Quote from: Brymus on January 14, 2010, 02:06:30 PM
Hey Phatt
VERY IMPRESSIVE INDEED
That sounded like a high end guitar rig for sure.
I am just curious why the reverb is first in the signal chain?
At any rate it definatly works good that way.
What is your noise floor like ?
And what part of the chain contributes the most noise ?
The single coils or one of the other pieces of equipment ?
Thanks for sharing I definetly enjoyed seeing/hearing your set up!!!!

Hello Brymus thankyou for leaving a comment.

Reverb unit in front is old school thinking and as hundreds of famous guiter tracks
where recorded in this manner ,,,Why change it?

Took me many years but it finally went clunk one day when I saw a photo of SRV with a *Standalone REV unit* sitting on top of his famous Dumble head.
Ding! the penny dropped, he was not using the internal REV circuits on fenders.
They where never designed to be driven into very hard clip.
When you drive them really hard the frist triode stage clips and multiplied again
via the Rev Driver circuit. By then the whole rev sound just claps out and distorts badly.

Outboard rev units don't normally suffer this fate which delivers the signal into
the Amp clean leaving your triodes (if using valves) to do one job well, not a compromise of two jobs.  
This is tricky to explain but simply put if the REVERB is Created CLEAN then you
can Drive the signal into Heavy distortion *After* Reverb creation and it sounds
fine.
Hope that makes sense.

I've spent years working it out and I've found that most *Onboard* reverb circuits are deadpan when compared to mine (or most other well designed OutBoard rev units)
There is a newfound interest in the older valve rev units but way out of my price
range so I wanted to perfect a SS unit that would come close to being as good as the the old valve unit's.

Noise floor;
           Very low when comparing to shop sold gear I'm very happy with mine.
Hum is close to negligable, Hiss goes up when using the *DDC* but the gain and
drive knobs hardly ever need to be past half on, 12 O'clock.
(in those Heavy samples the the drive knob was on 10 O'clock (4)
and the Gain knob at 9 O'clock (3) level out 12 O'clock (5)

I think most go wrong by assuming you MUST HAVE MORE GAIN no matter what and deal with the hiss and hum via some other means.

When really there should be much more focus on the *tone shaping* of distortion.
**If you amplify the right frequencies you don't need all the gain.**
Casscading Fets or triodes is a no brainer simply because neither can actually
produce square wave well and until that happens it won't ever sound as convincing as a simple well EQ'd diode clipper,, which actually CAN produce a close approxamation of the signal passing through a Valve power stage.
(power tube compression is considered by some the holy grail of tone)

Just EQ either side of the old TS9 circuit and it might suprise you.

A good example of the POWER of tone shaping can be shown thus;

Take ANY of those old VALVE Amps, fenders or marshalls from a bygone era and plug in a fender strat, now crank all the tone knobs well past halfway and then crank the volume past 7.  Play HARD and LOUD.
Now assuming the amp is unmodified and stock then I doubt whether you will like
what you hear as the MASSIVE bass will most likely turn it all to MUD.

So how come SRV was able to get such incredable tone out of amps like these.
Answer is simple,, *tone shaping*.

Via a simple little tone shaping trick any *STOCK* Super reverb or Vibroverb or
Marshall can produce that same sweet almost clean compression,
That distinctive Bell like tonal signiture.

This trick is totally external so any stock amp from that era will reproduce similar results. Sadly 9 out 10 Valve amps today don't have the part needed to make that trick possible as they deleted it.

EDIT, point being send the *Right Frequency Response* to the output valves and Amazing things will happen.
BTW this simple trick can't be done with ANY SS Amps,, sorry:(

Back to the subject of my gear;
Most of my stuff is all old school but just well EQ'd.
If Fet's are to be used then use them as MU boosters into a well setup clipper
setup and that maybe more user friendly and a lot less NOISE.

When I started out I wanted what most want,, that being an ALL in one neat little box amplifier, most call it the combo amp.

But having spent neary 30 years frigging around with all sorts of ideas I've come
to the conclusion that *ComboAmps* are a mugs game as there's always a compromise involved.

So obviously I have a totally modular setup now.
If the Amp goes down I can take my Maxiverb and PhAbbtone to any other Amp and get close to the same tonal signiture.
For me the all in one box concept is just to limiting now.
Cheers Phil.

Hi all,
Just a picture from the shed, My SS Rig.

Signal passes through,
Reverb> Tone box + DDC> Graphic> onto 120Watt SS PowerAmp.

Everything has *true bypass* switching.

The *White unit* is the *PhAbbtone and DDC* all in one box.
As I've mentioned the DDC circuit is a modified Nobels SST,
So these are plonked on top to give you some idea of what is inside the White unit.

(Also shown to give some idea of how the signal path could be setup with other equipment.)

This graphic utilises *both L&R channels* via an In/Out/In switch (Red switch top right) so you can insantly switch between two preset secondary tone shapes.

Oh the Maxiverb has no speakers, it was one of my many failed attempts at making a small amp but now just houses the Spring Reverb, hey why build another box.

Under that is the no name 12 inch driver which is a shame as it's one of the better Q'ed sounds I've heard from cheap speakers, Very close to a real Celestion.

The ugly brown bit down the very bottom is a *Rotery Speaker* disected from an old B5bR Yamaha organ. It only delivers a subtile sonic spin but I miss it when it's not there.

I also have a 15 inch Dia-achi 150Watt driver which I also like a lot, it's a toss up which one sounds better but the 15 has just a touch more treble suprisingly.

The 120Watt poweramp (black just under the white unit, partially hidden) is an old *Inkel* factory PA. I only use the poweramp part as it has a *link-in* on the back panel.

Just thought it might give people ideas to work with.
Cheers Phil.

Delete V1 per my previous recommendation, Then take it from there.
Phil.

Well LOL, Coming so highly recommended I had better do a good job of explaining what can be very confusing.
Before I start my observation of great guitar tone;
"""It has more to do with what you DON"T hear that what you DO hear"""

Adding there is no perfect system for two reasons;

Firstly guitar Amplification is so vastly complex that quite literally a 5 cent wrong component can wreak havoc on what would otherwise be a good sound.
There are just so many places where great tone can be won or lost that it's impossible to focus on a one line answer to great tone.

Secondly, add the simple fact that we all play different kinds of music, we all hear and percieve sounds in different ways. So toss a coin I say.

Many roads essentially lead to the same result and there would be countless ways to do the same thing.
(give or take a Decibel, Watt or Ohm and 10,000 guitarist's that will tell you there way is better)

Ways to do it, Pick one.
Resistive load,
Resistive attenuator,
Power brake type setup,
light bulb,
Coneless speaker.
I even used old wire Jug elements for a while  

Dana VVR.
King TUT's Power Scaling.
And countless other options or combinations of the above.

I do like King TUT's concept of *power scaling* and was attempting that until I realised that the limitaion was that no *post power Amp tweaking* could be implimented with his otherwise brilliant idea.
You are still bound to the raw sound/tone that a paticular amp can produce.

So in the end I opted for simple resistive load with a simple Voltage Divider line out and that gives the ability to *Re EQ*, add post poweramp time effects and then reamplify to whater SPL is needed.
The astute will recognize this point can also be used to take a record signal to track if needed.

I felt this gave me the most options and flexability for my needs and if you are on a strict budget this may also be the $cheapest$ way to do such things, Hint Winky.

PS, You may wish to have a listen to my SS rig MP3's as the only difference is the tube power stage is replaced with a SS distortion unit I built. All the other equipment is the same. Adding the Valve does sound marginally better.
I will eventually post short snippets of the ReAmp Rig.
http://www.ssguitar.com/index.php?topic=1446.0
Cheers Phil.

 Some success after all this time, you're doing well :tu:

Try changing *R41 220k* down to 22k.
R43 may also need tweaking try 47k or just in stall a 100k trimmer pot and be done with it.
Other options C24 can be reduced,, try 100nF,  I'd also look at C25 try 1nF.

This will alter the bandwidth of the rev,, so it may take time to perfect it.
Cheers Phil.

When you get off the high and mighty and act in a rational manner you will get all the help I can give,,, till then bash a wall.

"You think it can be fixed? Then fix it!",,, IF you Give me the info I ask for then I can improve it somewhat.
But without modification this amp will always HUM.

The Amp DOES have major design flaws and if you keep insisting it must be a quite amp because your mate has one then I doubt I can help you.
AS is the Amp is a dud.

YES!!! the Tubes Are to close together.***
YES the power transformer has no shielding.
YES it has to many gain stages.
YES the EFX loop is killing it.
NO!!!! the board is not right. (Ground plane is wrong.)

NO Without knowing the B+ Voltage I have no way of knowing the correct bias.

NO I can't do a FRIGGIN thing to help you if you get stroppy.

BTW I think there may be a misunderstanding about bias voltage,
that being the bias of -35VDC or whatever,,, was being taken while the amp was in standby,,,,,You need to know the **PLATE Voltage** and the bias voltage while the amp is ON,, not on standby.

Don't get angry get even,,, Educate yourself and learn how to fix/build these things yourself,,,, but that requires a lot of patience and reading. another hint

Do the ground work and I'll help,, go off half cocked and get mad again and I'll leave.
Cheers Phil.

Hi kikey, short answer,, BTDT,,, next please

IF and it's a mighty big if I walked into a music shop and the moment I played a SS Amp with CDrive my brain went WOW man this must be Current Drive,,
Then I'd be looking deeper but it did not happen for me.

Yes it does technically improve things but sonically on stage at a live gig with everything cranked you will never notice it,
Use of such slick ideas won't make you famous.  
I tend to leave all that out there ideas for the HiFi set.
Guitar amp hobby geeks are a little crazy but those HiFi chaps are on another planet :duh
my 2 cents worth.
Phil.

Quote from: billyjoe24 on January 11, 2010, 05:51:30 PM

It's a good hi-gain sounding amp, on the noisy side.
I will probably try to sell it at a good affordable price for someone.
Like I said, turn it up and it roars, noise and all.
It will kick the crap out of a vox night train or Haze or tiny terror any day, believe me!

Get your facts sorted if you want good advice!

From the very start I made the comment that this was a high gain monster but you totally denigned that stating it was way to clean and nice.  So make up your mind :duh

I've done enough simulations to know that this preamp is capable of swinging in excess of 150 volts at the master volume knob at which point the amp has gone way past distortion and into crud tone,,, Far out!!! Ouch and plain stupid circuit.  :loco

An EL84 only needs 30Volts signal swing on its input grid to produce full power.

Put an audio signal (CD cable) into efx return and see if you can get **Clean music** coming out the speaker.  If you still have crossover distortion there then the bias is way off.
Untill you define the B+ voltage there is no way to establish a bias point anyway.
I and others here have made several intelligent suggestions,,,, most of which seems to get fobbed off and you then become fixated on another part of the circuit.
So you are really adding to your own confusion.

I'll leave to you to go back and read the many comments that have been laid down,,otherwise I'll just be repeating myself  forever ever ever.
Have fun,,, Phil.

Quote from: J M Fahey on January 10, 2010, 03:19:20 AM
Well, *now* we can all talk about the same, *if* that schematic applies and C26 on the schematic is C26 on jonzilla's amplifier.
*If* that's so, the poor cap is all right, it's doing its job of coupling the beautiful sinewave generated in the audio oscillator so kindly provided by Marshall to test ..... our patience.
On a very wild hunch: lift one end of R40, that 220K resistor, *if* the numbers match between your amp and the earlier 230 .
If they don't, find it on the board, that is the 220K resistor that goes from the junction of C22/C23 to the junction (called node) of R42/R43.
Your oscillator should stop.
You *may* still have hum/noise problems, but those are conventional.
Phil: C26 is a polarized (cheap) electrolytic, and in theory you should have a bipolar (expensive) there; but ages of SS amp building have proved that polarized ones work. Conventionally we use + towards the active device, but in this case it's the same.

Mr Fahey,,, you are a Gem!

You have the knowledge,, I only have hunches
I did see that 220k R and head scratched because I had not seen that input used before.
It will be interesting to hear the results from Jonzilla.
Thanks for the crarification on using electro's for decoupling.
Phil

Have you got a 10 uF?
or even 1uF.

In fact anything bipolar or big greencap say .22uF.

The idea here is to see if you can get a signal through without the bad hum.
Something is leaking/bleeding through at low freq and wiping excess bandwidth may fix or at least norrow down the problem.

You may have to rebuild the rev pickup circuit.
Mentime check the tank and make sure it's CASE is grounded at the Pickup RCA.
and NO ground at the DRIVER RCA.

Phil.

Hello kiehano,
                   Check the SIZE of the file you are uploading,, 512KB limit.
Rename the file after a failure,, I had the same problem a while back
Phil.

Quote from: J M Fahey on January 09, 2010, 02:10:38 PM
Hi jonzilla.
Nice picture, it shows C26 *might* be related or not to the reverb cirduit, it certainly lives close to it, but I still donot know what it does.
Can you please post or refer to some schematic and point to it?
It might still be called C26 or not; the important thing is what it does.
Thanks.

Hello Mr Fahey,
                    Link to schem is on page one 13 down,, posted by *guitarpicker7* but here it is again.
http://schematicheaven.com/marshallamps/vs230r_2x30w_stereochorusrev.pdf
I assume it's close enough.
C26 decouples the Revpickup amp to the rev depth control pot.

Having built/tested just about every possible way to wire up a rev pickup circuit I've found that some of these reverb pickup designs are not to flash and can do some strange things under certain circumstances.

With some you only need a broken/open circuit rca cable and they squell like crazy.
To my understanding C26 is back to front (polarity) but you may know more about that?
Cheers Phil.

Hi Zappacat and JM Fahey, Thanks for the  :tu: vote

Will have a go at posting multiple files soon,, meantime there is always other things to do in life.
Phil.

Hi jon.zilla,
               Have you tried changing the cap for another?
Do that before you start off re engineering the rev circuit. :tu:

It does not even have to be the same Value, I think it was 100uF so even 10uF would be fine as long as it's the same voltage rating.
In fact there can be benifit from less bass in the reverb path.
Phil.

Quote from: tonyharker on January 08, 2010, 02:55:24 PM
Just looked at the characteristics for the Philips EL84.  For class AB Push pull grid bias should be -14.7 with B+ at 300v and -11.6 with B+ at 250v. 
-30v is sending your EL84s into cutoff which is why you are getting so much distortion.  The quiescent plate current with no signal should be 7.5mA in each tube.   For 17W output the plate current should be 46mA.  so your original bias of -14 was correct and you should get your tech guy to put it back to that value!  Alternatively get someone else to look at it who knows what they are doing! 
Regards Tony

I agree with it ,,,cept the 48mA @300VHT.
Assuming the plate voltage is normally close to B+

Then 300 x 048 = 13.66 ? Ouch!
Last time I looked Max plate dissapation was 12 Watts for EL84?

A vast majority of these copycat import amps have overly high B+
and this amp has the screens running at close to B+ so even at -15volts Bias
The Valves have little safty margin.

My bet is that this amp will have a B+ in excess of 350 VDC so my first port of call on this amp is insert larger value screen drop.
This concept is now becoming almost a unversal understanding as more people realise the screen grid is the weakest link in the valve.

It's interesting to note that there is only a couple of watts difference in output power from 250 to 320VDC and then an inaudible difference from 300 to 350VDC.

The funny part is that a pair of EL84's sound so much sweeter running at 250VDC.
Bigger voltage = less tone,, but no one gets the joke. :duh

Cheers, Phil.