Tube and SS poweramp differences?

[Sixstring]

I know PA sims are not "supposed" to be used with tube PAs, but I hate the idea of giving up some of the special characteristics of the modelled power amps and missing out on something.

That's not necessarily the case. If your running a tube power amp that has enough head room to give you clean power then you can run the P/A sims. It's only when you push a tube power amp into distortion that it becomes overly colored and redundant.

The 20/20 with it's EL84 flavor IMO is way to colored of an amp and adds too much of it's own to the Axe, it's a cool little amp but skews everything in the Axe. Step to a descent wattage SS or VHT 2/50/2 and you will see what I'm talking about. The differance is very clear when using the same settings in any given preset.

Personally if I were in your position I would go for a SS amp in the 3-500 watt range (bridged or not) or the VHT if you just can't live with out tubes and can afford it .

 

[fearlessflier]

I know PA sims are not "supposed" to be used with tube PAs, but I hate the idea of giving up some of the special characteristics of the modelled power amps and missing out on something.

That's not necessarily the case. If your running a tube power amp that has enough head room to give you clean power then you can run the P/A sims. It's only when you push a tube power amp into distortion that it becomes overly colored and redundant.

The 20/20 with it's EL84 flavor IMO is way to colored of an amp and adds too much of it's own to the Axe, it's a cool little amp but skews everything in the Axe. Step to a descent wattage SS or VHT 2/50/2 and you will see what I'm talking about. The differance is very clear when using the same settings in any given preset.

OK. Interesting. I am not against adding colouring the tone with the 20/20 per se. In a way, I think it might be nice to add my own 20/20 “sauce”. I’m pretty new to this so please let me know if my thinking is flawed. But I see the disadvantages of the 20/20 approach to be:

1. Colouring of tone by 20/20 means micing the cabs is the only way to get the tone to FOH
2. If I defeat the power amp sims in the AxeFX, I am restricted to adjusting the presence knob of the 20/20, how hard it is pushed (BTW, how do you “push” it more, higher output from AxeFX, lower vol on 20/20, or the other way around?)
3. I guess I’d be effectively using the pre-amp parameters of the AxeFX amp block only. So all the parameters in the amp advanced section would become redundant? Or just some of them?

And advantages (more questions than statement):

Using AxeFX with PA modelling into SS PA, there are effectively two poweramps in the signal chain, one modelling the dynamic response between the two stages, the other simply amplifying the final sound “in isolation”. Now, it seems to be conventional to place effects like delay, chorus, reverb after pre-amp and before power amp. Why? Is it important? I can understand “after pre-amp” but is the only reason that you need to amplify the effected sound? Or is it something to do with those effects being involved in the pre-amp and power amp interaction? I hope you see what I’m getting at.

I wonder if there is an advantage to having those effects between the pre and power stages? I would get that into the 20/20, but not using the AxeF sims. I kinda guess if there was significance to this, Cliff would have modelled an FX loop into the amp blocks.

I’m sure you can see that I’m rather torn here. You seem to know the 20/20. Have you ever actually tried to combine one with the AxeFX and tweak, or are you just basing comments on the fact you know the 20/20 is a “colourful” poweramp?

Personally if I were in your position I would go for a SS amp in the 3-500 watt range (bridged or not) or the VHT if you just can't live with out tubes and can afford it .

I’m not “married” to tubes. But they are all that I know, really.

If I do end up going the “uncoloured” route, I probably would lean towards SS, just to get more headroom in a 1RU unit. The ART SLA2 seems to get a few plaudits on this forum. Used ones are not common here (Australia), but a new one is about $500 and I can't get a cheap US one becasue AC power is different. Any other any other good SS poweramps you could recommend? I’d love to know of any with universal transformer so I could buy from US ebay (Amp quality would still be the top priority)

 

[Sixstring]

I know PA sims are not "supposed" to be used with tube PAs, but I hate the idea of giving up some of the special characteristics of the modelled power amps and missing out on something.

That's not necessarily the case. If your running a tube power amp that has enough head room to give you clean power then you can run the P/A sims. It's only when you push a tube power amp into distortion that it becomes overly colored and redundant.

The 20/20 with it's EL84 flavor IMO is way to colored of an amp and adds too much of it's own to the Axe, it's a cool little amp but skews everything in the Axe. Step to a descent wattage SS or VHT 2/50/2 and you will see what I'm talking about. The differance is very clear when using the same settings in any given preset.

OK. Interesting. I am not against adding colouring the tone with the 20/20 per se. In a way, I think it might be nice to add my own 20/20 “sauce”. I’m pretty new to this so please let me know if my thinking is flawed. But I see the disadvantages of the 20/20 approach to be:

1. Colouring of tone by 20/20 means micing the cabs is the only way to get the tone to FOH
2. If I defeat the power amp sims in the AxeFX, I am restricted to adjusting the presence knob of the 20/20, how hard it is pushed (BTW, how do you “push” it more, higher output from AxeFX, lower vol on 20/20, or the other way around?)
3. I guess I’d be effectively using the pre-amp parameters of the AxeFX amp block only. So all the parameters in the amp advanced section would become redundant? Or just some of them?

And advantages (more questions than statement):

Using AxeFX with PA modelling into SS PA, there are effectively two poweramps in the signal chain, one modelling the dynamic response between the two stages, the other simply amplifying the final sound “in isolation”. Now, it seems to be conventional to place effects like delay, chorus, reverb after pre-amp and before power amp. Why? Is it important? I can understand “after pre-amp” but is the only reason that you need to amplify the effected sound? Or is it something to do with those effects being involved in the pre-amp and power amp interaction? I hope you see what I’m getting at.

I wonder if there is an advantage to having those effects between the pre and power stages? I would get that into the 20/20, but not using the AxeF sims. I kinda guess if there was significance to this, Cliff would have modelled an FX loop into the amp blocks.

I’m sure you can see that I’m rather torn here. You seem to know the 20/20. Have you ever actually tried to combine one with the AxeFX and tweak, or are you just basing comments on the fact you know the 20/20 is a “colourful” poweramp?

Personally if I were in your position I would go for a SS amp in the 3-500 watt range (bridged or not) or the VHT if you just can't live with out tubes and can afford it .

I’m not “married” to tubes. But they are all that I know, really.

If I do end up going the “uncoloured” route, I probably would lean towards SS, just to get more headroom in a 1RU unit. The ART SLA2 seems to get a few plaudits on this forum. Used ones are not common here (Australia), but a new one is about $500 and I can't get a cheap US one becasue AC power is different. Any other any other good SS poweramps you could recommend? I’d love to know of any with universal transformer so I could buy from US ebay (Amp quality would still be the top priority)

I have used the 20/20 I have also tryed Peavey, VHT, Carvin, QSC, Crown, Crest Audio. Don't misunderstand me here, I'm not trying to tell you what to use it's just my opinion with my experience in what I have found after going through the whole Tube power vrs SS power. If the 20/20 is working for you tone wise then use it. It is possible to dial out some if not most of the color that the 20/20 lends to an amp sim, but if you like all your amp sims with the 20/20 flavor then it's all good. For me it changed the amp sims a little too much and involved too much E/Qing. A lot of Axe users were in the same boat comming from a tube world and then going to SS to try to get everything the Axe has to offer without changing what the simm is supposed to emulate.

The ART is not the only SS solution out there. You could go Carvin, QSC, Crown, Samson or whatever is redally avilable down under... I don't know what you have available to you so I guess you have to hunt around. Whatever you find just try to get a quality amp that has some wattage that's the main thing. The best thing would be to borrow or rent if you can and have a lash... :mrgreen: it would be a good experience for you to have the two on hand and do an A/B and see for your self how different the two really are.

 

[axel]

If I had to choose between using the Axe FX to all of its abilities, or a better end result,

You don't.

All due respect, on second thought, never mind, my power amp is warmed up.

 

[GM Arts]

My personal experience is that tube power amps, as a whole (as in not all) tend to have less brittle, sharp. as a group, they tend to be a bit more organic and compressy...less hard sounding. Most of these are adjectives desirable to eliminate in guitar tracks.

If I was seeking a loud FRFR, I would first look into the Aragon SS power amps from the 90's and early part of this decade. They were designed by David Krell and the 4004MKII can be had for less than $600. They are one of the best kept secrets in medium high end audio. They don't have harsh SS frequencies. They have power coils that are 55 pounds in weight. Why is that good? Never trust an amp that is lightweight. I've been told that these power coils store electricity...when the bass notes hit, all of the energy is right the to explode with immediacy out of the speakers without having to wait to draw in the full amount, and also lower amount, from the wall outlet.

Fascinating explanation, but there used to be some truth to the correlation between quality and weight for power supplies that could deliver and maintain power, stored in power supply capacitors for good transient and continuous audio power capability. But these days, manufacturers are switching to switchmode power supplies (sorry couldn't resist the pun), which don't need the large power transformers, so honest specs and a good set of ears are probably your best guide now.