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Messages - AcdNrg

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1
Discussions about the products / To pre or not to pre, that is the question
« on: February 10, 2024, 08:59:04 AM »
So I´ve completed my first API box with a nice collection of stereo compressors, ie 5176, 502, 554 and 4500. And I have to admit I´m totally hooked. So what´s next?

- I don´t do any microphone work, no vocals, no acoustic instruments (for now)
- Electronic music 99% with attention to sound and timbre
- I like to color my signals and normally record first, then send signals through the compressors, often with a touch of saturation.

I wonder if preamps make context in that sense. Or if their color originates mainly from the transformers, which I already have in the compressors. How close is running line signals through a comp (not doing much compression) to what I would get from running them through one of the pres?

I assume (no clue synth guy here) that dialing in saturation may be somewhat easier and better controllable on a pre? Finer level control? Can only compare to an elysia skulpter through which I played a synth once: it seemed that from "clean" to "fat saturation" could be dialed in over a much wider path of the pot. Would that be similar with 528, 512 etc?

And could you order the different models by "intensity of color"? Can´t build all of them at once, so I´m looking for the more obvious ones to go first and save the subtle ones for later. From a video I´d put the TS more into the subtle category in comparison.

Or should I go for some of the EQs and push them?







2
CP554 Diode bridge compressor / Re: Setup - no 0dB
« on: January 07, 2023, 01:57:26 PM »
So after careful inspection of all soldering joints, I found the black transformer cable to look fishy. Did a reflow, everything is golden now.

What bugs me a little is that my chassis (WES Audio Supercarrier II) does not seem to carry the stereo link signal. I may swap all sorts of modules to move my CP554 pair to the Neve R10, but this messes with the functional layout I had in mind.

I wonder is a switchable stereo link can be done by simply getting a 1 slot frontplate, drill a hole for a switch and connect both pin6 to it?







3
CP554 Diode bridge compressor / Setup - no 0dB
« on: January 06, 2023, 06:08:41 PM »
So on my 2nd instance, the assembly worked a lot easier already :)

However, it seems I can´t get the 0dB trimming (setup step 7) done: Output won´t get below 1.2x VAC on an input of 1.0 VAC.

Best I can get is 1.0005 VAC bypassed to 1.1224 VAC active

Yes, Gain is at 0dB and I can identify different outputs as per gain stage. However, maximum output is lower than expected, ie 6.480 VAC @20dB and 6.707 @22dB compared to the 12.5 to 13 VAC given in the setup docs.

What are the things to look at?


4
OK, it´s official now. I´m an idiot.

Since switching the threshold looked fishy, I decided to

- reflow all switch solder joints on the treshold switch
- reflow all connector joints on switchboard on PCB2

No change. Soooo, we´re in for the long run: Check all parts.

Low and behold, take a close look at D4



And that´s why DIODE Bridge Compressors will be known as Diodevil Bridge Compressors in my book from now on.

Let this be a warning to others to not build this kit over a long night with too many distractions...

Apologies for wasting your time and braincycles! I did a full calibration, all values within expected ranges, now I´m a happy man.

Best regards and thank you for your patience! 

5
It seems I get 0 VDC on every setting higher than -9dB:

jumper JMP1 pin1-pin2 installed / not installed

-21 dB: 3.546 / 14.783
-18 db: 3.132 /14.717
-15dB: 2.686 / 14.587
-12 dB: 2.277 / 14.279
-9 dB: 1.811 / 12.321
-6 dB: 0.0024 (slowly falling to 0.000) / 0.0006
-3 dB: 0.0003 / 0.0003
0 dB: 0.0003 / 0.0003
etc. no change up to 12 dB

I made sure the jumper bridge has contact, even if the setup looks a little flimsy :)




6
I get the 2.8 VAC on pin4 and 5 (2.799 + 2.798 ) against 0V

I don´t get any VDC on pin1 of JMP1 (marked by the dot), no matter if jumper is installed or not.

That said:
JMP1-pin1 to 0V = 0.0003 VDC
JMP1-pin2 to 0V = 0.0000 VDC
JMP1-pin3 to 0V = 3.001 VDC

For what it´s worth, on pin1 I get
12.336 VDC at Threshold set to -9dB
14.280 VDC at -12 dB
14.587 VDC at -15 dB
14.716 VDC at -18 dB

To be honest, I don´t know what I´m measuring here :), so hopefully those numbers make some sense to you.

The compressor still works (from meter movements and musical material)


7
Yes, spacers are in place. Added 4 washers for aesthetics, double checking that there is enough room for PCB2. That is resolved now.

Still can´t finish the calibration though. Everything is fine except the Threshold Stage, where I get much higher voltages than expected and no effect of TR3 at +9dB:




4. PCB1 Voltage
V+ = 15.746
V- = -15.808
PASSED

LED check
PASSED

5. BIAS
TP2-TP3 = 3.003V
PASSED

6. Input Signal
Output at Chassis = 1.0004 VAC
PASSED

7. 0dB Gain
Output : 1.0004 / 1.0006 VAC
Makeup: up to 13.165 VAC
PASSED

9. 3V Adjust
3.001V
PASSED

CV Adjust
Bypassed: 2.451 VAC
Active: 0.9782 VAC
PASSED

10. Meter Adjust
8dB
PASSED

Threshold Adjust
JMP1 1-2 OK

1kHz at -6dB
Threshold -6dB SET
Bypassed: 6.151 VAC OK
Active:
fccw 6.143 FAIL
fcw 5.022 FAIL

1kHz at -18dB
Threshold -18dB SET
Bypassed: 1.5502 VAC OK
Active:
fccw 1.5472 FAIL
fcw 1.1994 FAIL

1kHz at +9dB
Threshold +9dB
Bypassed: 6.152 VAC OK
Active:
fccw: 6.139 VAC FAIL
fcw: 6.14 VAC FAIL


Measured onboard:
r35 4.6947 kOhm OK
r43 2.19 kOhm OK


What am I doing wrong? From a quick audio test, the compressor works and is doing something, but the threshold calibration is totally bonkers.






9


Aesthetics aside, my concern it that the metal may connect to a neighbor module if that one is also "boxed". But as I didn´t finish final assemply, I can´t tell yet.

10
CP554 Diode bridge compressor / Re: Zener Diode Markings
« on: October 30, 2022, 05:13:22 PM »
For those that struggle with the diodes (like me, old eyes), this is what was in my bag. As I had a hard time reading the exact markings, it took me a while. All references based on documentation package 24 and of course things may change when replacements from other parts manufacturers are used due to availability issues.

----------------------------
D6
Zener Z2V7

Markings on body (black stripe to the left):
BZX
55C
2V7

----------------------------
D16
Zener Z12V

Markings on body (black stripe to the left):
ON  (or maybe DN)
24
2B

----------------------------
D20
Zener Z4V7

Markings on body (black stripe to the left):
BZX
85C
4V7

----------------------------
D4, D5 etc. (the set of 12)
NPN

Markings on body (black stripe to the top):
N914





11
Discussions about the products / Re: CP554, I need some guidance
« on: October 28, 2022, 04:17:08 PM »
So I decided to go for a "compressor tasting session" and ordered CP5176, LA502 and CP554, let´s see which of these will get the "stereo upgrade" in the next weeks. I´m deeply concerned the answer will be "all of them", but that thought won´t spoil my soldering fun weekend I start right now. 

12
Discussions about the products / Re: CP554, I need some guidance
« on: October 22, 2022, 10:18:45 PM »
Apologies for the late reply, but my day job was demanding these days :).

After lengthy discussions, a good bit of research and fruitless reaching out to certain vendors, I decided that I´ll need to try and test and find out what actually fits my situation and taste in the best way. I need to start somewhere and decided to go with Sound Skulptor - mainly because of good experience with the CP4500, but also because no other vendor is even close in completeness, openness and transparency regarding the components in the box. Many companies try to get away with buzzwords sans detail and some seem to mislead you on purpose.

That said: Is there a strong reason to order 2x CP554 at once, just because I might want to run them as a stereo pair some day? Or is it possible to start with one, find out if the diode-bridge is something I like and then get a 2nd unit later on - without being concerned about matched pairs of parts etc.? How similar can those units be calibrated?

It may sound a little strange, but I´m still new here, trying to learn about the different characters and purposes.  So instead of getting a pair of CP554 to get familiar with a single type (diode bridge), I wonder if it makes sense to get 5176 + LA502 instead of the 2nd channel for now.  I don´t own any 1176/LA2A clones yet, just a few mid range dbx, bss, mindprint things plus the xpressor.

Comments welcome!




13
Discussions about the products / CP554, I need some guidance
« on: October 16, 2022, 08:44:08 PM »
Hi to all!

So I´ve built my CP4500 a few weeks ago, was happy with the build process and am even happier with the results. Now there´s an appetite for more, hence this thread. My background is more in synths and modular, I´m not very experienced in the mixing and outboard processing world. That´s why choosing compressors is not the easiest for me and I´d like to ask the swarm intelligence a few things about the CP554. Apologies for referring to a second vendor, I´m trying to get the differences between the diode bridge compressors I find. 

0. What else is in my rack and what do I use that for?
dbx 560A
elysia mpressor 500
elysia xpressor 19"
100% electronic music, no mics, no vocals, no acoustic guitars. 80% material of the unts unts unts variety, techno, acid, sometimes house and the rest is soundscapes and ambient. Don´t look down on me for that, I played classic piano in my earlier life ;).

1. CP554 is a mono unit, so I´d need two for any bus application. That´s totally fine with me, as the ability to use it on two separate mono signals, probably earlier in the mixing process, is a welcome option. Money wise, 2x CP554 gets me close to the Heritage Successor, which brings stereo only -> it´s less flexible. However, there are some nice features like SC options and parallel compression. If only it was clear whether I´m looking for a channel or a bus compressor... but I mainly want to learn about bridge diode (BD) characteristics, try them out and apply them where they best fit. Thoughts about that?

2. There are some differences in timing and compression, and this leads to questions:
SS: Attack 0.5/1/2/4/8/16ms -- Release 100/400/800/1500ms/A1/A2 -- Compression 1.5/2/3/4/6/12:1
HA: Attack 0.05/0.2/0.5/2/5/20ms -- Release 25/50/100/400ms/A1/A2 -- Compression 1.5/2/3/4/6:1 + limiter


I wonder if these ranges lead to certain applications or types of signals. Probably not very black and white, more nuances (maybe big nuances), but I´m lost here. One can say that SS has benefits if longer release times are needed, whereas HA is super fast for attack and release. But I just can´t translate that into the use cases. Is it correct to say that the HA appears to be aimed at the master bus and that´s why they designed the timing in the way they did? And what does that say about the "best fit" for the CP554? Or is that maybe less related to the "where" of the signal chain, but more to the "what" as in "kind of material" (percussion heavy, transient rich, etc) or "how" the material is effected?

If I could, I´d just get both and experiment. But there aren´t any CP554 demo options and even if there were any: I already sold one of my kidneys for the eurorack modular :D. Reviews or demo videos are between rare and non-existent and most likely not for the genres I cover. And "just get both" isn´t the answer ^^. Same with plugins: the differences between those and their hardware counterparts are not exactly leading me to play with a DB compressor plugin to answer the questions above.

So maybe you can help me out?



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