Sontec Opamp replacements

[jarvis]

Heya,
I just found out that Joe over at JLM-Audio is now selling drop in replacements for the HS-2000/HS-2030 and, according to a picture he posted on instagram, he is also working on HS-6000 replacements with both the Sontec and 2520 footprint in one board. 
Just thought that might be of interest for some of you guys.  I sure find the idea of a pretty close to the original 430c clone kind of appealing. 

Best
Jannis

 

[boji]

+1 on that. Want his oldschool transistor matching scope!

 

[jensenmann]

How would you replace a HS6000? It´s a part of the main PCB of the MES432.

Other than that I´m wondering what transistors Joe´s using. The original ones are all sanded off, no information available at all. Maybe his replacement is just a DOA that fits mechanically but with different specs than originally. 600V/us slewrate is not that easy to achieve with discrete parts, let alone low noise and high gainbandwidth. Using an adapterboard with a fast chip opamp might be the easiest way to get close to the performance of the original DOAs. LT1357 looks good on paper except max. supply voltage.

 

[JohnRoberts]

How would you replace a HS6000? It´s a part of the main PCB of the MES432.

Other than that I´m wondering what transistors Joe´s using. The original ones are all sanded off, no information available at all. Maybe his replacement is just a DOA that fits mechanically but with different specs than originally. 600V/us slewrate is not that easy to achieve with discrete parts, let alone low noise and high gainbandwidth. Using an adapterboard with a fast chip opamp might be the easiest way to get close to the performance of the original DOAs. LT1357 looks good on paper except max. supply voltage.

600V/uSec?  I thought that fad ended in the 80s...

JR

 

[jarvis]

How would you replace a HS6000? It´s a part of the main PCB of the MES432.

That's true actually. Maybe the 462s  or the newer 250s revisions have them on seperate boards? Joe didn't mention the 432 in his post where he showed the boards, I just thought about it, since there is a schematic of that thing floating around.

Best
Jannis

 

[ruairioflaherty]

Other than that I´m wondering what transistors Joe´s using. The original ones are all sanded off, no information available at all. Maybe his replacement is just a DOA that fits mechanically but with different specs than originally. 600V/us slewrate is not that easy to achieve with discrete parts, let alone low noise and high gainbandwidth. Using an adapterboard with a fast chip opamp might be the easiest way to get close to the performance of the original DOAs. LT1357 looks good on paper except max. supply voltage.

From what I've seen and heard Joe has put a lot of effort into getting this right.  Burgess has been sloppy with his sanding over the years and if you have enough units you can piece together the info on what transistors were used.  I know of at least two people who've done that.  There's also other breadcrumbs out there if you know who to ask and where to look.

 

[ppa]

How would you replace a HS6000? It´s a part of the main PCB of the MES432.

Other than that I´m wondering what transistors Joe´s using. The original ones are all sanded off, no information available at all. Maybe his replacement is just a DOA that fits mechanically but with different specs than originally. 600V/us slewrate is not that easy to achieve with discrete parts, let alone low noise and high gainbandwidth. Using an adapterboard with a fast chip opamp might be the easiest way to get close to the performance of the original DOAs. LT1357 looks good on paper except max. supply voltage.

BTW my APP992 has 75V/uS of Slewrate, 1nV/rt Hz of voltage noise, 40 Mhz of unity gain BW.
Some my customers said me that their sontec 250 clones with APP992's inside sound very closed to the original ones.
But if they use different classic audio opamps (so with much less Slewrate and BW and higher noise than APP992) their clones are not so closed to the original ones. At this point maybe there is something in the sound that is really related to these features.
Even if active filters for audio (so many eqs as Sontec ones) need op amps enough fast but theorically not necessarily very fast, and, moreover, very quiet as Sontec and APP992 DOA's.
BTW I don't know the Sontec DOA's topology, but I suppose that they are different than mine, so is not the topology that plays the main role here.