My take on Noisy Cricket using a Raython JAN 6418

[iccaros]

here is my latest build, could still use some advice. This is the first usable version, for me this is version 4.

The issues I have right now, is when gain 1 is all the way up and fuzz is on, I get blocking distortion, or least that is what it sounds like. Also I am on my third 6418 and they are all kind of microphonic. I have that cured to usable with some rubber grommets around the tube and super-glued it to the board.  I would take gut shots but I know if I open it right now, I will tweak some more.


See kind of the glow..


Schematic


Sound Clips
Clean, or as clean as I like, using the guitar volume ---> http://dl.dropbox.com/u/14312589/Cricket%20cleanish.mp3
Dirty using Gain 2 ----> http://dl.dropbox.com/u/14312589/Cricket%20dirty.mp3
Dirty using gain 1 ----> http://dl.dropbox.com/u/14312589/Cricket%20dirty%202.mp3
Dirty using both gains, turning tone back to 6 and adding fuzz --> http://dl.dropbox.com/u/14312589/Cricket%20dirty%20fuz.mp3
Metalish.. Gain 1 & 2 @ max, no fuzz tone at 10 ---->>>http://dl.dropbox.com/u/14312589/Cricket%20Metal%20No%20fuz.mp3

This was recorded through a Marshall 4x12 (mode 4 cab) with a AKG Perception 170 about a foot in front, not direct with any speaker  through a tube MP to a 1/4in to USB to computer running N-Track. No effects added

all suggestions accepted, even guitar lessons

[Puguglybonehead]

There is a thread at DIY Audio dealing with the subject of 6418 tubes and their reputation for excessive microphony.

http://www.diyaudio.com/forums/tubes-valves/152752-jan6418-microphony.html

Looks like it's a question of appropriate impedance, more so than physical dampening, when it comes to taming microphonics.

6418's look very attractive for pedal use, (and also for synth DIY) Very power efficient tubes. They barely consume more current than LEDs do. I could see them working well for battery-operated amps. (like the Noisy Cricket) They were used in computers for some time, towards the tail end of the vacuum tube era, hence their ready availability, and reasonable price in the NOS market.

Nice sound clips there b.t.w. Sounds very promising!

[iccaros]

reading the post on the site, it looks like 1 meg impedance will fix that. So to help someone confused, does that mean 1 meg on the plate and on the gain pot ensuring there is not less than one meg to ground or should I try a 1meg pot as the plate resistor, AKA pentaboost ? I noticed that at higher voltages (closer to 30v) the ringing also goes away, but the lm368 dose not sound the same.

[iccaros]

I have been going over this, IF I need a 1meg load on the tube, and try to have a volume control stage between becomes very hard. I can see a very high pot 3 - 4 meg, with a 2 meg plate resistor, but noise become a problem along with recalculating for voltage over one meg, should probably tie the control grid directly to the plate..

Any one have good ideals on how to get me a 1meg input impedance on the LM386 with a volume control between?
Thanks for any help

[J_Fiddle]

A bit late to the party but...

This looks cool enough to try out just wondering a few things:

1) The JAN 6418 has 5 pins but your schem seems to have 6. What am I missing here?
2) Near the top just above the tube there's two resistors (R3 & R4) with doglegged kind of line between them. Is this a connection or does this cross over without a connection?
3) Which setting is for guitar (C2 .047uF or C3 .001uF)? Is one setting to turn it into a bass amp?
4) What's the config/pinout of the LM317?

Anyways, look pretty cool, if anyone is still looking at this thread and can answer these q's then you are most definitely awesome.

Thx.

EDIT: Just found a datasheet on 6418. Does this sound right?
Lead1 -> R3
Lead2 -> R4
Lead3 -> LM317 and R1
Lead4 -> R2 and C1
Lead 5 -> Ground.

[iccaros]

welcome to the party it never stops here 
to the questions,
1) I drew this in Visio so i used the standard pentode for the tube, it shows the control grid connected to the cathode is already wired in this tube, but if you subbed this for say a 6au6 or any other small pentode you would have to make that connection. 
2) that is a bad drawing, so I just updated it with a little better drawing, the more I look at it the more I want to redraw.. R3 and R4 all go to + voltage, and the tap off the bottom of R3 is the output and does not connect to R4.
3) .001 is guitar and .047 would make a better bass, these are not set in stone you could try .0022 or .0047 for guitar and .1 - .047 for bass.
4) I think I answer this in the new drawing, hit refresh if you do not see it..


NOTE..
this tube is very micro-phonic, I ended up wrapping it with bubble wrap it with rubber rubber grommets and hot gluing it down to keep it from ringing..

[J_Fiddle]

Woah, same day delivery! Impressive.
Your redraw is a lot clearer now. I know what your mean about the tube, I found a datasheet so it makes sense now. Only difference is your line 3 is line 5 on the d/s. But you say tomatoes and I say....

The LM317 pinout didn't show up tho do you use a trim pot to get the 1.2v or that fixed resistor R1?

Also I gather the switch near pin 7 of the 386 is your 'fuzz'?
And the end pot: 20Ohm 3watt, yes? Are you soldering a resistor in parallel with the pot?

And iccaros: you are definatley most awesome 

[iccaros]

updated drawing to note lm317 pin out and voltage note

I swamped pin 3 and 5 as they do matter, with 5 to ground for the heater, pin 3 is the cathode for all intents so the 1.2v sets the Cathode Bias.

not all LM317s work 100% the same, some will need to have a different value to get 1.2v

the pot is one of these its 25ohm, close enough for this work
http://www.radioshack.com/product/index.jsp?productId=2062299&filterName=Type&filterValue=Potentiometers

pin 7 does add fuzz

[J_Fiddle]

Excellent!!

Out of curiosity, since your inspiration for this project was the noisy cricket, you reckon it might be doable to have the tube bit up until C5 the same and then add the noisy cricket just the same as on beavis? Sort of just a tube tacked on the front end sorta. I know it's plagiarism, and its not got the 'I made this from scratch' feeling but would it work ok you think?

[iccaros]

that would work
I am thinking of using a 6au6 and re doing this..
look up lone wolf