Graph

SSL9k almost finished(some trouble)
« on: May 05, 2012, 08:02:08 PM »
Hi :) i almost finish my third DIY project(1st, MS20 clone, second a Gyraf 9 preamp)

Here is a pic



I couldnt make lots of tests, as you see, its only working and a mess wire, i am making it a new pcb for front panel, so i can give it a pad, phase, phantom, variable filter, instrument/mic, led meter, and a new PSU, with 15v integrated and better filtering.

But i wanted to know something.

I bought, some chinese mat02 for 7u$s each. There would be any improvement using an lm394 or mat12?

And.. i want to add it a balanced output. Currently how much output impedance does the ssl9k have? Its not like it needs a transformer, it sounds great as it is but i want to try to add an aditional coloration to see what happens and have the option to use, transformer output and active balanced output(maybe a cheap oep, or a lundal or cinemag)

Thank you :) once i finish everything i will post the project finished
« Last Edit: May 06, 2012, 07:53:47 PM by Graph »


pucho812

Re: SSL9k almost finished
« Reply #1 on: May 06, 2012, 12:22:21 PM »
mat02 was discontinued and the mat12 is a drop in replacement.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

Graph

Re: SSL9k almost finished
« Reply #2 on: May 06, 2012, 06:07:37 PM »
mat02 was discontinued and the mat12 is a drop in replacement.

I know mat02 is discontinued long ago, and lm394 the same. there are still some lm394 in my country.

The problem is that these mat02 i bought they have the same logo and i dont know if they are really good. To my ears, in my focal monitors(cms40) they sound good enough, nice low end and very low noise.

I will try to make another with LM394 and see if they sound different and for balanced output, not every hardware has unbalanced input.

Thank you

Graph

Re: SSL9k almost finished(some trouble)
« Reply #3 on: May 06, 2012, 08:11:14 PM »
Testing and trouble:

First, i found 2 problems with my ssl:

1) when i touch the metallic omeg pot to add gain some kind of hiss noise, or higher 60hz harmoics noise is added, when i am not touching it noise is gone

2) when gain is 3/4 aprox. of the knob, it starts to oscillate. Anyway that amout of gain clip easily a SM58 in my focusrite without gain on it(so i guess its adding more gain that it should be). Maybe the problem is the omeg pot?(2k2 instead of 2k5, with the 27 and 39 resistor)

I add it phantom power (for some reason 44.2v). And condenser mics just works. But there is a random ground noise that fades in and fades out sometimes.

Possible problems:

a) i use 2 PSU with 2 different transformers. The PSU or the 18v and phantom, uses a handbuilt 220:18+18v, maybe it needs 220:20v+20v, and is generating ripple in the phantom power as there isnt enough voltage? The other PSU uses a single transformer 220:15v with a simple 7815 and 7915 regulators

Thanks if anybody can help me if the problem are the PSUs i will just make a new one

Graph

Re: SSL9k almost finished(some trouble)
« Reply #4 on: May 11, 2012, 12:39:30 AM »
Testing and trouble:

First, i found 2 problems with my ssl:

1) when i touch the metallic omeg pot to add gain some kind of hiss noise, or higher 60hz harmoics noise is added, when i am not touching it noise is gone

2) when gain is 3/4 aprox. of the knob, it starts to oscillate. Anyway that amout of gain clip easily a SM58 in my focusrite without gain on it(so i guess its adding more gain that it should be). Maybe the problem is the omeg pot?(2k2 instead of 2k5, with the 27 and 39 resistor)

I add it phantom power (for some reason 44.2v). And condenser mics just works. But there is a random ground noise that fades in and fades out sometimes.

Possible problems:

a) i use 2 PSU with 2 different transformers. The PSU or the 18v and phantom, uses a handbuilt 220:18+18v, maybe it needs 220:20v+20v, and is generating ripple in the phantom power as there isnt enough voltage? The other PSU uses a single transformer 220:15v with a simple 7815 and 7915 regulators

Thanks if anybody can help me if the problem are the PSUs i will just make a new one
Some problems solved

1. phantom power works right now(well 43.8v.. works out for most of the mics, with 20+20v transformr i bet it wil hit 48v). a track was damaged
2. oscillation problems solved.. bad solder.

The only "problem" is when i touch the metallic case of the omeg pot it adds noise... anyways housed in a rack that should never happen, so i guess there is nothing to worry about.

Could a simple balanced circuit with a ne5532 like the GSSL wil work out?(cant get ssm2142 in my country)

Thanks anyways :)

Harpo

Re: SSL9k almost finished(some trouble)
« Reply #5 on: May 11, 2012, 06:46:25 AM »
1. phantom power works right now(well 43.8v.. works out for most of the mics, with 20+20v transformr i bet it wil hit 48v). a track was damaged
Change R2 on psu pcb from 240R to 220R for +48VDC out if you have at least 51V raw DC in front of your voltage regulator.

Quote
Could a simple balanced circuit with a ne5532 like the GSSL wil work out?(cant get ssm2142 in my country)
SSM2142 could be substituted by DRV134 or THAT1646 that might be availiable in your country.
A balanced line driver -as shown in the GSSL- will behave different from prementioned chips.
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams

Graph

Re: SSL9k almost finished(some trouble)
« Reply #6 on: May 11, 2012, 10:54:06 PM »
1. phantom power works right now(well 43.8v.. works out for most of the mics, with 20+20v transformr i bet it wil hit 48v). a track was damaged
Change R2 on psu pcb from 240R to 220R for +48VDC out if you have at least 51V raw DC in front of your voltage regulator.

Quote
Could a simple balanced circuit with a ne5532 like the GSSL wil work out?(cant get ssm2142 in my country)
SSM2142 could be substituted by DRV134 or THAT1646 that might be availiable in your country.
A balanced line driver -as shown in the GSSL- will behave different from prementioned chips.

thanks i ill check the raw voltage,

None of them are avaible in mycountry either(Argentina), so i wil try ebay option instead.

Thanks harpo


 

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