can see....

25

MP573 Microphone preamplifier / Re: Volume difference between units

« on: May 08, 2021, 08:24:26 PM »

The U1 IC's were mailed on Monday.

Hi
I still havent received these, and U1 i still shorted. Can this have any sideeffects over time?   Suddenly on of my units started behaving differently, the XLR input is much higher then it should. The DI is still on normal volume.