Topic: Sonosax innards?

[shaggy]

Me and Marc (leegeddy) had a some time to chat/hang and see a little music when he was in Seattle.  One of the things he wanted to see was in the insides of a Sax as he is trying to replace the Analog Devices IC pre-amp chip in his Beyer MV-100 (SSM2017 > SSM 2019).   We wanted to resolve a long standing debate about the similarities between the Sax and the Beyer which we concluded were not as similar as once thought.  The chip was not accessible, the PC board that holds the gain pots and electronics is attached beyond the three screws (silver circles, see photo below) that hold it to supports to the bottom of the Sax.  We took a flashlight and peered inside after taking the knobs off the pots themselves.  I saw a chip where the SSM2017 should have been that said (three lines worth of print):

'PORTUGAL'
'TL072P' or it may have said 'TL872P'
AND something else I couldn't read

BWT: Sahara Hotnights 7-30-2004 Easy Street Records, Seattle DPA4061>MPS6010>Oade2modSBM>M1 (20min)

ANDY

[Lil Kim Jong-Il]

Does the Sonosax manual include the schematic?  If it does, I'd compare that to the one in the MV100 manual.  The board layout is neccessarily different to accomodate the gain pots and XLR outs.

[shaggy]

Marc had a good peer into it and said that where the SSM2017 chip should be, this other one was in it's place (8pin DIP, if I heard him correctly).  I do not have a schematic for the Sax, I bot it used and have a photocopy of the user-manual only.

[jk labs]

Me and Marc (leegeddy) had a some time to chat/hang and see a little music when he was in Seattle.  One of the things he wanted to see was in the insides of a Sax as he is trying to replace the Analog Devices IC pre-amp chip in his Beyer MV-100 (SSM2017 > SSM 2019).   We wanted to resolve a long standing debate about the similarities between the Sax and the Beyer which we concluded were not as similar as once thought.  The chip was not accessible, the PC board that holds the gain pots and electronics is attached beyond the three screws (silver circles, see photo below) that hold it to supports to the bottom of the Sax.  We took a flashlight and peered inside after taking the knobs off the pots themselves.  I saw a chip where the SSM2017 should have been that said (three lines worth of print):

'PORTUGAL'
'TL072P' or it may have said 'TL872P'
AND something else I couldn't read

BWT: Sahara Hotnights 7-30-2004 Easy Street Records, Seattle DPA4061>MPS6010>Oade2modSBM>M1 (20min)

ANDY

Andy,

I'm not sure with what you mean with "I saw a chip where the SSM2017 should have been" .. 
Care to elaborate?

The SSM chip is a one channel balanced (pre)amplifier while the TL072 is a dual op-amp.
They are not interchangeable.

Regards!
Jon

[shaggy]

Jon,

Marc just said where the SSM2017 should have been there was this TL072P chip.  This is when we realized it is completely different.  DO you know a better chip that can replace the TL072P chip?  From what I understand from a quick search, the TL072 design is 30 years old!

ANDY

[Todd R]

Marc just said where the SSM2017 should have been there was this TL072P chip.  This is when we realized it is completely different.  DO you know a better chip that can replace the TL072P chip?  From what I understand from a quick search, the TL072 design is 30 years old!

And from what I understand, the Oade m148 (or at least the guts of it that matter) was designed about 20 years ago.  Maybe the sax design could stand to be mod'd, but I wouldn't assume that on age alone.

Oh, fwiw, I always heard (at least from sources I trusted) that the sax and the mv100 were different, but I had heard the 'sax used discrete transistors.  Looks like that isn't the case.  Though if we used our ears, we always should have known they had different designs.

[Tim]

they don't sound anything alike at alll.

[cwfen]

You could also use the INA217AIP amplifier chip from TI/Burr Brown to replace the Analog Devices chip... check out the mod yer dmic thread in this section for more details... also some good discussions on the old Oade tech. archives...

[jk labs]

Jon,

Marc just said where the SSM2017 should have been there was this TL072P chip.  This is when we realized it is completely different.  DO you know a better chip that can replace the TL072P chip?  From what I understand from a quick search, the TL072 design is 30 years old!

ANDY

Andy,

1000s of postings on the net concerns themselves with issues related to replacing dual opamps and their "sound".  The TL072 is a dual voltage feedback opamp with JFET inputs. If it is in a critical position (especially input device responsible for gain) it's replacement must be considered carefully.

Along with power supply issues (and possibly signal coupling caps) this will very fast become a "warm, hard, precicion, lousy, poor, noisy, silent, ...... mod".

Among the more popular standard opamps are devices made by BurrBrown/TI, Analog Devices, Linear Tech, National, ON (Motorola), Philips (NE5532), Fairchild, TI, NJM .. the list is near endless.
THAT Corporation makes some specialized devices and Elantec (now Intersil) was one of the pioneers if memory serves, behind current feedback. 

See DouglasSelf for some interesting info on opamps (albeit his list is not complete nor updated)
http://www.dself.dsl.pipex.com/ampins/webbop/opamp.htm 

Of the JFET flavor any of these will fit the bill OPA2604, AD712, AD8512...
But again, finding the optimum device requires detailed knowledge of the circuit, application as well as
experimentation and listening test.

Best of luck
Jon

[BobW]

SoundLabs, out of Oz, has Caps and ICs and pure silver wire with cotton dielectric, etc. 
An experimenter's paridise, for those who are willing to tinker with their expensive toys.
Don't "Humpty-Dumpty" a 'Sax   

BTW, if anyone knows of any US-based high-end / eclectic audio or component dealers, please PM me.

+T and thanks for the info JKLabs

[shaggy]

I never said they sounded the same.  There was this long standing argument that the op amp was the same chip.  I just thought a quick look/see would resolve the issue.  I have no intention of replacing the Sax's op amp chip.  Just trying to be the helpful ts.com-er!

Peas,

ANDY

[Lil Kim Jong-Il]

BTW, if anyone knows of any US-based high-end / eclectic audio or component dealers, please PM me.

http://www.percyaudio.com/


http://www.partsconnexion.com/ 


http://www.welbornelabs.com/parts.htm

[Tim]

I never said they sounded the same.  There was this long standing argument that the op amp was the same chip.  I just thought a quick look/see would resolve the issue.  I have no intention of replacing the Sax's op amp chip.  Just trying to be the helpful ts.com-er!

Peas,

ANDY

I know YOU didn't, I just hear all the time people say that the two boxes are the "same" and clearly they are not.

[BobW]

BTW, if anyone knows of any US-based high-end / eclectic audio or component dealers, please PM me.

http://www.percyaudio.com/
http://www.partsconnexion.com/ 
http://www.welbornelabs.com/parts.htm

+T and thanks !