First I say Welcome :tu:,
Next I say how about a link to Schemo of amp? That will speed the process somewhat.


Re your comment;
P.S.  If one suspects that an amp has lost some "oomph" in the low end over time, what would be the 1st thing to check?  Filter caps?

Try simple things before delving into the abiss
Try cables they do wear out,
Now many pedal changes have you made since first using the amp?
Has it been a while since Changing of strings?

you might add some little things to that list. 8|
Cheers, Phil.

Hi kikey,

"There are MANY ways to go when it comes to creating a good guitar sound and the sound some people like is terrible to others, its about taste. "

I Agree. :tu:

Only When you build it then you will know,, sadly you can't hear simulations.

Problem for me is that a lot of circuits work BUT more often than not there is something that's not quite right and you only notice it *After* all the hard work of building it all.

Notice I did not post my Tone box untill I had built and sold 7 of them to mostly *Working* musicians.

If I posted all my ideas I would fill all the pages with circuits that at the time seems like they had potential but now reside in the bottom of my spare parts bin. 

Heck it took me 10 friggin long years of painstaking doggered persistance just to perfect a SS stand alone reverb unit. It was disaster a plenty for 7 years or so but I picked up books (that may as well have been written in hyrogliphics) but ever so slowly I absorbed some of it ,,, well enough to at least build equipment that when displayed at my local music club turns heads a plenty.

Call me slow :lmao: But Geewizz I learnt so much from that experience by not giving up.

I agree if it works as your graph shows it will indeed come close to what you want.

The **Arh Huh** moment for me was when I was able to grasp that it is a culmination of tone shapes (Not just one Wizz kid circuit at one point in the signal path)

It's simply creating a shape that is then imposed onto another tone shape and so on.
Knowing just which part to tweak at which point in the magical mystery signal path is the hard bit. :loco

My Amp setup is the tone box shaping into a simple limiter clipper then the *big mid boost* which is the shaping of Valve power stages.
OK it's just a cab sim circuit but I find that misleading as both F and M type amps have similar tone shaping in the power stages, just more noticed in marshalls.
(speaker design also plays a part)

The rest is of course just simple Graphic EQ.

Other roads will likely lead to the same end,, I just find my way works for me and *importantly* it's not beyond the novice guitar player to grasp the concept.

Then the bonus,, it can be done with relitively cheap gear that may already be laying around in your pile of collected gear.

A point that may interest you;
I Swap the *Clipper and Cabsim* for a small EL84 Tube amp and that becomes my *ReAmp system*.

*Reamp* meaning resistive loading the speaker terminal of tubeamp output and tapping off a line level.
It's debateable which sound better. 0:)

My thought's,, it's just different.
Cheers, Phil.

Hi kikey,
           I was interested because it looked like it would impart a similar curve response like my PhAbbTone box and I wanted to sim the two shapes to see if there was any better performance.

So I've done the best I can to make it work.
I've Simmed the original you refered to as shown by *Daniele Savio* (GREEN trace)
   (The YELLOW Trace is as per your posting).

And here is the result, I've added the PhAbbtone response (BLUE Trace)
to give you some idea of what goes on.

I lack the knowledge to be able to forsee the deeper technical errors so it maybe capable of far better.

Re Daniele Savio's Universal Guitar preamp stuff.
I've never built it so I can't speak for it.

I will say that it's very complex compared to my setup.
Geez He's got 32 knobs on the front panel!! And I was concerned that mine with 7 knobs and a 7 band graphic was to much. :lmao:

Note the otherwise flat response of Active baxendall type tone circuits when compared to the PhAbbTone Rounded response.
ie, flat line boost all the way down to DC,, to the best of my understanding this is good for HiFi and likely close to useless for guitar.

A little side note,
If you care to simulate the classic Valve circuits you will see that most have Massive Bass response in the prestages but often have quite dramatic rolloff below 100Hz at the power Tubes. (ie, 40 to 60Db down at 10Hz)

Generally SS Guitar Amps have all the rolloff in the pre stages and Close to nil in the powerstage., almost the oppisite.
I can't prove anything as I'm no maths expert but I have a hunch it does effect the final result some what.
Thank for posting it all, Have fun Phil.

Just another short clip 4u all,
This is all done with ROC Strat copy, Same recording setup just cranked a bit.

Meantime a question if I may?, regarding uplaods,
Posting page states this;
"Maximum attachment size allowed: 512 KB, per post: 6"

Does that mean 6 attachments of 512KB Each,  or 512KB Total?
Thanks, Phil.

Hi everyone,
                Could not decide where to put this but as there is no actual *PowerAmp* being used to generate the audio then this seems the most logical place.
Well I figured enough talk why not a little demo of my PhAbb SSAmp Setup.

As just about any bit of gear these days (including mine) can produce copious amounts of distortion then why not demo those in between dynamics that are probably harder to reproduce with all SS equipment.

Tube Amps have an area which is on the edge of distortion and this was my aim, to nail/capture that in between *Rattle* that a lot of those famous tube amps where able to do so easily.
The Knophler sound is often a tricky one so I tried it out, see what you think.

First track is done with a bog stock Chinese Strat copy, I like it for this stuff because the Pup's are low winding only 4k DCR.
The second bit is Recorded with my other guitar (real 60's era Strat pup's)

(Maxiverb is a stand alone Spring Rev unit I desiged and built about 10 years ago,, and still going strong.)

Signal path;
Maxiverb > My PhAbbTone box > DDC (My Dynamic Distortion Control)
> A Realistic HiFi GraphicEQ > signal into Line mixer> Into Audigy SCard.
Adding no post efx of any kind.

There is very little difference between the line rec out sound and a real 100Watt power amp driving a guitar speakerbox (To my ears at least) but your speakers will colour the sound to some degree no doubt.

If any interest I will post more short demos and all the setup schematics, might give you some ideas to work on.
Sorry the file is short but only 500kb allowed.

Hope you enjoy, Phil.
Edit 2011
> Reloaded the files and Dloaded back to myself and it seems to be working OK now.<

Hi kikey,
           Just done a quick simulation and not impressed.
Giving only 3Db Boost/cut @100Hz and 7Db Boost/cut @ 2kHz.

The Mid sweep is looking like real trouble I can't get a decent mid cut or boost in the audio range and changing values around does little to improve it.
I may have missed something but won't work for me.

If you want to mess around get a bread board and test each new circuit you find.  It's hard work and time consuming but well worth it.
Or cheat a bit like I did and use both a *bread board and a Software simulator*
That way you can weed out the crap a lot faster.
When you do find a sim that looks good you can bread board test it and hear if it does actually sound impressive. 

Frankly my 3rd option is going to save you from years of frustration,
Build my *PhAbbTone box* as I've spent *Many Years* working out the best tone stacks for guitar.

If you feel like I'm bragging a bit,, well I make no apoligies as I've spent years building all these friggin circuits and Although I'm not the most qualified nerd on the planet I've *Done the Time* and put in the hard yards.

If you still need extra EQ after PhAbbTone then a simple graphic (after distortion box) will work wonders.
If you are interested the circuit complete with plots is found here;
http://www.ssguitar.com/index.php?topic=1136.0//

I'm about to post some sound samples of my whole setup so you might like to hear it.
Phil.

Hi koreth,
           Just had another look at your circuit

Re "More clean headroom"
R2 is way to small,, try 2k ish for a more sane progressive gain.

Re "More highs"
C7 (after VR2) is also 5 mile to large, try 10nF.
that will get rid of the big hump at 100Hz.

Re "the distortion"
With or without diodes the trick is to setup the two opamp stages with just the right amount of *gain* then the amp will probably respond/sound ok.

It's debateable whether diode clipping sounds much better that just letting the signal slam into supply rails in a small amp like this,
Diodes or not you will have to tweak it.

BTW, you obviously have some kind of software setup which looks like it can simulate,,so why not run a few sims yourself and you will see this all happen.
Phil.

Remember C26 itself might be dead ?
Try replacing it with a new one.
Phil.

Nice work Brymus ,,
but my concern is the NF path ,,, efx loop in between?? Head scratch?? Like what's gonna happen if the returning signal is in phase??

Surely that would then be a positive FB situation?
Hey if it works then no matter,, an I maybe missing something.

Phil.

Hello markRRoll
You don't just *LOOK* at a soldered circuit,, as even with good eye sight you will not see a (thinner than hair) strand of copper from a striped wire.
They fall off as you strip and can get soldered across tracks and it will drive you mad till you find it.  (Yes I'm speaking from experience)

Scub the track side of boards with a stiff brush*After* you solder them.

If you use sockets for opamps,, makes life a lot harder as it's just another place for a bad connection, (Personal Experience again) IMO they are trouble waiting to happen.
Phil.

Quote from: illpanteraa on January 02, 2010, 01:10:43 AM
well got to thinking  i went back and checked every transistor in the amp  and found  4  more

http://sound.westhost.com/project03.htm
Have a look at the schematic on the above page as it's about as simple as it can get, Only 7 BJT's and 50/60 watts.

The single BJT (under the diodes) is the VAS.

The reason I mention it is simply because nearly all modern SS amps are based on this basic concept, So if you can develop some understanding of how this one works then you have a resonable chance of understanding the more complex circuits.

More than once I've just cut the original poweramp in amps like yours and built a new power stage, as some are hard to get parts for and often an off the shelf kit or chip amp works just as well or better.
My 2 cents worth. Phil.

Hi koreth,
             I'm afraid there is little chance of *Clean* while you have Diodes (D2,D3) permanantly strapped across the signal path.
Try lifting them and see how it sounds ,that should give it more signal headroom.

For more brightness try lifting some of those caps that hang across the signal path as well. (try C12)
if TO Bright then half the value,, try 500pF.
I'm guessing but as JMF has noted this is just a TS9 type circuit with a speaker output.
Phil.

Hi Koreth,
YES! correct, +- means *postive and negitive* DCVolts
(with respect to Zero volts)
Phil.

Quote from Mace;
"So I guess over all my main question is how to do away with the bypass when I'm using the effects loop?"

I may be missing something but the question is not making sense to me.

WHY Would you need to do such a thing??? :duh
You then have 2 seperate inputs,,, So Where does the guitar plug in???

I'll guess and give an answer that may help

The effect loop is *After* all the preamp stuff,, ie, tone controls, dist etc.
You may need to create an efx loop at that point then loop out to RACK and back in to internal JC Reverb and Chorus.

Find the model that has the *SUB IN* then break the circuit there and make a simple in/out EFX loop and then all onboard efx will work.
Hope it helps. Phil.

Hi can I just say,
Without trying to dampen the enthusiasuim of all the budding home fixit folk.

These Discrete components are part of a High current DC coupled Poweramp
and generally (in my limited experience) if the output devices are blown then novice replacement of such will yield instant vaporization of $cost and hours of hard work.

DC amps are not just the Output Transistors
If the amp has already taken out the power transistors then it's highly likely the *Cause of the problem* is in the *VAS* stage. (Voltage Amplifier Stage)
This commponent is often a single transistor sitting further back in the circuit and usually takes the full Rail to Rail DC voltage.

Without the knowledge and equipment needed to test for problems it's going to take a lot more than a soldering iron and enthusiasm to fix it.

I recommend a lot of research before attemting to just swap a few burntout components.
Yes you could be lucky but I've messed around with a lot of these troublesome DC power stages and I've been caught out a few times. Even with the light bulb idea if there is instability in the VAS then the moment you think it's fine and you reconnect a speaker,, bang.
 
Some of the better qualified folk may wish to comment here because my explaination may just add confusion.
Phil.