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Author Topic: PhAbb Cruize Control  (Read 9865 times)

nipperiodic

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Re: PhAbb Cruize Control
« Reply #15 on: January 28, 2015, 07:15:07 PM »
I always wondered how some guitarists were getting so much use out of their volume and tone knobs. Thanks for explaining the power stage sag.

I went back and compared your clip to the Bonamassa video, and I gotta say, I think you nailed the effect/sound/magic. Very, very cool. I want to build one but I think it's out of my league for now.

For what it's worth, I'm throwing in a vote for you to design some type of compressor circuit so everything is always dialed in just right.

Again, awesome job.

phatt

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Re: PhAbb Cruize Control
« Reply #16 on: January 29, 2015, 05:49:38 AM »
@ "mexicanyella"
Hi Mex thanks for the feedback, :tu: good to know what others think
as we all hear things a bit different.
Full bore OD/Dist is fairly easy to get but it's all those subtle
in between sounds that are hard to reproduce, and more so with SS clinically clean amplifiers.
In my experience most SS rigs I've encountered have 2 or more channels where Clean is so glass clean you can use it as a hi fi amp and the other channels are just way over the top distortion, the later the model the more fizz/grunge they have which is obviously aimed at the market.
No offense to those that want metal, just not for me. :-X

@"nipperiodic"
Thanks for dropping by and adding comment.
Well tiss ironic that you mention Compressor  ;)
Have I got news for you!!! I've made some interesting inroads with compressor circuits which I'll post next. I did think of buying other compressors but you can waste a lot of money buying gear only to find it's no better than the other stuff you already own.

Re building your own;
The beauty of making your own gear is that over time you learn heaps and you get to know how everything effects the sound. Knowing your circuit and signal path inside out can be a big asset when things go wrong on stage. Just start small and read as much as you can absorb, at first it is a little slow
but you will soon build you knowledge base.

Phil.

phatt

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Re: PhAbb Cruize Control
« Reply #17 on: January 29, 2015, 06:11:19 AM »
OK here is my findings after ~ 30ish years trying to get my head around the age old question of Valve verses Transistor stuff and  overcoming the limitations of SS guitar systems which are often less than impressive.

There are many systems that do this trick but often expensive. Maybe no holy grail here but I think I've found (stumbled upon) an inexpensive way to avoid the negative effects compressors impart to the sound.
In my circuit just adding that extra magic to polish the sonic experience.

I've found a simple way to remove the horribul "Umph" compressors produce when dialed up hard. xP

Just so we are all on the same page;
Using a compressor (at least the pedal types guitar players use) is much like when you open
your mouth to speak and the split second you utter a word somebody slams you in the back and it takes your breath away and hello becomes, H-u - -low.

By the time a compressor starts to sound good the trade off is the Umph on every attack
which makes the instrument sound breathless and robs it of any dynamic feel while a saggy old valve amp which also compresses actually adds some mojo.

Why Why Why??? I keep asking myself. There must be a way to make a SS compressor work just like a Valve rig. :'(

Story so far; OK my "Ulite Compressor" is working but maybe the limits of LDR circuit are showing, not fast enough to react to completely remove the attack.
So thinking that the problem might be speed related I whipped up Rod Elliot's
ESP super Fast Limiter circuit on my test bed which has been running for the last 2 days.
OK it's very fast and with some tweaks might be better than the Umile unit.
ESP circuit here; http://sound.westhost.com/project67.htm

Now recall My Cruize control plus Umile idea works at low volume ok but at high volume
there is still an issue with volume difference between clean and distortion.
To test this I have no choice but to have my amplifier at a loud level otherwise you get a false sense of SPL levels.

Sadly I live in the burbs and have to respect my neighbors so I dragged out my cheap set of head phones and run the signal through my old ghetto blaster.
So with Hphones on and tweaking some values on Rods Fast limiter circuit I did 90% eliminate
the umph comp effect. oh goody :)

Now headphones can give you a false representation so for a short time I run through the Guitar amp
again at live loud volume just to be sure.

Damm it!!!  :grr :grr The umph was now worse than before.   :grr Arrh hair pulling  rage,,,Why, What 'n How? What the hell is going on??
After a stiff coffee and a few hours pulling weeds from the garden trying to escape my utter frustration a little ray of insight run through my mind. (insert light bulb here)
Hang on,,,Those el cheapo headphones I use have shocking low frequency response. Ding!!!!!!!!!!!! (Even more light bulbs)

Sure enough,, Rip off everything below 100hZ and indeed the horrible "umph" magically disappears
from the sound and you are left with a very realistic guitar sound.
Ok now it sounds a bit hollow but simply but running my old hifi Graphic EQ After the compressor solves that.
Sigh,, enough time spent on this for now just wanted to share what for me has been a big revelation.
This is getting long so I'll explain why i think it happens next time.
You will have to wait for sound clips as the over grown garden awaits me.
Phil.

phatt

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Re: PhAbb Cruize Control
« Reply #18 on: March 02, 2015, 06:50:37 AM »
I know I know,, I do get a bit carried away just because something works,, but over time and lots of a/b testing one realizes it's maybe not so good.
Tiss all part of the journey of experimentation.  ;)

Circuit update,
After much testing I've come up with another hair brain idea. "Cruize Control ver3"
I've reverted back to a triode front end much like the PhAbbzone which was very good but lacked the compression/sag effect.

A quick run through,
The preamp is just a 2 stage triode > into a HiWatt styled tone stack then buffered and boosted via an opamp stage which then drives a small 1k/8-Ohm line transformer the signal is then amplified via an LM1875 power chip.

The LM1875 output drives a small incandescent lamp which soaks up a fair bit of power as the signal becomes large, this creates the sag/limiting effect. Although the lamp idea works very well it's still not enough to keep the overall SPL in the range I needed for this to work.
The Ulite pedal compressor I have can't handle the bigger signals and hence it pops hard on too fast and destroys the effect. :(

Meantime a wonderful chap "mictester" over at FSB has a clever little optical compressor circuit and I thought I should at least try it out. Yoohoo it works and does not pop or muff the signal.

So the end result is a 3 stage unit which does what I want and only has 7 knobs. :dbtu:
After many hours of tweaking each part I've decided to build this,, damn now I've run out of sheet metal. :(

BTW the overdriven effect is likely some triode rattle and then at full volume maybe opamps hitting the rails but without a scope you don't know for sure but simulation gives a fair idea. Either way it sounds more convincing than using Diodes for clipping.
I'm getting spanky clean and loud with guitar volume at 4~5 and sweet OD past 7 but not the massive jump in volume.


Power supply is a 2 part setup;
12VDC 1 Amp for the DC/DC converter to give ~250VDC Ht for triode as well as the 12VDC heaters then a second dual supply delivering 18/0/18VDC for the LM1875 and then into 7812/7912 reg chips for dual 12Volt rails to drive the opamps.

2 points worth note;
The switch at the small transformer "Rock/Woody" was a mistake but it works so well I've decided to keep it.  (Likely some L/C quirk going on there?)
It sounds a lot like an old boxy amp from 50 years back with loose bass,, nice for those JJcale type riffs. In rock mode it's brighter and the bass is tighter. I like both. :)

The small lamp maybe an issue long term but it does not glow white hot,, time will tell. 
The test circuit has been running now for many hours each day in the last few weeks and I have plenty of spare bulbs anyway. (these bulbs are only 90cents at the local electronics store)

As I'm only running the LM1875 from 18volt rails it likely won't reach full output, it only needs to put out enough energy to light the bulb and increase the resistance across the filament.
The signal has to pass through the element and the resistance rises in sympathy with larger signals causing the Sag  effect as well as lighting the bulb, giving a visual indication of sag.

Thanks to Roly,s recent scale on light bulb limiters for amp servicing it seems the resistance in general rises about 10~15 times when hot so my lilliput bulb is about 10 Ohms cold So I'd say that would rise to ~100 Ohms or more when hot.
Which means the LM1875 chip is driving a Cold load of 10~12 Ohms (counting the 2R7 resistor) and ~100R when hot.

Though this bulb idea may look very backyard basic the limit/sag effect is very useable. No pumping or wonky release just a very smooth transition into a bigger fatter sound. <3)

My only concern is the noise creeps in (mainly hiss) at higher levels but no worse than many of the big name gear that is around.
Single coil noise is evident but with HBuckers it's not a problem.
Of course with wires running all over the bench most of my noise/hum/buzz/hiss will be resolved when it's all boxed up.

Give me a few weeks while I make some PCB's and mount the maze of wire on the bench into a case and I'll get some demos recorded then.

Phil.

J M Fahey

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Re: PhAbb Cruize Control
« Reply #19 on: March 03, 2015, 09:29:14 AM »
Hi Phatt, how ya doin' ?
You're being well spoken about at MEF, just check:

http://music-electronics-forum.com/t38920-2/

 8)

phatt

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Re: PhAbb Cruize Control
« Reply #20 on: March 04, 2015, 07:04:42 AM »
Thanks for the plug :tu:
Yes I certainly can attest to the idea that many of the problems that face the modern player can be traced back to too much bandwidth.

As to my project,, put aside for a few days as a dead amp awaits me on the bench looks like a dead power amp section. I might take a few pictures of this old Jade LB120 Amp (Aussie rig from way back)
Interesting build, all the parts mounted on the copper side of PCB.
Phil.

phatt

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Re: PhAbb Cruize Control
« Reply #21 on: May 13, 2015, 02:51:05 AM »
Well in spite of many setbacks I did end up building this idea into a working preamp.
I have no doubt the clever tecks here will shake their heads and wonder what the hell I was thinking,, :duh
But hey it does work. :tu:
There may well be better ways to do the same thing but this is almost devoid of any compressor effect even though the signal passes through two compressor stages.

The gain is very high and hiss with single coils is present at higher levels but then I've played pro gear with bad hiss at lower gains.  :-X
With HB's the hiss is almost non existent even at full bore.

Adding a short clip so you can make your own judgement.

The only knob used here is the volume control on the guitar, Starting out at halfway then turn up full.
Of course the strat has low power pickups and HB's make for a bigger distortion. (so another day for that, the wife is complaining)  ::)

Signal path, Cheap Strat > Cruize Control > Laney > into a mic at 18' off axis. No effects and no editing, just converted to MP3.
I've let it ring out so you can hear the sustain of the last chord,, I can't hear any compressor pumping or pops. I've made a few small changes so adding updated schematics.
Phil.

phatt

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Re: PhAbb Cruize Control
« Reply #22 on: May 13, 2015, 07:52:23 AM »
Oh I forgot, I did take some pictures while the sun was out.

Bare with me I'm trying to get my head around linking stuff,,,Hopefully this is the right way :-\



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Phil.

phatt

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Re: PhAbb Cruize Control
« Reply #23 on: May 13, 2015, 08:52:21 AM »
Now that I seem to have some idea as to upload/link pictures I thought I'd put it all on one page with a pic of front panel as well. These are up to date as of may 2015 and reflect the unit shown.

Front Panel;

screen shot on pc

Preamp Circuit 1/3


free adult image hosting

Sag Control Circuit 2/3


upload a picture

Mictester Comp Circuit 3/3


free image hosting

The supply is not shown to keep it simple but it's a 3 part setup the Valve section is powered via a redundant 15VDC laptop supply hidden on back panel. This is then used to power an oddball Valve kit I purchased some years back and was sitting idle. looks ugly but why build another circuit ;)

The rest should be obvious, a small transformer delivering ~ 17/0/17 VDC which drives the LM1875 power chip (Lamp Sag Compressor) then regulated 12V rails for the opamps.

Feel free to disect my brain storming ideas lol.
Now if I can squeeze all this into a small pedal that would be great.
I did have a go at using an LM383 (Car Audio) power chip but it would not light up the lamp enough to make it viable to run at 12Volts. Likely hard to find lamps small enough to make it work.

Phil.

J M Fahey

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Re: PhAbb Cruize Control
« Reply #24 on: May 24, 2015, 02:52:15 PM »
EX-CEL-LENT  :dbtu: :dbtu: :dbtu:

phatt

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Re: PhAbb Cruize Control
« Reply #25 on: May 29, 2015, 08:46:23 AM »
Thanks for the vote Juan.

I'll Update soon as I've re drawn the schematic mods. I used this a few times at gigs and found some issues which have now been rectified.

It's always a slow ongoing process when building oddball ideas like this. :duh

Basic problem was gain in the wrong place, not enough drive for AX7 to get into the sweet spot and too much gain after that. Sounded great but noise was then a big issue especially with single coils.
EMF on stage can be a nightmare with stage lights and such. :grr :grr :grr

Hiss and hum is now much better and the sweet zone of the triode rattle is much more progressive.
Phil.