PhAbbZone pedal

[phatt]

Hi all,
        Here's my latest venture which at first was looking like a fail but after last weeks gig I'm very happy with the result. <3)

This is my New front end floor control board,,, A bit bigger than I wanted but it makes life easier to tweak. I've learned not to squeeze things into tiny boxes especially as I'm the fool that has to fix it *IF* it stops making music. 8|

This took forever to prototype but hey It finally worked the way I wanted.

A hybrid with 1 AX7 and a tricked up distortion with 2 EQ stages as well as a switchable notch filter.

Also a parallel loop for the LessLee and other tricks I've built.

Due to the 2 years this took to perfect The front panel and internal pictures are from the first build but should give a clue as to the layout and basic setup.

The switching is all straight forward simple analog switching. No relays to ef up,  :trouble just plain old switches which unlike tecky circuits usually give a hint they are about to fail.

Powered via a plug pak from a dead printer delivering 18VDC which powers all the chips.
The high voltage is derived from the nixie psu using a 555 and inductor.
HT is around 260 VDC while the extra lm317 is set at 12VDC for filaments and also drives the nixie supply.

As to Why all this complexity? :duh

Well I've discovered that distortion is actually not that hard to get,, what is insanely hard to nail is all those in between sounds. as a lot of that magic may have more to do with the quirks of triodes.
See member KMG's Work on Fets,, really helped me grasp the finer details of how they work
(or don't work might be a better term)
I would have gone with some of his ideas but I had already got halfway through this build and I knew Real triodes where a sure bet.

The rattle of those old famous Amps has been the hard part for me to reproduce and that is the sound I wanted more than just the distortion.


I know some will want sound clips but you will just have to wait. 8|
Meantime here are some pictures and some of the schematics.
there are 8 boards in the final build so you will have to join up the schematics.

Anyway have fun with it may give ideas as to what can be achieved.
Phil.

[phatt]

Just some more schematics.

  OD circuit.
  Notch circuit.
  Master & Tone circuit.

As for the High voltage supply Just google nixie supply as that is all I used.
Phil.

[Roly]

Good one Phil.   :dbtu:

Just a couple of thoughts arising; relays with gold flashed contacts seem to be more available than gold flashed switches.  Got a repair on the bench where a mains rated switch has been used in the signal path for standby, and sure enough it's making intermittent contact at signal voltages.

Do you need R103?  Or is there a missing blocking cap at R102?

What's R6 for, offset bias on the output of U2a?

Can't see the op-amp type.

I think the larger case is a good idea; feets is big and stage space isn't at that short.  Can see this staying where it's put too.

[J M Fahey]

Phil, congratulations, IMPRESSIVE job !!! :dbtu:  :dbtu:  :dbtu:  :dbtu:
Now we *deserve* some tasty Aussie flavoured Music samples.

[phatt]

R103 is there simply because the first part of that circuit is mounted on a separate little pcb and just makes life easier while tweaking stuff.
I figure it's unwise to leave the grid with no DC reference.


Yes I do understand that R6 is not needed as it's DC coupled to previous stage but if removed the noise from the tone becomes a real issue and renders the buffer useless.

This was the BIG issue While building the original PhAbbTone circuit, noise is the enemy with hi Z circuits.

I'm not sure about the fine print when it comes to these tecky details but from my testing this produced the lowest noise.

It took me some years to grasp but I now fully realize just why there is a buffer in front of circuits such as the TS9.
A lot of over-hyped boatweak pedals actually remove the buffer and wack a massive amount of gain on the very first opamp.

The result is lots of gain but sadly 3 times the noise. yucko puckas.

My rule of thumb is thus; High Z input and high Gain then expect noise issues on a grand scale.
Buffer converts it too a much lower Z and THEN you up the gain.

But hey I'm all ears to learn if there are better ways to divide the square root by 13. winky.

Relays,, what!! oh god more circuitry,,, I'll be dead and gone before I ever get a handle on all that clever stuff you chaps build. lol

I guess it's a 2 edge sword as you are quite right a lot of those stomp switches are very cheap quality now and few hold much more than a few years.

Maybe one day I'll get brave but bad memories of my first fender Amp failing because of dodgy relay setup haunt me.

I've still got a Carling switch here some where that came out of a junked Wah from the 60's and it still going strong in a pedal So it shows that they did once make decent switches.
Thanks for the input, Phil.

Mr Fahey will just have to ,,,, wait for sound clips

[J M Fahey]

     

[phatt]

OK Mr Fahey has waited long enough,,  8|
I got some time to whip out a few takes of my pedal, Yes I even miked it up to grab the true sonic effect as best as possible.

The midi track is credit to a little demo from Cakewalk 7 files called *Boston Rain*

The guitar is the same old Casino $150 elcheapo Strat copy.

Not being the expert on the old midee stuff I think I've recorded the midi click by mistake but who cares,, it does not impair the sonic result.

I scratched my head trying to get my head around all the different sounds I can produce from this little box but that would take forever so a simple little riff of the sound I use the most.

As mentioned,, distortion is easy but the in-between stuff has always been a struggle to capture,, this box of tricks has gone a long way to cover that missing mojo.

Best way to explain that is to say; clean distortion that has a liquid feel when playing.

Only effect on guitar track is the Spring Reverb in the Laney (Now modded with the Tverb trick.)

I played this back through 3 different speaker systems trying to get an idea of the balance of tone but this should be big and fat with just a nice presence to the top end.

Dumbing it down via mp3 makes it even harder to define exact sound balance. I think it lost a little top end but to late to argue with inventors of mp3s  xP
cheers all hope you like, Phil.

[Roly]

The guitar is the same old Casino $150 elcheapo Strat copy.
...
Dumbing it down via mp3 makes it even harder to define exact sound balance. I think it lost a little top end but to late to argue with inventors of mp3s  xP

Ay, I've got one of those as my workshop guitar; only paid $100 for mine 'tho (friends with the guy in the 2nd hand shop  ).  Not great maybe, but quite satisfactory on stage too.  If you haven't tried it into 5 megs input impedance you should, really brings it up tonally.  :tu:

Had to do some MP3's for a web site and even diddling with Lame parameters the dynamics of some tracks were so badly compressed we dropped them from the sampler.

Even on crap 'puter speakers, then cans, that's a very nice demo Phil. +1  :dbtu:   I'll try running it out to the big system in the morning (heh heh). 

[J M Fahey]

Incredibly good sound  :dbtu: :dbtu: :dbtu:, *very* tasty playing  :dbtu: :dbtu: :dbtu: , congratulations  <3)

[phatt]

Thanks heaps guys, I really do appreciate the vote of confidence.
Well after all the years of blowing up stuff maybe I've finally been able to make something
folks would enjoy playing. :cheesy:

What I like about this is that it's all mostly coming from the pedal So if the Laney goes
futt on me I still have 2 other Amplifiers that can be rigged up to power speakers and deliver much the same result.

Of course if the pedal dies then I'm up the creek but oh well you can't cover everything.

@ Roly, yep Cheap strats and they work. :tu:
Only issue I had was the windings are prone to howl/squeal. :grr

Wax potting made a big diff but do be very careful with the heat and time dunked in wax as the
plastic bobbins are very cheap and not thermally stable,, as I found out

Only other mod was the addition of one small switch which joins Bridge + Midddle pu in series (effectively creating a humbucker).

Come to think of it I don't believe I've seen this trick done in this manner,, I'll post
the idea if there is interest.

Besides not having to purchase a new scratch plate and on older strats a rerouting of pu
pocket.

The advantage of this over a real HB is that it guarantees a balance when using HB sound as
I've always found it incredibly hard to find a level balance when using HB's with SC in the same axe.

I've actually done this series mod for several of the local chaps with rave reviews.

In my other guitar I do have Real ~60's era Fender PU's and they have a little more bottom
end response. Other than that there is not much difference between the 2.

Neither of my Strat guitars have big out put and if you do have those you might want to adjust the inputs to suit.

I did have a PRS here some time back and the PU output was so insane hot that I certainly would have no use for that crazy output.
My thinking is if you need that much output from a pu,,, you need a better amp. :duh

Re the big input Z;
Yep thanks for the tip, but I'll have to pass as I've had very little success with big Z inputs,, way to sensitive and just asking for trouble with hi gain circuits.
I've spent most of my time trying to get rid of excess bandwidth as it just destroys the sound,, especially at gig levels.
tho, it might work in a studio situation.
Just my observations.
Cheers,, Phil.

[Roly]

http://www.till.com/articles/PreampCable/

'tho I'd be more inclined towards a Source follower, but the thing is, presented with a very high Z the natural pickup resonance isn't damped and this makes it sound richer, this...



vs. this...

[kevin b]

Now that is a nice sounding box of tricks you have made.  :tu: :tu: :tu:
I am tempted to scrap my ideas and just build a PhAbbZone pedal.....
something to aim for...

Kevin

[joecool85]

Sounds great Phil, good job!

**edit**
Maybe I missed it, but what opamp did you use for that?

[QReuCk]

http://www.till.com/articles/PreampCable/

'tho I'd be more inclined towards a Source follower, but the thing is, presented with a very high Z the natural pickup resonance isn't damped and this makes it sound richer, this...

That's what a good buffer is made for: present a very Z to the pickup while feeding the following circuitry with a more manageable low impedence signal.

Edit: Actually typed too fast, as in "before reading your (very informative) link". Anyway, I do think a good buffer at the input of the phabb zone will do exactly that, provided the first guitar cord and contacts are of very good quality.


Nice sound clip by the way.

[phatt]

Thanks QReuCk and Roly,,
I guess my reply would be, ok try it suck it and see?

Yes you can up the Z if you want but you will likely run into trouble trying to balance the clean sound which will then have the hump as well as a lot more treble ,,which is EXACTLY what you Don't Want for this type of sound.

This mismatch is what sends the novice round the twist (did for me ) because quite obviously a lot of modern amps have way more bandwidth than is needed for rock guitar tone and finding the balance between the clean sounds and OD sounds is hard to balance even for professionals.

In My Demo the first quarter is done with only the preamp THEN I stomp on the DDC circuit which just adds more crunch but most ears would not notice the slight loss of top end.

NOW if I open up the input Z that balance will be lost and you will be forever fighting between a overly bright clean sound and a Distortion that is Too dark.

THAT issue is the main reason It took me so damn long to perfect it.
Both sounds worked but the darn thing was not balanced.  :grr

If I had a dollar for every multi channeled wizz bang dog box Amp that has that EXACT problem I'd be stinking rich. :lmao:

High Z on old Amps with one channel and minimum Valve count YES you need to get as much energy to enter the circuit and I'd agree You have no choice but to use high input Z.

Bear in mind the High Z input on old Valve Amps has not changed in 40 plus years but pu's and pedals have changed all that to the point where even a budget pu may have more wire than the Dingo fence in Australia. lol

In modern hi-gain multi channel Amps this High Z input is no longer needed ,,,IMHO only of course

The other side of this debate is that yes I have no doubt if you have the talent you could use very high Z inputs and still achieve same/similar outcome.

For me, the budget restricted amateur with limited knowledge,, well this way makes life so much easier.  Add,, why make life hard if there is no need 8|

A real example of what bone this dog is chewing on about;

I'm sure Roly has heard of Phil Emmanuel,
When I came to live in Nambour I had the pleasure of hearing Phil Emmanuel gigging at the local RSL hall as Phil E lives just out of town.
(for the benefit of others, Phil E is one of our top Aussie guitar players, the brother of Tommy Emmanuel).

I noticed Phil E used a *Carvin Legacy Amp 212 combo rig* so I did some research and found the schematic.

V1 Grid resistor is 220k,, even more interesting is PI input has 100k across the grid. HUM?
One could easy assume that 220k input would severely hamper the higher freq.

Having spoken with 3 players who have gigged with Him it seems to be common knowledge that Phil E likes to dial up the top end. So having now heard Him live as well as recordings I'd say Anyone who says that Phil Emanuel's sound lacks treble needs to get a hearing checkup. 

I'd also hazza guess and suggest that the reso hump which is accentuated with higher Z inputs may actually add even more complexity to the above problem.

Maybe someone with better ability can shed a better light on this subject as I don't fully understand it all,, but at least my real world experiments have shown me there maybe a lot more goin on inside the world of guitar sound and just hanging a 1 Meg resistor off everything may not equate to the desired sonic mojo.
Phil.