Hi everybody.
In these days I'm checking a vintage piece of gear for a friend, an equalizer module that used to be part of a mixing console installed in the iconic Crystal Sound Studio. This facility opened in 1967 in Hollywood, CA, and housed a number of historical recordings such as many hits by Stevie Wonder, Weather Report and many other artists.
Andrew Berliner, the studio's sound engineer, built most of the equipment of the studio with a highest-quality, no-expenses-spared attitude. Then, in the late '80s the studio was bought by Roy Bittan, long-time keyboardist for Bruce Springsteen's E Street Band, who recently decided to auction most of the studio equipment.
This eq module I have here includes many high quality components such as many military-grade precision resistors, 10 Grayhill rotary switches (still working flawlessly after almost 50 years!), a proprietary API-style discrete op-amp and finally a fair number of ICs labelled 'NE535V', possibly made by Signetics.
I've never heard before about this chip: judging by the connections on the pcb, it's a classic single op-amp in a DIP8 case. I suspect it might be somehow considered as an early version of the classic NE5534, but actually I couldn't find any valid info on the net.
So here's my request: does anybody know something more about this mysterious vintage chip?
Thanks!
In these days I'm checking a vintage piece of gear for a friend, an equalizer module that used to be part of a mixing console installed in the iconic Crystal Sound Studio. This facility opened in 1967 in Hollywood, CA, and housed a number of historical recordings such as many hits by Stevie Wonder, Weather Report and many other artists.
Andrew Berliner, the studio's sound engineer, built most of the equipment of the studio with a highest-quality, no-expenses-spared attitude. Then, in the late '80s the studio was bought by Roy Bittan, long-time keyboardist for Bruce Springsteen's E Street Band, who recently decided to auction most of the studio equipment.
This eq module I have here includes many high quality components such as many military-grade precision resistors, 10 Grayhill rotary switches (still working flawlessly after almost 50 years!), a proprietary API-style discrete op-amp and finally a fair number of ICs labelled 'NE535V', possibly made by Signetics.
I've never heard before about this chip: judging by the connections on the pcb, it's a classic single op-amp in a DIP8 case. I suspect it might be somehow considered as an early version of the classic NE5534, but actually I couldn't find any valid info on the net.
So here's my request: does anybody know something more about this mysterious vintage chip?
Thanks!
Looks like it's really close to NE 5532 dual op amp. NE535 is the single op amp.
5534 is the single version. If they are working replace the Electrolytic caps.
5534 is the single version. If they are working replace the Electrolytic caps.
Thank you all! 👍
Really appreciated.
Shortly I'll be testing the module, at first with a current-limited variable dual power supply, just to be on the safe side given the rarity and historical value of the device.
I'll keep you informed about the results.
Really appreciated.
Shortly I'll be testing the module, at first with a current-limited variable dual power supply, just to be on the safe side given the rarity and historical value of the device.
I'll keep you informed about the results.
It's more like a 741 with input stage degeneration resistors and adjusted compensation to boost the slew rate: 10 V/us for a 1 MHz gain-bandwidth product op-amp. As a side effect, the equivalent input noise voltage is fairly high.
Yes, that can be seen in the noise diagram, something like 30nV/Squrt(Hz) - any 5532 outperforms these
Because of the degeneration resistors, the input stages will be able to more or less linearly handle larger voltage peaks than a normal bipolar op-amp. That could be an advantage for DAC I/V stages.
No, not close at all, much simpler circuit, much lower GBP, much less drive strength, significantly noisier, no protection diodes across the inputs to prevent reverse breakdown of the input devices (these are essential for low noise BJT input opamps). It also may have phase inversion, the datasheet doesn't say its immune...
BTW that first datasource (the catalogue) seems very confused about prefixes, using capital-M both for milliamps/milliwatts and also for megaohms input impedance on the same line!!
It correctly uses pA for picoamps, but wrongly NA for nanoamps... Also intrigued why WF is used for watts? watts in free-air perhaps?
It correctly uses pA for picoamps, but wrongly NA for nanoamps... Also intrigued why WF is used for watts? watts in free-air perhaps?
Earlier "standards" for prefixes were different "back then." I don't know exactly when modern prefix standards were set or widely adopted, but I recall seeing old capacitors with values in "MMF" short for micromicrofarads or modern-day picofarads. I recall this in schematics from the 1960s, maybe the early 1970s. I don't recall seeing WF.
As a quick follow-up to my first post above:
I've finally managed to fire up this equalizer at its nominal voltage, and everything seems to work flawlessly. Even more than this: it performs exceptionally well in terms of both specs and functionality.
The frequency points are very well chosen for everyday use, and the user can create very unusual curves by using both the Boost and Cut controls for the same band set at different frequencies.
The actual gain values (designed with 1.5 dB steps) almost perfectly match what is written on the panel, and THD values are extremely low at any settings.
More than anything else, this piece of hardware exudes solidity and durability—something that is sorely missing in most devices built these days.
I've finally managed to fire up this equalizer at its nominal voltage, and everything seems to work flawlessly. Even more than this: it performs exceptionally well in terms of both specs and functionality.
The frequency points are very well chosen for everyday use, and the user can create very unusual curves by using both the Boost and Cut controls for the same band set at different frequencies.
The actual gain values (designed with 1.5 dB steps) almost perfectly match what is written on the panel, and THD values are extremely low at any settings.
More than anything else, this piece of hardware exudes solidity and durability—something that is sorely missing in most devices built these days.