What makes an All Tube amp ?
- Thread starter richard parker
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Funkfingers
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Re: What makes an All Tube amp ?
Fender makes a distinction between "all tube" and "tube powered".
In the former, everything that can be rendered through tube circuitry has been. (Gain stages, EQ, onboard reverb send/return, effects loop, output stage.) e.g. Custom Shop models.
Whenever any part of the system is solid state, the amp is described as tube powered. e.g. Hot Rod series.
Fender makes a distinction between "all tube" and "tube powered".
In the former, everything that can be rendered through tube circuitry has been. (Gain stages, EQ, onboard reverb send/return, effects loop, output stage.) e.g. Custom Shop models.
Whenever any part of the system is solid state, the amp is described as tube powered. e.g. Hot Rod series.
Edgecrusher
New member
Re: What makes an All Tube amp ?
This sort of highlights the situation though... Its one what manufacturer chooses to call their amps as there is no set ruling on what constitutes all tube or hybrid. Until there is some sort of consensus the blurry situation will remain.
Even then I dont worry so much about it. I certainly dont turn my nose up at an amp cause it has diodes in it.
This sort of highlights the situation though... Its one what manufacturer chooses to call their amps as there is no set ruling on what constitutes all tube or hybrid. Until there is some sort of consensus the blurry situation will remain.
Even then I dont worry so much about it. I certainly dont turn my nose up at an amp cause it has diodes in it.
Re: What makes an All Tube amp ?
The tone from adding another tube (or more) gain stage isn't the same as that from diode clipping. I think Marshall (or whichever manufacturer) is going for a certain tone when they utilize diodes in the gain channel. It's not necessarily there to "help" the tubes because they can't provide enough gain on their own. It's part of the voicing. I wouldn't consider those amps as hybrids. Nor would I consider it a hybrid if it uses solid state rectification. I would agree that calling an amp "all tube" would constitute that everything that can be done with tubes is done with tubes, including rectification. But I think of "hybrid" meaning that they use a tube pre-amp section and SS power section. If an amp has tube pre and power amp sections, it's a tube amp and if it sounds good, doesn't matter whether it's tube rectified or uses diodes as part of the voicing. Again, it's a tube amp. "All Tube" ... personally, I don't care. I think "all tube amp" versus just "tube amp" is more about semantics than anything else unless a manufacturer is trying to pass something off as a "tube amp" when it only uses tubes in the preamp, or as a buffer.
The tone from adding another tube (or more) gain stage isn't the same as that from diode clipping. I think Marshall (or whichever manufacturer) is going for a certain tone when they utilize diodes in the gain channel. It's not necessarily there to "help" the tubes because they can't provide enough gain on their own. It's part of the voicing. I wouldn't consider those amps as hybrids. Nor would I consider it a hybrid if it uses solid state rectification. I would agree that calling an amp "all tube" would constitute that everything that can be done with tubes is done with tubes, including rectification. But I think of "hybrid" meaning that they use a tube pre-amp section and SS power section. If an amp has tube pre and power amp sections, it's a tube amp and if it sounds good, doesn't matter whether it's tube rectified or uses diodes as part of the voicing. Again, it's a tube amp. "All Tube" ... personally, I don't care. I think "all tube amp" versus just "tube amp" is more about semantics than anything else unless a manufacturer is trying to pass something off as a "tube amp" when it only uses tubes in the preamp, or as a buffer.
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Edgecrusher
New member
Re: What makes an All Tube amp ?
Sorry but that isnt necessarily true. Many times the exact reason the diodes are there are to increase the gain cause without them the amp doesnt have enough. This is exactly how they are used in the JCM900 MKIII's
Funny enough a lot of people dont understand the situation or the thinking behind many of the designs. They think well if you need more gain just dump another 12ax7 in it and bam you got 2 more gain stages. Its not that easy and many times it can be easier to use diodes to do the same thing. Particularly in terms of noise and oscillation introduced into a circuit.
Amps like the 5150 that have tons of gain stages are actually pretty gnarly to design.
People bag on Marshall for their choice of diodes in the later JCM800's and the 900's but people forget that at the time Marshall was having serious problems with tube supply. Now... if you are a manufacturer that wants to bring out a newer higher gain amp but 80% of the tubes you recieve are microphonic what do you do?
You build a circuit that has a gain stage in it but its a low voltage one so its more tolerant of out of spec tubes so now instead of 20% of your tubes being usuable 40% are you add a few diodes infront of the gain stage to do the heavy lifting and you call it a day. In the 4100's they went even further and all the gain stages are diode. The tubes are the reverb, the tone network, effects loop and cathode follower.
None of this was done for "voicing" reasons. It was a stop gap measure against the tube quality they had at the time.
Thankfully the Russians got their act sorted out and were able to start belting out reasonably reliable tubes with the chinese following not long after.
Sorry but that isnt necessarily true. Many times the exact reason the diodes are there are to increase the gain cause without them the amp doesnt have enough. This is exactly how they are used in the JCM900 MKIII's
Funny enough a lot of people dont understand the situation or the thinking behind many of the designs. They think well if you need more gain just dump another 12ax7 in it and bam you got 2 more gain stages. Its not that easy and many times it can be easier to use diodes to do the same thing. Particularly in terms of noise and oscillation introduced into a circuit.
Amps like the 5150 that have tons of gain stages are actually pretty gnarly to design.
People bag on Marshall for their choice of diodes in the later JCM800's and the 900's but people forget that at the time Marshall was having serious problems with tube supply. Now... if you are a manufacturer that wants to bring out a newer higher gain amp but 80% of the tubes you recieve are microphonic what do you do?
You build a circuit that has a gain stage in it but its a low voltage one so its more tolerant of out of spec tubes so now instead of 20% of your tubes being usuable 40% are you add a few diodes infront of the gain stage to do the heavy lifting and you call it a day. In the 4100's they went even further and all the gain stages are diode. The tubes are the reverb, the tone network, effects loop and cathode follower.
None of this was done for "voicing" reasons. It was a stop gap measure against the tube quality they had at the time.
Thankfully the Russians got their act sorted out and were able to start belting out reasonably reliable tubes with the chinese following not long after.
Re: What makes an All Tube amp ?
Wow.....very weird definitions going on.
Diodes are passive, they do not add gain, they add "clipping" or "distortion".
And, as said already, how many guys complaining about a few diodes ruining their All Tube Amp, use 2-3-4-5 pedals that are Full Of SS devices.?
I have built two amps where I used diodes to bias the preamp tubes. If somebody told me that the amp was not "all tube" because of that.......
Wow.....very weird definitions going on.
Diodes are passive, they do not add gain, they add "clipping" or "distortion".
And, as said already, how many guys complaining about a few diodes ruining their All Tube Amp, use 2-3-4-5 pedals that are Full Of SS devices.?
I have built two amps where I used diodes to bias the preamp tubes. If somebody told me that the amp was not "all tube" because of that.......
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GilmourD
Burritotoneologist
Re: What makes an All Tube amp ?
Sent from my Moto X 2014 using Tapatalk
PicoValve is definitely a 100% all-tube signal path. I've been inside mine and made some minor mods to the circuit. Nice little amp.
Sent from my Moto X 2014 using Tapatalk
Re: What makes an All Tube amp ?
zzmoore ... that's my understanding of what diodes do as well, in this type of application. They clip the top of the waveform which results in a type of distortion but they add no gain. I think they actually reduce gain because of their effect on the signal. They may be there because the manufacturer didn't want to add pre-amp gain with tubes. But, I think I clearly stated that they are not necessarily used for that purpose. Again, they are not a gain stage. I am no tube amp designer and I fully admit that I can struggle with a schematic. But I do know that they may also be used to voice an amplifier for a certain sound (distortion).
zzmoore ... that's my understanding of what diodes do as well, in this type of application. They clip the top of the waveform which results in a type of distortion but they add no gain. I think they actually reduce gain because of their effect on the signal. They may be there because the manufacturer didn't want to add pre-amp gain with tubes. But, I think I clearly stated that they are not necessarily used for that purpose. Again, they are not a gain stage. I am no tube amp designer and I fully admit that I can struggle with a schematic. But I do know that they may also be used to voice an amplifier for a certain sound (distortion).
GuitarStv
Sock Market Trader
Re: What makes an All Tube amp ?
It's rare for diodes to be used to generate clipping in guitar applications without some kind of signal booster. Otherwise when you turn the distortion up you end up with a quieter signal. I'm assuming that when you crank a JCM800 with diodes in the preamp you don't end up with a quieter signal? If so, then I think we can safely assume that the diodes used for clipping are part of a gain circuit.
It's rare for diodes to be used to generate clipping in guitar applications without some kind of signal booster. Otherwise when you turn the distortion up you end up with a quieter signal. I'm assuming that when you crank a JCM800 with diodes in the preamp you don't end up with a quieter signal? If so, then I think we can safely assume that the diodes used for clipping are part of a gain circuit.
Re: What makes an All Tube amp ?
If there is any gain associated with diode clipping, it is due to gain being added to the circuit. Either another (or hotter biased) tube is switched into the chain, or there are SS Devices attached to the diode clipping. By themselves, diodes are lossy and would reduce gain.
Some of these guys that have these amps may know, from looking at the schem, what is really going on.
I have never, really, dealt with diodes in this situation before.
I have no education in this stuff, but I would say you two are correct.
If there is any gain associated with diode clipping, it is due to gain being added to the circuit. Either another (or hotter biased) tube is switched into the chain, or there are SS Devices attached to the diode clipping. By themselves, diodes are lossy and would reduce gain.
Some of these guys that have these amps may know, from looking at the schem, what is really going on.
I have never, really, dealt with diodes in this situation before.
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Steppin' Wolfe
New member
Re: What makes an All Tube amp ?
IMho, anytime the signal is processed in anything other than a tube, the amp is not an all-tube amp. Rectifiers do not process signal....they provide the power supply.
distortion created with diodes inserts soem solid state device into the signal chain. So does overdrive with IC's....as in say a JCM 900 HI-gain Dual Reverb....which also has solid state reverb, which quailifies as non-tube processing imho.
As to letting a manufacturer play with definitions in order to massage the market, that does not a tube amp make, either. EX: Fender HOT rod/Blues series, Peavey Classic 30 & 50, almost all modern Marshalls....there is solid state processing gong on in those amps...reverb for sure in the Fenders and Peaveys mentioned....and even more in a lot of Marshalls. I opened up a Vintage Modern a month ago.....solid state processing galore.....very inexpensively built amp for the money that people pay for them. I would take a 5150/6505 Peavey any day if I were looking for that type of amp...hi gain.
IMho, anytime the signal is processed in anything other than a tube, the amp is not an all-tube amp. Rectifiers do not process signal....they provide the power supply.
distortion created with diodes inserts soem solid state device into the signal chain. So does overdrive with IC's....as in say a JCM 900 HI-gain Dual Reverb....which also has solid state reverb, which quailifies as non-tube processing imho.
As to letting a manufacturer play with definitions in order to massage the market, that does not a tube amp make, either. EX: Fender HOT rod/Blues series, Peavey Classic 30 & 50, almost all modern Marshalls....there is solid state processing gong on in those amps...reverb for sure in the Fenders and Peaveys mentioned....and even more in a lot of Marshalls. I opened up a Vintage Modern a month ago.....solid state processing galore.....very inexpensively built amp for the money that people pay for them. I would take a 5150/6505 Peavey any day if I were looking for that type of amp...hi gain.
Edgecrusher
New member
Re: What makes an All Tube amp ?
It depends really on the exact amp. Some of the JCM900's the diode bridge doesnt include an IC as a gain stage and are only used for clipping. Others the gain stages are completely solid state. Some amps like the peavey ultra series have clipping diodes after the tubes. Some like in the jose arrendo mod the diodes are part of the master volume circuit. So it really all just depends.
It depends really on the exact amp. Some of the JCM900's the diode bridge doesnt include an IC as a gain stage and are only used for clipping. Others the gain stages are completely solid state. Some amps like the peavey ultra series have clipping diodes after the tubes. Some like in the jose arrendo mod the diodes are part of the master volume circuit. So it really all just depends.
Edgecrusher
New member
Re: What makes an All Tube amp ?
All the gain stages and clipping in a vintage modern is done with tubes. Sure if you open one up there are plenty of solid state components but they are for the switching and rectifying circuits. They are not in the audio path.
All the gain stages and clipping in a vintage modern is done with tubes. Sure if you open one up there are plenty of solid state components but they are for the switching and rectifying circuits. They are not in the audio path.
Nostalgic Distortion
New member
Re: What makes an All Tube amp ?
Rectifiers aren't in the signal chain but they do affect the signal, or at least they can affect the sound. Tube rectifiers drop voltage under load and don't recover immediately. "Sag". It can be heard in the output (softer attack, compression, bloom, sustain, spongier bass). I'm not arguing that it's "better" to use rectifiers (even though I am a Mesa fan and think they still have their place). Most amp designers probably don't think it is and the majority of amps are SS rectified now. But I think if were calling an amp "all tube", they get included. But again, I'm not hung up on the semantics. I don't care if it's a tube amp or an all tube amp if I like the sound.
Rectifiers aren't in the signal chain but they do affect the signal, or at least they can affect the sound. Tube rectifiers drop voltage under load and don't recover immediately. "Sag". It can be heard in the output (softer attack, compression, bloom, sustain, spongier bass). I'm not arguing that it's "better" to use rectifiers (even though I am a Mesa fan and think they still have their place). Most amp designers probably don't think it is and the majority of amps are SS rectified now. But I think if were calling an amp "all tube", they get included. But again, I'm not hung up on the semantics. I don't care if it's a tube amp or an all tube amp if I like the sound.
GuitarStv
Sock Market Trader
Re: What makes an All Tube amp ?
We're probably on the same page for this one. All tube isn't a guarantee of awesome, nor is having other elements in the amp design a sign of a poor amp.
We're probably on the same page for this one. All tube isn't a guarantee of awesome, nor is having other elements in the amp design a sign of a poor amp.