Super Champ XD: All tube?

[elicross]

I've seen the clips on YouTube and read glowing reviews here about the Super Champ XD, but I have a question about it: How does it work?

When the XD amps were first announced, I assumed they had a solid state preamp and a tube power section, since they do some form of amp modeling. But I've also seen them described as "all-tube" amps. Which is right? Are the various voicings on Channel 2 done by solid-state, digital modeling, or is that channel 100 percent tube?

Bonus question: Channel 1, the one with just a volume knob -- is that basically a BF Champ circuit with a 15w power section?

[redb]

my guess, again guess, is that it has a digital modeling bit that it then runs into the 12ax7and then into the two 6v6s

[NTBluesGuitar]

It is not all tube.

It's a tube power/output with digital preamp. Not really solid state (that infers transistors and opamps), but digital, meaning 0s and 1s and math applied to the input signal then fed to the tube power end.

Think about the Hot Rod series amps, they're not tube reverb, but have a reverb tank being fed and recovered with opamps. That's solid-state.

Digital is like those Boss FDR-1 pedals...how do you stuff a reverb tank in one of those? It's digitally modeled in the same way.

I'm still looking for a schematic to confirm, but I'm pretty sure I'm close.

[redb]

It is not all tube.

It's a tube power/output with digital preamp.

This is probably more accurate than it being all tube, but it does have tube preamp. I suppose having anything thats not driven (ie the effects) is not "all tube". Ill edit my post.

[elicross]

Thanks, TJ. I've always thought "solid state" meant "any electronics that don't use tubes." To me, even if a circuit uses AD/DA converters and DSPs and whatnot, it's still solid state -- so a digital circuit is solid state, but not all solid state circuits are digital.

[NTBluesGuitar]

Yeah, the way I see it, is that digital is to solid state, as solid state is to analog/tubes. Probably just my own semantics, but it's how I see it. There are likely some solid state parts in digital stuff though, so it's probably not the best definition. That, and digital modeling is pretty new, too.

Redb, I think that the one preamp tube is really acting as a phase inverter which is why I lumped it into the power/output stage. Again, I could be wrong on that. But considering the preamp models included, I can't see that preamp tube used specifically for an early stage amplification job, as all the amps modeled in the SCXD use those same early stages pretty differently.

If I ever find a schematic, or get to see the guts, I may be able to tell more.

In the end, it's a really fun amp and does sound pretty good. I always like playing with them when I'm at a music store.

[redb]

Redb, I think that the one preamp tube is really acting as a phase inverter which is why I lumped it into the power/output stage. Again, I could be wrong on that. But considering the preamp models included, I can't see that preamp tube used specifically for an early stage amplification job, as all the amps modeled in the SCXD use those same early stages pretty differently.

isnt it possible to have one preamp going into another though? I have an english muff'n pedal that EH insists is a tube preamp (though if thats true I dont know) and I run that into my amps input jack. So wouldnt it be possible to have a digital/ss preamp with the models in them and then run that into what would basically be a single tube preamp amp? Like, basically having two preamps and one poweramp in one box?

That would basically be the equivalent of sticking a multi effects pedal into the amp wouldnt it?

That being said, I dont know anything about circuites beyond what they teach you in high school physics (they dont teach us econ majors anything fun =/ ) so it may very well be a phase inverter instead of preamp amplification.

[bluestrat]

As I understand the SCXD:


the scxd is a hybrid tube amp.
2- 6v6's in the power amp section
1- 12ax7a in the preamp section.

the different tonal models are computer chip derived-
then sent through half of the 12ax7a then through the 6v6 power section.

(I think)

[ziess]

http://www.fender.com/support/amp_sc...r_Champ_XD.pdf

Basically right, but both halves of the 12AX7 are used.

[NTBluesGuitar]

Why didn't I find that schematic? Ugh.

It's definitely a phase inverter...which, technically, is the preamp. But there's no tubes in between the input jacks and there, that's for sure.

To answer the question, it's not 'all-tube'.

[redb]

Why didn't I find that schematic? Ugh.

It's definitely a phase inverter...which, technically, is the preamp. But there's no tubes in between the input jacks and there, that's for sure.

To answer the question, it's not 'all-tube'.

thats a satisfactory answer for me.

[John Richards]

The power output section of the SCXD is tubes, not solid state transistors, hence the nice "glassy tone". Tubes and transistors are both analog, not digital, devices that magnify voltages.

The preamp voicing section is all digital signal processing. That means that the incoming guitar signal is converted by an analog-to-digital convertor into a stream of numbers (2.6 million numbers per minute, or 44,100 per second usually. The numbers range from 0 to 65,000 if it's a 16-bit system). Every CD is the result of the same process. The digital "waveform" is then manipulated by computer math equations to be changed into a digital "waveform" that sounds like the various amps listed (Twin, Bassman, Hot Rod, etc). The math equations are written to simulate the equalization and resonance that exist in the various amp/cabinet/speaker combinations that we all know and love (the effects section does the same thing). The digital "waveform" is then converted back into a real analog voltage waveform by a digital-to-analog convertor that is fed into the power tubes and amplified enough to drive the speaker.

Here's an intersting article on digital guitar effects:
http://www.ewh.ieee.org/soc/es/Nov1998/01/BEGIN.HTM
It shows some of the actual math equations later in the article.

I don't know exactly what the 12AX7 does. Does anyone know if the SCXD design uses Tweed-style cathodyne or Blackface-style long tail pair 12AX7 phase inversion to drive the power tubes? And is there transistor preamplification between the DSP chip and the power tubes?

Sound-wise, the clean channel is the same as selector position 4 (Blackface) with the gain on 9 or so.

Considering that my beautiful analog input device (Deluxe American Ash Strat) is changed into a stream of numbers, I'm very impressed with the sound of the SCXD!!! It has a few setting combinations that have that harsher, flatter digital clipped resonance, but less than 10 out of the couple of hundred setting combinations that are possible (and quite usable). The only thing I'm not impressed with is the chorus effect. But I am just loving this amp.


Yes, that's a Weber ceramic Cali speaker, 14" tilt-back legs, and chicken head knobs for the selector switches. And yes, the whole neighborhood woke up to Voodoo Child recently.

John
San Francisco

[NTBluesGuitar]

I don't know exactly what the 12AX7 does. Does anyone know if the SCXD design uses Tweed-style cathodyne or Blackface-style long tail pair 12AX7 phase inversion to drive the power tubes?

Wow, thanks for that, John. You explained the digital-to-analog relation extremely well for me!

I'm not always good at using the words and getting them to come out right thing when trying to describe what's rollin' around in my head.

But to answer your question, my initial study of that 12AX7 in the schematic leads me to believe it's a split-load (cathodyne) phase inverter. But I only studied one half of it so far.

Regardless, I still think it's a really cool amp that sounds great. At the price, it's a real winner.

[elicross]

Thanks, guys. That clears up a lot.

So even the clean channel, with just a volume knob and no models, is not "all tube." I guess the fact that it has a 12AX7 and two 6V6s has led some people to think it must be all tube (which is kind of understandable, I guess; my own all-tube amp has just a 12AX7, one 6V6, and a 5Y3GT, and if it had a solid state rectifer, it wouldn't even have that last one ), and that misconception has kind of made its way around the Intarwebs -- which led to me wondering if it could be true, and if Fender had found some brilliant way to give an all-tube amp 20-plus different voicings.

It's a neat little amp, based on the Youtube clips I've seen. I should probably try one out in person...although I don't really need to find myself wanting a second amp. I've seen what that can lead to....

[Don]

I just tried one this morning and was pretty impressed! It's a nice little amp!

[NTBluesGuitar]

...my own all-tube amp has just a 12AX7, one 6V6, and a 5Y3GT...

But your amp is one of the the most pure circuits out there and kind of 'special'. Yours is the polar opposite of what a digital modeling amp is. What you would benefit from in the SCXD is the BlackFace sounds, reverb, tremolo, and the other effects. And of course, the Hot Rod channels...

Hell, a Tweed Champ and a BF Champ/Vibrochamp/Low-Watt European/et. al would definitely round out your sonic library for practice and recording uses!

Plus, it's a lot of fun. I'm seriously considering one for the office for practice/jams.

[bluestrat]

I'm seriously considering one for the office for practice/jams.

from one "tom" to another - go ahead and get an scxd for your office.
a "tom" wouldn't steer you wrong ....

[phantomman]

They really are kewl leetle muh-chines an' for the money, a bargain IMO. I love what John (above) has done to his. I'm bettin' it really kicks with that Weber.

[elicross]

But your amp is one of the the most pure circuits out there and kind of 'special'. Yours is the polar opposite of what a digital modeling amp is. What you would benefit from in the SCXD is the BlackFace sounds, reverb, tremolo, and the other effects. And of course, the Hot Rod channels...

Hell, a Tweed Champ and a BF Champ/Vibrochamp/Low-Watt European/et. al would definitely round out your sonic library for practice and recording uses!

Plus, it's a lot of fun. I'm seriously considering one for the office for practice/jams.

Yeah, the Tweed Champ was the perfect amp for me. I was wanting a real tube amp, never having had one before, to see what all the fuss was about and to know I had one absolutely pure, old-school piece of gear to play through. And of course, I needed something that I could crank without blowing the windows out. Nothing could fit the bill better than a 5F1, and the 10" speaker seems to give it warmth and depth that I don't hear in clips of 6" and 8" Champs. It's a sweet little amp.

I don't know that I'll ever actually get a Super Champ XD. I'm very intrigued by it, but do I actually need it? Probably not. (Then again, do I actually need to play guitar? Well...yeah. At this point, I do. )

I've been thinking about getting an AS73 or some other Gibson-scale, dual-humbucker guitar. If I decide the tweed Champ isn't the ideal amp for that kind of guitar, I'll definitely take a serious look at the XD. But the tweed isn't going anywhere anytime soon. I'll just have two amps.

[phantomman]

I'll just have two amps.

Only two?

[Don]

Here's the schematic from the Fender website.
http://www.fender.com/support/amp_sc...r_Champ_XD.pdf

It looks like the 12AX7 is the phase inverter for the 6V6 power section. I think that's the right way to do a hybrid amp.

[NTBluesGuitar]

from one "tom" to another - go ahead and get an scxd for your office. a "tom" wouldn't steer you wrong ....

How true! I'm definitely looking out for one.

Only two?

Hey, I only have 1 1/2...of my own. But there are usually at least two more that aren't mine laying around.

...I don't know that I'll ever actually get a Super Champ XD. I'm very intrigued by it, but do I actually need it? Probably not

I've been thinking about getting an AS73 or some other Gibson-scale, dual-humbucker guitar. ...

Well, I can tell you that my AF-75 was a bit much for that very amp.



It just saturated the amp too easily for my tastes, even in the second input. I was after a rich, clean, jazz/blues sound, though, and you may not be.

With that said, the SCXD (or another amp) may be what you need if you find the same with that Ibanez you're looking at.

[elicross]

That's such a nice-looking guitar!

I'm mostly interested in a Gibson-style semi-hollow guitar because I love the sound of B.B. King and Clapton's ES-335 stuff. (I'd been thinking about more of a Les Paul-type guitar, but then I realized a lot of the non-Fender blues sounds I like came from a 335 or 345, not an LP.) So I do like me some overdrive and breakup -- but I'm not sure I want that to come from the guitar pushing the front end too hard.

On the other hand, I'm still really tempted by the Classic Vibe Tele, too -- and I know that would sound fantastic through the tweed Champ.... It may be that I've got four guitars and two amps in my future. No idea how near that future is, though.

[NTBluesGuitar]

That's such a nice-looking guitar!

I'm mostly interested in a Gibson-style semi-hollow guitar because I love the sound of B.B. King and Clapton's ES-335 stuff.

On the other hand, I'm still really tempted by the Classic Vibe Tele, too -- and I know that would sound fantastic through the tweed Champ....

Your future sounds fun.

The reason I sought out the AF-75 was the Clapton 335 stuff, too. But, I also wanted a good, rich, jazz sound. Scofield is another reason I looked at the semi-hollow bodied model, but I did realize that his sound isn't dependent on how hollow his axe is.

I think semi- or full- hollow will get you where you want to be. The only reason I ended up with the full hollow was how it felt on me. Not trying to convince you to go against the semi-hollow, that's for sure!

Of course, the CV Tele is a winner no matter how you slice it.

I do know that there needs to be more amp wattage to get even closer. Just my pair o' pennies.

[Cygnus X1]

NT...Stop It!




I love that Ibby...

[jjthinline]

Speaking of of this amp...can I fit a 12" in there?

[bluestrat]

Speaking of of this amp...can I fit a 12" in there?

the cabinet's too small for a 12".

[goofballone]

Speaking of of this amp...can I fit a 12" in there?

the cabinet's too small for a 12".

Oh! Oh! sounds like project time!!!

[hieroglyph]

I didn't 'need' a SC XD, but when you consider that if you hunt around and get a little off list, it is no more money than a good pedal. In fact that is exactly how I use mine! I wanted a tremolo pedal and something that gave me some reverb aka a Deluxe Reverb vibe and then of course it does what that BOSS FDR-1 pedal does but better!

So I ordered it with footswitch, and run in stereo with other amps that don't have the FX it has or the Champ or Blackface or Bassman tones, and it gives you the best 'organic sounding' soundmix you could ask for - hell its cheaper than a Klon and 10 times as good!!!

How could you NOT

[javlib]

Do you get any Marshall type sounds with this amp?

[CocoTone]

Voice 13, gain on 3, gives you a very nice Marshall tone, and sounds great with a pair of Grennbacks.

CT.

[Direstraits]

I was contemplating one of these for it's versatility, but felt that what I really wanted was a straightforward small "all tube" amp & I eventually grabbed a Blackstar HT-5 combo. Admittedly you don't get all the voices of the Super Champ XD but it's worth trying if you can lay your hands on one. Really - you need to try one if you are looking for a small amp.

[Yardbird Mac]

I have one, and I'm thinking about buying another once I get back on track with my health. I would throw an A/B box between them in order to get more effects combinations. I wouldn't gig with it, but I might jam and record with it. I love this little amp!!!