Hello Findeton, 

I quote; "I have a jtm45 hand-made by myself, but i'd love to have a pedal that is able to get the classic tube distortion without having to mod my amplifier nor having to pump up the volume. There are many stompboxes out there, even some with tubes in them, but I like to do things by myself."

So I'll take it That this is the AIM of Your exercise?

Take the classic Bassman/ Marshall swap as an example;
Without changing anything (other that a rebias) change the 6L6/5881 to a EL34.

This turns a mildly hot bassman into a monster compressed OD machine.

"""""Pentodes where invented to overcome the limitations of triodes."""

Triode output stage has a distinct rounded top when driven hard only Tetodes and better still Pentodes can do the marshall *Square Wave* compression trick.

The sound you hear from you JTM is **Output compression** and has very little to do with triodes. (though the PI may hold some secrets).
Triodes can't do it With the aid of a transformer so what hope is there with only a triode?? :duh

Go the whole hog,, swap your JTM45 to 6V6 output and you will be lucky if it rattles on 10 as they have very low TC.

Or just triode strap you output tubes in the JTM45 to make them work like triodes?  I doubt you will like the thinner weaker sound.

Tube power stages are just big oversized, overweight, expensive *Compressors* 8|
Darn problem is that by the time they compress well they are to darn loud,
as you have noted.

Another clue can be found in some of the *early studio compressors* (names escape me here but) some of them actually used *phase splitters* and *Transformers*. (hint)
Though they worked well for audio they still could not pull off the same trickery as guitar amp outputs. (maybe because they only used triodes)

You obviously have the mind for vastly complex stuff (You leave me for dead) but I fear your base data is way off.

As I've come to understand with most things scientific,,,If you miss the basic concept all the maths in the world won't make it right.
Have fun, Phil.

It's probably a loosing battle trying to argue with the eternal wisdom of youth but here goes;

Get a blind fold,,, get someone to help you into a shop.
Now ask the man to plug into all the different amps and don't ask what you are playing through.

Just use your *God given ears* for *the purpose* they where *designed for*.

This industry is chocked full of *Name Droppers* and it is truely sick.
It's your money and amplifiers have a shocking depreciation value once they leave the shop.

50% of equipment sells on Brandname and gimiky looks and very few even come close to sounding brilliant. and I'm not just talking SS gear the valve gear is just as bad.

But then I'm obviously and old fella so my opinion will not count for much.
Phil.

Just find one of those horrible fuzzboxes from a bygone era where you can only play one note at a time,, only just passable as a musical note.
THEN try and play a full bar chord and the result has no correlation to any harmonic at all.
Off course these days that maywell be appealing to some music lovers  :lmao:
Phil.

A quick pic might help,
I used a couple of plugpaks while building several Discrete Poweramps, saves a whole lot extra work if you want to just find out if something works.
Be aware a lot are not well filtered and you may need to add some extra Caps for filtering. Not all are Full wave Rectified this can lead to excess ripple issues.
Phil.

Hello dogbox,,
                 There is no magic,,
Once you get to a certain tone/feel/distorted effect then *From that very point in TIME you record that sound/tone* THEN you make sure you Replay/RE-amplify through a *Flat Frequency responce Amplifier* then it won't alter the sound you hear very much.

Whether you create that point in time with exotic expensive mic,s/ preamps/ digital
recording software or simple cheap resistive network tapped from the speaker and a $10 hifi graphic is kind of irrealivant,,, as long as the RIAA curve (or whatever) of the Playback is kept flat then it will indeed sound the same.

Try playback of your favorite recording back into a (NonLinier) Marshall and the whole
sound/tone will be dramatically different.
****Yes Absolutly you can make an amplifier sound the same recorded as live.***

I've just been trying to get this through to some folks on another forum.
Because some recording magizine goes to great depth explaining how to place mics to get the best recording,,, followed on the very next page with a full page spread of the very latest mojo sounding *Recording Preamp*,,,,, complete with glowing $$$ Valves $$$.
Sorry it's just such obvious crap marketing,,, I've lived to long to fall for the fakeness of this industry.

If the average Joe (never going to make it Rock/Metal band) gets into a studio thinks for
one minute that the sound teck is going to spend half the day just placing mic's in the
right place to capture the *Magic* of your overrated brandname guitar amp,,, then you have a lot to learn about HOW it happens that a crap band can be made to sound passable.

Capturing sound via microphones is old school and $$$time consuming.$$$

Any serious recording studio just taps a signal and manipulates it via equipment behind the scene,, and he is unlikely to tell average joe band members the real secrets of recording.

They will pop in couple of mics for room ambiance and just to make the kids think it's for
real but in this day and age mic's are only used if you are seriously famous and then the
studio geeks will go all out.

I kid you not the sound on that PhAbbSSAmp Demo link is very close to how it sounds through the Speaker.
Cheers, Phil.

Thanks Teemu,
          I really appreciate the non mathamatical explanation. :tu:
Phil.

Quote from: Koreth on February 12, 2010, 02:58:55 PM
I know Teemu's book talks about some early SS designs that employed transformers, but that is largely unnecessary know, since SS devices have such an incredibly low output impedance. The impedance matching function an transformer serves in a valve design isn't needed to drive the speakers in a SS design. I wonder if one could work some transformer magic with an appropriately built 1:1 transformer between the output device(s) and the speaker.

Another thing to add to the (growing ever longer) list of things to research and experiment with, I guess.

All this maths stuff is fast leaving me behind but I do know this;
The transformer in a Valve Amp is a *voltage to current converter* ,,,So using a 1 to 1 OT with any SS design is likely not going to work as you might think.

It would seem that the conversion done through a transformer maybe very different than a transistor circuit.
Keep in mind that AFAIK transistors are generally *Low voltage, Low imp, High current devices*,,,whereas Tubes are Generally *High Volatge,, High imp,, *LOW Current devices*.

My guess,,To even come close to approxamating a valve design output implies that you need to run the OT off the Collector/Drain,, not the emitter/Source.

Again (with my limited unseratanding) It's certainly obvious with simulation that *High freq hash* does indeed exist on the plates of Power Tubes but magically dissapears at the secondary. (I assume due to the limited bandwidth of a given OT?)

In most SS designs this is passed directly to the speaker.
My 2 cents worth?
Phil.

Hi monkeyboy,
                   I know *Teemu* means well and with his incredable insight I have no doubt that if HE lived next door to me I would be brave enough to take on such a project.

*IF* that is not the case and you are starting out with little knowledge of electronic circuits then ,,,some things you might wish to consider???

The amp in *Un-altered Original Condition* will fetch considerably more money than many other SS Amplifiers that are technically better SS Amps for blues. (as Teemu mentioned)

I believe JC's are in the hall of fame of the most famous Amplifiers,,even though they are all SS.

Mess with it and make it useless means you have blown the value of a resonable investment.
IMHO,,, get another amplifier and go crazy with that one instead. :tu:

If that money value does not bother you then go crazy and to hell with original.
Phil.

Hey rodriki1,
                 I've spent the whole afternoon messing with your *Treble booster*
Very good work on your part 0:)

I was concerned that it could make the sound resonantly harsh,,, but with some tweaking it certainly can be made to work.

Gee wizz ,,, I may even incorperate it into my next Tone box build. :tu:

Here is what I've done to the basic concept.
Insert a 10k liner pot in place of the 2 x 5k6 resistors. (the center lug of 10k pot connects to the Cap)
***Bingo you now have an instant *presence* circuit***.

Used in conjuction with my circuit it certainly helps.

Suggested changes if using my setup;
1/  Insert 10k pot instead of to fixed resistors,, as this gives it the ability to cut or boost the notch,,, very nice.
2/ change 1nF to 2nF (helps to flatten the peaking effect)
3/ change 47nF to 150nF

So I've done my time finding out stuff now you can take it further,,, good luck.
Phil.

Just re-read the post above your reply,,, JM Fahey is no mug 0:)

Heck replacing opamps in such an amplifier is just thowing money out the window.
Phil.

All this for a 1% improvement?  hardly worth ansering....
Phil.

For blues JC120 is the one amp you would never want to use.

If the blues driver improves the sound somewhat then just keep the blues driver and loose the JC120 and get a better Amp.

I'm sorry if that insults some user of JC 120 but IMHO of 40 years experience with many amplifiers of varying quality,,,, JC distortion is one of the worst I've ever used.

Yes what you ask is ,,possible but cheaper to get a decent amp.

Cheers, Phil.

Quote from: Joe on February 11, 2010, 09:24:24 PM
Pushed output transformers are definately part of the "tube sound". This really shows up in professional tube amplifiers. The SVT Classic comes to mind, as well as a dimed JCM800. Raising the volume to 10 brings out a monster that wasn't there on 3.

Just some random thoughts...

Hi joe , Yes Transformers ,, and in my somewhat limited research it would seem that the the most famous marshall sounds where likely due to *VERY LOW* Primary windings used with EL34 tubes.

Also I noted that Jim Marshall was close to bankrupt at some point and used less than ideal transformers in Amps that now have *Legindary status* 

In my own testing I've found that a pair of 6V6 tubes driving the commonly excepted *Ideal* OT of say 6k6 primary was exessively harsh.

Without altering the circuit I opted to drive a *2k6* OT instead,,,
and my god it was a real eyeopener, A night and day difference,, beyound my wildest expectaions. <3)

some tube geeks claim the just mismatching the *Secondaries* of high primary OT's will effect the same result but I have doubts about the maths involved.

There was some good data on this subject over at *Obsolete Electronics* regarding the primary *match or mismatch* but that site is no longer in existance.

All I will say with some certainty regarding OT's for tube amps is simply that It makes one HELL of a difference to the end result.

As far as all the SS stuff goes a lot of it is beyound my ability,,, but ever so slowly I listern to chaps like you and I learn. :tu:

Cheers, Phil.

Hi rodriki1,
              Just one point,, if you build *Both* in the same box, notice the schematics for tone box is single supply whereas the DDC is split supply.

If you wish to build them both the easiest way round it is to convert the tone box circuit to a split supply.

My advice is *True bypass everything* that way you can instantly recall/compare differences.

Just thought I sould mention it.
Phil.

Quote from: rodriki1 on February 08, 2010, 06:39:58 PM
First i wanna thank you for your capacity to share that kind of knowledge.
I MUST SAY that is incredibly rare and precious...

i have been reading and researching those kind of stuff for years (i mean
- ideas about tube amps made with SS)...
but it´s very sad that we cannot find very much ideas to apply..
when the thing is good it is always protected..

I personally agree that tone shaping (equalization) can make the sound you want..
but sounds to me that a good circuit for tone shapping
in general gets very expensive...
in many ways it is very hard to me to get the sound of tubes in my country.
the problem is entirely mine, but i like the distortion produced
by tube amps...

thanks again hope you be happy with your research.

Hi Rodriki,
Very kind words so I thank you and I'm glad that you find my observations useful.

Re cost of good tone;
try this, http://www.ssguitar.com/index.php?topic=1136.0
That is the circuit I designed and built and is the tone control used in these clips. 8|

The tonal possibilities here are very broard and I can't imagine you could not get something close to ACDC sound.
Not counting the Reverb unit all the preamp gear here is cheap enough to build.
The *PhAbbtone* parts cost me about $30 Aus.
*DDC* is similar cost but more complex,, all doable for anyone with resonable pedal building experience. So in a box complete I can't see it costing over $150.

Oh and the *Graphic EQ* cost me $8 at S/hand shop.
----------
Re thoughts on tone:
A big *arh huh! Now I get it moment* for me was once I discovered that tone response is much like a garden hose laying on the ground,, where when you lift one point (the Q point) off the ground you also lift a fair part of the rest of the hose. Passive tone shaping does the same thing. (so tone is all just a big rubbery thing)

A bigger moment was understanding that tone is constantly altering as it passes through each passive and sometimes active components,, Not just the tone stack.

For want of a better explaination;
Tone is just one tone shape (response curve) imposed onto (or into) another element with a different shape.
What I think makes it difficult to grasp is that we all tend to go hunting for that *One magic circuit* that delivers the major component of a specific tone.
Truth is it's a culmination of many circuit topographries and tricks all working together that makes the final result.

Adding to that already complex situation  :loco is the simple truth that there may be many ways that effect the same end result.

For a novice, this is much like walking through a 3D mine field with so many twists and turns that getting it right first go is impossible. :duh

The magic of the classic Marshall amps that are now famous actually have a unique Flaw.
""It is in fact the design Flaw that makes it so great.""

if you ever find yourself with a *Genuine* older model all valve Marshall,, try this out.

At low *level volume* turn the tone controls up and down and note how they affect the freq response.

Now crank the volume way past halfway and play a few rifts/power chords,,, while you are doing that start playing with the tone controls again ?
You will now realise they don't work very well and depending what guitar and how far you crank some tone controls may no longer seem to function AT ALL 

The compressing output stage renders the tone stack almost non existant?? Hum??
Early Marshalls tend to develop a huge wall of midrangey honk that suits the rock compressed sound. below 100hZ just falls like a brick and the combination of dramatically altering impeadences and output transformer limitations of high freq kill off above 4khZ. choise of speakers helps too.
It more complex than that but I won't get into pointless detail.

Now take a Peavy Bandit, All SS (only cause I've been fiddling with these recently)
Try cranking up the drive and notice how the tone controls still work as effectivly as they did with no gain/distortion.
technically it could be argued that the Peavy tone works better than an old Marshall?,,
No argument from me,,, but which Amp would you rather use?

You see the Peavy uses *Active* Tone shaping,, not passive.

It also suffers from WAY to much bandwidth,, way to much low freq content below 100hZ and the treble is extreme even by comparison to some other SS Amps.

Yet some players love those Bandit Amps? and that's kool,,Everyone want's something different but if you wish for a Bandit to sound like my clips you will be tweaking it for a very long time.

What I've found is that passive *Before* the distorting device and Active *After* seems to work very well together. There are probably other ways but I do actually play guitar and I've only got one life.
What is most interesting is that my setup seems to have the very same tone control flaw as the Marshall. :tu:
----

Try googling *Ed Rembold Marshall cab sim* or grab a schematic of
a Marshall JTM 30 or 60 Valve Amp where you will find the *Built in Cab sim* which is an add on SS circuit which does a respectable job of the sound required.  (No distortion though just tone shaping).
The marshall cab sim is a little less complex than my DDC but delivers similar results. I've built 5 of them so I know they work.
----

You mentioned Vox, I'll assume here you are reffering to Brian May Sound?

Consider this,, Brian May used the *** Normal** Channel,,not the *Bright* channel  (as most assume) to get his particular sound.
So simulating the tone stack seems rather pointless because the normal channel on a Vox AC 30 *Has No Tone stack*. The signal passes through a 500k volume pot and the only other tone altering device is a *Top cut pot* mounted across the PI section.
Simply by implimentaion of a rather basic treble boosting transistor circuit in front of the Normal input will deliver that particular tone.
---
Re the circuit you give seems to do nothing in my simulation but I may have missed something?

Have fun with it all, Cheers, Phil.