An acquaintance of mine has made the following assertion (see [1] below). This is counter-intuitive to me and doesn't match my experience; my response is at [2] below.
This is a smart guy; he works in scientific research and builds amps on the side.
I would love to hear your thoughts on this issue.
[1]
• Power tubes have very little to do with tone quality unless they are driven to clip
o This will only happen in a scenario where the preamp chain is relatively low gain and the power tubes are clipped through high volume settings (I would assume especially master volume settings) and/or higher input from the guitar (e.g. hot pickups or hard playing)
o At clipped levels power tubes will make a huge difference in tone quality
• Therefore, the any tone differences between EL84, EL34, 6L6 amps have little to do with the power tubes and mostly are due to amp design, preamp tubes, and biasing
Furthermore, he asserts:
"Everything else being equal you shouldn’t be hearing much difference between different tubes until they’re driven to the point of clipping. This is based on my experience designing and building amps. Output transformer, preamp and speaker define most of the tone of a medium to high gain amp. Cleans are a different story, there breakup comes into play when you hit the strings hard and there’s no preamp to speak of (just a couple of triodes and that’s it).
You see similarities between Boogie IIC+ and Fender because Boogie IS a Fender with an extra gain stage or two and tweaked tone shaping. These days they hypocritically brag about their patents on stuff other people invented decades ago, but back then they didn’t see anything wrong with “borrowing” their designs from Fender. That’s why it farts out when you turn the Bass knob past around 4 on the gain channel. They took a Fender circuit (with tone stack after the first stage) and threw in some more gain and master volume.
Likewise, you hear similarities between Ace and Marshall because Ace is most likely a Marshall from gain architecture standpoint (I assume it’s similar to Recto with a few component values changed and a different output transformer. And Recto is pretty much based on Soldano SLO with different voicing and a few bells and whistles). I have not played Lonestar/Dr Z/Vox, so I won’t comment on them.
The main reason why LSS and LSC sound differently is because:
a. They have a different output transformer. OT is a very important part that defines your amp’s high frequency roll-off and bottom end density.
b. Their tubes are biased differently, with LSS biased hotter. This further emphasizes the differences between the two, since smaller transformer will change its frequency response differently as you increase idle current. This is also why 100W amps sound differently with two out of 4 tubes pulled out – less core saturation, slightly different frequency response.
Also, even though Mesa claims that LSS is “Class A”, it really is not (and neither is Vox), in all modes but 5W (at 5W it has no choice because single ended amp can only be class A). The max you can get from four EL84 in “real” class A is about 10W per pair.
Here’s an article that explains why that is: http://www.aikenamps.com/VoxAC30classA_2.html"
[2]
My response:
This is very interesting information; that said, as an experienced player I observe that: EL34s sound boxy, 6L6 sound round and fendery, EL84 sounds bright and chimy. Am I hearing the sounds of different (but similar between e.g. Marshall/Ace) designs, not different output tubes? I don’t know enough about amps to know. Required premises for the argument would be: Lone Star ‘Classic’ is fundamentally a fender (clean channel is very Fendery); similarities between Marshalls (among themselves) and in comparison with an Ace are enough that it’s not the EL34s that make them sound the same to me; LSS is enough like a Vox or Dr. Z to account for the similarity in sound.
It is hard for me to imagine that amp designers use different tubes if they really make little difference. I would assume they would then design their amps to sound as desired (preamp stage, trannies, etc.) and then use the most reliable power tubes possible. I understand that EL84s are less reliable then 6L6; it is therefore counter-intuitive that e.g. Mesa would use them for anything.
Where did you get your information on LSS/LSC?
I’ve heard the argument about true class A vis-à-vis LSS and AC30 and it is compelling.
This is a smart guy; he works in scientific research and builds amps on the side.
I would love to hear your thoughts on this issue.
[1]
• Power tubes have very little to do with tone quality unless they are driven to clip
o This will only happen in a scenario where the preamp chain is relatively low gain and the power tubes are clipped through high volume settings (I would assume especially master volume settings) and/or higher input from the guitar (e.g. hot pickups or hard playing)
o At clipped levels power tubes will make a huge difference in tone quality
• Therefore, the any tone differences between EL84, EL34, 6L6 amps have little to do with the power tubes and mostly are due to amp design, preamp tubes, and biasing
Furthermore, he asserts:
"Everything else being equal you shouldn’t be hearing much difference between different tubes until they’re driven to the point of clipping. This is based on my experience designing and building amps. Output transformer, preamp and speaker define most of the tone of a medium to high gain amp. Cleans are a different story, there breakup comes into play when you hit the strings hard and there’s no preamp to speak of (just a couple of triodes and that’s it).
You see similarities between Boogie IIC+ and Fender because Boogie IS a Fender with an extra gain stage or two and tweaked tone shaping. These days they hypocritically brag about their patents on stuff other people invented decades ago, but back then they didn’t see anything wrong with “borrowing” their designs from Fender. That’s why it farts out when you turn the Bass knob past around 4 on the gain channel. They took a Fender circuit (with tone stack after the first stage) and threw in some more gain and master volume.
Likewise, you hear similarities between Ace and Marshall because Ace is most likely a Marshall from gain architecture standpoint (I assume it’s similar to Recto with a few component values changed and a different output transformer. And Recto is pretty much based on Soldano SLO with different voicing and a few bells and whistles). I have not played Lonestar/Dr Z/Vox, so I won’t comment on them.
The main reason why LSS and LSC sound differently is because:
a. They have a different output transformer. OT is a very important part that defines your amp’s high frequency roll-off and bottom end density.
b. Their tubes are biased differently, with LSS biased hotter. This further emphasizes the differences between the two, since smaller transformer will change its frequency response differently as you increase idle current. This is also why 100W amps sound differently with two out of 4 tubes pulled out – less core saturation, slightly different frequency response.
Also, even though Mesa claims that LSS is “Class A”, it really is not (and neither is Vox), in all modes but 5W (at 5W it has no choice because single ended amp can only be class A). The max you can get from four EL84 in “real” class A is about 10W per pair.
Here’s an article that explains why that is: http://www.aikenamps.com/VoxAC30classA_2.html"
[2]
My response:
This is very interesting information; that said, as an experienced player I observe that: EL34s sound boxy, 6L6 sound round and fendery, EL84 sounds bright and chimy. Am I hearing the sounds of different (but similar between e.g. Marshall/Ace) designs, not different output tubes? I don’t know enough about amps to know. Required premises for the argument would be: Lone Star ‘Classic’ is fundamentally a fender (clean channel is very Fendery); similarities between Marshalls (among themselves) and in comparison with an Ace are enough that it’s not the EL34s that make them sound the same to me; LSS is enough like a Vox or Dr. Z to account for the similarity in sound.
It is hard for me to imagine that amp designers use different tubes if they really make little difference. I would assume they would then design their amps to sound as desired (preamp stage, trannies, etc.) and then use the most reliable power tubes possible. I understand that EL84s are less reliable then 6L6; it is therefore counter-intuitive that e.g. Mesa would use them for anything.
Where did you get your information on LSS/LSC?
I’ve heard the argument about true class A vis-à-vis LSS and AC30 and it is compelling.
