Meaning what you already have is quite good.
You asked about 741b which would definitely merit replacement, but TL071 there, besides being quite good, is just a small part and is used very conservatively., as in:
1) noise is being taken care of by the bipolar front end.
2) Op Amp is used with very low gain (meaning a lot of NFB), which extends its bandwidth and lowers its distortion by a big factor.
3) anyway sound goes through a ton of other stages, so improving a little just this part won't make an audible difference in the full mixer performance.
And remember this is a very good, properly designed mixer.
You asked about 741b which would definitely merit replacement, but TL071 there, besides being quite good, is just a small part and is used very conservatively., as in:
1) noise is being taken care of by the bipolar front end.
2) Op Amp is used with very low gain (meaning a lot of NFB), which extends its bandwidth and lowers its distortion by a big factor.
3) anyway sound goes through a ton of other stages, so improving a little just this part won't make an audible difference in the full mixer performance.
And remember this is a very good, properly designed mixer.
From what I am able to understand, my mixer has that circuit but with 741 chips
It seems the following generation tlo71 's were used. I wish I could find schematics for the rest of the channel. Would a photograph of the circuit work to help analyze. This is for a studiomaster 1977 12 channel mixer.
Thank you all.
It seems the following generation tlo71 's were used. I wish I could find schematics for the rest of the channel. Would a photograph of the circuit work to help analyze. This is for a studiomaster 1977 12 channel mixer.
Thank you all.
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You chopped off the ESP Audio logo on the schematic ?
Low Noise Balanced Microphone Preamp
By Phil Allison
(Edited by Rod Elliott - ESP)
Updated 17 May 2008
I did. And allot more.
Its the only drawing I have been able to find in reference to my mixer, thanks to you and whomever posted the link on another site, I should have done the same.
Its the only drawing I have been able to find in reference to my mixer, thanks to you and whomever posted the link on another site, I should have done the same.
But if that's a Rodd Elliott design why are you showing it if you have a Studiomaster/RSD mixer with a different circuit and parts?
It's like going to the Doctor and show him a friend's X ray plate.
Yea, I know, both of you have a heart, lungs, liver, etc 😉
By the way, you shouldn't have obscured that you were posting a Rodd Elliott propietary design.
It's like going to the Doctor and show him a friend's X ray plate.
Yea, I know, both of you have a heart, lungs, liver, etc 😉
By the way, you shouldn't have obscured that you were posting a Rodd Elliott propietary design.
Yes, Rod Elliots designs are all copyright. If any of you want to link to a circuit of Rod's then please put a direct link to the project concerned.
(rodrigosalvata... I've deleted the E.S.P. diagram. If you want to repost then put a link as outlined above. Thanks 🙂)
To me its like going to the doctor with xrays of an alien with 1 heart, 2 brains and 5 lungs, and asking how it works.
I had stated above that I was already aware of my mistake, but perhaps was not clear enough.
Copyright or not, I regret not showing enough respect for someone elses work.
What made me to be curious about my mixer was thinking it had a common, well regarded and upgradable circuit, but I have not yet enough knowledge to know what is common and not.
I had stated above that I was already aware of my mistake, but perhaps was not clear enough.
Copyright or not, I regret not showing enough respect for someone elses work.
What made me to be curious about my mixer was thinking it had a common, well regarded and upgradable circuit, but I have not yet enough knowledge to know what is common and not.
http://www.audioschematics.dk/downloads/schematics/consoles/sm 16-4 channel.tif
I have found here the exact schematics for the mixers channel.
Is it possible to determine which op amps can be swithed for tlo71 or 5534?
Also which are the signal, coupling and de coupling caps?
Thanks
I have found here the exact schematics for the mixers channel.
Is it possible to determine which op amps can be swithed for tlo71 or 5534?
Also which are the signal, coupling and de coupling caps?
Thanks
After a 30-second visual scan I don't see anything that isn't compatible with a TL071. If the 10 pF capacitor in the uA748 "Presence" filter really DOES connect to pin 6 (the opamp output) instead of pin 8 ("compensation" on the uA748; not used on the TL071) then it should be removed.
The 220 uF capacitors in the "LED DRIVE" section of the circuit are power supply bypass capacitors (also called decoupling capacitors). The 33 uF capacitor in the LED DRIVE circuit is a smoothing capacitor for the clipping indicator. Every other capacitor in that diagram is in the direct signal path, though some of them don't have much effect on some frequency ranges. The signal coupling capacitors are the large electrolytics - 10 uF, 100 uF and 1000 uF.
Dale
is this : Low Noise Balanced Microphone Preamp , aside from the opamps used, the same circuit as this attached Drawing sent to me by the guy who Designed the RSD/Studiomaster 12 into 2, from 1977, I am working on.
If so, would I be hurting or helping the attached design by replacing the 741´s with tlo71´s? Is it possible to describe what, in theory, would change? Just finished recapping and everything is stable.
thanks,
Rod
Attachments
Download some opamp datasheets.
You will find a few where the opamp manufacturer suggests similar methods of coupling in a discrete LTP.
You will find a few where the opamp manufacturer suggests similar methods of coupling in a discrete LTP.
I also want replacement for my old 741 Opamps if possible, my poweramp section has one which working fine but I just can't drop TL071 there, it makes one powertransistor (Q2) to conduct all the time. I guess that is happening beause TL071 is not rail to rail, I don't know so far tried 4 different TL071's either they all went bad or something wrong. I remember tl071's being unstable with power Vs+/- I drop the schematic below.
Also want to replace the other 6 741's on input&reverb channels. So far I had to replace 2 741's of channel 2, because there was hiss&oscillation from that opamps, placed tl071 and viola! all the noise is gone and channel is working maybe my tone control for bass&treble range a bit shortened but not that much noticeable. But something makes me wonder, If poweramp meant to work with 741 how about my preamp? Am I making my preamp less effective by swapping 741's? I don't know much about Opamps but when comparing TL071 & 741, latter is rail to rail, which could make a difference?
I don't know much about Opamps I am open to suggestions !
Also want to replace the other 6 741's on input&reverb channels. So far I had to replace 2 741's of channel 2, because there was hiss&oscillation from that opamps, placed tl071 and viola! all the noise is gone and channel is working maybe my tone control for bass&treble range a bit shortened but not that much noticeable. But something makes me wonder, If poweramp meant to work with 741 how about my preamp? Am I making my preamp less effective by swapping 741's? I don't know much about Opamps but when comparing TL071 & 741, latter is rail to rail, which could make a difference?
I don't know much about Opamps I am open to suggestions !
Your diagram shows opamps marked as 741 but with pinouts applicable to a different device in a larger package. The normal 741 is an 8 pin chip. So a lot of unknowns with this one.
These are all single channel 8 pins, for some reason pcb has 16 pin holes drilled but opamp sits on 8 pin socket, only 5 pin has paths +/- volts, +/- inputs and one output as seen on schematic. I don't know why manufacturer drilled 16 holes for each single channel opamp, but it is there, and pin numbers are kinda odd because 8 pin Opamps are meant to be used on 8 pin sockets not 16, so I think this explains odd pin numbers.
About my previous tl071 they might be all blownout for some reason, I just checked them with an opamp tester, all of them fail to flash the led, meanwhile 741's did flash the led
Here is my tester circuit: at 17:51
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That circuit would work just the same for a TL071 as a 741 running on say 9 volts. Make sure the TL071's are genuine parts and not fakes or actually dual opamps.
The TL07x family have phase inversion, I'd not risk it with those unless you are sure this won't cause problems. Plenty of modern opamps available with better performance.
I found an old 741 datasheet which shows that it was offered in a 14-pin DIP. https://www.physics.wisc.edu/courses/home/spring2020/623/ds/LM741-opamp-new.pdf
Ed
Ed
- CA3140 - CMOS, almost R-R, medium speed similar to 5532
- LM318 - Bipolar, works from dual 5V, high speed, 50V/us slew rate +extendable.
