Sontec Mastering Eq (impossible to find)

[MattGray]

Originally Posted by phild

Thanks, Larry. I didn't know this - I love this kind of stuff.

I can see why some guys use the John Hall amps in the older broken Sontec's (a stock 430B is still my fav EQ of all time) but why swap out an API amp when they sound good and are in good supply?

Yes, even if there was such a thing as the 'best op amp' if you had it in every piece of gear there would be less distinction & character to separate them. Variety is the spice of life, too much of a good thing can be a bad thing

I'm still trying to decide whether my API 550 sounds better or just different since balancing the input with Lundahl transformers. The top end is smoother but the bottom is less focused & not as tight as the old unbalanced input. Depends on the track, now I'm thinking I'll put another mod in to have both options. First things first though, have to find me a good passive EQ... shoot out pending in the next couple of weeks. Got these units coming in for eval...

•*Buzz Audio REQ-2.2
•*Massive Passive
•*Mini Massive
•*SPL Pass EQ

Matt

[Silvertone]

Something of interesting note about the Buzz. When I asked Tim Farrant the designer of the Buzz Audio REQ 2.2 why he used resonance filters he replied, "Why resonance? well this pertains to the use of real chokes and capacitors as the filter elements. Filter circuits used in the GML or Sontec are "electronic" simulations of real inductors (or chokes) so you make a capacitor/resistor network "look like" a choke. These are easier to manipulate than real chokes. I wanted to make an EQ with the real thing!"

And it only took Tim 10 years to develop this EQ! Well worth the wait for me...

I must also add that with the ability to put a transformer inline and then vary the amount of saturation this puppy ends up being two EQ's in one... both very useful.

Congrats Doug, I hope the wire arrives without a problem.

[phild]

Originally Posted by MattGray

Yes, even if there was such a thing as the 'best op amp' if you had it in every piece of gear there would be less distinction & character to separate them. Variety is the spice of life, too much of a good thing can be a bad thing

I'm still trying to decide whether my API 550 sounds better or just different since balancing the input with Lundahl transformers. The top end is smoother but the bottom is less focused & not as tight as the old unbalanced input. Depends on the track, now I'm thinking I'll put another mod in to have both options. First things first though, have to find me a good passive EQ... shoot out pending in the next couple of weeks. Got these units coming in for eval...

•*Buzz Audio REQ-2.2
•*Massive Passive
•*Mini Massive
•*SPL Pass EQ

Matt

I won't be switching out the Api amps out of my unit anytime soon. I like it as is.
The 550 definitely sounds different after balancing the inputs! But i know quite a few folks who also prefer the unbalanced version. The transformer makes things too smooth maybe?

Why do you want a passive eq?

[Paul Gold]

Originally Posted by Silvertone

. Filter circuits used in the GML or Sontec are "electronic" simulations of real inductors (or chokes) so you make a capacitor/resistor network "look like" a choke.

This is called a "gyrator". Like most things in audio there are good arguments on both sides. The Buzz has little computers to control all the switching that needs to be done to make it behave like a modern full featured EQ. It's an impressive design. The only downside I see is that because of it's complexity you would need more than a Swiss Army knife to fix it.

[Silvertone]

Originally Posted by Paul Gold

This is called a "gyrator". Like most things in audio there are good arguments on both sides. The Buzz has little computers to control all the switching that needs to be done to make it behave like a modern full featured EQ. It's an impressive design. The only downside I see is that because of it's complexity you would need more than a Swiss Army knife to fix it.

Most switching is done via relays... cool to hear them switch out when you power off... just like my old Edyne console.

No downside as Tim made everything modular... Pretty much plug and play, so you might have to pull two "lockable" cable leads and pull a card out... IMO much easier than some designs I've seen.

You really have to hear this EQ... she has become the new "power lifter" here at Silvertone.

[MattGray]

Originally Posted by phild

I won't be switching out the Api amps out of my unit anytime soon. I like it as is.
The 550 definitely sounds different after balancing the inputs! But i know quite a few folks who also prefer the unbalanced version. The transformer makes things too smooth maybe?

Why do you want a passive eq?

I'm hearing you re: API... I am really fond of the 2520 opamp sound in both the 2500 & 550M's. you're perhaps right about the smoothness wish I had the transformer on the mid & high bands & no transformers on the lower bands. The next best option would be to add a switch to choose either option for when it's needed.

As for why a passive? Well I want an EQ with really smooth shelves... something that sounds completely different to the Sontec 432 or the API but still complimentary. Any other ideas?

Matt

[phild]

Originally Posted by MattGray

I'm hearing you re: API... I am really fond of the 2520 opamp sound in both the 2500 & 550M's. you're perhaps right about the smoothness wish I had the transformer on the mid & high bands & no transformers on the lower bands. The next best option would be to add a switch to choose either option for when it's needed.

As for why a passive? Well I want an EQ with really smooth shelves... something that sounds completely different to the Sontec 432 or the API but still complimentary. Any other ideas?

Matt

There are mods to make things better and mods to make things different. Looking back I could use the 550 in either state.

Sorry that I can't help with too many ideas about passive EQ's. Any EQ would be complimentary if you liked it? I do like the Focusrite Blue 315 in my setup (def. not passive). I used to own an MP for a few years - I could use one of those again if I had to. Good luck with it!

[Paul Gold]

Originally Posted by Silvertone

Most switching is done via relays...

From the pictures on the website it looks like the filter sections are switched in and out via relays. Within the filter sections the RCL combinations are switched with electronic switches controlled by the PIC's.

[ed littman]

Originally Posted by Paul Gold

From the pictures on the website it looks like the filter sections are switched in and out via relays. Within the filter sections the RCL combinations are switched with electronic switches controlled by the PIC's.

I'm getting one in this Thursday.
All the mixes are finally in for my album.
My record will be the 1st full project with this eq....very excited
Tis the season for a bbq....you brooklynites should pile into a van & come out for some fresh air
e

[dubrichie]

Originally Posted by Silvertone

Yes they will Phil. My friend Scott has swapped them out in a few components.

John Hall also designed all the Electrodyne A1000 & A2000 op-amps, some Quad Eight op-amps AM3 (along with a young Deane Jensen I believe) & AM4 and the Sphere op-amps (and mic pre-amps). John also designed the mic pre-amps in the Quantum Audio Lab consoles... all hail John Hall!

sorry for the OT, but i have a question.

i am considering buying an Audient ACS-8024 mixing console.

Audient offer a "modified" version with 990 opamps on the mix buss.

could i use the John Hall SPA-690 opamps instead?

are there any issues with pin compatibility / voltage requirements / etc.?

how can i buy these opamps?! any idea of cost?

many thanks,

all the best,

[StephenMarsh]

Steve Firlotte
Inward Connections
818-883-9012
Sfirlotte - at - socal - dot - rr - dot - com

I believe they are a direct swap for 990's too - check with Steve,

690's cost less than $100 each


--Steph

[dubrichie]

nice work man!

[Tim Farrant]

Originally Posted by Paul Gold

From the pictures on the website it looks like the filter sections are switched in and out via relays. Within the filter sections the RCL combinations are switched with electronic switches controlled by the PIC's.

Yes this is correct. We use a PIC to encode from a simple single pole 12 position switch the required code to control the CMOS switches that switch the EQ components. If we used a mechanical switch instead, it would be VERY costly and complex.

Because the audio level at which the CMOS devices are operating is quite low, the non-linearity of these devices is not an issue, and no measurable increase in distortion compared to a mechanical switch is noticed. I understand the Great River EQ also uses CMOS switching, if it's done right, it's not a problem!

Cheers
Tim.