I know i´m beating a dead horse, but, have anyone tried this?

[DougH]

Finally, I guess I will say that the sound - which most people focus on, might be secondary to the way the circuit reacts for me. A lot of circuits sound pretty darn good or fun, but the feel is incorrect. I can believe that I might have it backwards - since I guess I value feel maybe more than the final sound.

I hear what you are saying, Aron. This is where I have focused my attention on the last few amps I've built.

[dschwartz]

Finally, I guess I will say that the sound - which most people focus on, might be secondary to the way the circuit reacts for me. A lot of circuits sound pretty darn good or fun, but the feel is incorrect. I can believe that I might have it backwards - since I guess I value feel maybe more than the final sound.

I hear what you are saying, Aron. This is where I have focused my attention on the last few amps I've built.

i also agree, in fact that´s the point of the ideas shared in this thread..like "ok, we know how to filter a distortion to sound really great, but hey, how about the feel of it?" Maybe for rythm players is not a big deal, but for lead players, like me, we can get really picky about the feel of the distortion.

[aron]

I think we think alike! :-)

Daniel, do you remember the Peavey op amp distortion patent that was around a few years ago???

Also, have you ever played with Joe Davisson's diode compression? It is really, really good for feel.

[Paul Marossy]

Paul,

I understand what you are saying and in fact, I have read those documents that you linked to as well. So I ask these questions now:

If tubes are so great by themselves as overdrive/harmonic generators, why isn't the majority using tube-based pedals?
If tubes alone produce that wonderful sound, then why are there so many bad sounding amps and preamps that only use tubes?
Why are there so many guitarists out there using stompboxes for distortion and sustain?
Why is modeling not the ultimate generator since it should be easy to add harmonics to the base signal?

For one, it's not practical. I didn't say that only tubes sound good. But if you run let's say a BSIAB into a solid state amp, do you think that would sound good? If not, why is that? I like dist/OD pedals, but into a tube amp. As a standalone circuit for direct recording, I would never use that, even with a cabinet simulator. Modelling is pretty good these days, but it still seems to be lacking something, but I can't pin down exactly what it is.

I have noticed the "dry/stiff" feeling with certain FET designs, but later designs do not exhibit this problem. Anyway, a little reverb or compression goes a long way.

I can't stand the sound of a dry amp, I always use a touch of reverb.

Finally, I guess I will say that the sound - which most people focus on, might be secondary to the way the circuit reacts for me. A lot of circuits sound pretty darn good or fun, but the feel is incorrect. I can believe that I might have it backwards - since I guess I value feel maybe more than the final sound.

I agree with that somewhat, but for me, I shoot for both. I also like tube rectifier "sag". I really don't care for SS rectification, sounds too harsh for my ears.

[Paul Marossy]

Paul..solid state devices can create even harmonics as well as tubes, and tubes can create nasty odd harmonics, it´s much more a topology thing that a device thing.. that "tubes Vs SS" paper is so old, biased, and it doesnt consider topology and filtering. Did you know that an AB tube power amp stage produces ONLY ODD harmonics? and it CANCELS even harmonics? and hey, it´s 100% tubes!!! and 90% of guitar amps are built with that topology!
Russel hamm paper is beloved by many, but to me is full of....manure...

OK, then explain to me why tube amps are still preferred by 90% of guitar players. There must be something going on that makes it better sounding than solid state. It should be frowned on, I mean tube amps are very heavy and tubes are expensive & inefficient. And yet the tube amp still persists in the guitar world. I don't think it's all only because of the circuit topology. I know that 90% of tube guitar amps have AB Push-Pull power stages. I've owned both types of guitar amps, and the tube amps sounded way better to my ears.

I still maintain that it's due to differences in harmonic distortion in the devices, how those devices treat those harmonics, compression and THD of the devices themselves - in addition to circuit topology. Maybe it's the THD that people notice the most?  Look at the THD of an EL-34 power tube, it's pretty high compared to a power transistor for example - like 20% compared to 0.5%.

Tubes still sound warmer but that shouldn't be if, as you say, an AB push-pull power section produces only odd order harmonics. Maybe all these studies have it backwards and people actually think that mostly odd order harmonics sound better?

[aron]

>OK, then explain to me why tube amps are still preferred by 90% of guitar players.

I'm guessing but I think it's the entire amp - the tubes, transformers and speakers. The entire package sounds good. It's my guess, but I am also guessing that there are a lot of good guitar tones coming out of hybrid modeling amps and simulators.

I play a tube amp because of the feel. I have heard modeling amps that sound better than my setup for sure, but I like the feel of my amps.

>ut if you run let's say a BSIAB into a solid state amp, do you think that would sound good?
I think it stands a good chance to sound good for the type of music it was designed for. Yes.

In fact, I have gotten good tones out of my small pedalboard - all solid state, through a PA. It has feel and a decent tone.

I'm not arguing against tubes of course, just that I have not played a tube pedal that sounds better than my SS stompboxes. On the 90% section,  don't most guitarist use a stompbox to augment the tube amp? It's kind of tough to find gigging guitarists that don't have an overdrive pedal.

[dschwartz]

I think we think alike! :-)

Daniel, do you remember the Peavey op amp distortion patent that was around a few years ago???

Also, have you ever played with Joe Davisson's diode compression? It is really, really good for feel.

HI ARON:
i don´t remember the peavey opamp distortion, but i´ve read teemukps book, and there´s the supersat circuit which is pretty interesting in the way it modifies freq response alog gain settings..on my texas brownie i took a similar approach, much cruder but aiming to alter the freq response along the gain ranges.

you mean the diode compression opamp? nopes, never played it..

Paul..solid state devices can create even harmonics as well as tubes, and tubes can create nasty odd harmonics, it´s much more a topology thing that a device thing.. that "tubes Vs SS" paper is so old, biased, and it doesnt consider topology and filtering. Did you know that an AB tube power amp stage produces ONLY ODD harmonics? and it CANCELS even harmonics? and hey, it´s 100% tubes!!! and 90% of guitar amps are built with that topology!
Russel hamm paper is beloved by many, but to me is full of....manure...

OK, then explain to me why tube amps are still preferred by 90% of guitar players. There must be something going on that makes it better sounding than solid state. It should be frowned on, I mean tube amps are very heavy and tubes are expensive & inefficient. And yet the tube amp still persists in the guitar world. I don't think it's all only because of the circuit topology. I know that 90% of tube guitar amps have AB Push-Pull power stages. I've owned both types of guitar amps, and the tube amps sounded way better to my ears.

I still maintain that it's due to differences in harmonic distortion in the devices, how those devices treat those harmonics, compression and THD of the devices themselves - in addition to circuit topology. Maybe it's the THD that people notice the most?  Look at the THD of an EL-34 power tube, it's pretty high compared to a power transistor for example - like 20% compared to 0.5%.

Tubes still sound warmer but that shouldn't be if, as you say, an AB push-pull power section produces only odd order harmonics. Maybe all these studies have it backwards and people actually think that mostly odd order harmonics sound better?

Interesting points.. but, hey, 90% of guitarrists use SS amps...if you mean only proffessional guitarrists, well, most of them will have pictures of them with nices tube stacks behind them, but a great deal of them will use modeling for recording and tubes for live..

I dont want to get into the tube marketing and hype because that´s subject for other thread...

Tube amps are great, they set the bar of what a great amp should sound like, that´s true..but solid state has its own merits and deserves some respect. I have played many amps, i have tube and ss amps, and i have no real preference between both, both sound pretty good on their own right. As aron pointed out, tube distortions mostly suck unless it is a well filtered preamp like mesa formula or similars, but tube od´s, high or low voltages simply suck, the harsher distortion i have ever heard is the ultra famous chandler tube driver, man that pedal sounds like a big muff on a really bad day!!..i´ve built a mesa type preamp with 4 12ax7 gain stages, and it sounded really good, but it took me like 2 months of building and a lot of cash. A week later, i build a dual rectal (my heavily modded version of dr boogie) and was blown away by it..it sounds amazing for a fraction of the cost and hassle..who cares about odds and even harmonics..it sounded good to me! (and to many of my customers saying that´s the best distortion they ever played with)

anyway..

i hope my old lady gives me some free time to protoboard these ideas..

[PRR]

> Solid state decices typically have almost no even order harmonics at all.

Huh? A naked transistor makes about twice the second harmonic of a tube.

Some of the antique one-transistor "fuzzes" must be up near 20% 2nd before they clip.

I'll semi-agree on two grounds:

1) 20% 2nd harmonic is not a strong flavor, and these boxes will quickly go to clipping which overwhelms all notion of "simple distortion"

2) most tranny amps (and anyting more than 1 transistor) have usually been "optimized" to make 2nd harmonic very low.

> read these pages several years ago .... dead on.

I'm suspecting that, despite a lot of good (and more bad) thinking and even traces of research, nobody really understands the ear's perceptions "dead on". Like the 7 blind men and the elephant. Even after they blog all their notes and read others, they don't have a complete picture, just several important points.


> simulation results were interesting

Yes, but never forget: SPICE lies. Even when it is technically accurate (which is doubtful for its models of tubes or opamps), it can't say what it "sounds" like. Or "the way the circuit reacts for me", as Aron sees things.

> opamp stages with a single clipping diode

This can be built and heard, and subjectively evaluated, in less time than it takes to set up a good batch of SPICE's lies.

[DougH]

As aron pointed out, tube distortions mostly suck unless it is a well filtered preamp like mesa formula or similars, but tube od´s, high or low voltages simply suck, the harsher distortion i have ever heard is the ultra famous chandler tube driver, man that pedal sounds like a big muff on a really bad day!!.

The SIB stuff does me in. I don't understand why so many people seem to be in love with them. They sound horrible to me.

I don't have a strong feeling about tube vs. ss in pedals in general. My pentode driver sounds really good and the compression feels good but it is almost too mushy. Some day I may go back and look at fixing that. May just need a tweak to the screen circuits. I've breadboarded another low voltage tube pedal I was happy with too. Never got around to building it, mainly due to the fact that it's a harder build due to the tubes etc. I don't think there's anything "special" about tube pedals though. A lot of them sound horrible because they are really horrible designs, just like some ss stuff.

IMO a key to good "feel" is to have a little touch of compression. I've added "sag resistors" to my last few amps, to emulate what a tube rectifier does in the power supply. This feels really good to play even when the gain is cranked up high. I think the trick is to not overdo it. You just want a little clamp down on the attack and then a nice long release to help it sustain. There is also the issue of having enough headroom. If you have the gain tuned in a way that you can control it with your guitar volume (without low input impedance tricks, although that might work okay too), you have a good chance of it being touch sensitive and having the ability to control the amount of distortion with your picking pressure. I think all of this would be helped with a higher supply voltage. But I'm coming from the amp perspective too.

[dschwartz]

> Solid state decices typically have almost no even order harmonics at all.

Huh? A naked transistor makes about twice the second harmonic of a tube.

Some of the antique one-transistor "fuzzes" must be up near 20% 2nd before they clip.

I'll semi-agree on two grounds:

1) 20% 2nd harmonic is not a strong flavor, and these boxes will quickly go to clipping which overwhelms all notion of "simple distortion"

2) most tranny amps (and anyting more than 1 transistor) have usually been "optimized" to make 2nd harmonic very low.

> read these pages several years ago .... dead on.

I'm suspecting that, despite a lot of good (and more bad) thinking and even traces of research, nobody really understands the ear's perceptions "dead on". Like the 7 blind men and the elephant. Even after they blog all their notes and read others, they don't have a complete picture, just several important points.


> simulation results were interesting

Yes, but never forget: SPICE lies. Even when it is technically accurate (which is doubtful for its models of tubes or opamps), it can't say what it "sounds" like. Or "the way the circuit reacts for me", as Aron sees things.

> opamp stages with a single clipping diode

This can be built and heard, and subjectively evaluated, in less time than it takes to set up a good batch of SPICE's lies.

i know that spice lies, but it gives you a theoretical idea that must be proven on proto. That´s why i said interesting..like "worth to breadboard". My favorite design, my texas brownie was concieved this way, i designed what i wanted in spice, and then put in on breadboard and tweak it to sound as i like. sipice just gets you on the ballpark or just gives you an hypothesis to prove..

[Paul Marossy]

Alright, I guess I should have been a little more clear with the point that I was originally trying to make. I like to use a tube amp that sounds great clean. Once I find that sweet spot for the tone, I dial in my pedals to also sound good with it. This creates a platform for whatever effects I might use. The amp I typically use these days is an old 60s 15 watt amp with an EZ81 tube rectifier, a pair of EL-84 power tubes with a couple of 12AX7 preamp tubes. It only has a volume control, tone control, and controls for the tube tremolo. This amp also uses a "split load phase inverter", which you don't see very often. It has a single Eminence OEM 12" 20 watt alnico speaker in it that sounds very good. Also have the GGG digital reverb installed between input jack and input on first preamp tube. I get a lot of comments about how nice the amp sounds.

My philosophy is to take a great sounding amp and push a well designed distortion into the input. The end result usually sounds great, once I dial everything the way I want it. My experience is that usually if the amp sounds great clean, is "touch sensitive" and has a nice warm & dynamic tone, then it gets better from there with whatever pedals I might feed it as it's pushing the amp itself into a little distortion as well. So, in my case, the tube amp is working in conjunction with the solid state pedals.

Which brings me again to harmonic distortion and tube amp design. Here are some well known facts from various publications.

1 – Harmonic distortion in an amplifer stage is caused by non-linear action of the vacuum tube

2 – In a tube, an asymmetrical waveform creates 2 nd order harmonics

3 – In a tube, whenever you have 2 nd order harmonics, a strong 3 rd order harmonic will also be present. This is pointed out in an article referred to earlier as "manure".

4 – In a tube, when you flatten both halves of the waveform, a 4 th order harmonic will be generated.

5 – When a triode tube is overloaded, 2 nd order harmonics are created.

6 – When a pentode tube is overloaded, 3 rd order harmonics are created.

7 – Even order harmonics generated in a tube output stage are cancelled out in a push-pull output stage, but this does not mean the amplifier generates no even order harmonics, because even order harmonics from the preamp stages will pass thru right to the output. Only those generated in the output stage itself are cancelled.

8 – There is sag in the typical tube amp due to tube rectifiers, power transformer and even filter cap response in some cases

9 – The output transformer adds its own distortion

10 – Tubes have much more THD than solid state devices. In an AB push-pull stage, 6L6 is around 2%, EL84 is around 4% and an EL34 is about 5%. 12AX7 is around 5%. Solid state devices are generally much lower in the 1% or less range.

11 – The speaker type, size and efficiency all also help to comprise the overall tone of the amp, not to mention that it also acts as a filter.

12 – Tube amps very often utilize NFB (Negative Feedback) to minimize distortion as much as possible.

Now when you take all of these factors into account, they are what makes a tube guitar amp have the complexity in the tone. Obviously circuit topology, tone controls and other filtering plays a role, too.

I know that solid state devices can create 2 nd order harmonics, but they as a rule don't ordinarily create hardly any 2 nd order harmonics in a "normal" circuit. If you remove the tubes and the tube amp with all of their peculiarities from the equation, in my opinion, the end result is harsh sounding because the added effect of the tubes is lost; ie THD, more harmonic distortion, etc.

Many guitar pedal distortions massively clip the signal so you get something approaching a square wave. A square wave is a waveform that is built up from a series of harmonics derived from the fundamental frequency. A true square wave will have 3rd, 5th, 7th, 9th, 11th, 13th and 15th harmonics. The rise and fall is very abrupt, straight up and straight down. For an audio signal, all of these combined odd order harmonics would not be considered to be a pleasant sound by most.

The bottom line FOR ME is that I like my distortion/OD pedals into my tube amp(s), but I don't like them as a standalone unit for recording direct, they simply don't sound good. Too harsh and bright and the feel is totally different because there is no interaction between all the things going on in a tube amp. When I record stuff, it's direct, no miking amps or anything. I have an entirely different philosophy for that. (No modelling whatsoever, either)

Here's another one of my quirks: I don't like tube amp distortions. I think most of them sound like crap for my tastes, probably because it's all preamp tube distortion and not power tube distortion, which sounds much better. I've only ever really liked one tube amp distortion, which is my "Octal Fatness". 6SJ7 pentode on the input. Sounds fantastic.

Anyway, what made me write the first post in this thread is because I built the ROG "English Channel", which is a fine FET emulation of the Vox AC-30 but it's not the real thing. One of my friends has an AC30, and it's far more dynamic, warm and jangly sounding than my English Channel thru a tube amp is. I wonder why that is?

[aron]

>One of my friends has an AC30, and it's far more dynamic, warm and jangly sounding than my English Channel thru a tube amp is. I wonder why that is?

It's going through another preamp too  - but as you pointed out it's not the same thing.  I have a feeling that solid state can work very well, but it needs to be the entire amp designed- not just the preamp. The reason that overdrive pedals sound - buzzy or lack feel when direct recording is because they are only one part of the element of an amp IMO.

If you had done the entire amp - as solid state - or even the entire preamp - designed the circuit for the solid state amp - preamp, output section, all EQ, I bet it might sound darn good. I am not talking about an emulation, I am talking about designing a good sounding/feeling amp.

OK, here's one. Do this.... Have you ever recorded the output of the amp -  what is being sent to the speaker using an attenuator?  I mean, have you ever heard the tone that is being output from the output transformer? I have. It may surprise you.

[dschwartz]

probaly that sounded like screeching a fork on a dish?

[aron]

Pretty amazing. I have used the Red Box, Fixed Resistors and Weber MASS to "listen" to the output. Very insightful.

[Paul Marossy]

It's going through another preamp too  - but as you pointed out it's not the same thing.  I have a feeling that solid state can work very well, but it needs to be the entire amp designed- not just the preamp. The reason that overdrive pedals sound - buzzy or lack feel when direct recording is because they are only one part of the element of an amp IMO.

If you had done the entire amp - as solid state - or even the entire preamp - designed the circuit for the solid state amp - preamp, output section, all EQ, I bet it might sound darn good. I am not talking about an emulation, I am talking about designing a good sounding/feeling amp.

OK, here's one. Do this.... Have you ever recorded the output of the amp -  what is being sent to the speaker using an attenuator?  I mean, have you ever heard the tone that is being output from the output transformer? I have. It may surprise you.

Good points. I haven't tried the attenuator thing, don't have one. What's so interesting about it?

There is one killer sounding solid state amp that I like - the Lab Series L5. Ty Tabor used one on the first few King's X albums. Fantastic thick crunchy distortion sound. I know that solid state can also sound very good if it is designed well. That particular amp was designed by Bob Moog. He knew what he was doing. But most solid state amps don't sound good to me. Too clean, stiff, sterile. And those distortion sections on most SS amps sound cheesy - too fizzy and thin sounding for my taste.

[dschwartz]

It's going through another preamp too  - but as you pointed out it's not the same thing.  I have a feeling that solid state can work very well, but it needs to be the entire amp designed- not just the preamp. The reason that overdrive pedals sound - buzzy or lack feel when direct recording is because they are only one part of the element of an amp IMO.

If you had done the entire amp - as solid state - or even the entire preamp - designed the circuit for the solid state amp - preamp, output section, all EQ, I bet it might sound darn good. I am not talking about an emulation, I am talking about designing a good sounding/feeling amp.

OK, here's one. Do this.... Have you ever recorded the output of the amp -  what is being sent to the speaker using an attenuator?  I mean, have you ever heard the tone that is being output from the output transformer? I have. It may surprise you.

Good points. I haven't tried the attenuator thing, don't have one. What's so interesting about it?

There is one killer sounding solid state amp that I like - the Lab Series L5. Ty Tabor used one on the first few King's X albums. Fantastic thick crunchy distortion sound. I know that solid state can also sound very good if it is designed well. That particular amp was designed by Bob Moog. He knew what he was doing. But most solid state amps don't sound good to me. Too clean, stiff, sterile. And those distortion sections on most SS amps sound cheesy - too fizzy and thin sounding for my taste.

yes, specially entry class amps, and some marshall valvestate sucks, there are many SS amps oput there that sound very lousy..is just that making a good sounding SS amp is more dificult than making a good tube amp, needs more design effort. SS will never replace tubes, never ever, and there´s one big reason..TUBES are TUBES, they have history, legacy, they are cool..a tube amp has more "life" since you have to take lot more care about it and be gentle..when you play tubes you feel like youre using the same electrons that jimmy once used, they are trapped in time there into the vacuum..very romantic stuff..SS are workhorses..there´s nothing romantic about transistors, they are ugly, and they don´t relate with you, they dont glow in the dark, and they are used for computers..cold stuff, no soul there, no emotional attachment.. when you burn a power tube is like "ohh noo, MY tube!, what did i do to you!!, ill miss you, my amp will never sound the same without you!!" .. a transistor blowing is like "pffff, little silicon piece of crap!!! now i´ll have to replace you and no one will miss you!"

[aron]

There is one killer sounding solid state amp that I like - the Lab Series L5.

The sad part is I was there when the lab series was out. Did we think much about it? No, not really. What made it cool -  I believe it had compression built in. I think that was the feel.

[Paul Marossy]

There is one killer sounding solid state amp that I like - the Lab Series L5.

The sad part is I was there when the lab series was out. Did we think much about it? No, not really. What made it cool -  I believe it had compression built in. I think that was the feel.

Maybe. I have a schematic of it, but I never really sat down to study it. I really haven't heard much of its clean tones, but I know that BB King and Allan Holdsworth also used one at one time. I never even heard of the Lab Series L5 until I met a friend of mine who had one. I thought it sounded pretty good. I was surprised to find out that it wasn't a tube amp.

[PRR]

> I wonder why that is?

Because BJT transistors can make a LOT of 2nd harmonic, or with their incredible gain, can easily be slugged for "low" THD, but NOT the "mild" THD of a naked triode.

JFETs have the same "problem" as vacuum tubes: the "valve action" is all spread out in space, not atom-thin as in BJTs. JFET distortion is roughly the same magnitude as a tube, but at typical voltages is NOT the same character.

And many of your numbered reasons too. Other parts, gain structure, EQ, how you connect things, and their interaction. Tube amps are fairly simple (or perhaps just too costly to get complicated); it seems like an accident that we've happened across musically useful "tones". We have more leeway in transistor design, and lose our way.
> Lab Series L5 ... I thought it sounded pretty good. I was surprised to find out that it wasn't a tube amp.

It is very dated, unsophisticated, except the A110 distortion stage. Hi-pass signal is fed to the control port of a VCA. This gives rising-with-frequency 2nd harmonic; to around 7% at/above 2KHz. Moog had good ears and simple taste in design.

[Caferacernoc]

I think it's pretty established that something like a Fetzer Valve jfet or a rangemaster with a bipolar transistor can create plenty of even harmonics. Same thing with opamps and diodes. If you create assymetrical clipping you get even harmonics added to the odd harmonics. What I think tubes do better than transistors is they go into and out of clipping better. That gives the nice feel and pick sensitivity. Opamps particularly, to my ear, just don't transition well. And the note decay crackles and fizzles. If you play super distorted so you never let it clean up the distortion character can sound great. But if you want to play between blues and crunch it's just not the same. I think that's why a compressor helps SS.
When I read about tubes, the jist I get is that they are actually a more linear amplifier in raw form than SS. SS needs loads of negative feedback to be clean. Think op amps. So a tube can transition smoothly into clipping and back out better because it isn't fighting so much negative feedback.