FET model of 18 watt. Heresy or not?

[LeeMo]

I'm not sure if anyone has posted this link here before now.
http://www.runoffgroove.com/eighteen.html
It looks like it would be fun and edu-ma-cational and inexpensive.
What are your views?


LeeMo

[LeeM]

Blasphemy my friend! No slab of silicon can compete with a thermionic device.

Speaking blasphemically, I suspect that with the right speakers and a good player in a band context, the typical listener would say it sounds just fine. I don't believe anyone can judge adequately from a small sample coming thru computer speakers though I'm sure many will try.

[LeeMo]

Notice the simularity in our nom d' plumes. Does that make us "birds of a feather(plume)?

LeeMo

[bnwitt]

LeeMo,
your teasing right? God those clips almost made my ears bleed. That guy doesn't really believe they sound similar to the clips of the real 18 watt does he? Man, no tubes no OT=no low order harmonics and no warmth. Just grating awful FET distortion that made me want to pull my own fingernails out. I was begging for mercy before the end of clip 1. I tried solid state for 25 years and there is just no comparison to tubes an trannies.

LeeM,
you gotta get rid of your small computer speakers and get a 7.1 high fidelity speaker setup to really appreciate 24 bit sound. Clips sound great that way.

[LeeMo]

Yep, I know better. I just thought that it would be interesting to build some of the projects on his site. Maybe even an 18 Watt-are-you- kiddin-me?



LeeMo

[LeeM]

No offense to anyone who claims they can hear the difference but I wonder how one is influenced by what one expects to hear. Most of the "tubenuts" are predisposed to hate the sound of solid state so when they hear something that's solid state, they automatically hate it. I have 4 tube amps and they all sound good to me albeit all different. I've heard some good players sound very good through equipment that most tube afficianados would thumb their noses at. I agree that a good tube amp will always sound better than a good s.s. amp but I don't agree that all s.s. amps sound like crap or that you can't get a good sound without tubes and an OT. Maybe my ears just aren't good enough to tell the difference.

[bnwitt]

Most of the "tubenuts" are predisposed to hate the sound of solid state so when they hear something that's solid state, they automatically hate it.

Lee,
I read your two posts and I guess I'm a tube nut, but I wasn't for 25 years. I used to poo poo tube superiority and made it my quest to find a great solid state amp to prove myself right. I now own or have owned just about every single solid state amp or preamp that has been made including pods, cybertwin, vetta, VG-88, original JC120's, hybrids, pedals yadda yadda yadda and all I can say is two things.

1. If you can't hear the superiority in a quality tube amp over any solid state amp (with the low order harmonics, the part an interleaved paper OT plays in the tone and the touch and response tube circuitry adds to your performance), or because of your inability to hear it you think

anyone who claims they can hear the difference

is just overcome by emotion or delerium in there effort to be right above all logic, then there is definitely something wrong with your ears and your logic.

2. If you think putting "no offense" in front of a post that calls people "nuts" and insinuates that they are incapable of making real ascertations of tone without letting their emotions rule because the just have to be right, then you have alot to learn about tact.

Any pro (player or amp marketer) will tell you that solid state just doesn't sound the same as tube. And most will tell you tube sounds better. Not more reliable, not less trouble, not lighter, yes indeed a real pain in the butt in many ways, but tube sounds better. Now this is from a guy who let his emotional baggage(sore back and thin pocket book) tell him other wise for 25 years. Straight up, no B.S. bad ears and all(tinitus)and I am certainly not a newbie or dillusional. I will say that not all tube amps are well designed, however, but the great ones cannot be touched tonally by any solid state replica I have found.

No offense

[Plexi]

"""your teasing right? God those clips almost made my ears bleed"""

Thats funny..
i listened to all the clips.. The trem clip don't even come close.
Believe it or not,someone posted a pic of an 18 watt Solid state amp on e-bay. Alot thought it waas something made up. But if you look at the ad in the Doyle book,page 13, read the Roy Orbison ad. It says they were making 60 and 18 watt Solid state amps. Or as they say, "The New"
Transistor combination amps.

I have to agree, some of the clips were not all that good sounding.
In all my years of playing,I know of one solid state amp that sounds great.
Or works great for a guitar amp. Its just alot of people would never thingk of trying or useing it for guitar. Thats as close of a hint i will give.

Richie

[RossH]

I know of one solid state amp that sounds great.

A Vox Royal Guardsman?

Another snippet from: "Ken Fischer's List Of Ten Good Sounding Old Amps That Are Overlooked (No Particular Order):

5) Here's a curve! Vox Royal Guardsman. Yes, it's solid state! This amp is the half power (and cheaper) brother to the Super Beatle and has a clean sound most modern tube amps would "die" to have. If you want distortion make sure it all comes from a box. The early transistor output stage fails when pushed. I just want to know why todays solid state amps can't come close to the sound of this Vox?

~ Ross

[ColinM]

Richie
Are you talking about a solid state Leslie?
I used one on a session, oh a good 16 years ago. It belonged to the studio and had been adapted (I think) to take a guitar input. I used it on the suggestion of the producer/studio owner.
It sounded superb, at least on the track on which I played it did - although it wouldn't work for everything...
My own favourite SS amp is the Lab Series 100 watt combo. Three different speaker configurations, a fab compressor and a 'multifilter' control that enabled you to 'voice' clean sounds in a really useful way. They were never going to sound like Marshalls, but you wouldn't buy one if that's what you wanted...
When they appeared in the late 70's/early 80's, I was into jazz guitar playing. The Lab was my favourite amp then - believe it or not I'd have happily swapped my 18 for an L5 - so glad I didn't
How about the Musicman hybrids? Still sound good to my ears...
Regards, Colin

[gtrmac]

It should be kept in mind that the "emulations" that those guys design are only the preamp stages from various amps. Since it's true that a lot of what we like about tube amps comes from the output tubes and the transformer the FET "models" are limited in what they can do.

But I think they're cool toys to play around with and I plan on making a couple to use for direct recording at home.

[zaphod_phil]

I just took a look at that schem. It seems to have been done more as a fun experiment than as a serious emulation of a Marshall 18W. So I think we should continue to take it in that vein. Here's the deal, FETs basically have very linear and symmetrical characteristics in comparison to tubes. So basically you get a linear response until the amplified signal hits the supply rail voltages, and you get a harsh-sounding cutoff. Tubes just don't behave that way. They're both more non-linear and asymetric at the extremeities of signal, and also compress parts of the signal. So it would take a quite a lot more FETs and other stuff to try to truly emulate the operating characteristics of tubes. Also, SS amps don't have the same dynamic range

Yes, some SS amps can sound nice and warm, but they're not that common. Some of the very old ones have OTs and sometimes even mid-stage transformers in them as phase splitters, and some even lack negative feedback, so you can get a warmer and more natural sound. IIRC the PV Dweezil amp was based on an old SS radio console that Dweezil Zappa found, and liked the tone of when he played his guitar through it. So he took the thing to PV and asked them to build him an amp using the same basic design. I've never heard one of these things in real life, so I don't know whether it's really as good as Dweezil seems to think....

[GaryB]

Hello all,

I am Gary from www.runoffgroove.com. I've been reading this thread and decided to clarify some incorrect things that were said:

I know this jfet emulation of the 18 watt circuit most definitely does not sound exactly like the real amp. I'll further say that I'm sure each of the amps you've all built do not sound the same to each other. I know this, since I do own and have used tube amps (primarily Marshall) for the last 20 years. SS will never sound like tubes, but some characteristics can be replicated with SS devices and proper filtering. How many of you use stompboxes between your guitar and amp? Do you have an all tube, all high plate voltage signal chain?

There was a reference to a "trem clip." We did not make a soundclip of the emulator using a tremolo. I think the clip you reference is of another circuit altogether.

There was a comment saying the amp emulations are only of the preamps. That is incorrect. If you examine the schematics closely, you'll see half of the phase splitter and a stage of the power amp done in jfet. Why only half the phase splitter? There is no need for a push-pull stompbox, right?

I have no illusions of this emulation being the same as an actual amp. It is, however an excellent overdrive pedal that does capture the overall tone of the 18W amp. Two of the builders on this site (they shall remain nameless) have built this circuit as well as the amp as described on this site. Both have let runoffgroove know the circuit does sound uncannily similar to their homebrews.

I know the quality of the sound on the clips is not professional. I also know my playing is not that great. However, the clips are designed to give you a resonable sample of what the finished circuit will sound like. I assure you, the sound is not as harsh or non-dynamic as you may think. As I have said, I have played tube amps for 20yrs. While the jfets are not exactly the same as tubes, you'll notice some interesting similarities.

The intent of these emulation pedals is to allow a player to have a couple or so setup through a clean amp. This offers a player a chance to get an analog simulation of different amp types, available at the stomp of a switch. It is meant as an effect, not a replacement for our beloved tube amps. Please try to keep an open mind.

My advise is to try this circuit and see for yourself. Get a breadboard and all the parts as shown in the schematic and just try it. Put the circuit through a clean amp and see how close it gets to the sound of the tube amp. You may like what you hear.

Thanks for your time,
Gary
runoffgroove.com

[Plexi]

"""There was a reference to a "trem clip." We did not make a soundclip of the emulator using a tremolo. """

That was me. i listened to all the clips,it was late,and i didn't read all what was used. One said trem,and had a trem effect. I thought they were all the 18 thing. So that was my fault.

There were some of the clips that weren't too bad, what ever was used.
The more clean to slight overdrive were the ones that seemed better.
I think one was a stones clip.
I like pedals,some don't but they are like anything,some are good,some are crap..lol Most of my pedals are all old stuff. I only have a few of them. And use them for getting different sounds. Nothing wrong with just straight tube amp,and nothing wrong with useing a pedal into a tube amp.
At least thats my opinion.
I like to see people experimenting and trying things. And as you said,some of the recordings may be on the hot side. I know even with tube amps,if you don't get it recorded good,it will sound nothing like the 'real' amp' being recorded.

Richie

[zaphod_phil]

I know this jfet emulation of the 18 watt circuit most definitely does not sound exactly like the real amp. I'll further say that I'm sure each of the amps you've all built do not sound the same to each other. I know this, since I do own and have used tube amps (primarily Marshall) for the last 20 years. SS will never sound like tubes, but some characteristics can be replicated with SS devices and proper filtering. How many of you use stompboxes between your guitar and amp? Do you have an all tube, all high plate voltage signal chain? ... I have no illusions of this emulation being the same as an actual amp. It is, however an excellent overdrive pedal that does capture the overall tone of the 18W amp.

Hmmm, I think maybe I see a little self-contradiction there!

Anyway, here's a funny coincidence. Just this morning I was listening to a set of soundclips from several vacuum tube boost/distortion pedals currently available on the market. The clips were part of a review done by Guitarist magazine in the UK. I was actually very dissapointed by what I heard. They could either do a reasonable clean tone or else a totally over the top, fuzzed-out, hi-gain sound, like a SLO 100 on Ex-Lax. Yet, my SS Marshall Drivemaster pedal, which has clipping diodes inside (yikes!), can do a whole wide range of really nice overdrive and distortion sounds, which (at least in this demo) none of the tube pedals seemed to manage. Fascinating....

So yes, you could certainly say this FET design has been influenced or inspired by the Marshall 18W, complete with preamp, PI and power stage. And I think that's a perfectly valid thing to do. However, if you put it under a 'scope and look at the way the signal waveforms compress and distort, due to the dynamic characteristics of FETs being so different from tubes, it will be immediately apparent that it won't sound very much like a real 18W at all. But then I don't think anyone is really claiming that it would. So yes, I'm sure this design would in fact make a real nice distortion box, maybe even nicer than those real expensive tube ones!

[BTremblay]

However, if you put it under a 'scope and look at the way the signal waveforms compress and distort, due to the dynamic characteristics of FETs being so different from tubes, it will be immediately apparent that it won't sound very much like a real 18W at all.

Wouldn't it be simpler to actually listen to a circuit, rather than use a 'scope to determine how it sounds?

Gary and I have developed several FET-based pedals that are based on tube amps. We obviously understand the limitations of such an approach and our goal is not to reproduce tube behavior with solid-state devices. We're merely hoping that a stompbox overdrive circuit based on a tube amp can offer some of that particular amp's tone.

[zaphod_phil]

It may be more fun with a 'scope! And our ears can be decieved more easily than our eyes - I'm sure you've also heard of ear fatigue for instance. Anyway, what I was actually trying to say was that your ears will confirm what you can actually see happening in the circuit, the 'scope providing the explanation of what you're hearing if you like...

And I'm completely in favour of what all you guys are doing. Keep up the great work! Now if you could find a way of making a FET compress the signal as it heads towards saturation, but not when heading into cutoff, you would really be onto something cool...

[Graydon]

Gary,

Welcome to the 18W group! I like what you did with the 18W circuit and the FETs. The first thing I thought was "I want to try that circuit!" I think that you should just ignore all the naysayers (there will be lots of them here, that is for sure, all good guys too) and continue with your work. It is work like that which will eventually cause the state of the amplifier art to progress. Things you will learn in those exercises to replicate various tube amps will help you later when you finally design and build your Mona Lisa which may end up being SS.

[GaryB]

Thank you, Graydon. I appreciate your words of wisdom.

All these posts have been an interesting and educational read. I have enjoyed seeing others opinions and perspectives.

Perhaps in my "contradictory" statement I should rephrase and say "SS will never sound EXACTLY like tubes."

I do recommend trying these circuits. These are the most amp-like of dirt boxes I've heard so far. I'm not tooting our own horn, as we did not design these circuits. They are literal translations of the amp circuits, adapted to 9V power. I understand this is very similar to some of the Men@tone pedals.

If you think you might use an overdrive or distortion, they are worth investigating further. Feel free to visit Aron's Stompbox Forum. There have been a few that have crossed from amps to pedals and some that have gone the other way. You can never have too many skills, you know!

Again, thanks for everyone's time.

[Psalm150]

Heresy! It must be burned at the stake!

Just kidding. I think this is fascinating! If I ever used a SS distortion pedal, this would be the only way I would go. Those early SS Vox amps had an incredible clean sound. I think because they were built like tube amps with output transformers etc. A SS Vox was close to #1 for clean at the last Tone Fest.
I still don't like the way SS distorts though. I do use a dual 12ax7 pedal modified to my liking for extra dirt. At lower gain settings it sounds very good (higher gain can get buzzy). I had a pedal a while back that had one 12ax7 and one FET. Even that was too much SS. You could still tell the difference, mostly in the feel but also in the sound.
And that's probably the biggest problem for me with SS; the feel is off.
But again, I think this SS 18w project is great! A lot better than digital modeling!
Just my thoughts.