Pod XT or Vox Tonelab SE

Quattroste

Does anyone have either of these especially the Tonelab and care to let me know what you think?

feylya

http://www.boards.ie/vbulletin/showthread.php?t=295629

Could be handy. I'm still undecided. The Tonelab does seem to be cool though.

Quattroste

Dammit. That's not what I wanted to hear. I wanted to hear the Tonelab all the way!!!!

I think I'll just get the Tonelab SE. Someone on the other thread said the tube was just their for fun but on my Big Ben overdrive its not just astethic!

Beecher

I have a tonelab here, got it for late night practicing with headphones but it has made its way into my main rig. I a/b it with my Engl pre-amp, use the Engl for distortion and the tonelab for clean.

Sounds wise it definitly sounds a lot more tube like than a pod-xt, but the POD has a superior selection of effects. Check out the tonelab yahoo group (im way too tired to look for it), theres some demo songs of it which are savage, aswell as the tonelab patches to achieve those tones!

sei046

I prefer the tonelab personally coz it sounds more authentic but they are both great

Custom22

I don't know if its been said but as the voltage being used in the tonelab are so low, the valve is in fact lit up by a couple of LEDs and not glowing like one in proper amp would. Still, thisobviously doesnt affect the sound; its still doing its intended purpose, just sort of disappointes though. No big deal. I'd go for the Vox.

Custom22

http://www.korgstudios.com/forum/topic.asp?TOPIC_ID=4139

Useful.

Eoin Madsen

Custom22 wrote:

I don't know if its been said but as the voltage being used in the tonelab are so low, the valve is in fact lit up by a couple of LEDs and not glowing like one in proper amp would. Still, thisobviously doesnt affect the sound; its still doing its intended purpose, just sort of disappointes though. No big deal. I'd go for the Vox.

Not entirely true. All you need to light up the valve filament as per usual is 12vDC or 6.3vAC. Any more or less is quite bad for the valve. The fact is, 12AX7s really don't glow that much, it's usually the power stage valves that people see.

As for doing it's intended purpose - that depends on what you think it's supposed to do. In that circuit that valve can't possible operate like a valve in a guitar preamp. A 12AX7 runs with anything from 100-300 volts on the plate. The amount of plate voltage affects the amount of gain/headroom of the valve. With 12v on the plate, it's safe to assume that the valve is not contributing to the amplification at all.

Custom22

Eoin Madsen wrote:

Not entirely true. All you need to light up the valve filament as per usual is 12vDC or 6.3vAC. Any more or less is quite bad for the valve. The fact is, 12AX7s really don't glow that much, it's usually the power stage valves that people see.

As for doing it's intended purpose - that depends on what you think it's supposed to do. In that circuit that valve can't possible operate like a valve in a guitar preamp. A 12AX7 runs with anything from 100-300 volts on the plate. The amount of plate voltage affects the amount of gain/headroom of the valve. With 12v on the plate, it's safe to assume that the valve is not contributing to the amplification at all.

Well, read what I posted. I said the voltages being used (in the valve's circuit obviously as thats what we're talking about right..) in the vox unit are not high enough to light it up. So, entirely true.

By intended purpose I, of course, didn't mean the intended purpose of the valve itself but rather its intended purpose in the vox unit. So despite the marketing ploy by Vox (or whoever makes it), its still doing what they said it would. I should have said its *advertised* role or something instead. i do get how you could have taken it that way.

*EDIT* Totally true about 12AX7's not lighting up that much. But still, it doesnt light up at all. There simply isnt a glow at all.

Paladin

Eoin Madsen wrote:

With 12v on the plate, it's safe to assume that the valve is not contributing to the amplification at all.

How do you know its 12V on the plate?

Eoin Madsen

Custom22 wrote:

Well, read what I posted. I said the voltages being used (in the valve's circuit obviously as thats what we're talking about right..) in the vox unit are not high enough to light it up. So, entirely true.

Which is incorrect - the voltage being used here is enough for the valve filament to light up as per normal. If your filament isn't lit at all then the valve isn't working. I don't know how you could tell tbh, without removing the LED.

Paladin wrote:

How do you know its 12V on the plate?

Well, the unit takes 9vAC through an external transformer. The valve plate needs DC so I presume there's a rectifier and filter/regulator inside the unit which gives in the region of 11-12.6vDC. Which is, incidently, the same as the operating filament voltage of the ECC83 - which really can't be deviated from spec without damaging the valve. I suppose they could be ending up with a lower plate voltage but I can't see how it could be getting higher. Having another transformer seems unlikely, and more than a little inefficient.

Custom22

Eoin Madsen wrote:

Which is incorrect - the voltage being used here is enough for the valve filament to light up as per normal. If your filament isn't lit at all then the valve isn't working. I don't know how you could tell tbh, without removing the LED.

I didn't see any glow when examing one bearing in mind the LED situation. Didnt seem to be lit up at all really. Maybe it is cut out of the circuit if you're not using an amp model or dist. effect. I just didnt see any glow, not diffucult to tell.

Eoin Madsen

The filament should always be on, it's a separate circuit to the plate voltage. Cutting filament voltage out and in is never done because it's quite bad for the valve.

I would guess the valve is essentially an effect, not a gain stage (with such a low plate voltage the signal would be heavily distorted all the time if it was). So assuming it's in parallel with the signal path, the circuit will probably work even if the valve is dead.

The ECC83/12AX7 was simply never made to operate at such low voltage. Those are voltages for transistors.

HusseinSarhan

I dont think its parralell. I think its actually a 1/4watt poweramp or some such.

Eoin Madsen

Not on that voltage.

HusseinSarhan

I know, what you're saying makes sense really. I just heard that somewhere. Hmm I'll have a look on google.

HusseinSarhan

VOX Valve Reactor Circuit Delivers True Tube Amp Sound
ToneLabSE features the acclaimed VOX Valve Reactor found on Valvetronix series amps and the ToneLab amp/effects modeler. The VOX Valve Reactor circuit uses a 12AX7 triode vacuum tube together with an actual low-wattage tube power amp circuit, a virtual output transformer, and a dummy speaker circuit that simulates the impedance changes of a real speaker. It also reconfigures itself so that its characteristics are the same as the amps it's modeling (class A, class AB, negative feedback circuit, etc.) This means that all of the nuances of the original amp model including sound, feel, distortion and presence are reproduced.

Thats in the Tonelab SE.

Quattroste

Yeah but its got a tube that glows How cool is that.

Eoin. I already have the a Big Ben pedal from Vox which works off the same principal I guess. I also have a tube amp(Laney LC30) and the overdrive you get from the Big Ben is similar to the overdrive on the preamp stage of the Laney. As you know, I don't have the facilities to drive the output tubes as my neighbours and family are still alive!

I am not tube snob, I know I love that sound but its generally the artist that makes it good for me and I'm just not that talented. I reckon I could easily be fooled by Digital modelling over the real thing. It seems people generally think both units are good once you get past the glowing tube(but its soooooo cool ) in the Vox.

Anyone want to give me a Tonelab Demo?

Eoin Madsen

I notice it says "together with" the low-watt output circuit. At no point does it actually say what the function of the valve really is. I can accept that the stuff might sound great, I just can't really see how the valve could contribute to that in the tradition use of a valve. Maybe a small amount of harmonic distortion mixed in really does improve the perceived sound.

I might go digging for some schematics and see if I can turn up some more concrete information. You should pull the valve and see if the pedal still works.

Eoin Madsen

Quattroste wrote:

I also have a tube amp(Laney LC30) and the overdrive you get from the Big Ben is similar to the overdrive on the preamp stage of the Laney.

Distortion works by using one gain stage to overdrive the following gain stage. The gain control in your amp, for example, is after the first gain stage. You control the output of the first gain stage - and when it gets high enough, the second gain stage begins to distort. Adding a pedal to boost the level before the first stage in the amp works no differently. It may introduce some distortion of its own, but a lot of it will be the valves in the amp distorting.

Quattroste

There is a someone selling Tonelab's on ebay and he changes the valve prior to selling them. He "claims" that it really makes a difference! Whether its true or not is a different story but if it is, then that would point to the fact that the valve does make some difference.

Paladin

Eoin Madsen wrote:

Distortion works by using one gain stage to overdrive the following gain stage. The gain control in your amp, for example, is after the first gain stage. You control the output of the first gain stage - and when it gets high enough, the second gain stage begins to distort. Adding a pedal to boost the level before the first stage in the amp works no differently. It may introduce some distortion of its own, but a lot of it will be the valves in the amp distorting.

I think I must be misunderstanding you.
Are you suggesting that the purpose of the output from a distortion pedal for example is an increase in signal level to force a gain stage (Im not sure which one you are suggesting) to distort?

HusseinSarhan

Eoin Madsen wrote:

I notice it says "together with" the low-watt output circuit. At no point does it actually say what the function of the valve really is.

Erm, nope. Read it again, it doesnt merely say "output circuit" but rather "an actual low-wattage tube power amp circuit". As there is only one valve in the machine its function must be in this output cicuit, not just for preamp use. Anyway, I think the pedal actually does have a low-wattage, valve driven, output stage.

fitz

Problem with that is that it's a pre-amp valve type.

HusseinSarhan

Quattroste wrote:

There is a someone selling Tonelab's on ebay and he changes the valve prior to selling them. He "claims" that it really makes a difference! Whether its true or not is a different story but if it is, then that would point to the fact that the valve does make some difference.

I've heards subbing a 12AU7, 12AY7 or a 12AT7 in place of the 12AX7 actually discernably changes the tone; due to the gain level of each tube. All are cleaner than the 12AX7.

To save confusion, these are some of the common names used for preamp valves or tubes if you are from America. The ECC ones a British names I think.

12AX7 = ECC83 = 7025A
12AU7 = ECC82
12AT7 = ECC81
12AY7 = 6072A

fitz

Paladin wrote:

I think I must be misunderstanding you.
Are you suggesting that the purpose of the output from a distortion pedal for example is an increase in signal level to force a gain stage (Im not sure which one you are suggesting) to distort?

A lot of valve amp users will treat they're rig exactly this way, with their distortion pedals essentially dirtying things up only a bit, while giving a bit of a boost, and pushing the amp into overdrive.

Quite effective too.

HusseinSarhan

fitz wrote:

Problem with that is that it's a pre-amp valve type.

No problem at all, you can use it for low wattage output applications no bother. As is done here.

Paladin

fitz wrote:

A lot of valve amp users will treat they're rig exactly this way, with their distortion pedals essentially dirtying things up only a bit, while giving a bit of a boost, and pushing the amp into overdrive.

Quite effective too.

(Note: the term 'Distortion' herein is referring specifically to clipping distortion).

Yes I agree.

This is probably what Eoin meant. its just the statement

Distortion works by using one gain stage to overdrive the following gain stage.

is not true.

If a stage is to add distortion, it should need no help from the future stage, unless you are trying to distort a distorted signal like mentioned above. This is a subjective thing though.

Stage 1 can be your distortion pedal, creating a distorted signal. Stage 2 can be a pre-amp that adds no further distortion to this signal.
You can if you like, add distortion with the pre-amp, but the distortion is pre-amp distortion not caused by the input.

If stage 2 distorts because of a very high input, then it is because the user chooses stage 2 to distort. They can simply turn the gain down and it will not distort. This is the case with any gain stage.

The introduction of distortion (or not) is why there exists a gain and volume know on pre-amps, but only a master volume on the power amp. The power amp should never distort (according to design anyway, but users sometimes like it when they do).

As I write that, I am wondering if it is power-amp distortion Vox are trying to recreate.
I did a lot of research when I was doing my project analysis on valve amps, and basically the conclusion I had was that valve and transistor power amplifiers are not the source of audible difference in sounds unless you push the power amp into distortion, at which point the characteristics change.

This seems pointless since 99% of people do not operate valve amps at absolute full volume (which you need to do to get this distortion unless you use a hot-plate).
Umm... this post is going to get prohibitively long if I start going into all this now (while at work), so I think I will leave it for another day...

Eoin Madsen

Paladin, you misunderstand me. A "gain stage" is not a pedal or preamp. A preamp will contain two or three gain stages in itself. A distortion pedal may also contain several. The input level into a gain stage is what causes clipping in that gain stage. To get a single gain stage to distort you'd need it to have such a low headroom that guitar signal alone would cause clipping.

The harmonic differences between valve and solidstate amplification at low levels are documented. If I find the references again I'll forward them on to you.

HusseinSarhan, poweramp/output circuit is semantics. In the case of a preamp with a low watt "power" stage, it is more or less just an output circuit. But that's beside the point. Your conclusion that the valve must form part of that circuit is unreasoned. Read how they put it: it more or less says that it's not part of that circuit.

Regarding the ECC valves, you can use one or (more commonly) several ECC83/12AX7s as a low wattage output stage, though it's rare. The ECC83 itself has the highest gain factor of any of that valve type. All of the others you mention have less headroom and used in a single valve application such as this, should distort more easily.

Quattroste

This is great stuff lads. I'm learning a lot.

Eoin Madsen

No problem. Personally, I find it enjoyable... except for that slight edge.

Let me clarify something about volume/gain etc. since I remember a time not long ago when I had a lot of misconceptions of my own.

A volume/gain etc control is a potentiometer. Which is a variable resistor with one end connected to ground, the other end connected to where your signal is going, and the moveable centre connected to where your signal comes from. Turned all the way one way, you signal goes entirely to ground (there's no ground resistance). Turned the other way, your signal divides between a small part going to ground, and the rest continuing along the circuit (assuming the circuit has potential). That's it. It doesn't change the amplification factor of the valve or the transistor. The boost happens, all you do is reduce the level to stop one gain stage from overloading the next. In systems without the number of volume controls we have these days, they used less gain stages.

HusseinSarhan

Eoin Madsen wrote:

HusseinSarhan, poweramp/output circuit is semantics. In the case of a preamp with a low watt "power" stage, it is more or less just an output circuit. But that's beside the point. Your conclusion that the valve must form part of that circuit is unreasoned. Read how they put it: it more or less says that it's not part of that circuit.

Regarding the ECC valves, you can use one or (more commonly) several ECC83/12AX7s as a low wattage output stage, though it's rare. The ECC83 itself has the highest gain factor of any of that valve type. All of the others you mention have less headroom and used in a single valve application such as this, should distort more easily.

Ok, I don't get how my assumption is unreasoned but we'll leave that aside. They did say the it was an actual low wattage tube power amp circuit, not a transistor driven one. Anyway, I get what you mean about the preamp in an amp being a mini output stage in and of itself, makes sense, somethings got to drive the power section. I get what you mean. Now, I know the gain levels that go along with the different valves I mentioned differ. All being less than the highest, the 12AX7. If used in a preamp slot, you'll get less dirt out of them, they are lower gain. The signal will be cleaner. I think what you are saying only applies if the valve were to be used in a power amp. In which case, it would more quickly clip. Please correct me if I got you wrong. Hmmm, so in effect you are saying that the valve IS in fact, used in the so called "power amp" of the Tonelab. *EDIT* I reread what you posted just there, you were obviously speaking hypathetically about it breaking up more*EDIT* If that is what you mean by this "single valve application". When I said, "all are cleaner than the 12AX7", I meant strictly in a preamp senario. All have less gain, hence less dirt.

Paladin

Eoin Madsen wrote:

Paladin, you misunderstand me. A "gain stage" is not a pedal or preamp. A preamp will contain two or three gain stages in itself. A distortion pedal may also contain several. The input level into a gain stage is what causes clipping in that gain stage. To get a single gain stage to distort you'd need it to have such a low headroom that guitar signal alone would cause clipping.

Aaah, yes.

Thought I misunderstood what you meant alright. It was the talking about pedals boosting levels before going into preamps that confused me. Didnt realize you were talking circuit gain stages.

I stopped my ramblings earlier, before I mentined one of the conclusions of my valve project was that the overdrive output characteristic of the valve PA was caused by the transformer.

Did you notice that the speel that Vox give claim they cive the effect of the valve AND transformer?

This is why I suspect they may be trying to introduce valve PA distortion.

Eoin Madsen

HusseinSarhan wrote:

All have less gain, hence less dirt.

Not at all true. I think your understanding of gain is incorrect. Less gain means less headroom, which can mean more or less "dirt" depending on where it appears in the circuit. It's harder to cause distortion in an ECC83 than in a ECC82, but it's easier to use an ECC83 to cause distortion in the following gain stage.

As a valve taken in isolation, a 12AX7 will have the cleanest sound with the same given input signal. In this instance it's irrelevent, because with less than 12v on the plate the valve should have virtually no amplification or headroom anyway.

Paladin, I'm quite sure that OT has a huge impact on the output sound, but since there are very discernable and well documented sonic differences in both clean amplification and breakup between the different types of poweramp valves (eg EL84s, EL34s, 6L6s, KT66s etc.) it seems unlikely that the OT is the only contributer to the sound characteristic. It's not surprising that Vox have noticed the importance of the OT and are attempting to work it into their design, but I'm fairly certain that all amp modellers attempt this to one degree or another.

I'm presuming you mean poweramp when you say "PA"?

HusseinSarhan

Eoin Madsen wrote:

Not at all true. I think your understanding of gain is incorrect. Less gain means less headroom, which can mean more or less "dirt" depending on where it appears in the circuit. It's harder to cause distortion in an ECC83 than in a ECC82, but it's easier to use an ECC83 to cause distortion in the following gain stage.

I fully agree with you. I think I just didnt get my message accross right. I was speaking in terms of preamp/poweramp relations. If you swap say a 12AX7 in the first gain stage of an amp for a 12AY7 it will be cleaner if you turn the master right down and induce preamp distortion on the chanell. OK, now if you are actually using a 12AX7 as your power amp valve (single ended we are presuming) than it wil be cleaner, as you said, more headroom, more gain. I think I ought to have made that clear in my previous post. Although I did say:

If used in a preamp slot, you'll get less dirt out of them, they are lower gain. The signal will be cleaner. I think what you are saying only applies if the valve were to be used in a power amp. In which case, it would more quickly clip.

Ok I shouldnt really have actually brought the word gain into it as it does confuse the matter. Its all, as you said, relative to where they are used, when talking about distortion.

Back to the point though, I think the Vox actually does have a mini valve power amp going on inside it. I dont really know why you think thats so unlikely, or at least I think thats what your take on it is.

Paladin

Eoin Madsen wrote:

I'm presuming you mean poweramp when you say "PA"?

Yep.

Do you have sources for these documented sonic differences between the valves?

I am going buying a John Linsley Hood book on the subject in the next few days. Would like to know what data there is available on this area. I have read qa fair bit, but nothing that documented differences between specific valves.

What I have learned about the PA with valves, (and in my experiments, experience, designs and recordings, none of which are vast enough to be 100% conclusive) is that there is no audible difference between valve power amplifiers. (Pre amps, yes!).

The reason for this is that power amplifiers are just supposed to be clean. Any open loop differences (and there should be none) are rendered miniscule with feedback. And they are damn clean in general.

Eoin Madsen

Yep.

Okay, it'd probably be best not to, it's just confusing.

Paladin wrote:

The reason for this is that power amplifiers are just supposed to be clean.

I can accept that this is true for valve poweramps intended for PA applications but certainly not for poweramp stages in guitar amplifiers. Which is beside the point anyway. For one, intent has very little reflection on result in the case of a lot of technology - transistors achieve better what valves were originally intended to do. And aside from that, "clean" is not the only sonic characteristic, there are timbral variations not associated with overdrive or spectral colouration. Honestly, do some googling on the subject and you'll find answers quicker than I can give them to you. The only debate I've across is whether valve or solidstate is "better", I haven't really encountered anyone disputing that they sound different tbh. I can accept that the difference is likely to be more pronounced in a preamp, but obviously successive amplification is a big part of that. Given how fundamentally dissimilar the technologies are, I can't really understand how you could possibly expect that they would produce the same results.

HusseinSarhan

Eoin Madsen wrote:

I can accept that this is true for valve poweramps intended for PA applications but certainly not for poweramp stages in guitar amplifiers. Which is beside the point anyway. For one, intent has very little reflection on result in the case of a lot of technology - transistors achieve better what valves were originally intended to do. And aside from that, "clean" is not the only sonic characteristic, there are timbral variations not associated with overdrive or spectral colouration. Honestly, do some googling on the subject and you'll find answers quicker than I can give them to you. The only debate I've across is whether valve or solidstate is "better", I haven't really encountered anyone disputing that they sound different tbh. I can accept that the difference is likely to be more pronounced in a preamp, but obviously successive amplification is a big part of that. Given how fundamentally dissimilar the technologies are, I can't really understand how you could possibly expect that they would produce the same results.

Yeah, definately different. Sure you can hear differences between difference brands of, say, 6l6's. Let alone differences between transistor and valve power amps. Not that I ncessarily could identifywhci hwas which though, I'd be able to tell that there was a difference in most cases though.

Paladin

Eoin Madsen wrote:

I can accept that this is true for valve poweramps intended for PA applications but certainly not for poweramp stages in guitar amplifiers.

I assume you have never designed or built a power amp if you make a statement like this.
I have to admit, I used to think this too
Now I know better.

The power amp on the vox AC30 has a THD (Total Harmonic Distortion) figure of less than 0.1% (human threshold for hearing this is between 0.5% and 1%) at worst when operating at about half power (as measured by me, not read or heard 2nd hand). Ive designed and built guitar amplifiers. The guitar amplifier design handbook (if one exists) still uses the same fundamental methodology as it always did.
If you want to change a signal you do it before the power amplifier!

The power amplifier stage in valve amps certainly can distort when volume is pushed to the max, but that is volume dependant. You cannot get the power amp (in the AC15/AC30) to distort unless you make the amp output more power than it was designed for.
Given that you would like a nice tone even at quiet volumes it is absolutely wholly unreasonable in my opinion to attribute power amp distortion as to why valves supposedly sound good.
Should they not sound good at low/medium volumes? They certainly do, and there the poweramp (which is what PA stands for) is definately not adding any audible distortion.

This is not opinion. This is fact. I have read it. I have tested it. I have verified it.

Before I did electronics I believed all the hype about valves. I thought valves must be doing something that makes them sound better. I really was a believer.
I did my final year project on the subject to try and find out why valves sound better than transistors.
I used the same pre-amp for the AC15 and for a power amp I built. There was no audible difference. It just wasnt there. I couldnt hear it, I couldnt measure it. I had to hold up my hands and say the premise of my project was all wrong. I disproved (to myself anyway) what I set out to study.

The AC15 and AC30 are arguably *the* defining valve amps. If it is not the power amplifier in them then its not the power amplifier in any guitar amp. Thats my opinion. You have to look elsewhere, and thats possible what vox are doing with the valvetronix setup.

There are so many people who believe incorrect things about valves.
And I believed it too because I read it in so many places, and heard it from so many musicians.
I did occasionally find people who argued against mainstream belief, but they were so outnumbered I gave them no credence.

Id recommend this book by John Linsley Hood if anyone is interested in finding out more:
http://www.elsevier.com/wps/find/bookdescription.cws_home/676414/description#description
He died a couple of years ago, but he really knew his stuff.

[edit]
I will upload something you may find interesting tonight. For my project I did a recording of a piece of music through my poweramp (about E1 of components) and the vox AC15 poweramp at the same volume levels with the same preamp. I then spliced them together so that halfway through the piece swaps from one amp to the other. There is a slight volume discrepancy if you put it through really large high quality speakers. That (probably) came from my freeware normalising software.
[/edit]

Eoin Madsen

Tbh, I assumed you meant "clean" in broader terms rather than just clean vs distortion, since there a dozen other factors which colour the tone other than distortion.

PA is the abrieviation for "public address".

Paladin

Eoin Madsen wrote:

PA is the abrieviation for "public address".

Yes, I apologize for the ambiguity I caused.
I forget there is a world outside electronics. I must visit it more to play guitar

sei046

so is it Xt or Tonelab lads?:D

fitz

Neither, it's a decent valve amp.

Paladin

Id go with the vox because I like vox

Havent tried either though so umm, why did I even reply...sorry

LundiMardi

i'd go with the vox too, cos it looks pretty, and we all know that's what *really* matters.