'All tube' may not mean all tube...

TC 57

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You often see tube amps described as 'all tube'; but what does that mean? When you delve further into the technicalities many tube amps are actually a hybrid of tube and solid state working together . The initial gain stage of the overdrive is SS. Digital Reverb has mostly replaced the spring tank, same with tremolo. with a MOSFET in the gain stage, some pedals inc. overdrive will react differently. It may explain also why people cant hear much or any difference in sound quality between SS and Tube amps. SS amp technology has improved a lot of course.
Genuine all tube amps, tube driven overdrive, spring reverbs, more tubes in the circuit, are still out there, if you can pay the extra, but they sound superb...
 

mexicanyella

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Superb sound means different things to different people, and being all tube in design does not guarantee it. Tonal preferences and dynamic response preferences vary, and everyone juggles their own “hear with their eyes/hear with their ears” psychoacoustics issues differently. I don’t think it works to generalize as broadly as your last statement does.

On the other hand, it’s a great time to be a guitarist (and/or bassist); there are about a zillion choices at different price points all along the all-tube, tube + SS, all-SS spectrum, and many ways to achieve (subjectively) great sound.
 

Dacious

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Virtually every Mesa Boogie since the F series uses all tube signal paths for the input, including drive/overdrive and reverb. Mostly they sound great but 'great' is subjective.

Solid state for things like reverb or tremolo where you don't want (much if any) distortion can work. Mesa with its early noughties F-series used chip driven and recovered reverb with long spring tank and it's great. Vox AC15C1 and AC30s use chips for the reverb and tremolo and they're pretty fine with the right tank.

I prefer real tube reverb and trem myself - but I can't definitively state it sounds better. Of course, chip driven reverb and tremolo normally comes with PCBs. I'd prefer tagboard construction which is usually all tubes from a maintenance perspective.

Modern Riveras use chip driven reverb and it's great.

As far as the input signal and output section goes I much prefer tubes. A MOSFET clean boost in the signal chain appears to be not too bad. I use a digital effect board in front for convenience. Of course being able to run tubes hard at volume is great.
 
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bgmacaw

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I prefer real tube reverb and trem myself - but I can't definitively state it sounds better.

I find it's kind of subjective and depends on the situation. While I like the spring reverb and trem on my '73 Princeton Reverb, I often find that I like the sound of the modulated reverb on my Keeley Caverns better in more situations. I also like the versatility of my Ernie Ball Expression Tremolo sometimes.
 

loopfinding

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Tonal preferences and dynamic response preferences vary, and everyone juggles their own “hear with their eyes/hear with their ears” psychoacoustics issues differently. I don’t think it works to generalize as broadly as your last statement does.

Right, I find it funny how mosfet is not okay in a working amp, but perfectly kosher or praised in a dumble.
 

mexicanyella

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Please list amps the manufacturer describes as “all tube” that have SS or digital gain stages.

I used to hear guys carrying on about their Marshall tube amps but not mentioning the solid state components helping achieve the crunch in the dirty channel. Or the pedals in front of the amp. Or the fact that they weren’t pushing the amp hard enough to really get their “tubes being pushed” ya-yas.

Anyway Marshall’s usually sound good to me; I wanted to tell those guys to relax. Amp sounds great, tubes or not. Go play something.
 

mexicanyella

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Does it make a difference if the rectifier is solid state or tube?

I had a pair of Valco 1 x 10 tube amps, which used 5Y3 rectifiers. On one of them the power supply transformer winding that supplied the rectifier heater current (I think?) was breaking down. If I pulled the tube rectifier and used a plug-in SS replacement rectifier, it got around that issue and allowed me to delay replacing that transformer.

With the SS rectifier in place, the amp had quite noticeably faster response, a stiffer dynamic feel and seemed significantly louder than with the 5Y3. I tried it on both amps abs the effect was the same.

With those, I preferred the 5Y3, but the SS one saved me some cash and bought me some time so I used it.
 

Peegoo

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Fender's marketing for the Super Champ XD boasted a 12AX7 as a preamp tube. Technically it's a preamp tube (it's before the power stage in the circuit), but practically it's not because the preamp on these amps is a sound engine microprocessor (100% digital modeling). The 12AX7 tube is a phase inverter for the pair of 6V6 power tubes.
 

printer2

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I had a pair of Valco 1 x 10 tube amps, which used 5Y3 rectifiers. On one of them the power supply transformer winding that supplied the rectifier heater current (I think?) was breaking down. If I pulled the tube rectifier and used a plug-in SS replacement rectifier, it got around that issue and allowed me to delay replacing that transformer.

With the SS rectifier in place, the amp had quite noticeably faster response, a stiffer dynamic feel and seemed significantly louder than with the 5Y3. I tried it on both amps abs the effect was the same.

With those, I preferred the 5Y3, but the SS one saved me some cash and bought me some time so I used it.
So how does the tube rectifier slow down the response?
 

tfarny

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In general I don't think anyone should say with any confidence that one things sounds better than another except to them personally, or for a specific purpose.
To state that SS gain stages of any kind are a degradation from the purity of tube based amplification seems a bit over the top, to say the least. To cite an obvious example, Blackface twins use a SS rectifier and that is benchmark amp for many, many players and has been for decades.
I definitely prefer SS tremolo pedals to many amp trems, in fact I used to use a Boss TR-2 tremolo in front of my silverface super. The pedal was quieter and produced a much greater range and variety of tremolo sounds than the amp.
Should I say the Boss pedal is "better" than the vibrato channel of a classic amp?
And I am really sure that I cannot distinguish tube driven spring reverb from the best digital copies in a blind test.

Finally, even the most classic all-tube designs aren't necessarily the tone you are looking for. I used to have a handwired champ clone with a toggle switch to defeat the tone stack, zero transistors. It had two really great sounds, neither of which were loud enough for gigging or quiet enough for apartment use. It might have been a "good" amp but it wasn't really very "good" for me, except for recording (which I don't really do) or occasional loud practice when my wife wasn't around.
 

mexicanyella

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Fender's marketing for the Super Champ XD boasted a 12AX7 as a preamp tube. Technically it's a preamp tube (it's before the power stage in the circuit), but practically it's not because the preamp on these amps is a sound engine microprocessor (100% digital modeling). The 12AX7 tube is a phase inverter for the pair of 6V6 power tubes.
Am I correct in recalling that at least some of the Vox modeling amps used a 12AX7 after the modeling preamp as a tiny power tube, imparting some kind of power stage compression/non-linearity mojo, which was then amplified to speaker-driving levels by a SS power amp?

If so, to me that seems like a cool way to get some real “reminiscent of a tube amp” feel with a single preamp tube. But I may have that wrong, and my playing time on those Voxes is almost nil anyway.
 

mexicanyella

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So how does the tube rectifier slow down the response?
First let me say that my understanding of how electricity works is not that far removed from how home household plumbing systems work...so anyone who wants to jump in here, please do!

But my understanding is that those 5Y3 tubes in my amps had current flow and efficiency limits, and when some super badass thing I had just played demanded a big macho jolt of current to reproduce the ass-kicking waveform at the speaker, the tube rectifier could get taxed and “lag” a perceptible amount in delivering the rectified current the circuit was asking for. Whereas the SS rectifier just delivered with no perceptible lag.

And despite that, with that particular amp I liked the saggier response better.
 




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