Soundcraft B100 (TL072...again)

[znus]

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

Thanks in advance!

/z

 

[wintermute]

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.

 

[znus]

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.

 

[Osvaldo de Banfield]

4017 is a decade divider. In respect to TL072, try ST´s TL072. For me they are the better choice.

 

[znus]

4017 is a decade divider. In respect to TL072, try ST´s 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?

 

[Osvaldo de Banfield]

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.

 

[znus]

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

 

[wintermute]

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.

 

[Osvaldo de Banfield]

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 didn´t listen any malfunction. What is bad in your sounding? Distortion, noise, both?

 

[znus]

Again, date of manufacturing. I used TL071/72/74 and TL081/82/84 for years and didn´t 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.

 

[yd1cvj]

From picture, type of IC is TL072 from JRC, while the written 4017B just production code. TL072 is op amp

 

[znus]

Thanks all, so far. But we're not there yet

Gonna try changin stuff on 2 channels before going crazy on all channels.

Right now I have 6 DIL8 sockets. I will solder these into place later this week. And I just picked up:

1.) 4 of Burr Brown 2134 (expensive, compared to TL072)
https://www.elfa.se/elfa3~se_sv/elfa/init.do?init=2&shop=ELFA_SE-SV&item=73-120-36

2.) 4 of Analog Devices OP275GPC. (also expensive compared to TL072) I got a tip that these were good for the eq.

https://www.elfa.se/elfa3~se_sv/elfa/init.do?init=2&shop=ELFA_SE-SV&item=73-275-05

3.) 6 of ST TL072IN

https://www.elfa.se/elfa3~se_sv/elfa/init.do?init=2&shop=ELFA_SE-SV&item=73-117-31

(the pages are in Swedish but I think you can understand the specs)

And now I can do the following

Replace the existing six JRC TL072's with the ST072's on two channels

OR

Replace amp & summing with BB 2134 while using AD 275GPZ for the eq

or any other combo. What do you think? Will it work?

 

[Simon B]

If it ain't broke, don't fix it!

Don't think quantising noise could be an issue here really.

Must be something fun you could do with those op-amps?

 

[znus]

If it ain't broke, don't fix it!

Don't think quantising noise could be an issue here really.

Must be something fun you could do with those op-amps?

I agree with you Simon but the fact that there are 6 different TL072's between the channels annoys the h*ll out of me

I will change them. It's only 3 per channel x 8. Bigger recording consoles can have all that on ONE channel. Gotta check the master channel and PSU too. Who knows what's lurking there?

 

[znus]

Did a little test earlier today. I changed one TL072 on channel 1 (the IC2 one) and replaced it with a 2134 and something definitely audible happened.

If I look at the master bargraph boosting +15 db on MF at 8 kHz on channel 1 and on channel 2 (channel 2 = all TL072) I get 1-2 db higher peaks on Channel 2 but it sounds a lot grainier. None of the channels are peaking so it's not distortion.

SOMETHING is different though and channel 1 is easier on the ears. Maybe it's the db difference playing me a trick but 2134 is, without a doubt, changing something for the better on channel 1. At least when boosting the eq. Less grain

Wierd, and interesting. I did not expect to hear a difference, so it's not me wanting to hear it. Listening to samples of a ride cymbal I heard more of the bell on the TL072 channel 2 and more sizzle on the BB 2134 channel 1.

Then I did IC1. HF sounds less honky with the 2134. Cant decide if its frequency band or q-width? And there goes IC3. LF - can't say I'm hearing the same drastic change as I did on the MF. I think I can rule out I'm changing the frequencies since it's definitely working in the same area. Well, I'm not saying I can hear the difference between 60 Hz and 66 Hz, but still... ..

I wish I had the knowledge and gear to measure stuff but for now I just gotta go with what I can hear. Since it's only 3 IC's per channel * 8 it's not that much time & money. It's fun and educational and I'm gonna change all of them + beef up the PSU.

All in all I'm a happy camper

 

[Simon B]

...I did not expect to hear a difference...

Of course you expected to hear a difference!

If you didn't, why on earth are you doing this?

Incidentally, this isn't blind testing, so I'm afraid it reveals nothing. If it makes you happy, that's fine, but it's of little value to anyone else.

 

[znus]

Of course you expected to hear a difference!

If you didn't, why on earth are you doing this?

Incidentally, this isn't blind testing, so I'm afraid it reveals nothing. If it makes you happy, that's fine, but it's of little value to anyone else.

Actually, i didnt. I suck at hearing nuances and the main reason was getting one chip in there, instead of six different, and maybe upping the specs while doing so. I could always play something through the 072 channels and then the same material through the 2134 and let you hear for yourselfes?