Sontec Discrete Opamps options

[kogstudio]

Hi there,

I'm wondering if anyone has tried out different discrete opamps in their Sontec based EQs and what they recommend and why?
e.g.
JLM99V
Melcor 1731
J990
App992
Quad8 AM-10
Any other options recommended?
This is for the individual filter bands and also the input buffer and output amp.

And also the perceived differences in tone for DOA on individual filters vs output

Thanks

 

[alexg]

I'd like to hear some answers to !
Nobody ?

 

[Indecline]

Am-10's run off of +-28v, so they are not like typical +-16v 2520's

Honestly, I find discrete opamps all sound fairly similar. 990s are slightly cleaner, 2520s fairly round, 1731's slightly rolled off. Again, these are fairly small differences that I hear. You'll be happy with any of them

 

[ruairioflaherty]

It sounds boring to say but if you don't need the (usually) increased output drive capability of a discrete opamp then why use it in a circuit like this.  Sure the original Sontec uses a discrete in some models but that is because they couldn't but off the shelf opamps at the time to do what they want.

 

[kogstudio]

Has anyone ever done a proper shoot out between an actual Sontec and one of the clones?
If so, what did they find?

 

[peterc]

Some interesting opamp observations on this page:

http://www.electricalaudio.com/phpBB3/viewtopic.php?f=5&t=491&start=60

Its a blog so try searching for 'Sontec' and it will go from post to post.

Peter

 

[Ben F]

Has anyone ever done a proper shoot out between an actual Sontec and one of the clones?
If so, what did they find?

I found that the sound of the Sontec is the HS-1000.  Otherwise it sounds cleaner more like GML. 

 

[dogma]

I believe people have subbed out Hs1000 for PPA's opamps. Hes on the white pages - I think its the APP992? JLM makes adaptors and I think may stock replacements..

 

[jensenmann]

Has anyone ever done a proper shoot out between an actual Sontec and one of the clones?
If so, what did they find?

I´ve had my Igor-Sontec (with OPA2604s) sitting next to original Sontec 250c, 462 and 432. I found the original ones to sound better. In fact I´m going to get rid of all those OPA2604s in my clone and replace them with something else - which still has to be determined what it´s going to be....

JLM audio used to offer a replacement for the original HS-something opamp. Dunno if they still do....

Since I´m servicing gear for two mastering studios in my area I frequently have Sontecs on my bench. 250s tend to break a lot and  build quality is a joke. The original DOAs almost always have defective tantals, btw.

 

[kogstudio]

I´ve had my Igor-Sontec (with OPA2604s) sitting next to original Sontec 250c, 462 and 432. I found the original ones to sound better. In fact I´m going to get rid of all those OPA2604s in my clone and replace them with something else - which still has to be determined what it´s going to be....

Thanks,
Can I ask 2 questions?
1 - How much difference do you hear between the 250 series and 462 or 432?

2 - What are the differences (better wise) between the Igor Sontec and real ones (eg better top end etc). Is it much of a difference or is it subtle?

 

[jensenmann]

My mastering buddies were both not thrilled with the Igor Sontec. The 432 and 462 both sounded cleaner, more pleasing and relaxter, while the original 250 is a lot softer and more musical in it´s main application (28kHz hi shelv). This may sound a bit discouraging for Igor-Sontec users but it is not. We´re talking mastering here, where the last % makes all the difference.
My Igor Sontec for itself is a great EQ and eats many "professional" products out there for breakfast. But to get it on the same level as the originals I have to redo a few things, like chips (thanks to ppa for his hint via pm), filter caps, etc.

 

[kogstudio]

My mastering buddies were both not thrilled with the Igor Sontec. The 432 and 462 both sounded cleaner, more pleasing and relaxter, while the original 250 is a lot softer and more musical in it´s main application (28kHz hi shelv). This may sound a bit discouraging for Igor-Sontec users but it is not. We´re talking mastering here, where the last % makes all the difference.

Was the Igor Sontec vs 432/462 comparison done on a blind test / ABX test? or was there the potential of confirmation bias?
[always interested... imprinting/damage from science background...]
Re opamps, from my tests so far.
I personally found that putting APP992 and Quad Eight opamps on the input and output stages made a slight improvement over 5534's (clearer, more definition and extension).  API2520 lost a little of the transient response in the upper mids up (subtle though) when on input/output but bass was nice (subtle improvement over 5534 for low end, perhaps not as good for highs).
Changing out 5534's for other DOA's on the filter boards made very little discernible difference.

 

[simonsez]

My mastering buddies were both not thrilled with the Igor Sontec. The 432 and 462 both sounded cleaner, more pleasing and relaxter, while the original 250 is a lot softer and more musical in it´s main application (28kHz hi shelv). This may sound a bit discouraging for Igor-Sontec users but it is not. We´re talking mastering here, where the last % makes all the difference.
My Igor Sontec for itself is a great EQ and eats many "professional" products out there for breakfast. But to get it on the same level as the originals I have to redo a few things, like chips (thanks to ppa for his hint via pm), filter caps, etc.

Igor sontec circuit is more like GML than 250, although they both similar.  We need a fast and strong character DOA to get more shine out of our sontec  build......

The new 250 put all discrete opamp on the filter board.

 

[ppa]

My mastering buddies were both not thrilled with the Igor Sontec. The 432 and 462 both sounded cleaner, more pleasing and relaxter, while the original 250 is a lot softer and more musical in it´s main application (28kHz hi shelv). This may sound a bit discouraging for Igor-Sontec users but it is not. We´re talking mastering here, where the last % makes all the difference.

Was the Igor Sontec vs 432/462 comparison done on a blind test / ABX test? or was there the potential of confirmation bias?
[always interested... imprinting/damage from science background...]
Re opamps, from my tests so far.
I personally found that putting APP992 and Quad Eight opamps on the input and output stages made a slight improvement over 5534's (clearer, more definition and extension).  API2520 lost a little of the transient response in the upper mids up (subtle though) when on input/output but bass was nice (subtle improvement over 5534 for low end, perhaps not as good for highs).
Changing out 5534's for other DOA's on the filter boards made very little discernible difference.

thanks for testing and comments, but i have just a note to add.
I remember you have bought from me two APP992's so I guess you have done this test with only these ones.

I known your result you have had, and for this reason I suggest to my customers to use four APP992's inside their Sontec eq.

The matter is that exclusively with four APP992's the main signal path is made with DOA's only.
With two DOA's the signal goes through  IC opamps too.
An audio chain sounds as its colored  stages, since a very transparent DOA cannot add nothing to sound but it limits itself to amplify the signal as it is, so  you listened pratically still the NE5534's.  ;D  ;D

 

[kogstudio]

thanks for testing and comments, but i have just a note to add.
I remember you have bought from me two APP992's so I guess you have done this test with only these ones.

I known your result you have had, and for this reason I suggest to my customers to use four APP992's inside their Sontec eq.

The matter is that exclusively with four APP992's the main signal path is made with DOA's only.
With two DOA's the signal goes through  IC opamps too.
An audio chain sounds as its colored  stages, since a very transparent DOA cannot add nothing to sound but it limits itself to amplify the signal as it is, so  you listened pratically still the NE5534's.  ;D  ;D

Hi there,
Yes, I wanted to avoid the 5534's, so I hard bypassed the filter boards in my test with the APP992 and Q8 opamps tests (ie only input and output stage had signal running through it, so all NE5534's were out of the circuit ).
I am also happy to send you the test files if that is of interest to you? APP vs Quad8 vs JLM99V

While you are here, do you think a germanium opamp would lend useful characteristics to one of these EQs? (you used to make one in the past yes?)
Or are there any other alternate coloration options that could be chosen coloration wise?

 

[ppa]

In this month I am developing a new germanium opamp that can be used as a normal 2520 silicon DOA.
The previus one has too high bias input current.
I am waiting the  production boards to make other tests.
It can be used at dual 24V of power supply as at 16V too.

attached a photo of it 

 

[mitsos]

question for Igor Sontec users: 
Does the Igor "Sontec" use center-tapper pots like the original?  I've seen the Fabio PCBs and I think they use normal pots, from what I understand center-tapped pots are necessary for proper operation. 

 

[Biasrocks]

Does the Igor "Sontec" use center-tapper pots like the original?  I've seen the Fabio PCBs and I think they use normal pots, from what I understand center-tapped pots are necessary for proper operation.

Yes, center tapped. We put in a group order with the manufacturer for the correct pots.

As far as opamp choices go, you can make a dramatic change depending on your choice of IN/OUT opamps and in the filters too.

Read the build thread, lot's of good info there.

Mark

 

[OTRM]

Read the build thread, lot's of good info there.

Mark

Can anyone point me to this topic please?
Thnx
OTRM

 

[jensenmann]

https://groupdiy.com/index.php?topic=28215.0