Is a Soldano SLO a "cold clipper" ?
- Thread starter JMP/HBE
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devastone
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
Not sure what you are asking, if it is "are the preamp tubes run at low voltage and are basically functioning as clipping diodes?", the answer is no. Also, no diode clipping. There aren't any SS components in the signal path so the tubes have to be running at correct voltages to amplify the signal.
Not sure what you are asking, if it is "are the preamp tubes run at low voltage and are basically functioning as clipping diodes?", the answer is no. Also, no diode clipping. There aren't any SS components in the signal path so the tubes have to be running at correct voltages to amplify the signal.
devastone
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
I had to go look it up, explanation here - https://robrobinette.com/Tube_Guitar_Amp_Overdrive.htm#Cold_Clipper
So, yes, the 3rd gain stage in the gain channel of the SLO (the one with the 39k resistor on the cathode) is a "cold clipper" as is the 2nd gain stage in a JCM800.
Sorry, I totally misunderstood the original question!
I had to go look it up, explanation here - https://robrobinette.com/Tube_Guitar_Amp_Overdrive.htm#Cold_Clipper
So, yes, the 3rd gain stage in the gain channel of the SLO (the one with the 39k resistor on the cathode) is a "cold clipper" as is the 2nd gain stage in a JCM800.
Sorry, I totally misunderstood the original question!
JMP/HBE
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
There is something unique to the 39K Cathode resistor on V2b on the SLO preamp. The MESA Dual/Triple Rec copies the same preamp. I thought it may lower voltages in the Preamp to produce clipping of some sort. Also was wondering about the bias on 5881's in the SLO are they biased cold ?
The MESA DR 6L6's are biased cold to produce a sort of clipping hence the : "cold clipping".
Not sure what you are asking, if it is "are the preamp tubes run at low voltage and are basically functioning as clipping diodes?", the answer is no. Also, no diode clipping. There aren't any SS components in the signal path so the tubes have to be running at correct voltages to amplify the signal.
There is something unique to the 39K Cathode resistor on V2b on the SLO preamp. The MESA Dual/Triple Rec copies the same preamp. I thought it may lower voltages in the Preamp to produce clipping of some sort. Also was wondering about the bias on 5881's in the SLO are they biased cold ?
The MESA DR 6L6's are biased cold to produce a sort of clipping hence the : "cold clipping".
devastone
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
From the link I posted:
"The cold clipper gain stage is a very useful tool for voicing an amp's overdrive tone. It is used in many high gain tube amps to generate early and smooth sounding overdrive tone.
For minimum distortion a tube should be biased halfway between cutoff (when all electron flow is stopped) and saturation (when electron flow is maxed out). A 1.5k cathode resistor for a typical tube amp 12AX7 triode gain stage is very close to center bias. A cold clipper's very large 10k to 39k cathode resistor sets a cold bias that leaves very little room on the cutoff side so the guitar signal can easily be clipped when the signal's negative lobe on the grid reduces electron flow through the tube and electron flow is shutdown completely. The cold clipper is designed to clip on the cold side of the operating point. This clipping is asymmetric because there's plenty of room on the saturation side of the bias point so the guitar signal's negative lobe is clipped while the positive lobe passes unmolested and carries the original musical content. This asymmetric clipping generates mostly sweet sounding 2nd harmonic distortion."
It basically biases the signal to the negative side so it clips asymmetrically which generates a lot of even order harmonics.
"Cold Clipper" as defined in the article has nothing to do with the output tubes, and the SLOs have adjustable bias IIRC, so no reason to keep them biased cold.
From the link I posted:
"The cold clipper gain stage is a very useful tool for voicing an amp's overdrive tone. It is used in many high gain tube amps to generate early and smooth sounding overdrive tone.
For minimum distortion a tube should be biased halfway between cutoff (when all electron flow is stopped) and saturation (when electron flow is maxed out). A 1.5k cathode resistor for a typical tube amp 12AX7 triode gain stage is very close to center bias. A cold clipper's very large 10k to 39k cathode resistor sets a cold bias that leaves very little room on the cutoff side so the guitar signal can easily be clipped when the signal's negative lobe on the grid reduces electron flow through the tube and electron flow is shutdown completely. The cold clipper is designed to clip on the cold side of the operating point. This clipping is asymmetric because there's plenty of room on the saturation side of the bias point so the guitar signal's negative lobe is clipped while the positive lobe passes unmolested and carries the original musical content. This asymmetric clipping generates mostly sweet sounding 2nd harmonic distortion."
It basically biases the signal to the negative side so it clips asymmetrically which generates a lot of even order harmonics.
"Cold Clipper" as defined in the article has nothing to do with the output tubes, and the SLOs have adjustable bias IIRC, so no reason to keep them biased cold.
JMP/HBE
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
Yes yes thats its. Mike Soldano was the first to use the 39K Cathode resistor [more or less he claims] but all the Amp builders were kinda figuring out stuff like Master Volumes, Cascaded Preamps, ect close to the same time. I have known for many years the value of Asymetrical clipping in amps & pedals but i couldn't remember some of this. Thanks for clearing that up. You're a smart man.
devastone
Well-known member
FuseG4
Our Neighbor Totoro
Re: Is a Soldano SLO a "cold clipper" ?
FWIW 10k is the marshall JCM800 cold clipper and you can even put the resistor values on a switch and pick your flavor!
Of note also is the plate load resistor bypass cap on the same cold clipper stage. This cuts icepick highs and is another part of the SLO sound
FWIW 10k is the marshall JCM800 cold clipper and you can even put the resistor values on a switch and pick your flavor!
Of note also is the plate load resistor bypass cap on the same cold clipper stage. This cuts icepick highs and is another part of the SLO sound
Joey Voltage
New member
Re: Is a Soldano SLO a "cold clipper" ?
Yes, The Slo has what has been coined a "Cold Clipper", but in the SLO it so extreme, it's nearly a half wave rectifier. Amps like the SLO, recto, 5150 etc.. that use one can also suffer from IMD because of it too. Amps like the H&K triamp that also use this used a bit of voltage feedback around that stage as well to try to mitigate it.
Michael also does factory bias the 5881's in those amps cold as well and recommends doing so not because of warranty, but because he feels it sounds best that way. I believe he prefers something like 20ma per valve.
Yes, The Slo has what has been coined a "Cold Clipper", but in the SLO it so extreme, it's nearly a half wave rectifier. Amps like the SLO, recto, 5150 etc.. that use one can also suffer from IMD because of it too. Amps like the H&K triamp that also use this used a bit of voltage feedback around that stage as well to try to mitigate it.
Michael also does factory bias the 5881's in those amps cold as well and recommends doing so not because of warranty, but because he feels it sounds best that way. I believe he prefers something like 20ma per valve.
JMP/HBE
Well-known member
Joey Voltage
New member
Re: Is a Soldano SLO a "cold clipper" ?
Correct. It’s typically looked at as the “bad” unpleasant and dissonant type distortion in audio but the other side of this is that you will also have varying degrees of it with the “good” distortion, so it’s just a byproduct of distortion in general. In the slo’s Case it’s isnt terrible and it’s part of that amps sound honestly. It’s more audible especially on longer sustained chords.
On a related topic, some say that extremely cold biased stage was a happy accident, and he was really reaching for a 3.9k and misread the multiplier color band. Mike would tell you he was actually aiming for a more symmetrical square wave from the preamps output. I honestly think it was both. That stage is almost a contradiction in some ways. It distorts like mad, but it’s also the most responsible for how somewhat refined the slo’s preamp sounds as well.
Correct. It’s typically looked at as the “bad” unpleasant and dissonant type distortion in audio but the other side of this is that you will also have varying degrees of it with the “good” distortion, so it’s just a byproduct of distortion in general. In the slo’s Case it’s isnt terrible and it’s part of that amps sound honestly. It’s more audible especially on longer sustained chords.
On a related topic, some say that extremely cold biased stage was a happy accident, and he was really reaching for a 3.9k and misread the multiplier color band. Mike would tell you he was actually aiming for a more symmetrical square wave from the preamps output. I honestly think it was both. That stage is almost a contradiction in some ways. It distorts like mad, but it’s also the most responsible for how somewhat refined the slo’s preamp sounds as well.
misterwhizzy
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
If someone answering your question needs the picture, do you really trust his or her response?
Yes/no ?
If someone answering your question needs the picture, do you really trust his or her response?
JMP/HBE
Well-known member
Re: Is a Soldano SLO a "cold clipper" ?
I Graduated College no Computers, looking at the Pictures ...
I Graduated College no Computers, looking at the Pictures ...
