SB4000 Support Thread

[sr1200]

You should be as close as your 12v rail... 13 is a little low... As far as the different values than whats listed on the board... if you look at the schematic, there are a whole bunch of alternate part values based upon which VCA setup you're doing the THAT chips depending on the variation have a certain set of support components to match.  Trust what serpent sent and follow that schematic (also follow it for the correct jumpers you need in that section as well)

 

[nickvivid]

ahh ok that explains things. theres no mention of that in the build pdf. ill double check my values based on the "that" chip i have with the schematic

 

[sr1200]

Yeah theres a big table on the schematic that you gotta follow that has the resistor values and the jumper locations to use for each chip including the quad.

 

[nickvivid]

OK i did that, but still nothing was necessary to mod on the power supply board. I'm still getting low voltages - even lower when the main board is connected and there's henceforth a current draw. The +/- 15 Drops to about 12v.

 

[sr1200]

Yeah there was nothing on there regarding the PS... i was more referring to the post you put up about there being part numbers that didnt match up.  First things first, the PS is NOT connected to either the main board or the front panel yes?  Second,  Id say chances are that one of the resistors you put where there was "supposed to be" a pot on the PSU is either way out of tolerance or ya got the wrong value in there.  Should be noted that if you DO put pots in there you can fine tune the voltage.

 

[nickvivid]

Solved it, i accidentally wired the transformer for 230 and not 110. d'oh! Once i changed the wiring everything was spot on. Solid 12v and 15v measurements . I'm glad you pointed the schematic to me though, as i missed 2 jumpers and had 2 resistors that needed different values based on the "that" chips i have, so thank you for that!

 

[MBlom]

Hi. I'm really interested in building an SSL clone. Have been searching for builds and kits every now and then for some years but never came across the Serpent Audio PCBs and kits. I've been under the impression that an SSL clone would cost me at least $500 to build but that doesn't seem to be the case here. So, my question is:

Are there any parts that could be hard to find if I buy just the PCBs and do the component searching on my own? So far I've only built diy-kits but thought I'd take the step to assemble components myself just to get more into learning about the schematic and circuits.

I realise that the answer may be in this thread already, but 50 pages is quite mindnumbing to skim through for me. Especially since I'm not that used to component serial names. I hope you don't find me too lazy, at least I'm aiming to get more competent as a DIYer.

 

[nickvivid]

Quick update: Ran and tested, runs great! Thank you everyone

 

[MBlom]

I wonder about the quad VCAs. As I'm quite new to DIY I don't want to complicate things too much, but I don't want to skip the quad VCAs if the unit will be significantly better with just a relatively small amount of extra work.  (I've built a studio and soldered patches and cables en masse so I know my soldering and schematic reading).

nickvivid: Did you buy the kit or just PCBs? If the latter, was it difficult or confusing getting all parts right?

 

[nickvivid]

I bought the kit and front panel from serpent, digikey for the parts in the bom that werent included, and the compressor vu meter, hairball audio. got a cheap 1ru case on ebay. Then just a soldering iron, you need a dremel to get everything in the case, and screws from the hardware store, and plenty of extra wires to get it all together. All told cost about $500. Still finishing up the case, but sounds every bit as good as i hoped on initial tests. Even though I have been in the repair biz and studio biz for years, this is my first real kit i built since the heathkit days of my childhood - certainly a project with an increased amount of intensity compared to those days, and i did it right on the first try - save for my wiring mistake initially on the power transformer. If i can do it, anyone can. it took about 5 days of work in total.

Nick

 

[daal]

Hi there,

Started my build, doing a quite detailed step-by-step blog of it here :

http://stereodramadiy.blogspot.fr/2012/07/sb4000-quad-vca-recap-post.html

Feel free to take a look and let me know if you have some feedback !

 

[wave]

Hi there,

Started my build, doing a quite detailed step-by-step blog of it here :

http://stereodramadiy.blogspot.fr/search/label/SB4000

Feel free to take a look and let me know if you have some feedback !

Looking good so far. You could try using some smaller standoffs or just some washers and nuts to bring down the height of your PSU so the caps don't touch the top of the case.

Dave

 

[daal]

Thanks ! Will try the washer/nut solution as my standoffs are already quite small. I was also thinking about putting something in the middle of the rack to put the top case a little bit more straight, as it's not really beautiful bent as it is. The Modushop case I used is not top notch for this, as the top and bottom elements are only screwed to the side elements, and the back is only screwed to the side elements as well. As a matter of fact, this can have another inconvenience, as the back plate can be pretty much bent too when inserting / removing XLR plugs. Maybe i'll add some screws with L stuff to make it a little tighter to the top/bottom elements.

Also I got another question : I want to tie both send and both return signals as explain by Ruckus. If I put a wire going from the right send connector to the left send connector and another from this L connector to my TS jack, will it be ok ? Or do I have to have two wires tied together on the TS jack ? I think it's the same but it seems kind of weird to me to tie a wire from an output connector to another output connector (I'm quite a newbie so please excuse if it's a lame question).

 

[wave]

Interesting, I used a par metal case as well and the top and bottom screwed to the back making it pretty stiff. I'm not plugging/unplugging the xlrs tho. It sits in my rack and I do my patching in a bay.
I wonder if par metal changed the case fabrication?

Dave

 

[daal]

Sorry Dave, I meant Modushop, I edited my previous message (and added a wiring question too)

 

[wave]

I think, if I understand this correctly, that you want to take a wire from the jack to each screw connector on the board but it does seem like it would be the same as if you jumped from the L to the R on the screw downs.
If I was doing it, I would just wire from each to the jack.

Dave

p.s. i dig your blog too. Etheory did his like this and it helped me out a lot when i built my unit. I didn't do quads so I'm interested to hear your results

 

[daal]

Yes thanks !!

I just finished my build, all voltages are good. Only visible problem (didn't plug audio yet) is that the SC switch won't light up when engaged... Any idea of where I should look ? Wiring from switch to main board looks ok.

EDIT : it's okay, was only a bad connection in the connector (did not screw it all to the bottom on a wire ... Will continue the testing / calibrating

My next issue is as follow :
- First I want to be sure to understand which mode SSL mode is. In order to see something at TP11 / TP12 I had to have th Internal Sidechain released and the EXT In switch in EXT In position
- If this is right I have an issue. I was able to make TP8 and TP11 the same value, but when adjusting TP12 / VR7, I am on the maximum value of the trim pot before obtaining the same value as TP10 ...

Any idea ? I guess the two channels should have the same readings, as they have the same construction. Will check if I see something wrong !

 

[daal]

I finally did go to sleep, leaving this as is, because it was 3AM and I wake up at 7AM

More information on my case :
- On the PSU board, I had to move the trim pots to obtain 15V, originally was more like 12V (even pre trimmed at 1K33).
- Other than that, all -+12/15 are correct / stable
- Power Led lights up
- SIFAM Meter lights up, and needle seems to give some response to some events (turning on / off), but won't move when audio passing, even with some compression settings. As it's not calibrated, I assume it's no big deal.
- Bargraph meter never lights up (not calibrated either).
- The two channels pass audio.
- Control board pots seem to have some impact on sound as I can ear different levels of compression when playing with them. Haven't tested them all extensively or unit by unit though.
- In / Ext In switches might be reversed in my case ? Have to go to Ext In position to see "SSL Mode" voltages at TP10.
- Step 2 seems OK except I still got some distortion. Is this normal ? Also I assumed I have to be with threshold all the way to the right (+20), and gain all the way to the left (+0).
- On step 3, with a 1kHz tone going in (average level, not too hot) I got 1.46 on TP8 and 1.45 on TP10. I was able to obtain correct value on TP11, but on TP12 I can only go up to 1.21 with the trim pot to the max.

That's where I'm stuck. I didn't manage to find incorrect values on resistors for now but I'll keep looking, and tonight I'll try to follow the path to see if I see something, but as audio passes I don't know if I'll see something special ?

Here is an Hi-Res (More Hi-Size than Hi-Res ...) picture (in the link, don't want to slow down the forum too much) of the main board (nothing is connected on the pic but everything was wired good).

http://imageshack.us/f/845/mainboardhires.jpg/

For those interested I'll update my blog right now with the last steps of the build (and troubleshooting ).

EDIT : I've verified my Ext In Switch and for me it's correctly wired (See in attachment). I got black on center pin, and to Common, and Red on the bottom pin to N/O on the board. But I see voltages on TP11 / TP12 only when the switch is in bottom position (so normally connected to the center and top pin which is empty ... no ??)

Also it seems like I got my ribbon cable wired backward ? Yep , it definately is backward. Will have to fix this first and restart calibration...

 

[wave]

If the ext in switch is down toward the words ext in then it's right.

Dave

 

[sr1200]

If that ext switch is a TOP DOWN pic... the switch when in the UP position  it is taking the EXT IN (down would be off). 
What kind of audio connectors are you using? (i only ask b/c i made a stupid mistake on one of mine that i used TRS connectors on)
The ribbon cable being backwards would screw EVERYTHING up... do that first... Also with calibration, make sure you go back after each step and make sure you still have unity gain.  For some reason my second unit decided to get out of whack with unity after a couple of calibration steps... once i reset to unity, everything calibrated nicely.