Whoops

Re: SSL 9K Mic Pre
« Reply #680 on: January 14, 2017, 09:55:26 PM »
More info from an old website:


SSL9K Mic Pre-Amp

The SSL9k (aka "DIY9k") preamp is based on the channelstrip of the SSL 9000 mixing console. Andy Millar was one of the designers of this desk, as well as Keith aka SSLtech from the GroupDIY forum. Some interesting background info on the SSL pre can be found here.
The DIY9k has become a very popular first-time build, as the parts aren't too difficult or expensive to source, and the lack of high voltage tubes makes it somewhat harder to kill yourself in the process (albeit not impossible - so please adhere to safety standards as outlined elsewhere). Another reason why people like this project, is that Gustav is selling a magnificent set of ready-to-solder PCBs in his thread on the 'white market'. To go along with these PCBs you should download this pdf, which contains BOMs and valuable info regarding component placement. I updated the BOM for the mainboard with a few correction it can be found here
Building Blocks

The DIY9k package consists of 3 PCBs. The big one is the mic preamp itself and features a balanced input for the mic signal. The output is unbalanced and is usually connected to the balancing board (included). If you are running an unbalanced system, this step is not required. Each balancing board can house 2 balancing chips and serve 2 channels. The third element is the PSU board. You only need one PSU board for a multichannel build. However, the number of channels is limited by the ratings of the power transformer, and eventually the voltage regulators. If you decide to build a second PSU for +/- 15 Volts, you will need to use an extra PSU board. Balancing boards are available separately from Gustav, if the ones included with the preamp boards are not enough.
Decisions, Decisions....

There are a few things that need to be decided before ordering parts and pcbs:
How many channels?
This will determine the type of Power Transformer needed. I am going to quote a post from PRR dealing with this:
you are looking at about 55mA or 1.7 Watts per channel. 2 channels? 110mA or 3.4 Watts.
(If a transformer is) 7.5VA per winding, which to me means it should be able to supply 416mA per winding.
0.416A AC. Safe DC current is about half that, say 200mA.
So right here, we see the transformer is working a hair over half its rating.
The regulators DO "burn" the difference between the raw 18V*1.414= 25VDC and the 15VDC output. 25V-15V= 10V, 10V times 110mA is 1.1 Watts in each regulator."


FWIW, I measured a current up to 65mA on a channel, but this was with the gain right up and overdriving the channel well into distortion (i.e. not a realistic scenario), but it's worth noting that 55mA is the current under normal operating conditions.
What type of Enclosure?
You will need to decide how many channels you want to fit into each enclosure and what kind of front panel you want for your machine. You can either buy a pre-drilled case for your particular project (although I am not aware of any specific DIY9k cases, there are a few universal mic pre cases around), or you can buy a blank case and do the drilling yourself. Either way you will need to make some fairly big holes for XLR plugs (24mm Diameter) in the back plane which requires specialist equipment. If you want to house the power transformer inside your mic pre enclosure you have to make sure it will actually fit in!
Pad, Phase, Phantom Power?
If you are planning to use the DIY9k to record anything loud (guitar amps, drums including overheads, etc) you will need a pad, because the DIY9k is still fairly sensitive on its lowest gain setting
If you want to use Condenser Mics, you will need to supply (most of) them with 48 Volt Phantom Power. The 48 Volt rail is included in the standard build, however, the switching arrangement is not. Neither are the components to light up an LED to indicate presence of Phantom Power.
A Phase Reverse Switch is obligatory in any multi-mic setup to deal with phase cancellations. The only situation were you could skimp on this is a one channel setup. So called "universal input" schematics are available, I quite like the one by jensen. Alternatively you could treat yourself to the very popular JLM go-between kit (and add a D.I. if you like, now or later)
Issues and Snags:

Every project has it's little difficulties - like hard-to-get components or cumbersome workarounds - and the DIY9k is no different. This chapter deals with the most likely problems you'll incur and solutions people have found.
Power Supply:
The Problem:
One of the DIY9k's peculiarities is the necessity of two dual power rails, at +/-18 Volt and +/-15 Volt respectively. This is due to the two models of opamps used: The 5532 (which needs +/-18V) and the TL052 (which needs +/-15V). The TL052's maximum voltage rating is actually 18 Volt, but actually running it at this voltage would not allow for any variations in the power supply and put this chip at risk. The 5532s could be run at 15 Volts, but this is said to result in less headroom being available.
The Solution(s):
1. The Diode Voltage Drop
Here a few diodes (usually 1n914 or 1n4148) are used to drop the 18 Volt supply to a voltage palatable for the TL052. The Voltage drop across these diodes is about 0.7V, so with 3 in series you would end up at about 16 Volts, which is safe enough for the TL052. It is important to remember that you need to do this twice, once each for the positive and negative rail.
(+18V hole) ------diode>l-----diode>l-----diode>l----- (+15V hole)

(-18V hole) ------l<diode-----l<diode----- l<diode----- (-15V hole)

2. The Dual Power Supply
Since Gustav is sending a PSU board with each preamp board, you already have two of them with a stereo set. By doubling up on a few components you can use the same transformer to run two PSUs with the required voltages (as well as the 48 Volts for phantom power). The second power supply is identical to the first, with the voltage regulators replaced by the respective 15 Volt models. Thus, the 7818 is replaced by a 7815 and the 7918 by a 7915 on the second board. Components that are related to the 48 Volt rail don't need to be placed again. !!!!!! LINK TO DIAGRAM TO FOLLOW!!!!!

3. Lower Voltage all over
This is pretty much the only option if you are planning to build the SSL9k into an API 500 series format, since only +/- 16 Volts are available on the standard 500 series cases. (NB: The 51x alliance is about to change this!) geoff004 seems to have good results with this approach.

Testing The Power Supply:
The Problem:
When testing the unloaded power supply with a meter, the -18 side reads -29 or so.
The Solution:
Test it with a load. Put a 1k resistor parallel to your test leads. The LM7918 has a tendency to overshoot when unloaded.

MAT-02 Transistor:
This one tends to be hard to get hold of. The LM394 is a good replacement.

Dual 2.5k rev-log pot:
Pretty much impossible to find. Closest alternative is a Dual 2.2k rev-log from audiomaintenance. The fact that it is a smaller resistance results in the minimum gain being higher (less gain range, see below in theory section). Another way around this, is to use switched resistors instead of a gain pot. Please refer to the modification section.

Offboard wiring with Gustav's pcbs
It might be a good idea to widen some of the pin holes on Gustav's boards using a 1-1.6mm drill.
This will help with the offboard wiring, especially when using stranded wire. On the PSU board, you will need to widen the holes for the bridge rectifier and the 1n400x diode, as these components won't fit otherwise. Best to get this done before populating the boards with anything.


Modifications and alternatives

Gain Switch instead of potentiometer:
The resistor values needed are discussed in great detail in this thread. Or you can try Harpo's Switch Step Calculator in Excel file format.

Matching Resistors for best CMRR:
To achieve the best CMRR performance, the following resistors should be matched as closely as possible:
R72 and R108, R75 and R110, R71 and R107, R73 and R109, R88 and R115, R81 and R117, R78 and R114

Balancing ICs
Popular replacements for the original SSM2142 are:
burr-browns DRV134 (which is a drop in replacement)
That corporations 1646 (you can replace the 51Ω Resistors and the 100uF Caps with a jumper and leave out the 10k Resistor when using this chip)


Whoops

Re: SSL 9K Mic Pre
« Reply #681 on: January 14, 2017, 10:00:53 PM »
some more info:

Scratchy Gain Pots
Note that matching the resistor pairs R105 & R69, and R109 & R73 is important to have the input section balanced and not have scratchiness when you turn the gain pot. I had the 1k resistors a few ohms apart and I could hear it on the gain pot. Fixed that and it is now very quiet.


POT
BUY 2,2K Rev LOG at:
http://www.audiomaintenance.com/acatalog/potentiometers_carbon_16mm_diameter_dual_gang.html




Re: SSL 9K Mic Pre
« Reply #682 on: February 14, 2017, 12:42:19 PM »
I know this thread is all but dead, but Neeno's pdf has since been removed. Does anybody have a current parts list? I've got PCB's, but other than that, I have NO idea where to start.

G-Sun

Re: SSL 9K Mic Pre
« Reply #683 on: February 14, 2017, 12:54:09 PM »
I know this thread is all but dead, but Neeno's pdf has since been removed. Does anybody have a current parts list? I've got PCB's, but other than that, I have NO idea where to start.
https://docs.google.com/spreadsheets/d/1m1jNXCboA8Tdixu3e11LmLTdjGkYykNJA3UcSU36Tw4/edit?usp=sharing
HJFP2, ssl9k, Harrison Ford Filters
My music

Whoops

Re: SSL 9K Mic Pre
« Reply #684 on: February 15, 2017, 08:03:32 PM »
I know this thread is all but dead, but Neeno's pdf has since been removed. Does anybody have a current parts list? I've got PCB's, but other than that, I have NO idea where to start.

No it's not,
I've posted it on page 34 in this thread.

Your starting point is reading the thread. Then you go from there

Whoops

Re: SSL 9K Mic Pre
« Reply #685 on: January 31, 2018, 01:46:16 PM »
someone asked me this file

Stepped Gain Switching for the SSL 9K


aviel

Re: SSL 9K Mic Pre
« Reply #686 on: March 04, 2018, 02:47:32 AM »
Hey Guys,
completely new here, i though i will start with the ssl 9k (my first big diy project).
can someone post a link to gustav website with pcbs? i searched for it here and in google and couldnt find.

Thanks!

TillM

Re: SSL 9K Mic Pre
« Reply #687 on: March 04, 2018, 01:59:20 PM »
Hey Guys,
completely new here, i though i will start with the ssl 9k (my first big diy project).
can someone post a link to gustav website with pcbs? i searched for it here and in google and couldnt find.

Thanks!

https://pcbgrinder.com/SSL-9000-9K

here you get the PCB.
But these are for API 500 series.

bernatvm

Re: SSL 9K Mic Pre
« Reply #688 on: January 03, 2020, 12:22:33 PM »
Hi guys!

Just finished soldering two channels and have some strange behaviour on booth. To be clear they're not mounted in a chasis yet, but over my bench.

I got a lot of hiss when I connect a microphone cable. If I connect the mic directly to the pcb (have a small connector soldered there) the hiss is quiter and I'll say ok to be used.

Another thing that happens is that i get distortion if the gain is low, like half quarter of the pot or so. Before you ask I'm using Audio Mantenance Pots.

EDIT: Resoldering the same pot seems to have resolved the distortion problem.
« Last Edit: January 03, 2020, 02:31:37 PM by bernatvm »

Whoops

Re: SSL 9K Mic Pre
« Reply #689 on: January 03, 2020, 08:56:00 PM »
Just finished soldering two channels and have some strange behaviour on booth.

Hi,
if you have the same problem on both it probably means you did the same mistake on both of them.

Measure voltages in all opamps. What voltages do you have at Opamp pins?

Print the schematic, and start to recheck all the components and connections and mark the checked parts in the schematic with an highlighting marker pen.
Start with all the resistors, check all resistor values, sometimes is easy to make a mistake like using 68k instead of 68r. Check all resistors

Check all caps values

Check all electrolytic caps orientations

Check all Opamps orientations and pin outs

Check Transistor positioning


Re: SSL 9K Mic Pre
« Reply #690 on: January 31, 2020, 03:35:33 PM »
hello

a friend just gave me 10 SSL 9K 51X ver 4,2 pcb's...By BRUNO 2000

I m looking at the  list of components i would like to make one by myself ....thx for your reply

Antoine





Hi guys!

Just finished soldering two channels and have some strange behaviour on booth. To be clear they're not mounted in a chasis yet, but over my bench.

I got a lot of hiss when I connect a microphone cable. If I connect the mic directly to the pcb (have a small connector soldered there) the hiss is quiter and I'll say ok to be used.

Another thing that happens is that i get distortion if the gain is low, like half quarter of the pot or so. Before you ask I'm using Audio Mantenance Pots.

EDIT: Resoldering the same pot seems to have resolved the distortion problem.

Ricardus

Re: SSL 9K Mic Pre
« Reply #691 on: January 31, 2020, 04:53:50 PM »
hello

a friend just gave me 10 SSL 9K 51X ver 4,2 pcb's...By BRUNO 2000

I m looking at the  list of components i would like to make one by myself ....thx for your reply

Antoine

 Wow. Weird. I just bought 10 myself!   :)
Audio mastering for hire..

Whoops

Re: SSL 9K Mic Pre
« Reply #692 on: January 31, 2020, 08:49:11 PM »
hello
a friend just gave me 10 SSL 9K 51X ver 4,2 pcb's...By BRUNO 2000

Hello Antoine,
welcome to the forum, I'm sure you will have a great time around here, and that you will have fun and learn a lot.

Before posting please take some time and read the forum rules first, they are the basis for this community:

https://groupdiy.com/index.php?topic=6650.0

Pay special attention to Rule number 4 and 6, as most of new members around will fail in one of those 2:

4. You will find that the members of this community are incredibly courteous and respectful of each other, so please reciprocate those gestures. Leave the Flame-war mentality at another forum.  Personal attacks as well as general hateful comments (regarding race, religion, gender, sex, etc...) will not be tolerated.

6. Use the search function (thoroughly) before posting.  It is quite possible your question may have already been answered by knowledgeable members that have been generous with their time.  A tremendous wealth of knowledge is actively updated and compiled in the "Meta" threads--take advantage of them.


_______

you are in the wrong project thread, this thread is for the older SSL 9K pcbs  pcb designed by SSL Tech and pcb's were sold by Gustav.

The boards you have are API 500 series format, the project was called SSL 9K5, go to the proper project page here:

https://groupdiy.com/index.php?topic=42552.0

mr_dot

Re: SSL 9K Mic Pre
« Reply #693 on: February 23, 2020, 05:28:37 PM »
hello everyone,
I'm having an issue with an ssl 9k preamp clone and I'm hoping you could help me.

first, I'm  looking for a schematic, can't find it anywhere anymore

second, maybe you know what can be a problem. it's a four channel clone and yesterday I discovered  that all the channels differ in gain, second is more quiet  then the first and third and forth have even less gain. I will do additional tests in the next two days, I didn't have a lot of time.

I'm trying to find somebody who is willing to look at it in my town (Belgrade, Serbia)  but it's not easy because people won't take DIY stuff for repair, and me not having the schematic does not help. it is a very clean and neat clone, I know a guy how build it (he's not able to help me, and I'm waiting for him to check if he has the schematic), and it worked great until couple of days ago.

thank you :)

Whoops

Re: SSL 9K Mic Pre
« Reply #694 on: February 23, 2020, 05:53:58 PM »
first, I'm  looking for a schematic, can't find it anywhere anymore

Original documentation for this projects attached (with schematics and BOM)

Whoops

Re: SSL 9K Mic Pre
« Reply #695 on: February 23, 2020, 05:55:59 PM »
second, maybe you know what can be a problem. it's a four channel clone and yesterday I discovered  that all the channels differ in gain, second is more quiet  then the first and third and forth have even less gain. I will do additional tests in the next two days, I didn't have a lot of time.

So you build it, now it's troubleshooting time:

Measure voltages in all opamps. What voltages do you have at Opamp pins?

Print the schematic, and start to recheck all the components and connections and mark the checked parts in the schematic with an highlighting marker pen.
Start with all the resistors, check all resistor values, sometimes is easy to make a mistake like using 68k instead of 68r. Check all resistors

Check all caps values

Check all electrolytic caps orientations

Check all Opamps orientations and pin outs

Check Transistor positioning


 

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