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Best Opamps to replace TL072's in TAC Scorpion-II
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#31
2nd August 2011
Old 2nd August 2011
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Quote:
Originally Posted by Samuelito View Post
bump!

Anyone knowing where to get the adapting socket for mounting the OPA1642 through holes?

Thanks,

Sam
Cimarron Technology, Inc.

If you want cheaper ones check out ebay.
#32
2nd August 2011
Old 2nd August 2011
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Thanks you!

Cheers,


Sam
#33
19th September 2011
Old 19th September 2011
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Hi everyone,

Has anyone modded the s3000/3100/3200 modules?
Cheers,

Sam
#34
19th September 2011
Old 19th September 2011
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#35
20th September 2011
Old 20th September 2011
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Quote:
Originally Posted by Samuelito View Post
Hi everyone,

Has anyone modded the s3000/3100/3200 modules?
Cheers,

Sam
yes
#36
20th September 2011
Old 20th September 2011
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Quote:
Quote:
Originally Posted by Samuelito
Hi everyone,

Has anyone modded the s3000/3100/3200 modules?
Cheers,

Sam


yes
Can I ask, what have u done on them?

I would like to reduce the noise, basically and give them a warmer sound for summing, but I'm not sure which opamp would suit me best here and if it possible to remove some el caps aswell.
I'm half the way to recapping them and it would be a good time to mod them.
Thanks,

Sam
#37
21st September 2011
Old 21st September 2011
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Define "warmer", please. I did not swap chips because I wanted to change the sonic impront of the desk. I believe that improving measurable parameters will improve sound somhow, though. That´s why I´ve replaced the TL072s with OPA2132/2134 except the Faderamp position with LT1358 for some technical reason: lower selfnoise, better drivecapability at the insert point (with EQ engaged) and LT1358 running with a better OSI as faderbuffer. It´s quite some time ago that I did it and hence cannot remember if I had to tweak the bandwidth limitation of the opamps.
I did change many other things, too. The Scorpions were made on a budget and had some corners cut. By todays standards there can a lot be improved in terms of parts quality. Not on a budget, though. So I changed the gainstructure of the desk, changed many EQ frequencies and EQ caps, increased many electrolytics, removed some electrolytics. Added many many bypass caps, additional rail buffering, most important renewed the ribbon wires and fader connectors.
When you swap opamps you always have to check if the circuit oscillates. You cannot judge from listening that it runs flawlessly. If you don´t measure you risk damaging all or some of the new chips, overheating, headroom problems, increased distortion, ..... If you don´t know how to measure oscillation let someone else do it or better leave the desk in a working state as it is.
hope that helps
#38
21st September 2011
Old 21st September 2011
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Hi
It is fairly easy to tell if your 'mods' have caused unwanted oscillation because you get a little trail of smoke from your tweeters and maybe the monitor amp as well. It could appear on the headphone mixes too. Probably won't hurt the desk much though.
Matt S
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#39
21st September 2011
Old 21st September 2011
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Maybe under severe conditions, but most of the time the oscillations are low levels, sometimes as low as a few millivolts. You need good test gear to see them and the understanding of their cause and cure. Stray capacitance on scope probes can also cause it leading the inexperienced on to a long path of chasing ghosts.

A final check with a good distortion analyzer will tell you if things have degraded or not.
#40
21st September 2011
Old 21st September 2011
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Quote:
Originally Posted by jensenmann View Post
Define "warmer", please. I did not swap chips because I wanted to change the sonic impront of the desk. I believe that improving measurable parameters will improve sound somhow, though. That´s why I´ve replaced the TL072s with OPA2132/2134 except the Faderamp position with LT1358 for some technical reason: lower selfnoise, better drivecapability at the insert point (with EQ engaged) and LT1358 running with a better OSI as faderbuffer. It´s quite some time ago that I did it and hence cannot remember if I had to tweak the bandwidth limitation of the opamps.
I did change many other things, too. The Scorpions were made on a budget and had some corners cut. By todays standards there can a lot be improved in terms of parts quality. Not on a budget, though. So I changed the gainstructure of the desk, changed many EQ frequencies and EQ caps, increased many electrolytics, removed some electrolytics. Added many many bypass caps, additional rail buffering, most important renewed the ribbon wires and fader connectors.
When you swap opamps you always have to check if the circuit oscillates. You cannot judge from listening that it runs flawlessly. If you don´t measure you risk damaging all or some of the new chips, overheating, headroom problems, increased distortion, ..... If you don´t know how to measure oscillation let someone else do it or better leave the desk in a working state as it is.
hope that helps
Thank you.

I was planning on changing the fader opamp (U3) for a LME49720 as I did in the s1000 modules (including a pair of .1uf mono ceramic caps from 4 & 8 to ground). Were I'm not that sure is if I can remove every el cap from the power distribution to the U2 position (2nd opamp). U2 is also compromised by the fader switch as I saw in the circuit diagram (if I'm not mistaken), so I was thinking of the possibility of swaping that one too. When I said warmer I was thinking of some kind of a dirty sound as a tape saturation would do. Options; that's what I'm searching by modding the s3000 modules.

I'm not a technical guy in this matter, but I'm trying to learn as I go. Until now everything is going smoothly and clean; above all, clean. Always following tips from the guys who know better. When I fill the it's too much, I prefer playing it safe.

Thanks again to everyone for all the tips!!

Cheers,

Sam
#41
27th September 2011
Old 27th September 2011
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What about the AD8599?
Shame that is a SOIC chip. I would prefer not using an adapter.
Same thing with the OPA1642. I'm still waiting for TI to make the PDIP version.
#42
27th September 2011
Old 27th September 2011
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You will wait forever, no DIPS. Everything modern is SOIC, except some National parts. TI bought National so that may also change.

Aries and Brown Dog make adaptors. That's the price of admission.
#43
27th September 2011
Old 27th September 2011
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manzini is offline
Due my incompetence to do SOIC works, no equipment and my fingers are like hot dogs... Just today received this from ebay to replace my tl072 on gap pre73.



Perfect and very mint !! a very clean work.

More cheapest with shipping, also to Europe from USA, that a local buy of two lme49990 and the adaptor.
Attached Thumbnails
Best Opamps to replace TL072's in TAC Scorpion-II-lme49990-dip8.jpg  
#44
27th September 2011
Old 27th September 2011
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Ok. I'll check that out. I knew Brown Dog but not Aries.
Should I take some extra care when soldering the opamp to the adapter?
Apart from soldering in the right position...

Cheers,

Sam


PS: If anyone has used AD8599's before I would really appreciate some opinions on them.
#45
28th September 2011
Old 28th September 2011
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Quote:
Originally Posted by manzini View Post
Due my incompetence to do SOIC works, no equipment and my fingers are like hot dogs... Just today received this from ebay to replace my tl072 on gap pre73.
Waste of money and time. There are no 072's in the GAP 73 audio path. Just a bunch of BC184 transistors and a 2N3055 power transistor. I used Toshiba 2SC3329BL's, those lowered the noise nicely.

The AD8599 is a very quiet and clear part. A bit slow and dark compared to the LME's and OPA's. Good for those that want a softer top end. They also make a single version.
#46
28th September 2011
Old 28th September 2011
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Well, not wasted, I have another cheaps and olds preamps with tl072 or equivalent.

This bundle (dual lme49990 on DIP) is similar that anothers I got (AD825, AD767, etc) for avoid to me to work with SOIC in DIY learning & experiments.

I find also an advantage for me, because, curiously I found this kits more cheapest that the shop prices for the individual IC's: farnell, digikey, mouser, etc.

I found a TL072 on my pre73 and want to test if replacement have audibles changes. You said: Not in the audio path !!! a mistake then, I did not find any IC in the "originals" schemas, and really replace the tl072 for anothers (opa2134, lme49720na) don't change, not audible. I am waiting to receive an scope to see.

Yes !!! Weeks ago, reading you, Mr. Williams I got (very hard to find, but not imposible) 2sc3329BL and motorola 2n3055, match the toshibas and Voila !! near 20 db's of noise floor drop.

Just this exceeded all my expectations.

A wonderful result. I think it is simply the best change / mod that you can do and very cheap if you do not fall into the trap of paying a lot for these Toshibas.

Thanks Mr. Williams.
#47
28th September 2011
Old 28th September 2011
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Quote:
Originally Posted by manzini View Post
I find also an advantage for me, because, curiously I found this kits more cheapest that the shop prices for the individual IC's: farnell, digikey, mouser, etc.

You've got to watch out though for counterfeit products. It might actually be a cheap op amp with a new label. Not necessarily, but it has happened before, especially with expensive ICs.
#48
28th September 2011
Old 28th September 2011
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Oh yes yes, bigs counterfeit !! of course.

I do not buy the first time, investigated and never told me. avoid "or large commercial stocks" NOS/OLD items and try to find really or some credible, "old man" garages sales. A measure of protection is not spending much money, just a few dollars, try harder, but then buy a few months later to have the desired amount.

I began to search 2sc3329bl in March.

Despite these precautions, I got some faulties 2sc3329bl and some Motorola 2N3055 fakes.

"hard to find" also expresses this fact.

After a few tricks, you get some reliable suppliers.

Yes! I Lost some bucks (near 15$) but after get 50 toshiba's by 5$. I think the balance is favorable.

My gear now is 20dB's noise floor better for only 25$. No expensive or esoterics mods.

No risk no gain.
#49
30th September 2011
Old 30th September 2011
  #49
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Well. First day of testing and a small issue jumped up.
The S1000 modules are eating all the power from the PSU.
Both lights from the 10A of the PSU go out when I plug more than 1 strip.
Me first guess is that the mono ceramic caps from the rail to ground are eating the power of the PSU.

I could have bought the wrong mono ceramic caps for this purpose.
Her are some photos of the S1000 modules.

Mods:

AML preamp kit
Fader amp LME49720
Removed every el cap that was left on the strip leaving only the ones on the preamp section.

Suggestions are always welcome!!!
Attached Thumbnails
Best Opamps to replace TL072's in TAC Scorpion-II-img_0185.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0186.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0187.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0188.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0191.jpg  

#50
30th September 2011
Old 30th September 2011
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#51
30th September 2011
Old 30th September 2011
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slenderchap is offline
The shorting links which you have put in place of the capacitors are shorting the power supply to ground.

Why not just follow the instructions for the preamp kits the way it is intended.

Colin
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#52
1st October 2011
Old 1st October 2011
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Hi Colin,

I did... Is just that later I changed the fader amp for further improvement.

I'll start putting back C30, C31 & C32 and see what happens.

Cheers,

Martin
#53
11th October 2011
Old 11th October 2011
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Thanks Colin,

Stupid novice mistake a did. Everything is working now.
Ready for testing!!
Thanks again!!

Sam
#54
11th October 2011
Old 11th October 2011
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Quote:
Originally Posted by manzini View Post
Due my incompetence to do SOIC works, no equipment and my fingers are like hot dogs... Just today received this from ebay to replace my tl072 on gap pre73.



Perfect and very mint !! a very clean work.

More cheapest with shipping, also to Europe from USA, that a local buy of two lme49990 and the adaptor.

Wait, there's only one chip in the GAP73, and it's a meter driver. Not in the signal path.

Why are you doing this?

Or do the new ones use chips somewhere else now?


john
#55
12th October 2011
Old 12th October 2011
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sorry for the offtopic.

Quote:
Originally Posted by NEWTON IN ORBIT View Post
Why are you doing this?
john
Hello John
Basically because I don't understand some issues and somethings on the circuit and satisfy my curiosity and learn:

Yes, that I thought.
This is not in the signal path and apparently should not affect, however I did this test and I was surprised by my curiosity:

With a 180ohm resistor and near cranck maximum gain (position 75db, output at 4pm).

With the LME49990, I have not been exhaustive testing because I'm more than a month with all my gear apart and began with acoustic treatment in my bedroom-studio.

I do not have the full test with pictures but in a quick test, observed (listening) noise spikes, but with the same noise floor than opa2134. LME49990 it seemed bit clearer, flat, but showed a strong 20dB peek distortion near 100Hz. I could not put the opamp bypass to ground before dismantle all my gear.

Only a bit: I have a ground Issue on the PSU board to solve (you can see at 50Hz with harmonics).

I explain the pictures:

Pre73 MKI (not new unit) Stock. TL072



Pre73 mk-I Stock (TL072) after little changes on PSU board ground. Not complety solved.



Pre73 MK-I with 2sc3329BL and TL072



Pre73 MK1 with 2sc3329 and OPA2134



Now I am searching the picture with the LME49990 (same noise level, but little better, flat noise but with a 20dB peak at 100Hz).

Opamp not in the signal path ? I don't know, but with some effect on performance. 5dB - 7dB less noise floor.

In the coming weeks, when I have finished the acoustic treatment, I will continue investigating this issue (LME49990 and Opamp effect in pre73) and learn to solve the remaining HUM.

I think that -120dBs are the noise inherit for pre components and card, cables, etc. I received the scope but is still in the box.

Kind regards.
Attached Thumbnails
Best Opamps to replace TL072's in TAC Scorpion-II-pre73-mk1-stock.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-pre73-tl072-stock.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-pre73-mk1-2sc3329-tl072.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-pre73-2sc334-opa2134.jpg  
#56
12th October 2011
Old 12th October 2011
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Hey, yeah, this thread is about another topic, but if you want I can pm you and let you know what all was done to my GAP.

Or start another thread here maybe.

Anyway, the ground thing...yeah. The chassis is floating of course on this thing, because of the line lump transformer.

Those nasty ceramic disc caps in the input and outout...yank them things.

Thing is, it then sounds better, but is oscillating for some reason when you take them out. My guess is, that in place of a real grounding scheme, and to save money using a wallwart, these are in there as a low pass filter for rfi? If you take them out, then ground the chassis it stops, and is quiet.

Much nicer sounding.

john
#57
13th October 2011
Old 13th October 2011
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manzini is offline
John, thanks a lot for your PM offer, very grateful. The pre73 ground schema for me (noob) it's a nightmare and my pre still got irritating hum.

when I finish the acoustic treatment, in a couple of weeks, I will continue my learning-research to solve things in my pre73, collecting info, pictures, samples and data to open a new topic thread about.

Returning to the topic (excuse me):

Beware !!! with my lasts messages. LME49990 is not a direct replacement for the TL072.

Kind regards.
#58
19th October 2011
Old 19th October 2011
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Well, back from the test!!!

First impressions:

- Drastic change in the sound of the board for good. REALLY open; detailed across the entire bandwidth.

- Board is really sensible now. Tracking drums with almost every pad engaged. Trying always to give the pre a stable amount of gain (about half the way through).

- Crackling pots and faders. WTF?!!?! Didn't happen before...

- Even though I was really careful with levels, I encountered distortion peaks from time to time. I couldn't get a decent level in the board without saturating the converters. There was no correlation between the meters on the board and the ones on PT. Thing that didn't happen before either.


I uploaded some more photos from the strips with details of the mod and an audio sample from the test where you can reference the sound aswell as the distortion problem.


Test details:

No EQ - No compression

Room - Blumlein - Neumann M149 - HPF 120Hz - about 3 meters from the drums and slightly to the right ( nice snare position )
OH - AB - Gefell UMT 70s - Cardiode
HH - Neumann KM184
BD - Beta 52
SD top - Revox M3500 + SM57
SD bot - SM57 - (Phase rev)
R tom - AKG C3000
FL tom - AKG C5600

Mics - Scorpion S1000 modules - DOut to PT ( BLA Digi 002 + BLA Tango 24)


Mod details:

AML S1000/1001 preamp update module
Fader amp LME49720
Removed the el caps market in red in the schema




Ideas:

I ****ed up somewhere!!!
Shorting the caps of the power (stupid mistake) ****ed something.
I'm mising something... C 22 ??? or the 2.2 uf cap on the overload section....
The bypass caps are not the appropriates

I'll take one of the modules back to its original state and test it. I'll post something later this week.


Hope these info helps someone in the future. Challenging task!!!

Cheers,

Sam
Attached Thumbnails
Best Opamps to replace TL072's in TAC Scorpion-II-img_0214.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0215.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0216.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0218.jpg   Best Opamps to replace TL072's in TAC Scorpion-II-img_0219.jpg  

Best Opamps to replace TL072's in TAC Scorpion-II-s1000-schema.jpg  
Attached Files
File Type: mp3 test scorpion.mp3 (2.67 MB, 94 views)
#59
19th October 2011
Old 19th October 2011
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Hi
Maybe it is not as 'stable' as you think.
OK it doesn't oscillate when sitting still but some op amps in certain configurations can partially 'latch up' or other misdemeanors when overdriven.
The SSM2015 (mic pre chip) was good at this in that if you took it to clipping the output would give a short burst of oscillation which you had to wait to finish before it would go 'linear' again. The SSM2016 had this problem solved as I used it as a plug in replacement on the AMEK Classic.
Matt S
#60
19th October 2011
Old 19th October 2011
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How the heck did you come to the conclusion to just leave all the electrolytics out? Do you think that the designer of the desk was so clueless to put (costly) parts into the desk that have no purpose? Put your electrolytics back in and all problems will be solved. As long as you have no idea what you are doing and don´t know how to use el. test gear (scope, etc) better let others with skills do that stuff.

Sorry for being harsh, but many people will follow this thread and in worst case copy what you do, hence destroying their desk.

@Matt: have a closer look at the pictures!
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