"J20" (K-20X Preamp, only OD and with 071 instead of 072)

[phatt]

My guess is you can take the signal out straight from the treble wiper,,,
BUT you are then totally dependant on what you plug into next.

My point is sure it works *asis* but why build something and cost cut if it is likely to cause pain and frustration somewhere in the future?

One only has to read the constant flow of interface issues with pedal boards to see that cheap short cuts like this are trouble in the making.

Having simulated the circuit I can see why Joe cool likes it so up to him how he wants to build it but if I did build it,, NoWay I would leave it hanging out like that.

If you want stuff to interface with almost anything then *Buffer* or wear the pain somewhere down the track.
Phil.

[joecool85]

Ok, sounds good guys.  I'll probably add a buffer into the next version which will be set up to run on 9v.

[anttyj]

Alright, who wants to build a vero K20-X preamp?  It's all verified electronically on paper, but hasn't been built yet.

I've been building this veroboard version of preamp and in doing that I noted one needs to cut the copper strip at c12 or c13 in order to prevent short-circuiting parallel-connected C5 and R5. Unless you do that, you will also directly connect pins 1 and 2 of IC1 together. This is not good from the viewpoint of gain of the first half of the IC.
I've notified joecool85 of this and he says hasn't got the time to check it just now but urges me to report my observation on this list.
In a few days I'll be testing the preamp once I've got my +/- 12 V power supply working...

[joecool85]

Thanks anttyj for posting this, I look forward to hearing how the preamp works out for you once it is fully built.  Maybe even a pic and a sound clip?

[anttyj]

Thanks anttyj for posting this, I look forward to hearing how the preamp works out for you once it is fully built.  Maybe even a pic and a sound clip?

Well, I've got it built now and it works nicely. I followed your parts placement otherwise to the letter but moved all other components but the IC to the non-copper side of the veroboard (as a slight mental exercise). In addition, the cutting of copper strip at c12 was indeed necessary, as indicated in my previous post.
I put the preamp into an aluminium diecast box together with a small 8-watt TDA2030 PA built from a kit. The latter provides plenty of volume for home rehearsing.
Overdrive works well, too, and you can see the red LEDs blinking when a guitar string is struck.
Having built a number of solid-state ham radio transmitters in the past, I was slightly concerned of eventual self-oscillations due to proximity of the input and output copper strips of the TL072 but these concerns proved unfounded. There is no sign of instability of any sort.
With my guitar disconnected from the input jack and with the lid of the box in place, the amp is amazingly quiet, no hum, no noise, not anything. Nevertheless, with the guitar connected, the sensitivity is more than ample for full-blast blockbuster operation.
I'm attaching a mediocre-quality picture of the preamp and PA in the aluminium box. The camera of my Nokia C5 mobile phone isn't very well suited for close-up work...
The two not-yet-connected jacks at the rear wall are for connection to an effects box (in my case the t.c. electronic G-Major guitar processor).
The dual-voltage power supply is external and, it is heavy-duty enough to supply power for a TDA2050 power amplifier I'm planning to build for gig use. As the amp is now, I'll try it at our band's rehearsal location the coming Sunday.

[joecool85]

I followed your parts placement otherwise to the letter but moved all other components but the IC to the non-copper side of the veroboard (as a slight mental exercise). In addition, the cutting of copper strip at c12 was indeed necessary, as indicated in my previous post.

anttyj, it was designed for ALL parts to be placed on the non-copper side.  I'm not sure how you could even solder them down if you put them on the copper side.  The "tracks" are shown on the diagram for reference, just like most all vero layouts.

[anttyj]

anttyj, it was designed for ALL parts to be placed on the non-copper side.

Yes, of course. It was my first assumption but then flipping the veroboard upside down to cut copper tracks at the right locations becomes another mental exercise. Therefore I chose to consider the layout as copper-side illustration to be sure I cut the tracks at the right places. After that there was no alternative but to solder the IC on the copper side.

I'm not sure how you could even solder them down if you put them on the copper side.  The "tracks" are shown on the diagram for reference, just like most all vero layouts.

Okay. Though I've got more than 50 years of solid-state building experience, I admit most of it has been dealing with printed circuit boards and much less with veroboards. It is possible to solder  components on the copper side but you have to be very careful not to short-circuit the tracks with bare component leads.
With PCBs, it is customary to publish both the component-side and the foil-side pictures to help avoid confusion.Perhaps you could assist potential builders of this preamp by publishing the layout also seen from the copper side?
Now that I've succeeded once, I'll build the next one according to your original design.
I'll try to provide the sound clip you requested a little later after I've figured out how to best connect my effect box to the preamp...

[J M Fahey]

Dear anttyj.
Most Vero designs you´ll find in these Forums (and many others) are drawn using the *excellent* Bancika´s "Do it yourself Layout Creator".
I suggest you search for it and download a copy for your own enjoyment.
I much prefer the somewhat older Windows version rather then the newer Java based multiplatform one, specially because 99% of published designs are compatible with the older one.
It´s a full fledged PCB design package, which has the exact needed functions and no more, to shorten the learning time (it´s very intuitive even for non electronics guys) *but* it shows Vero designs component side only.(what others would call "from above")
Enjoy.

[anttyj]

Thank you, J M. I downloaded the program but it seems to be a Windows-only thing. As I'm 99% of the time in Linux (Fedora), I didn't try it out as yet. However, I have got XP in one of my computers so I'll try the program in the near future.
Circuit diagram CADs and PCB layout design programs have been around for some time but I never felt the necessity to learn to use one. This is probably because I seldom design circuits or PCBs myself. This might be as good a time to start as any...
Thanks again - and thanks to Joe whose preamp layout prompted me to build something after several years of resting on the proverbial laurels!

[J M Fahey]

Yes, *there is* a Java based version which runs on anything, including Linux, but designs are not compatible with the old, Windows one.
Fact is, there is a ton of designs around, made with the old one, which became the de facto standard.
Just check http://aronnelson.com/gallery/main.php
There are *thousands* of designs and layouts there, most of them made with DIY Layout Creator.
It´s very intuitive and quick to learn.

[anttyj]

Well, I tried the diylc-3.0.9-beta but it won't run in Fedora-15-x86_64 Linux. Googling around a bit showed it *does* run in some flavour of Linux, such as Puppy Linux. Fedora just flatly declares: "Permission denied", even when trying to start it as superuser (root). This may be because Fedora is _the_ "bleeding edge" Linux distro with advanced built-in precautions. My guess is it won't accept other libraries than its own, but I didn't really look into it closer.
One possibility would be running DIY Layout Creator in a Windows emulator such as Wine or qemu but installing those emulators may bring along their own problems.
Anyway, all this is probably somewhat beyond the scope of this forum. I'll install diylc in Windows XP where it probably will run "out of the box". Thanks for your input, J M!

[joecool85]

Thanks again - and thanks to Joe whose preamp layout prompted me to build something after several years of resting on the proverbial laurels!

Your welcome!

[runce]

hello from Lithuania! I have sereos problems building my op-amp/tone/buil-in effects. will this schematic work with fender tone schematic? will the Rin and Rout match? and can I use gainclone? I olready have gainclone and cab with V12. second question, what should I do to get realy high-gain distortion?

[joecool85]

Not sure how I missed this, but the Mid pot should be 500 ohm, not 500k !!!  I finally got a chance to play with the tone stack in a sim and found the error.  It makes a HUGE difference!

You can get away with a much more common 1k potentiometer though.