Leegazzy - Carvin Amp

[dimirock]

Forgot to say to the all the great guys posting here:
Thank you for being willing to help!!! Only through experience of trial and suffering can the soul be strengthened, ambition inspired, and success achieved

[bool]

Ok... so I can't say anything specific with this ampsim - I'm simply  not familiar with it.

From a first glance, fet voltages all seem ok ... all passable, within a certain tolerance margin. To me, this negates a need to change anything in the circuit, especially IF you are able to bias the fets to 4,5V as suggested on the schematic.

(since you already measured the source voltages, this is the basic mechanism to "fet matching").

I'll repeat the suggestion to build a "signal probe". If you connect to a computer, this can be something simple, like a high-impedance buffer - followed with a level (volume) pot. (you will appreciate this when debugging fet pedals or fuzzes that contain gain stages which swing close to supply rails internally ...) With a probe you can "listen" to what exactly is happening within each stage and use this knowledge to either "learn" or to debug the pedal.

Since you speak about this "soul" stuff ... It looks like mother Destiny threw something along your way to "figure it out" on your own.

Onto more practical stuff: You could either a) treat this build of yours as a dis-functional device and use it to learn the ins and outs - or b) use and bias it so it works its best at 18V, with two batteries, and mark it as a "SE" or "HV edition".

... so there.

[J0K3RX]

Dimi, from reading your last posts it sounds like you are frustrated and might have given up on it? For being new to electronics it apears that you have got a really good grasp of it realitivly quickly... When I get to this point on something like this it pisses me off then i HAVE TO kick some ass and figure it out! Most of us here have been down this road a few times if not more... Do a search for Black Forest and look how many pages there are and I was only going from the actual tube schematic, no layout basically from scratch... There are many pages now and even more in other forums... You are only on page 2. If you want to give up that's cool but you don't strike me as the type to give up.. I would make sure you don't have some jacked up jfets first!

[dimirock]

Absolutely not!!! Just trying to gather more people here! Was frustrated....looking at the boards and struggling with my lack of knowledge
I had the real Legacy in 2006. What I found with this layout is that, it has THE SAME character!!!
And this a whole new world for me!!! Also found that a little miss-biasing is leading to the REAL tubes SAG and Compression!
I was amazed!

I can help the community to Fine Tune theirs schematics by ear and just asking for some help.
As you know I have a background working on many samples and demos.

Btw.
I've found the man who made the great sounding demo on youtube, but he is not responding...
Demy Mortelliti

Over the years I was always open to share all my knowledge...
Thank you!
Dimi

p.s
Hope every friend is feeling great tonight!
https://soundcloud.com/diminalbantov/fall-asleep-again

[bool]

Yeah you can tweak the "vibe" with misbiasing the fets a little ... I mentioned before that it is possible to get some fine vibe if you misbias in a "staggered" manner - one a little cold, one a little hot ... etc. But it takes time and cherry-picked fets.

But fwiw I'm back to opamps and diodes. For better sleep, heh.

[dimirock]

Looking for real j201 and 2n5457. If someone is willing to help and sell a few please write me!

The transistor I own are all fake....

A friend of mine measured them.

Here are 3  of "j201":

iDss and Vp
2.7mA   / 2.09V

1.88mA / 1.63V

2.41mA / 1.92V

All 10 that I have are like that.

Dimi

[J0K3RX]

Looking for real j201 and 2n5457. If someone is willing to help and sell a few please write me!

The transistor I own are all fake....

A friend of mine measured them.

Here are 3  of "j201":

iDss and Vp
2.7mA   / 2.09V

1.88mA / 1.63V

2.41mA / 1.92V

All 10 that I have are like that.

Dimi

That's a bummer dude.. kinda thought you may have gotten some re-purposed components... 

If they are from China or Hong Kong (ebay) you should be highly suspicious and stay clear of those as much as possible!



You could order some from Mouser or Digi-key no? or I think Smallbear may ship to your country? I know Mouser and Digi-key both guarantee that you will get genuine parts and go to great lengths to make sure they do not deal counterfeit parts! I believe Smallbear does as well and has an excellent reputation!


Can we put this "Fake or Not" debate to bed once and for all?
To the nay-sayers - disbelievers
Look up/google - Detection of counterfeit electronic components through ambient mass spectrometry and chemometrics
Why would Mouser, Digi-Key and other large distributors have "Anti-Counterfeit Parts Risk Mitigation"? http://www.mouser.com/anticounterfeitparts/

So, the next time you guys load up at Tayda just keep that in mind... They have no certifications last I looked but, they do however have a great satisfaction guarantee and return policy and from what I have seen they make good on it almost 100% of the time. They are a Hobbyist supplier and I doubt they supply to the military, automotive, medical or any other that require industry wide certification of their components. Handling, packaging and delivery of components is another area that requires certification and must be taken into consideration as well. 

If the supplier that you are buying from does not have the following certifications then good luck to you and your pedals or whatever you are building...
AS9100C and ISO9001:2008 and ANSI/ESD S20.20-2007 certifications.

This is a HUGE deal for medical, military and countless other industries where lives hang in the balance. They can not afford to have failures due to counterfeit failing or out of spec components and go to great measures to make sure this does not happen.

[bool]

So look here...

http://www.diystompboxes.com/smfforum/index.php?topic=109908.0

Since you are from europe region, chances are you can get BF24x types more easily.

They will sound slightly different in "gain" circuits.

Everybody will suggest that you build your effects with sockets so you can swap the active (or other) components to check them out first.

An audio probe makes things much easier.

Good luck.

[dimirock]

Thanks! I found 10 working j201's
Still the pedal runs better on 18v...
Now I should learn the "proper" way to wire the board with shielded wire in the box...
I've got some nice high pitched squeals...

Whats the best shielded wire for the high gain pedals?

Thanks guys! Appreciate your time and knowledge!!!

[J0K3RX]

There are other factors to noise in these pedals but shielding the input, output and gain pot wires is a good start. There are many types of good shielded wires... the foil kind you use inside your guitar will probably work fine. Board layout has a lot to do with the noise and tone was well, where your power wires and traces can affect the signal too. Make sure your input and output jacks are as far away from each other as physically possible inside the enclosure, on opposite sides is good... I can tell you that vero is not optimal layout for quality high gain design so, your efforts may be in vein...

[bool]

+1 on vero layouts.

Short of having a proper PCB, a good layout can be done on a perfo-board, nearly as good as a proper PCB. There are some caveats with that, but in general - if you take care to "clear" the redundant pads on a perfo-board, you can get a very good final build (by using a small 3mm dia drill, similar to how you "kill" the strips on a vero).

I always reccomend the perfo-board builds. That's usually how I test my layouts before transferring onto a PCB. (This is of course only valid for a single-sided or a single-sided+ground-plane layouts - you can't do a full double-sided layout on a perfo).

[J0K3RX]

One thing I noticed on the Leegazzy schematic is that Calvin did not use much filtering on the power besides the 100u cap... That could be improved! Another thing, this is where an audio probe really becomes useful, you can easily track down the source or sources of noise/oscillation and make an effort to eliminate or at lease lower the noise to an acceptable\expected level. On just about all of the JFET/MOSFET and even tube high gain preamps I build now I employ a gate between the 3rd and 4th stages, commonly referred to as the JSX noise gate because it can be found in the Peavey JSX "Joe Satriani" signature amps on the lead channel. It was used before that but was pretty much obscured and hidden and didn't offer much adjustment if any at all.. Preferably I would not want to use a gate at all but with ultra high gain that's just a wet dream.. There is another gate that is similar and has much better transparency and removes all of the noise without any noticeable loss that I have been tinkering with. It can be found in the Legendary super rare Elan Metalhead amps and preamps. If you're curious about it you can find it if you know how to use a search engine and you are persistent..   Obviously the first objective is to get it as quiet as possible using conventional methods then throw a gate on it to make it dead silent.    By the way - there is no need to match JFET's for this preamp, won't do much good.

Edit: another thing you can do is get rid of the trim pots. Once you have biased it where you like it remove the trimmers and measure them with your meter then replace them with metal film resistors of the same values... There is probably not gonna be one thing that removes the noise but a combination of things so, every little bit helps. Look to lower the noise in the beginning stage, that is where you don't notice it much if at all but even a little noise there becomes a wild mess by the time it passes through the last stage and into the tone stack.

[bool]

The Peavey "gate" is essentially a variable LPF (yes really!!!) But you can't beat it for its low-part count efficiency imho.

[Maik]

Hey Dimi,
if you need some transistors check Musukding.de
The J201 are real there!

[dimirock]

Yeah, but found something strange.
I ordered 10 pieces from them and I had my first success to test and power up my boards. They are great!. Even no need to match them!

After a week or so I ordered 30 pieces, again from musikding.de and the new j201'a are different.
Different markinga, different look.
Hard to get them working again, just a random Fuzz sounding effect.

Also on the first ones / the working ones/ there is a  stamped  small L, Q letters in the circle on the back . With letters on the front F  BK30. The new ones are with F625 letters and empty circle.


I'm really motivated on the Fet emulations and hope to improve my knowledge and the sound of them. Even I'm in the beginning of this , love the sound coming from the fets.

Here you can hear a demo of my 1st successful build of the Plexi Drive . Used 3 from the firs order from musikding. They biased great with the fixed resistors. 4.5, 4.6. 4.4v and the pedal sounds great!
https://soundcloud.com/diminalbantov/dyi-plexi-drive

[duck_arse]

dimi - the manufacturer has an injection mould with a number of cavities, so each time he whams the mould together and shoots in the goo, he gets 4, 8, maybe 16 complete transistors each shot. when one of the cavities gets cold or choked, the plastic "half shots", producing rejects. manuf wants all good, so he scratches a number/letter into each cavity, then he knows which heater to replace/nozzle to clear. (the same procedure is used in any multi-cavity injection mould for smallish parts; IC's, toothbrushes, fuzz box knobs ......)

the cavity number is what you see on the back in the circle. it is virtually useless as a means of batching parts for the end user (you).

[dimirock]

Yeah, I see.
But with the first order - 10 pieces J201. I had great success and my test were great. My Plexy sounds great!

The new ones are different batch/ I think/ ?! And now I'm in the beginning of my struggling to make them sounds OK. Ordered 30 pieces after my successful experience.

[dimirock]

Finally my DIY Jfet Carvin Legacy Pedal is ready for boxing. What is your opinion?  
https://soundcloud.com/diminalbantov/carvin-legacy-diy-jfet-pream

[J0K3RX]

Finally my DIY Jfet Carvin Legacy Pedal is ready for boxing. What is your opinion?  
https://soundcloud.com/diminalbantov/carvin-legacy-diy-jfet-pream

Love it! The compression and definition of the notes sounds like tubes. How do you like it as compared to a Legacy? What was the chain that you used, cab emulation etc..? What did you finally come up with for jfets, voltage you are using 9v / 18v..?

[dimirock]

Its connected direct to my TC Desktop Konnekt 6, then the cab from Carvin V3 in Amplitube - some delay and reverb.
No booster in front. Gain at 15-16 o'clock. I had no success to make it work on 9v, it cant push my jfets to open and saturate on this voltage.
Using a small 9 to 18v strip bord to power it up.  
No changes on the original schematics. the  j201s are biased by ear. All this half voltage bias is nonsense! You should have really great and precise matched transistors for this. Right?
 All the voltage on the 4 stages are different.

About comparing it to my real Carvin Legacy, yeah the feeling and the frequency spectrum is really close! Love it!