SB4000 Support Thread

[jonathanmorbin]

The easiest and cheapest way is to buy the pcb and front panel from the serpent audio website and then order all the parts from Mouser using the BOM. You may find one or two part missing from the BOM so be prepared to order it all, build it and then find you may have to order a couple of missing parts.

If you don't want the hassle of having to creating a shopping list in mouser then just buy the parts package from the serpent audio website. it may cost a fraction more but it may save you time. I found that if you have an old piece of equipment lying around that you can steal the case from then that will save you £60-£80.

unfortunately you will have to pay the customs charge, the only way around this is to design and build your own pcb, buy a rack enclosure from your country of origin and make the front panel yourself. Then buy all your parts from Mouser.

I have built two units using the first method and it probably cost between £380 and £480 depending if you do the quad VCA modification.

 

[MarioXLR]

Hi, thanks for that.
I'm from Portugal and i was trying To get it somewere in europe.
There are some other options in europe, for example GSSL from PCB grinder, but when i saw the schematics i realize that this one is better... What you think about that???

Thx

Mário.

 

[jonathanmorbin]

The serpent audio PCB is definetley better. It has all the Modifications already on it as well as a bargraph meter section. You may be able to do the gssl cheaper but you will need a bit more knowledge to do it and you will have to buy and implement the modifications afterwards if yu wish to have them.

 

[EmptyMusicBox1]

Hi ! i have an interrogation :

i have the same Sound in Oxford and SSL Mode ...

i think it's not Normal

can you help me please

thanks

 

[Harpo]

i have the same Sound in Oxford and SSL Mode ...
i think it's not Normal

Depending on your audio program could either be yes or no.
Is your unit compressing at all with signal above threshold?
With a mono program feed and in-phase XLR cables both modes will/should behave the same.
Checking with a mono program feeding both L/R inputs, but one side with polarity inversed, Oxford mode would compress as expected, Aarhus mode would not compress at all, because summed L/R signals in front of the sidechain would cancel out.

 

[EmptyMusicBox1]

thanks HARPO

After test when i'm in GSSL mode with the Inv-Phase the compression is Over

in Oxford mode the compression is Ok

But with the audio signal i can't Heard the difference

 

[Harpo]

After test when i'm in GSSL mode with the Inv-Phase the compression is Over

Whatever this might translate to, no compression or overcompressing.

But with the audio signal i can't Heard the difference

As already said, it is program dependant.
Loud signal at center (most often vocal and bass) might get more compressed in GSSL mode. IE coherent signals get summed, generating a higher control voltage for the sidechain-VCA. You could adjust/tame/feature this overcompressing of centered signal behaviour by use of the sidechain-filter. In Oxford mode this will behave a little different for the separate L/R sidechain-VCAs, because there is no summing of signal in front and only the greater of both shaped and timed control voltages affect both sidechain-VCAs to keep stereo image intact.

 

[EmptyMusicBox1]

Sorry for my English but in gssL mode with a /phase I have no compression !

 

[EmptyMusicBox1]

About this Video https://www.youtube.com/watch?v=EQD8GPhFGYE

On the SB4000 the Oxford Mode is compensate on Audio and GR Meter ?

 

[Harpo]

On the SB4000 the Oxford Mode is compensate on Audio and GR Meter ?

and maybe related from previous page

the out and Vu Level of the Oxford is "offset" than the GSSL Mode ?

You got me scratching my head for hours what the question might be.

The GR-meter shows the amount of generated control voltage for the audio-VCAs.
IE more GR-meter - more gain reduction/compression, no matter what mode Oxford/Aarhus.

The VU-meter shows the amount of audio level, depending on switch setting left or right side and input or output.
IE more LEDs lit - more audio level, no matter what mode Oxford/Aarhus.

Depending on audio program, Oxford mode and Aarhus mode might/will differ. Might be just the other way round for a different song.

 

[EUC]

Hi just had a quick question. I've read through the entire thread and just wanted to make sure i'm doing this right.
I finished the build with the quad vca mod built by serpent and am only getting audio in bypass mode. When the compressor is active i get no signal.
My rails on both psu and  on to the main board measure out correct. I had made the beginners error of installing the Tl074 chips backwards so first power
on i got smoke. Turned it off saw i blew R183 replaced that then replaced all of the Tl074 chips. Hooked it all up still no audio when compressor is activated. I'm going through the steps that have been mentioned previously in this post to trouble shoot and i was wondering with the Quad VCA do i need to remove all of the THAT's and jump wire 1-8 on all 8 of them to see if i might have blown them? Also would the other IC's have blown or only the one's that were in backwards? Thanks for the help.

 

[sr1200]

Youll get audio when the unit is OFF! Don't use bypass as a comparator for anything.  Anything that WAS in backwards, replace.

 

[yodv]

Hello, i.m new user and i.m french...
I finish my SB 4000 with 4 VCA but i have 2 problemes, 1: in bypass mode Led level don't work? 2: the right channel input work but no output?
Thanks

A French Guy who don't speak very well!!!!!

 

[elielsolis]

hi. Im missing the two 91k resistors and i cant seem to find them in stock. Is it possible to sub them for 100k maybe?

 

[Harpo]

hi. Im missing the two 91k resistors and i cant seem to find them in stock. Is it possible to sub them for 100k maybe?

Maybe. I'd use your 100K in parallel with 1M to get close to 91K. A 82K instead of 91K for R135 with VR16 pretrimmed to 15K should do as well.

 

[MarioXLR]

hi

i´m trying to go to serpent audio website and google is saying that is a dangerous website, Contains Malware!

Anyone knows anything about this?

king regards

 

[jonathanmorbin]

does anyone know where the schematics for the psu are? I am having a small problem that my +12v rail is reading 11.98 and therefore doesnt turn on my illuminated switches. Wandering if there was a resistor i can tweak to get this or is it just a case of changing the regulators? my -12v is fine.

 

[Harpo]

does anyone know where the schematics for the psu are?

there is only one schematic, covering the complete build. PSU is right side about center.

I am having a small problem that my +12v rail is reading 11.98

close to perfect. no problem.

and therefore doesnt turn on my illuminated switches. Wandering if there was a resistor i can tweak to get this or is it just a case of changing the regulators? my -12v is fine.

Whatever your illuminated switches might be...

 

[jonathanmorbin]

I found the schematic, i missed it when i was looking through it. My Illuminated switches wont turn on though unless they are fed over 12v. i used an external 12v which read 12.08v and it switched on the LED in the switches. There is definitely a voltage being fed to the switches however as i said it reads 11.98v. i know this is near perfect and it doesnt cause any other problems. Is there anything i can do to try bump the voltage up a bit? is trying new regulators my only option or will this not help?

 

[Harpo]

My Illuminated switches wont turn on though unless they are fed over 12v. i used an external 12v which read 12.08v and it switched on the LED in the switches.

My cristal ball is still blury, at least now I know there probably is a LED inside your switch doing the illumination. With additional info which colour LED is inside, the supposed 1K resistor values for R140 and R141 for 10mA Ifwd with 2V forward voltage drop LEDs that obviously need to decrease for allowing more current (not voltage) for your higher forward voltage drop part could be calculated. Knowing your illuminated switch part number would make it easier to get the needed info from the parts datasheet. Maybe you simply have fitted higher than 1K resistor values for R140 and R141.

There is definitely a voltage being fed to the switches however as i said it reads 11.98v. i know this is near perfect and it doesnt cause any other problems. Is there anything i can do to try bump the voltage up a bit? is trying new regulators my only option or will this not help?

Standoff diode in the center leg of the 7812 would rise voltage by about 0.6V, requiring to lift this center pin to get the diode in between. I'd prefer the prementioned resistor change/decrease.