An op-amp setup for some linear amplification is quite linear until output voltage is reaching the supply limit. This is a quite abrupt transition from total clean to distorted sound and contrary to the desired soft transition.
I think he's just saying that op-amp saturation sounds rather unpleasant.
Edit: Beat me to it. ^
Ok, so your point is that hard clipping in an op amp sounds terrible. Ok, I agree. Now what does that have to do with the discussion?
I referred to #17
Could you pls calm down? Its only audio
Haha! Touche
Actually I don't 100% with KSTR's post #17 but if "easier" were changed to "more flexible" then I would agree 100%
What is STFU? Some kind of Canadian slang?
The OP wants to improve the sound of his guitar amp by substituting a "better" opamp. There is very little to be gained by this. What will make a guitar amp sound better is the introduction of low order gently rising THD like that of a vacuum tube. As the signal arises from the noise floor THD steadily increases to about 10% before hard clipping is reached.
Danyuk's article uses small amounts of local feedback to make a JFET act more like a tube. Too much local feedback will make the circuit too linear and you might as well use an opamp.
Link: http://www.diale.org/pdf/Triode-Emulator-by-Dimitri-Danyuk.pdf
jfetrer's comment suggests he is using a CFP configuration. That configuration usually employs too much feedback to properly emulate a vacuum tube. But it's a step in the right direction.
I can tell when nothing but opamps are in the signal path. A non-linear element like a JFET or a tube will often mask any opamps.
No argument from me!
here's a freebe.
I have plots somewhere on diyaudio with different calibrations, domminant 2nd or 3rd or what ever mix. Head-room? Its there.
you can tweak for music instrument or hifi. Must have a real time analyzer though.
You can trim for lowest THD, flat THD, band specific THD and whatever mix of harmonics. (R2 and R10)
I was only able to do this with the P-channel J174. Not sure if its due to jfet N-Ch ion impact physics or what. Other p-ch jfet were not as amenable. Also the circuit is just plain shitty as single supply.
So there you go.
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I have plots somewhere on diyaudio with different calibrations, domminant 2nd or 3rd or what ever mix. Head-room? Its there.
you can tweak for music instrument or hifi. Must have a real time analyzer though.
You can trim for lowest THD, flat THD, band specific THD and whatever mix of harmonics. (R2 and R10)
I was only able to do this with the P-channel J174. Not sure if its due to jfet N-Ch ion impact physics or what. Other p-ch jfet were not as amenable. Also the circuit is just plain shitty as single supply.
So there you go.
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I really don't think Peavey designed the preamp to 'rely on ESR to damp any local resonances'----do you? I think they just stuck the cheapest IC (a 4558) into the cheapest dc-blocking electrolytics (2.2uF) they could find. I'm cheap also, so I think putting my $25 into better opamps (OPA1642) and better 10uF film caps is worth a try. The circuit (fortunately) has close +/- decoupling (0.1uF) caps and sufficient (100pf) feedback capacitors to handle faster opamps. As Fahey pointed out, a JBL speaker would probably be the BEST upgrade; but they aren't to be had for $25. If guitar amps 'are not hi-fi', then just what are they? Low-Fi? Also, note that my usage here is for a PEDAL STEEL GUITAR, which is quite a different application than a regular six-string electric guitar.
HighFidelity is an audio reproduction characteristic.
A guitar amplifier is a piece of audio production equipment.
Those two genre are very different.
Guitar amps are not hifi.
Agreed. Pedal steel guitar is indeed a very demanding application... and the key component sure is the speaker which must be extremely clean and well damped. Even the slightest amount of "cone cry" ruins the sound completely.... as does any amount of hard clipping...
You want clean, so the opamp needs to be kept out of clipping. Does not matter if you change from one chip to another, they are all going to fall apart once you hit the voltage limit. Changing out an IC for a lower noise one is a valid exercise. With the amount of NFB we have distortion is not a concern (my opinion) especially in a live setting. Mind you if you want the preamp to work as a compressor or to add tube color that is a different ballgame.
For pedal steel you want to keep the initial picking transit from overloading the stages, this means all the way down the line to the output section. Since you are not trying to get distortion from the preamp, you might find that the power amp may be your limiting factor. Again, the attack is the first thing to distort, might be best to put a limiter in front of the amp,
If you have faith in the people that say swapping an IC will give you a better sound, just do it. If you believe, it will sound better even if nothing changes, does not matter what others say. I agree that using the best speaker that you can get will have the biggest impact on your sound. Maybe make/get a tube preamp/SS tube sounding pedal and put in front of your amp as a limiter. Anything to keep the signal level less dynamic (tame the pick attack).
For pedal steel you want to keep the initial picking transit from overloading the stages, this means all the way down the line to the output section. Since you are not trying to get distortion from the preamp, you might find that the power amp may be your limiting factor. Again, the attack is the first thing to distort, might be best to put a limiter in front of the amp,
If you have faith in the people that say swapping an IC will give you a better sound, just do it. If you believe, it will sound better even if nothing changes, does not matter what others say. I agree that using the best speaker that you can get will have the biggest impact on your sound. Maybe make/get a tube preamp/SS tube sounding pedal and put in front of your amp as a limiter. Anything to keep the signal level less dynamic (tame the pick attack).
Your comment is also unbelievably stupid and shows you have no clue on Musical Instrument amplifiers.
Just *one* example, there are thousands,here´s a record made using such amps, which not only was "a hit" but .... gasp !!!! .... TRIPLE Platinum.
They used early Peavey amplifiers, with discrete transistr preamps and power tube amps.
Ever heard of Rory Gallagher?
He not only used discrete local feedback SS amplifiers but he used part f the schematic on an album cover, he liked it so much
I can clearly see a BC109 in his beloved Stramp amplifier schematic.
Ever heard of Creedence Clearwater Revival?
They used early SS Kustom amplifiers,with a mix of discrete and early Op Amp preamps .... remember they were recorded in 1969 and thereabouts.
And so on and on and on ......
Your comment is also unbelievably stupid and shows you have no clue on Musical Instrument amplifiers.
Just *one* example, there are thousands,here´s a record made using such amps, which not only was "a hit" but .... gasp !!!! .... TRIPLE Platinum.
They used early Peavey amplifiers, with discrete transistr preamps and power tube amps.
Ever heard of Rory Gallagher?
He not only used discrete local feedback SS amplifiers but he used part f the schematic on an album cover, he liked it so much
I can clearly see a BC109 in his beloved Stramp amplifier schematic.
Ever heard of Creedence Clearwater Revival?
They used early SS Kustom amplifiers,with a mix of discrete and early Op Amp preamps .... remember they were recorded in 1969 and thereabouts.
And so on and on and on ......
Your post is also really stupid, and as you are not, I wonder why you are attacking me. I assume this is intentional demagoguery on your part to get back at me for something? Or perhaps just trying to make a big splash as free advertising for your commercial business?
jfetter posited that DISCRETE SS AMPS WITH ONLY LOCAL FEEDBACK are superior for guitar. As if even this debated, he actually posted such an example as to make it clear this was his point.
You presented 2 amps which are not only have non-discrete SS components such as tubes or op amps, but that do not even meet the criteria of only local feedback, they employ GNFB. They do not even meet 50% of the criteria. As for the Rory Gallagher amp, you go ahead and build it from that album cover schematic and tell me what it sounds like.
I hate demagoguery.
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I went to a small guitar show today and ran into a guy I know that plays Steel Guitar. He had several Steels he was trying to sell. One had a little effect box attached to one of the legs. I ask him about it and he told me it was just a buffer that isolates the pickup from the usual foot operated Volume pedal. He says most pro players use one or something that does the same thing. Some Volume pedals have one built in, a Peavey Session 500 has one builtin. You run the guitar straight to the amp and your Volume pedal connects to two jacks on the front of the amp. He says the buffer helps maintain the guitar's tone no matter where the volume is set. Maybe this is what the OP needs instead of an opamp upgrade.
Buffering the pickup indeed eliminates sound degrading when attenuating using the pot. This effect is technically well understood and works for any string instrument with traditional magnetic pickups. Anyway, this looks a bit off-topic here.
Yes, a lot of pro steel guitar players use a buffer inserted right out of the guitar BEFORE the volume pedal or any other effects boxes. The most highly regarded is one called a "Li'l Izzy" (~$140)---I do not know what is inside it, but my guess is some sort of FET circuitry--either discrete or opamp. Since so many professionals swear that it dramatically improved their sound, I thought that it would be advantageous to emulate it somehow by using an upgraded preamp section and a volume pedal 'loop' added to my cheapie Peavey Basic 50 amplifier. The cost of 4 opamps, 4 film caps and a couple of jacks would be within my extremely limited budget.
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