SSL 9K & 4K (E Series) 500 / 51X NEW BOARDS Mic Pre Thread 2011

[TillM]

If you used the correct Pot for gain I don't believe it's the gain pot, it's probably something in the circuit that is wrong.
It could be a lot of different things impossible to know at a distance.

Before anything you should:
-Check all Electrolytic caps values and Correct placement.  They are polarized + and - are on the correct holes?
- Check all resistor values
- Check all capacitor values
- Check MAT02 placement, is the orientation correct
- Check all IC's Orientation
- Check all solder joints and check for possible solder bridges
- Measure the voltages across each IC and transistor Pins, do a voltage chart, show us

Do you have a friend with electronics knowledge that could help you?

Tomorrow I go to a friend.
He is electrician and also has a oscilloscope.
One thing came in my mind.
For the Second Build I use the Switches from the BOM.
For the First build I use Switches from my local Hardware shop.
They only have 20v. From the BOM they have 250v.
Maybe this is the fault.
Thanks for your help.

 

[Whoops]

They only have 20v. From the BOM they have 250v.

I really don't think the switchs voltage rating is the issue.
But I would change the 48V Phantom Power switch.

 

[TillM]

I really don't think the switchs voltage rating is the issue.
But I would change the 48V Phantom Power switch.

I've found the mistake.
The 2k2 Poti is broken.
I repaired it and do some solder work again.
Now, everything works perfect.
Thanks to everybody at groupdiy who helped me, esspecially Whoops!
Now i'm looking for new preamp projects 

 

[Whoops]

Happy you sorted it TillM,
wish you good fun in recording with it

 

[Whoops]

I'm looking to buy some 4K pcb's,
if anyone has some spare ones that could sell or will never finish his project just let me know

Thank you

 

[audiophreak]

Hello All,
                Looking to build two more of the SSL9k mic pres, and Gustav seems to only offer the 500 series , anyone know where I can get a couple of the older PCBs he used to sell ??


Thanks in advance 

 

[Whoops]

Hello All,
                Looking to build two more of the SSL9k mic pres, and Gustav seems to only offer the 500 series , anyone know where I can get a couple of the older PCBs he used to sell ??
Thanks in advance 

Hello Audiophreak, if you don't want to do the 500 series format it's fine you can still use the current pcb's, use them in the format you want.
At the present there isn't really any reason to do the 9K in the older pcb's, you don't have PAD, 48V, Or Phase, so you had to get a Go Between or something similar, also the POT is wired (more uneeded wires) there was no provision in the board for 15V to supply the TL052, so you had to improvise a voltage reduction. Also the Output was unbalanced so an extra balancing pcb and circuit was needed.

With the present 9k pcb with the 500 series format you have all that in 1 board.
If you don't need the variable highpass filter or the Led Meter you just do populate or bypass those parts on the board.

 

[audiophreak]

Thanks Whoops !!  what about the edge connector ?

 

[Whoops]

Thanks Whoops !!  what about the edge connector ?

I just solder the wires directly to the pads where the connector would go, it's a matter of personal preference as I always prefer to have soldered wires instead of connectors, it's one less thing that can contribute for intermittent connections.

But if you prefer to have the edge connector just buy it from Capi:

http://capi-gear.com/catalog/product_info.php?cPath=84_86&products_id=147

 

[audiophreak]

Aaahhh, I prefer a soldered connection as well , Thanks for the tips !!

 

[Whoops]

This was a great idea but was overshadowed but the 9K5:

https://groupdiy.com/index.php?topic=46784.0

 

[Whoops]

It's not my build I just found it in the forum

SSL 9K5 with Bo's DI:

 

[Scimitar]

Scratchy Gain Pot & Oscillation  (Resolved)

So, having finished two of the 9k5 modules, unfortunately, the one has the scratchy gain pot which then turns to oscillation when the gain is turned up past the 1 o'clock position. I have matched R105 & R69 as well as R109 & R73 as suggested in a thread elsewhere on this forum, to no avail.

Since the one module  is working perfectly, I do thankfully have a working reference. My next step is to compare voltages between the two since it has also been suggested that one of the causes of the scratchy pot issues is likely to be dc voltage offsets in the servo section, or gain control. (The Pot itself checks out fine and I have not been able to spot any misplaced components)

If anybody with similar issues has managed to resolve them, I would be very interested in what the root cause was.

Faults traced :-
- After quite a bit of hunting, the issue turned out to be poor contacts on the dual 2k2  gain pot - the solder terminals that are crimped to make contact with the pot tracks on the pot itself- I had to remove the pot and re-crimp all of the terminals with a pair of long-nose pliers.
- The oscillation on the one board turned out to be one of the transistors on the one side of the ssm2212 (MAT02 replacement) which had failed, I suspect as a result of the intermittent pot terminals. I had to replace the ssm2212.

 

[audiophreak]

This was a great idea but was overshadowed but the 9K5:

https://groupdiy.com/index.php?topic=46784.0

Thanks Whoops !!  Good read and info and those pix sparked some ideas ...    ;D

 

[justinheronmusic]

Is there a pretty big sonic difference between the 4k and the 9k? I'm still having a hard time pulling the trigger on the 9k. I would be using these as makeup gain for the DIYRE SB2 summing box. Thoughts?

 

[Whoops]

Is there a pretty big sonic difference between the 4k and the 9k?

The circuit is totally different, compare schematics.
4K is said to be more "grainy, dirtier, more rock n rool"
9K is said to be "Clean, a lot of headroom, Hifi sounding"
Those descriptions are not my words, but the best thing is for you to listen both.

I would be using these as makeup gain for the DIYRE SB2 summing box. Thoughts?

I have some thoughs, use other thing as the makeup gain.
SSL 9K has huge gain you don't need that for makeup gain in a summing mixer.
Better to use your 9K's as microphone amplifiers and something else for makeup in your summing, like for example just the output section of a Neve BA283 card

But in the end it's your choice, I'm just telling you my thoughts

 

[theokbird]

Hey there,

so i built up a 9k board awhile ago and finally got around to using it  ;D  after double checking my calibration for the HPF, which is solid, i'm hearing lots of static/white noise/ hash when i turn the gain pot up past 45 or so, it starts coming in around 30 but gets really really bad up at the top of the pot, which at first wasnt that crazy to me considering i'd likely never ever use that much gain but i also think maybe theres something wrong... i can certainly poke around the circuit and do some voltage measurements...does anyone have a suggestion of where to start or can offer some insight?  i dont have a scope, just tone generator and frequency analyzer in my DAW...

thanks!

 

[Whoops]

Use an audio probe

Inject signal at the input
Follow the schematic
Probe and listen before and after each component

 

[theokbird]

Thanks Whoops,

edit**

i've narrowed it down to IC23 and IC30, on pin 2 the signal is clean, on pin 5 the signal has all the noise i'm hearing. i'm using NE5534P for all ne5534 positions, so i swapped the IC's for the ones in 22/29 and it does the same thing, goes in clean, comes out with lots of noise as gainn increases, so i dont think its the individual IC's.  noise starts starts coming and increasing rapidly  from gain pot turned cw about 70% and beyond, so i'm wondering is this just the nature of this pre?  those are very high gain levels so i'd imagine it gets a little noisy at the top, but this noise seems extreme to me..

when probing i noticed the noise seems to be localized to gain pot and IC's associated with it, and the signal has noise from that point on from the schematic.

all voltages look good going to all IC's and the cap orientation and resistor value is good.  If anyone has a suggestion as to how to proceed i'd be super grateful!  I have access to a scope now, just not sure exactly where to use it to get the measurements i need

thank you thank you

 

[theokbird]

Anyone have a suggestion? I'm kinda stumped :-\