SSL 9000 - Mic Preamp

[TobWen]

Hi there,

I want to build several MIC-preamps to test, what sounds best.

On a website, I have found the schematic of the SSL-9000 MIC-section.

Can I make it even better or is it at its best?

Is it possible to connect phantom-power (48V) to it?

Why does it have 2 potentiometers?

Here it is:


Best Regards,
Tobias

[li_gangyi]

check this page out...sjows how to add a phantom power supply to any mixer...

http://sound.westhost.com/project96.htm

[TobWen]

thanks! I hope, I won't blow everything :-))

what do you think about the SSL ?

[li_gangyi]

I gather i's rather complicate for a mic preamp... to replicate it u need a good layout and a fancy PCB. Try this one
http://sound.westhost.com/project66.htm
A PCB is available...and I gather the circuit is rather "standard" you could do with better Opamps of course...but I tried and didn't hear any difference. Might be because I use it for PA...

[TobWen]

the PCBs etc. are avai. for this schematics.

MMh ... the project66 you posted, seems as simple as a Behringer.

I think, I should go the SSL-way ... there must be some kind of sound in a 800.000 EUR console :-))

[li_gangyi]

can post a link to the PCB?? Thanks in advance...would like to try out a few pres as well...

[haldor]

Originally posted by TobWen
the PCBs etc. are avai. for this schematics.

I think, I should go the SSL-way ... there must be some kind of sound in a 800.000 EUR console :-))

Please post a link to this website! I would love to build a pair of SSL mic preamps.

Phil

[moamps]

Originally posted by TobWen
On a website, I have found the schematic of the SSL-9000 MIC-section. Can I make it even better or is it at its best?

Hi,
for me, the best sounding mic preamp is discrete or tubed with step up transformer (1:10 to 20). NE5534 isn't the best opamp, and this SSL preamp IMO can't be .................

Is it possible to connect phantom-power (48V) to it?

Yes.

Why does it have 2 potentiometers?

This is dual pot for two stage gain control, IMO.

Regards

[MrTransistorm]

One of the first areas that a console designer will make compromises is in the mic preamp. Don't assume that since the console costs hundreds of arms and legs that the mic pres are top quality. This circuit may indeed sound really good, but it really is more complicated than it needs to be.

A few things that caught my eye (somebody tell me if my logic is flawed):

1. Discreet front ends are difficult to stabilize. Look at all of the fancy high frequency compensation required around the first stage! It might be wise to have some local NFB around the op amps. Board layout is critical. The power supply must be squeaky clean.

2. Why use two stages? Any improvement will be swamped by the added noise and distortion of having another pair of op amps in the chain. Also look at R114/R78: the bias current from the following inputs would generate excess noise in those high value resistors.

3. TWO servos? Only the second one is necessary. Both use first order filters: more noise. There are much better choices for low offset than TL op amps.

OK, I'm done picking things apart. You'd be surprised how well a standard three op amp instrumentaion design will work. Also, check out the Project R preamp published in Recording Magazine a couple years ago.

[bishopdante]

I am not too surprised that the SSL circuit is a bit convoluted. The reason why the SSLs were used as the industry standard top flight desk during the 1970s and early 80s was because they were fully recallable. That means eqs, fader levels, routing, dynamics, the whole lot. This was very rare at this time, and the competing fully recallable desks were even more expensive than an SSL. In actual fact from a sonic perspective they are a bit nasty sounding. The word is brittle or thin sounding. The other reason why they are an industry standard is that they have gating, compression and expansion on every channel. There is so much wire and components in an SSL that it has a measurable latency of around 200ms, which can cause phasing problems. Nobody in a studio would be caught dead using one of these desk's mic preamps, dynamics or eqs for recording a critical vocal or drum overhead. They would use some lovely Neve outboard.

Try to get the schematics for Neve 1081 pres, or Amec preamps. That is where the quality is at.