500 series Sontec / GML type eq

[abbey road d enfer]

By that logic, Sontec and Mackie EQs sound the same…which they do not.

Probably because they have different Q, and the Mackie implementation is not as thorough as GML's.

Getting a “transparent” IC-based EQ to sound really good is no simple feat.

It is within grasp of a decent esigner, provided he has no interference from bean-counters and/or mktg dept.

There’s a reason why people like Sontec and Massenberg EQs but pan similar EQs from Yamaha, Allen & Heath, Mackie, Soundcraft, etc.

Certainly, but it's not the EQ design that makes the difference, it's the surroundings. There may be also dubious choices of frequency range or BW.

 

[Quantum J Audio]

Can we move this debate to another thread please, It's irrelevant to the 250 build project.

 

[abbey road d enfer]

It's irrelevant to the 250 build project.

Is it?

 

[Gold]

The Sontec/GML EQ is a bridged T filter. The Mackie and most of the others are SVF. That might have something to do with it.

 

[abbey road d enfer]

The Sontec/GML EQ is a bridged T filter. The Mackie and most of the others are SVF. That might have something to do with it.

The response of a bridged-T EQ and a SVF EQ, (or a Wien-bridge EQ) can be made strictly identical. They're all biquads.
Any difference can be chalked to designer choices and/or implementation.
An EQ with poor rail decoupling or grounding will sound noticeably different than one that doesn't lack in this respect. Rail voltage and choice of opamps are also part of these differences.
Inductor-based EQ's may produce differences (although their theoretical responses can be identical; these differences would be due to the non-linear nature od real inductors (they vary with frequency and amplitude).

 

[Gold]

The response of a bridged-T EQ and a SVF EQ, (or a Wien-bridge EQ) can be made strictly identical. They're all biquads.
Any difference can be chalked to designer choices and/or implementation.

Implementation is everything. Especially to the end user, who doesn't care what topology it is. Only that is does what is asked of it while sounding good.

Different topologies are better at certain things. It would be hard to design a Wein Bridge EQ that could have continuously variable bandwidth like an SVF. Academically I'm sure you could get them the same. Practically the topology influences other choices which influence other choices. Implementation which greatly influences the end result.

 

[abbey road d enfer]

It would be hard to design a Wein Bridge EQ that could have continuously variable bandwidth like an SVF.

Not difficult at all. It's been done quite often.

Practically the topology influences other choices which influence other choices. Implementation which greatly influences the end result.

Certainly. There is a reason why some swear by Neve EQ's, when their shortcomings are obvious.

 

[Quantum J Audio]

In the interest of keeping this thread on track to the 250 build project. Here is a nice video from forum member @shoetique going over his thoughts on the build and operation of the unit. Full kits now available to pre order in the white market