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hello
it has used c7,c11 as non polar 1uF capacitor. but i am unable to find this nonpolar cap with so high value in the market. i have also read the technique to use two polar electro cap can be used in series to behave like a non cap(++ --). can i apply this here??especially at the c7 positition. if not then plz say if there any alternative with out loosing any tonal effect. can i use any smaller value of c7 instead.
thanks for reding my question. plz help.
C11 is not critical and can be a small electroylitic of around 1 to 10uf. The same goes for C12. Both these caps just decouple the voltage provided by the resistive dividers. Larger cap = slightly longer time for circuit to stabilise from switch on.
The 4558 and the 741 are both ancient devices... I would replace with TL072 for the 4558 and TL071 for the 741. Straight swap and they also have low power consumption if you are by chance using a 9 volt battery.
C7 has to be 1uf or thereabouts. Again a modern electroylitic would be fine here (+ end to opamp) or as suggested, two small 0.47 in parallel.
The 4558 and the 741 are both ancient devices... I would replace with TL072 for the 4558 and TL071 for the 741. Straight swap and they also have low power consumption if you are by chance using a 9 volt battery.
C7 has to be 1uf or thereabouts. Again a modern electroylitic would be fine here (+ end to opamp) or as suggested, two small 0.47 in parallel.
In a circuit such as this I doubt you would hear any difference between caps tbh
The only real question is whether you can hear a difference between them, and without that decision being influenced by anyone telling you this or that is better before the listening test. In many cases you will "hear" what you want to hear and believe what you want to believe.
The only real question is whether you can hear a difference between them, and without that decision being influenced by anyone telling you this or that is better before the listening test. In many cases you will "hear" what you want to hear and believe what you want to believe.
Hi Paku, no idea why you would want to use the 741 for audio unless you really like bad quality !?! When you send me a PM with your address I will send you 4 x 1 uF MKT caps with 5 mm pitch ( if that is what you need ). C5 should be a 4.7 uF MKT too for optimal results when not thinking of the used opamps.
I don't agree with Mooly, good caps give better results than bad caps. This is not a question of belief. You can learn this with some simple tests.
However, modern electrolytic caps can be very good but film caps are just better when they're in the signal path. No need to replace them after some years.
But boy, a ua741 and a 4558 for audio.....
BTW film is the common word for "plastic" film caps, there are several different film materials of which mylar (MKT) is the cheapest/smallest and MKP (polypropylene) is one of the better but physically much larger types.
I don't agree with Mooly, good caps give better results than bad caps. This is not a question of belief. You can learn this with some simple tests.
However, modern electrolytic caps can be very good but film caps are just better when they're in the signal path. No need to replace them after some years.
But boy, a ua741 and a 4558 for audio.....
BTW film is the common word for "plastic" film caps, there are several different film materials of which mylar (MKT) is the cheapest/smallest and MKP (polypropylene) is one of the better but physically much larger types.
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No kidding. But then, the circuit is from the 1970'ies... I'd upgrade those opamps to something more sensible. OPA134, LME49710, etc. Although, it could be argued that using an ultra-low distortion op-amp in a circuit that's designed to give some distortion (caused by the diodes in the feedback path on the '741) would be overkill. But at least use a NE5532 or similar.
The circuit as-is will give pretty high odd-order harmonic distortion. If you want more even-order distortion ("triode sound"), change the diode arrangement D1~D6 so it becomes asymmetric. E.g. have four diodes in series in one direction and only two in the other. You can experiment with that until you get the tone you like.
~Tom
Totally missed the diodes in the schematic but I already suspected distortion was deliberate (of course after I posted my previous post) ! I obviously need to look somewhat longer at schematics, sorry. If distortion is wished then do not change a single opamp as they were likely chosen for their distortion and/or sonical characteristics.
Still I would use a 1 uF film cap for C7/C11 just as the schematic says to have the meant sonical character. If the design is tested to sound as it does now any change will make it sound different, especially when you change values. I one made the mistake by changing a coupling film cap in a Fender bassman amp that was too small in value in my opinion and it was so wrong in sound that that I quickly changed it back. Lesson learnt, won't make the same mistake again
off topic: just asked myself what would happen if you have a Roland 808 and replace the old caps in it for new ones ? Will it still sound just as phat as we know ?
Still I would use a 1 uF film cap for C7/C11 just as the schematic says to have the meant sonical character. If the design is tested to sound as it does now any change will make it sound different, especially when you change values. I one made the mistake by changing a coupling film cap in a Fender bassman amp that was too small in value in my opinion and it was so wrong in sound that that I quickly changed it back. Lesson learnt, won't make the same mistake again
off topic: just asked myself what would happen if you have a Roland 808 and replace the old caps in it for new ones ? Will it still sound just as phat as we know ?
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The 4558 is probably a JRC NJM4558. A guitarist friend told me this has the best sound for distortion pedals.
No, 5532 is not better.
4558 has output stage that with 6.8K - 7.5K from output to + rail can can be biased in audiophile quality opamp. However, noises could be lower, speed could be faster, input currents lower, but anyway when I see 4558 in an old pro gear I bias it's output instead of replacing by something new.
5532 is what come to the fashion after 4558 in pro audio. It is like AKMS-74 after AK-47, the same Kalashnikov of pro audio. But the older one still sounds better... However, if you have OPA1612 in DIP case you can replace both in consoles, preamps, equaluzers, compressors, stc..., with great success, but if you don't... Don't rush.
Speaking of original questions, both caps can be electrolytic, and it changes nothing sound-wise. Also, which opamp you use here also almost does not matter: results are different levels of noises and output shifts, that would be good if any newer opamp than 4558 is used.
4558 in this type of pedal does not give any difference. This pedal uses diodes in negative feedback; they distort. If you want some other effect from this pedal, you may add one more switch that shorts out some diodes in feedback, so clipping starts asymmetrically. It would add some musicality to distortions, blues-like clipping of SE amp.
Also, long time ago I made and used a pedal similar to this one, with gain pot before the limiter controlled by pedal. It was easy and convenient, to use a pedal to control overdrive by foot.
4558 has output stage that with 6.8K - 7.5K from output to + rail can can be biased in audiophile quality opamp. However, noises could be lower, speed could be faster, input currents lower, but anyway when I see 4558 in an old pro gear I bias it's output instead of replacing by something new.
5532 is what come to the fashion after 4558 in pro audio. It is like AKMS-74 after AK-47, the same Kalashnikov of pro audio. But the older one still sounds better... However, if you have OPA1612 in DIP case you can replace both in consoles, preamps, equaluzers, compressors, stc..., with great success, but if you don't... Don't rush.
Speaking of original questions, both caps can be electrolytic, and it changes nothing sound-wise. Also, which opamp you use here also almost does not matter: results are different levels of noises and output shifts, that would be good if any newer opamp than 4558 is used.
4558 in this type of pedal does not give any difference. This pedal uses diodes in negative feedback; they distort. If you want some other effect from this pedal, you may add one more switch that shorts out some diodes in feedback, so clipping starts asymmetrically. It would add some musicality to distortions, blues-like clipping of SE amp.
Also, long time ago I made and used a pedal similar to this one, with gain pot before the limiter controlled by pedal. It was easy and convenient, to use a pedal to control overdrive by foot.
Wavebourn, your findings do not correlate with my findings on 4558. When I was a child I learnt that replacing them for the (then best) audio opamp NE5532 was a step forward....
Wouldn't use NE5532 nowadays ( input current, speed, offset etc. ) although it is a very good measuring device. I would use one of the newer National types instead when I would smell a 4558 in a device for HiFi. In fact I recently found some and replaced them for LME49860 which was more than a big step forward.
Back to the subject, we're going off-topic.
Wouldn't use NE5532 nowadays ( input current, speed, offset etc. ) although it is a very good measuring device. I would use one of the newer National types instead when I would smell a 4558 in a device for HiFi. In fact I recently found some and replaced them for LME49860 which was more than a big step forward.
Back to the subject, we're going off-topic.
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If instead of replacing them you would bias them as I described above, you could be surprised. Especially, when it is a console with several of them in each channel strip. Replacing by 5532 you get like "better SS sound". Biasing them you are getting like tube sound from SS console.
Here is an example:
http://wavebourn.com/female_sample.mp3
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