[BUILD] SSL 9K2

[Spencerleehorton]

Hi Guys,

where are these boards available from?

regards

Spence.

 

[tomas1808]

Hi,

I built my first of four. Having problems with the TL072.

If I leave the chip out the pre passes audio perfectly with loads of gain. Crackly pot though (due to the lack of DC Servo I believe).

When I put the TL072 the audio becomes very crackly and distorted, with a hi freq oscillation. Can barely hear my voice with the mic.

I did all of the corrections (trace cuts, jumpers, etc) except for the bypass caps in the 5534s, I did put one on the TL072 with no noticeable change. 

I am powering this with 18V bipolar, cant see this being a problem as all chips are able to handle the voltage.

Any ideas? Also, is there a chart with the correct voltages for the SSL 9K somewhere?

Thanks!!

 

[3nity]

good luck mine are still working intermittently
no support either

 

[tomas1808]

Yes. However I cant complain because I knew I was buying defective boards!

I am confident I will make them work though. I mean this is almost the exact same circuit as Bruno's 9K5 which seems to be working correctly.

Anyone has a 100% working SSL9K2?

Thanks!

 

[3nity]

You say without IC31 pot becomes scratchy but mine dont...it works as it should

 

[tomas1808]

Thanks, I thought the scratchy pot was because of the missing TL072.

 

[3nity]

What you mean defective boards?
the only defect were some traces to cut and jump.
other than that they were supposed to work as it should!
Thanks.

 

[tomas1808]

You have a point there.

However, there is the possibility that they are actually good and we just built them wrong.

That is why I asked if anyone got one working correctly.

We will see.

 

[3nity]

i built 4 and none is working correctly..and not a lot built them!

 

[tomas1808]

Well, that sucks :-\

 

[tomas1808]

3nity and everyone building this:

Just found what is hopefully the last mistake in this board.

C93 and C94 are wired incorrectly. Compare the schematics with Keith's.

My 9K2 seems to be working correctly now. I'll do some measurements later.

Hope this helps!

 

[3nity]

Wow!
Yeah! thats a nice little finding!
I tried looking at the schematics but couldnt find anything!

Gotta try this later!

 

[gemini86]

Hey guys,

Just wanted to jump in and let you all know I am not abandoning this!

I understand the frustration in things not working as they should. 3nity, I didn't realize you were still having ongoing problems, really sorry to leave you high and dry. I've been overworked the last few weeks, but I'm going to make some time this week to get to some projects, this is first on my list.

Tomas, good find, I'll have to review your findings and make corrections to my files. Sometimes a fresh pair of eyes really goes a long way. (and what impressive eyes they are)

If I don't post again by wednesday in this thread, please send me a message or post here! As of now, it seems that the problem has been found, but I haven't the time to take a close look until later.

 

[3nity]

No worries Rodney!
So far im very satisfied on hows it going
I have to try that last finding!
Good luck!

 

[tomas1808]

Absolutely, no need to worry.

I really needed some small format 9K boards so this layout is godsend to me, with or without errors.

Thanks for the boards Rodney!

 

[3nity]

I cut the trace coming from C93-c94 to R119 and jumper it C93-C94 to Pin 2 IC31....no sound.
Weird.

What has been you experience Tomas?
Thanks.

 

[tomas1808]

Did you cut the correct trace?

You can only cut at the straight line shown in the pic, otherwise there will be no sound!

 

[gemini86]

http://imgur.com/a/Tl2C8

I hope any of this makes sense, sorry for the crude drawing.

It sounds like you accidentally cut the feedback loop around U24.

 

[tomas1808]

Wow, I think its clear now  ;D

 

[3nity]

Alright it works like a champ!
Thanks Tomas! i made a mistake and cut at the wrong spot!
Its all good now!

Im really happy!

Good luck!