28 posts
For any of you folk that has a Vox Valvetronix or Tonelab, or might be thinking of getting one, we've just completely revamped the site - so please do look in & tell us what you think!
http://www.valvetronix.net/valvetronix/
Rich :) :)
Cool site.
I have an issue with one of your articles.
What, exactly, does the Fletcher-Munson effect have to do with whether your amp is tube, or has tubes, or doesn't? Physics tells me that Fletcher-Munson is completely unrelated to the type of equipment generating the sound.
He's right. The Fletcher-Munson effect is only about how the human ear hears frequencies at different volume levels (where mostly we don't hear highs and lows as well at lower volumes).
Here's how I understand it from my Line666 days. With tube amps, as you turn them up, the upper end rolls off a little and you get natural compression. So even though highs are more noticeable at higher volumes, the natural roll-off takes care of a lot of that.
Even though modeling amp models are based on cranked tube amps, they don't behave like a tube amp as you turn them up. The treble doesn't roll off as you turn up a modeler since there aren't valves. So you have to adjust your eq on the patches for higher volume situations to kill the icepick.
It isn't an issue that only affects modelers, but it is a bigger and more common problem with modelers at gig levels.
Cool site.
I have an issue with one of your articles.
What, exactly, does the Fletcher-Munson effect have to do with whether your amp is tube, or has tubes, or doesn't? Physics tells me that Fletcher-Munson is completely unrelated to the type of equipment generating the sound.
Hi Charger - thanks for looking in & reading stuff!
To answer your query, the type of equipment has everything to do with it. Whilst Fletcher Munson affects all amps to varying degrees, FM tends to be more pronounced with DSP amps as compared to valve amps. Allow me to explain.
You'll have gleaned from the article that as volume is raised, so you need to up the mids - because at higher volumes its these frequencies that the human ear 'likes' & hears more of. With an all tube rig, as the amp is cranked the tonal characteristics generated by (in particular) the power tubes change to 'naturally' give more mids. This is one of the reasons that valve amps are often perceived as louder & punchier than pure DSP amps or SS amps and why they're perceived to cut through better.
But its a misconception that valve amps are actually louder in real terms to the same equivalent SS/DSP amp. In fact, 50w is the same power output on any amp - SS, DSP, hybrid, or all valve - and with the same speakers & speaker sensitivity you'll have exactly the same real volume.
The reason your ears perceive its punchier & louder is because the tubes are producing more of those mid frequencies & the 'nice' harmonics at volume that our ears like. Which is why a lot of valve amps don't sound good until the power tubes are working harder, but (attenuators/hot plates aside) you have to crank the amp to get there.
With a pure DSP amp, the algorithms are trying to emulate not just valve tone per se, but also that changing valve response as you raise volume. But what valves do naturally is actually very hard to capture & reproduce digitally - which is why modelling keeps evolving, & trying to get nearer to that response. The only full DSP amp that gets close enough to 'change' with volume is the H&K Zentera which uses 2x32pt Sharc chips. Although the Line 6 Vetta uses the same chips, its processing power is massively diluted - just compare all the amp models & effects to the comparatively meagre number in the Zentera. But the Zentera concentrates on quality - the algorithms are much more complex, & the processor is used to generate a much more authentic tone & valvelike response than the Vetta accordingly. If you put a Zentera & Vetta side by side at volume, you'll immediately hear what I mean - the Vetta goes mushy (FM effect) very quickly. So much so that L6 now install an FM switch to help alter the amp at volume because the amp model algorthams on their own aren't sophisticated/detailed enough to do it.
Vox' solution to the problem, & cut the cost of processing, was to use valves in its unique valve reactor circuitry, thereby reducing the processing power needed to get not just a more authentic valve tone, but also valve-like response at volume - so at volume, the V'x really does respond like an all-valve amp & is much less affected by FM - because the valve-reactor design is changing tonality at volume just like an all-valve amp does.
In fact, Line 6 specifically sets their on-board EQ to sound good at bedroom & store demo levels - so folk think the amp sounds great initially, only to find that the EQ is all wrong at volume & the amp goes mushy. With the Valvetronix 'Blue' series for example, the onboard EQ is set for gigging levels. At the same lower volumes (just like an all-tube amp) it can sound lack-lustre (as my AC30 used to be in the bedroom!) and lack richness of tone and clarity. But crank it to gigging volume, and just like an all-tube amp, it comes into its own.
Sorry that's a bit long-winded, but i hope it answers your question.
Rich ;)
I have to disagree. We deal with Fletcher-Munson with monitoring speakers, and there is nary a valve in site, yet the curve applies. It applies to all sound. Certainly, some tube amps compress as they are turned up... as do some speakers (not tube), some solid-state amps... but, that doesn't necessarily mean that they alter physics as they are turned up. That's where I find the article, at the least, misleading. An accurate explanation of Fletcher-Munson would probably be more helpful, or more informative.
charger — Sep 09, 2008I have to disagree. We deal with Fletcher-Munson with monitoring speakers, and there is nary a valve in site, yet the curve applies. It applies to all sound. Certainly, some tube amps compress as they are turned up... as do some speakers (not tube), some solid-state amps... but, that doesn't necessarily mean that they alter physics as they are turned up. That's where I find the article, at the least, misleading. An accurate explanation of Fletcher-Munson would probably be more helpful, or more informative.
Sorry Charger, but what I've tried to explain really is correct. And I did specifically say didn't I that FM affects all amps! You can't avoid it - but its the degree of susceptability to FM that varies as between SS/DSP & all valve amps.
I've had these discussions with Line 6 technical direct - I used to be Flexboy on Channel 6 & liaised directly with Darren Brown who led the team that designed & built Flextone III - We were having detailed discussions on this very theme, because I was facilitating feedback from L6 users on what they wanted for FlexIII, & raised problems of FM on the Flextone II. Its the tonality change in valves as they're cranked that mitigate (but not avoid) the effects of FM, & that is the single biggest challenge for designers of DSP gear to emulate because of the large processing power & complex algorithams needed.
Rich ;)
I understand what Rich is getting at having once been a modeling dude. I'll agree with him that he didn't say it only applied to modelers (seemed pretty clear to me) but that it is MORE problematic with modelers than tube amps. It was the topic of MANY threads over at Line6 and how to make Line6 amps sound decent at gig level.
Stop staring at the tree brother. :D
So it appears to me it's more of a situation where Charger is talking specifically about the physics of the Fletcher-Munson curve and Vox is talking more about how different types of guitar amps change as they get loud (which is not quite the same thing).
I think Charger is correct in saying that speaking of the effect as you do in the article is kind of misleading because it's not really a pure description of Fletcher-Munson, but it is accurate in terms of how the different amps reproduce sound and how much different amplification systems are affected by Fletcher-Munson, due to their natural change in frequencies as they get louder.
Make sense?
Tripper
I'm still finding this challenging to understand as a technical article. And when you post about something that has a solid physics foundation, it's usually better to avoid throwing your opinion into it, and treating it as fact.
That said, I haven't found a single source on the web or anywhere else that validates the claim that tube amps are less prone to Fletcher-Munson than solid state amps. But, by far, the clearest refutation of your claim is in the origin of the Fletcher-Munson curve itself. This theory was described in 1933. The first patent on a solid-state transistor was taken out in 1947. Thus, obviously, all of the experimental theory for Fletcher-Munson originated on tube amplifiers.
Fletcher-Munson is a measurement of how our ears evaluate sound at different levels. Whether there is a tube in the volume path or not has nothing to do with that equation.
I certainly won't argue with you that most modeling amps sound pretty crappy, and sound even more crappy when you can hear them better, but if you write an article on physics, it's not supposed to be based on opinion. There is no "opinion" in physics--that's a hypothesis.
Charger, not having yet read the article, just the conversation here, what it seems to me that you are still missing is the relationship between the two. Rich isn't saying FM doesn't apply or applies differently, per say, to a tube amp. Just that tube amps frequency response changes at volume, and that they have attempted to replicate this IN RELATION TO the FM curve, in their designs.
Probably shouldn't make this assumption without proof, but I'd assume the FM curves are based on a FLAT source, of which a tube guitar amp is certainly not. That's where what Rich says comes into play. If you read through any of Dars amp posting and see all the shelving that goes on, the mids are pushed on these amps to varying degrees AND guitar speakers almost all roll off low end and high end, further pushing a broad mid freq. output.
One of the things I want to do when I get my scope, is see just what a freq curve looks like after going through an amp, or pedal. Just to see exactly what the output IS after all that shaping. But that's pre speaker as well, so, put a speaker in the mix, more high and low rolloff...
The point being, if the source has more mids ( or bass and/or treble, if that were the case) already, the AFFECTS of the FM curves would be different.
I'll read the article, but so far, I GET what he's saying.
Edit: which article am I looking for?
interesting side note....
I noticed a long time ago that the same area that there is a big dip in our ears sensitivity is also the area where most guitar speakers have a big peak that's ALMOST the same curve but inverse. The boost in the speaker almost matches (flattens) the dip in our hearing. And many mics have a peak there too. hmmmm ;)
Charger, I readily acknowledge that I'm not a techy or a physics major - but the posting wasn't intended to be a technical research document. It was intended to help folk get better tone at gigging volume by understanding that our ears hear differently at volume - the short message is simply 'raise your mids' because at volume, that's what our ears like more. Its a very amicable, interesting discussion, & I certainly have no problem with us agreeing to differ - but we do differ. I've played the Vetta, Zentera, Valvetronix, Flextone & more valve amps than I can remember - and whatever your opinion is on the 'physics', I'm a simple guitarist - & there IS a difference in the way valve/non-valve amps react at volume.
As far as most modelling amps sounding crappy - well, I've played next to all valve amps that sound crappy compared to my Valvetronix (but then it is a hybrid, with valves, & not a pure DSP amp). I certainly don't rate the L6 Vetta or FlexIII - far too digital.
But a lot has to do with experience and knowledge of an amp, and how its used. In the right hands, a 'crappy' amp can sound good, and in the wrong hands a good amp can sound crappy. Most often, the modelling amps folk hear are the smaller versions made to a tight budget and fitted with crappy speakers that simply don't do the modelling justice. So naturally a 1x10" budget end modelling amp designed for home practice rather than gigging is likely to sound pretty naff as compared to a 2x12 valve amp that's specifically designed as a gigging amp. I've put my AD120VTX (with an EQ in the FX loop) through the 4x12 V30 Marshall cab in our rehearsal rooms, set it to UK modern (Marshall JCM2000) and directly A/B'd it with the real JCM2000. I kid you not Charger, you'd be amazed at the tonal & modelling accuracy - none of us could tell any perceivable difference - other than the real thing actually muddied more at volume! :o
Understanding EQ is particularly important with modelling amps (nence my EQ in the FX loop) because unlike a conventional amp, EQ interraction works very differently with each model & you do need to spend some time getting to know it. A common problem is that folk set a great patch in their bedroom, only to find its crap live at volume. Most often its because they don't understand about EQ & how to set their patch at volume, or even how to position their amp - & that's all this 'article' was ever trying to help with - & not to be a physics research paper. ;)
Rich :)
DreamTheaterRules — Sep 10, 2008Probably shouldn't make this assumption without proof, but I'd assume the FM curves are based on a FLAT source, of which a tube guitar amp is certainly not. That's where what Rich says comes into play. If you read through any of Dars amp posting and see all the shelving that goes on, the mids are pushed on these amps to varying degrees AND guitar speakers almost all roll off low end and high end, further pushing a broad mid freq. output.
But how is that different from any other amp? The tube output stage (which controls the volume) merely amplifies what comes into it. There is nothing inherent about a tube amp that would make it automatically compensate, or compensate
more, than any other type of amp.
For reference, this is the section I take issue with.
Chances are you've probably just come up against the 'Fletcher-Munson' effect. FM affects ALL amps, but pure DSP (digital signal processing) amps suffer worst because (unless you have a top-end one such as an H&K Zentera) the processing power and software can't make the amp behave in the way that an all-valve amp does when its cranked.
As you crank an all-valve amp the valves get hotter, & the amps tonal characteristics naturally change such that the effects of FM are minimalized. That's why all-valve amps will often sound very punchy, can seem louder, & cut through the mix more easily than low-mid range pure DSP amps.
I just can't see that as factual; it seems to be opinion at best. And possibly not even true.
voxman — Sep 10, 2008Charger, I readily acknowledge that I'm not a techy or a physics major - but the posting wasn't intended to be a technical research document. It was intended to help folk get better tone at gigging volume by understanding that our ears hear differently at volume - the short message is simply 'raise your mids' because at volume, that's what our ears like more. Its a very amicable, interesting discussion, & I certainly have no problem with us agreeing to differ - but we do differ. I've played the Vetta, Zentera, Valvetronix, Flextone & more valve amps than I can remember - and whatever your opinion is on the 'physics', I'm a simple guitarist - & there IS a difference in the way valve/non-valve amps react at volume.
It's just, to me, akin to me posting an argument where I say "there are two types of preamps for microphones. Tube, and solid state. Tube preamps, because of
X voodoo, typically sound better. Solid state microphone preamps have more issues to overcome, and therefore typically sound worse."
Not that I take issue with your personal experience-- we all hear what we hear-- but when I read this, it appeared to be a treatise on Fletcher-Munson, and I was prepared for something with actual science behind it, and instead it seems to be an opinion piece.
I was prepared for something with actual science behind it
Nah, you want 'New Scientist' for that type of stuff! :D ;D
Last night I was prepared for actual sex...still didn't get any though! :( :D ;D
The technical angle on the FM curve is purely how your ears respond - perceived volume within the sound spectrum vs actual SPL.
The human ear perceives "like" a multi-band compressor and limiter focused on the mid range
At low SPL lows and highs are perceived lower in volume than the mids. (it pays to hear in this range - voices etc. - evolutionary boosted)
As SPL grows the lows and highs are perceived louder while these same compressed mids start to lose out and are perceived relatively quieter.
At raging volumes the perceived sound is as scooped as the metallica wannabes XT patch :D
How you tune your amp into this perception is a matter of judgement for your ears and the mix of sound it sits in.
Modellers may well have a scoop built in to make them sound big and raging at low volumes.
Why is that ?
To make them sound to punters like they are sitting in front of a raging valve amp at full volume with their ears compressing the mids.
Scoop sounds big - because big sounds are naturally perceived as scooped by your ears.
A Volcanic Eruption is classic scoop sound - it will not sound bigger by EQ'ing up the mids up - it will sound smaller and possibly more interesting but not bigger.
But even quietly heard it will be perceived as something big if it booms and sizzles
Practically with guitar and amps - already scooped sounds will sound like muddy shit at loud volumes as the natural scooping of the ears will start to take effect and the you will need more mids to balance things up.
This isn't a property of valve amps - it is a property of the of low volume scooping optimised to sell to punter modellers
Very perceptive post there Noel. :D
charger — Sep 10, 2008[quote author=DreamTheaterRules link=1220982736/0#11 date=1221077760]Probably shouldn't make this assumption without proof, but I'd assume the FM curves are based on a FLAT source, of which a tube guitar amp is certainly not. That's where what Rich says comes into play. If you read through any of Dars amp posting and see all the shelving that goes on, the mids are pushed on these amps to varying degrees AND guitar speakers almost all roll off low end and high end, further pushing a broad mid freq. output.
But how is that different from any other amp? The tube output stage (which controls the volume) merely amplifies what comes into it. There is nothing inherent about a tube amp that would make it automatically compensate, or compensate
more, than any other type of amp.
For reference, this is the section I take issue with.
Chances are you've probably just come up against the 'Fletcher-Munson' effect. FM affects ALL amps, but pure DSP (digital signal processing) amps suffer worst because (unless you have a top-end one such as an H&K Zentera) the processing power and software can't make the amp behave in the way that an all-valve amp does when its cranked.
As you crank an all-valve amp the valves get hotter, & the amps tonal characteristics naturally change such that the effects of FM are minimalized. That's why all-valve amps will often sound very punchy, can seem louder, & cut through the mix more easily than low-mid range pure DSP amps.
I just can't see that as factual; it seems to be opinion at best. And possibly not even true.
Charger, I think your issue is with verbage. I "think" the part that you don't like is the "the effects of FM are minimalized." But, I do understand this as it states "effects of" and explains the frequency changes that can occur in cranked tubes as being complimentary to the FM curves. I would not like the verbage if it said that FM was minimalized. But it's saying "the effects of FM" are minimalized, by a volume induced mid boost.
Heck, you're a tech writer. I know you understand the concept of what Rich is saying. How would you write it to make it more clear?
DreamTheaterRules — Sep 11, 2008
Heck, you're a tech writer. I know you understand the concept of what Rich is saying. How would you write it to make it more clear?
I wouldn't. There are tons of articles already on Fletcher-Munson, I'd just point to one of those. ;)
I do not know the science behind the FL thingy. It makes sense, if you are on the listening end of a 'why does my modeling amp sound like ass when turned up' website.
Lets get to it. Tube amps sound better when they are cranked. FMC or no FMC. That is where they sing, and our ears hear it. Simple.
But the modeling amp sites tell us that it's the FMC thingy that is making our amps sound bright and harsh.
I have owned 2 Flextone II's, and a Valvetronix. The Vox did better, but there was still something missing. I have also owned a Mesa Roadster and (still own) a JSX. When the two latter tube amps are turned up, they just sing.
So with my experience using both types of amps, I have to believe the FM Curve is nothing more than an excuse for modeling amp makers. Sorry. But my JSX sounds INSANE when it is cranked. My ears like the JSX LOUD.
Sometimes we put too much worth into aural science. I think we should take a few steps back and listen to our ears ;)
Can't believe all the ruckass on this :o- all I did was tell you guys that our site had been revamped! ::) ;D
Rich :)
You mean you never got the notice? Our criticism has been revamped as well! ;) :D ;D
Yep! And it's no extra charge!
Rich,
I'm still surprised that people seem to be missing the point... LMAO!
Johnny, Rich isn't saying that the FM curve is why tube amps sound better than modelers. He's saying that tube amps CHANGE in frequency balance as they are cranked, and modelers do not. And, that this CHANGE is more complimentary to the FM curves.
There is one thing in question here. IF the frequency changes on most tube amps, as Rich indicates, then his statement is 100% valid. I was doing a little poking around trying to find info on that issue, and then the weekend hit, football, no power etc. BUT, the few things I found seemed to support that fact, but I didn't find enough yet to be sure. But IF that statement about the frequency changing with volume increase in tube amps is correct as stated, then Rich's comments are absolutely correct AS STATED.
That said, I believe the issue is a LITTLE more complicated than that, as we all know that distortion is harmonic and thus, adding gain to any amp adds high end by default. But, if you followed some of Dars amp analysis you'd know that many amps shelve off the top.... meaning even the harmonic content would mainly be in the mids.... adding mids to the overall volume....
So far, from what I've read, Rich's statement is legit. So what I am trying to say here is, congrats on the new web site, Rich! ;D ;D
further, to get back to the issue of tubes vs. modeling amps...
I've read a lot about modeling process, but I remember Fingers talking about how they take several points along the curve, and somehow simulate the rest. So, Line 6 does not take a JCM800 and model volume at 1, then 1.5 then 2 then 2.5 etc nor do they try treble off, then .5 then 1 then 1.5 etc... they take a couple measurements, then simulate the curve between them. If modeling advances to the point where they can take more points of measure, they can start to program in the changes that occur along with them.
For example, how many of you have tried a tube amp that hits a HUGE volume increase between whisper quiet, then kinda loud, in just a 1/10 of 1 position on the volume knob change? Maybe somewhere around 1 on the knob... Just suddenly BOOM get's way louder. And, how many have an amp that somewhere above that, hits a nice spot where it suddenly get's full and sounds good? But modelers don't do this. They gradually gain in volume from that whisper quiet to loud, in almost perfectly linear fashion. And they gradually get more full as the knob is turned, they don't hit a magic spot.
Well, both of my tube amps have similar spots where, when turned up loud, they suddenly hit a spot where they sound better. Compression has kicked in, and perhaps there is more mids... but I think this is the spot Rich is talking about.