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Old 7th May 2012, 11:35 AM   #1
znus is offline znus  Sweden
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Cool Soundcraft B100 (TL072...again)

Hi!

I wanna try changing op-amps on 2 of my Soundcraft B100 channels. And while I'm at it I'm gonna install some sockets too.

I'm not unhappy with the sound but then again, I haven't heard anything else than these JRC TL072BD 4017B.

I've read nothing but horror stories (soundwise) about the JRC's and I'm glad there are only three per channel. Should be amp, eq and summing, right? So what are my options as direct replacements? I'm looking for lower noise and more clarity, just like everyone else

And yes, I've searched this forum (and others) for similar threads but couldn't find any good match. Not that many small broadcast consoles around, I guess

Click the image to open in full size.

Thanks in advance!

/z
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Old 7th May 2012, 12:01 PM   #2
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I'm assuming that the TL072 is just a standard 072 dual jfet opamp, in which case the opa2134 would probably be a good candidate for a replacement. It has lower distortion, lower noise, higher slew rate, yet is still not so tricked up that it will give problems if the layout wasn't designed for it. Are you sure that the 4017 is an opamp? sounds like a CMOS IC number, not an opamp...

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Old 7th May 2012, 12:05 PM   #3
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Quote:
Originally Posted by wintermute View Post
I'm assuming that the TL072 is just a standard 072 dual jfet opamp, in which case the opa2134 would probably be a good candidate for a replacement. It has lower distortion, lower noise, higher slew rate, yet is still not so tricked up that it will give problems if the layout wasn't designed for it. Are you sure that the 4017 is an opamp? sounds like a CMOS IC number, not an opamp...

Tony.
Hi, and thanks for your reply.

Please check the three IC's on the board in the picure above and tell me what you think. They are clearly (maybe not in the pic) labeled 072BD, JRC, 4017B.
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Old 7th May 2012, 12:29 PM   #4
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4017 is a decade divider. In respect to TL072, try STīs TL072. For me they are the better choice.
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Old 7th May 2012, 12:39 PM   #5
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Originally Posted by Osvaldo de Banfield View Post
4017 is a decade divider. In respect to TL072, try STīs TL072. For me they are the better choice.
Hmm...well, it probably doesn't come as a surprise but I really don't know what I'm talking about Are you saying the chip (three of them) 072BD JRC 4017B in the picture above ISN'T an opamp but a decade divider?
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Old 7th May 2012, 12:46 PM   #6
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Originally Posted by znus View Post
Hmm...well, it probably doesn't come as a surprise but I really don't know what I'm talking about Are you saying the chip (three of them) 072BD JRC 4017B in the picture above ISN'T an opamp but a decade divider?
No, in your case the 4017 is the manufacturer date: week 17 of year 04. CD/MC/HCF4017 is a Johnson decade divider.
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Old 7th May 2012, 12:48 PM   #7
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No, in your case the 4017 is the manufacturer date: week 17 of year 04. CD/MC/HCF4017 is a Johnson decade divider.
So it's a batchnumber then.....and they are TL072's? Just need to clarify before ordering stuff
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Old 7th May 2012, 12:51 PM   #8
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ok sorry I should have put my glasses on I thought you were listing two types of chips! I tried searching on 072BD JRC 4017 but couldn't turn anything up. perhaps the 0417B is a batch code or date code???

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Old 7th May 2012, 01:22 PM   #9
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Quote:
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ok sorry I should have put my glasses on I thought you were listing two types of chips! I tried searching on 072BD JRC 4017 but couldn't turn anything up. perhaps the 0417B is a batch code or date code???

Tony.
Again, date of manufacturing. I used TL071/72/74 and TL081/82/84 for years and didnīt listen any malfunction. What is bad in your sounding? Distortion, noise, both?
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Old 7th May 2012, 01:37 PM   #10
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Again, date of manufacturing. I used TL071/72/74 and TL081/82/84 for years and didnīt listen any malfunction. What is bad in your sounding? Distortion, noise, both?
No malfunctioning right now. I had the B100 serviced one year ago because of some zipper/quantisizing noise while turning the gain knob on one channel. The tech switched one TL072 and the problem disappeared.

Now, checking more channels there's up to 5 differend brands of TL072, so far. Haven't checked all 8 channels and master yet.

All capacitators seems fine. No leakeage or swelling

Jut thought it'd be nice to upgrade the TL072's to something better than JRC-brand. And while doing so installing sockets for future replacements.
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