Introducing the Skyhunter V2 Low Voltage Tube pedal

[iccaros]

This is something I have been working on for almost a year, I think I am very close to how I want it to sound. There is nothing new about this, its a "ValveMaster" as Rick puts it, and a Lone Wolf put together.

here are some pic's



Here is the schematic so far


and here are some video.. The camera is my phone so one is really overdriven, I did not know a 15Watt amp on 3 would overdrive the phone.. but it does..  the other I turned down the amp to 1 on the pre and on the master to not overdrive the phone..

welcome all comments...

[Toney]

Hey nice work Icarros.
I have been working on something using the Lone Wolf as a basis too.
As it stands there the character of the distortion sounds really good in some ways but also I can hear are grainy rapid decay that could be better? Saying that in the spirit of honest feedback - not at all a criticism.
  It's hard to tell with the audio but yeah looking good. 

[iccaros]

All comments are good..  To clarify, is a Grainy Rapid decay the same as no sustain? I think the distortion is a touch harsh, a little bass heavy and not smooth enough.. but I will record sound clips with a good mic and post..

Any suggestions on how to address this issue? Plus I liked the soft switch.. looked to be an interesting approach with out using relays...

[amptramp]

Nice looking unit!  Just a few thoughts on the schematic:

Is R5 really necessary?  This is a cathode follower, so plate resistance just lowers the headroom available because the same current flows in both resistors and you have a 1/101 divider there for headroom.

Are you going to add a coupling capacitor at the 6AU6 screen?  You may not get proper pentode operation without it.

R1 should be on the grid side of the bypass switch or you will get the mother of all switch pops.

SW1 should have its pole on the grid side and select between input and ground.  It should have a second pole that switches the output from effect or input line in true bypass fashion.

The second switch should select cathode follower or pentode output.

R2 is 550 ohms which is not a standard value.  560 ohms would be standard.

You may want a resistor to ground from the output jack or you may get another source of pops.

[iccaros]

Awesome review.. Thanks.. I was tired and editing a prior drawing and see I missed some things.. Will update and post, refresh as needed.
Thanks

Nice looking unit!  Just a few thoughts on the schematic:

Is R5 really necessary?  This is a cathode follower, so plate resistance just lowers the headroom available because the same current flows in both resistors and you have a 1/101 divider there for headroom.

Damn.. this is not a cathode follower anymore.. That was not working well for me, So I canned it, I thought I was going to put an EQ and but did not, so I opted to change.. Will change the schamatic.

Are you going to add a coupling capacitor at the 6AU6 screen?  You may not get proper pentode operation without it.

is this a bypass cap on the screen or to ground?

R1 should be on the grid side of the bypass switch or you will get the mother of all switch pops.

I have not noticed, but it does have nothing before it right now.. So I will change to be safe.. I have it on the input jack, so I will move it to the grid

SW1 should have its pole on the grid side and select between input and ground.  It should have a second pole that switches the output from effect or input line in true bypass fashion.

not drawn, but this is a dual true bypass. Selecting switch one only selects the 12AT7 and switch two will only select the 6AU6.. they true-bypass around sending inputs to ground if not selected. I figured others would know how to wire, but that could be a mistake on my part.. If I am miss understanding please let me know, I do trust your opinion. 
The second switch should select cathode follower or pentode output.

R2 is 550 ohms which is not a standard value.  560 ohms would be standard.

I had 550 from some kit, I wanted in the 500 range, as 1K did not make this sensitive enough to guitar input in my opinion, adjust for taste..

You may want a resistor to ground from the output jack or you may get another source of pops.

I had one, and I did not see a difference.. There is one in this pedal, so I will add back to the drawing..

[iccaros]

sound clips
Recorded in Ntrack, no effects, except re-verb on the amp set to 1.2 using a ART TubeMP through a first act USB 1/4 adapter. SM57 Center Cone of a Eminence Red Wizard 8ohm. A modded Carvin vintage 16, wtih soak turned in to a preamp control and the volume placed after the phase invertor. EQ is setup more like a Marshall.  Guitar is an un-modded Les Paul Classic from the 80's

First Clip is just the 12AT7. I play clean, no effect then set the knob to 25% 50% 75% 100% going back and forth at each setting between bridge and neck pickup
http://dl.dropbox.com/u/14312589/Skyhunter%2012at7%2025%2050%2075%20100%20no%206au6.wav

Second clip is the 6AU6 alone  I play clean, no effect then set the knob to 25% 50% 75% 100% going back and forth at each setting between bridge and neck pickup
http://dl.dropbox.com/u/14312589/Skyhunter%206au6%2025%2050%2075%20100%20no%2012AT7.wav
Same as above but with 6au6 always at 25% and adjusting the 12AT7
http://dl.dropbox.com/u/14312589/Skyhunter%2012at7%2025%2050%2075%20100%20%206au6%20at%2025.wav

Other way around, 12AT7 stays at 25 and 6AU6 goes through the changes

http://dl.dropbox.com/u/14312589/Skyhunter%206au6%2025%2050%2075%20100%20%2012AT7%20at%2025.wav

Last both tubes on, both same settings, 25% 50% 75% 100%
http://dl.dropbox.com/u/14312589/Skyhunter%20both%20tubes%2025%2050%2075%20100.wav

[amptramp]

I meant to say bypass capacitor from the 6AU6 screen to ground.  You may get operation somewhere between pentode and triode without it.  Not necessarily bad, but you are giving away gain without it.

[iccaros]

cool, I was also reading that using pentodes at low voltage, to use the screen as  a control grid , tie the top grid to + voltage and not cathode if possible and to take the control grid and tie that to + voltage..

Avoid grid confusion! The first grid (the grid physically closest to the cathode; what in conventional tubing is called the control grid) should be tied to 12V. If you're using a conventional tetrode or pentode in space-charge mode, make sure you put 12V on the control grid, and use the screen grid as the control grid. Pentode suppressor grids are almost always tied internally to the tube cathode, but if the suppressor grid comes out separately to a pin, try putting 12V on the suppressor as well. This may allow greater gain in some circuits, as you have two grids accelerating electrons toward the weakly charged plate. --> http://www.junkbox.com/electronics/lowvoltagetubes.shtml

[amptramp]

24 volts may be kind of a no-man's land - too low a voltage to get normal operation but too high fora space-charge grid direct connection to B+.  I would try it but you will have lower gain than a pentode and you could exceed the control grid and suppressor grid capabilities which have no rating, although there is a rating for the screen grid.  You may need a resistor in series with each of the grids that are pulled up.

[iccaros]

I may try 12v on those. I have it available.. but any positive above cathode should have the same effect, do you think?

[zambo]

@ Iccaros - I love this thing! I put the 12au7 in and you were right, its my kind of thing with that in it. Love the 6au6 boost. very singing quality too it. love the voicing of it. Thanks!!

[iccaros]

nice video, shows a good range, sounds nothing like my clips 

[cnspedalbuilder]

@Iccaros, I saw that you posted a link to this on the "ECC83 tube preamp" thread. The pedal sounds amazing.

The schematic and other Dropbox links seem to be dead. Can you repost the schematic, or (better) a vero layout?

[printer2]

This might help.

http://www.diystompboxes.com/smfforum/index.php?topic=93194.0

Speaking of 6AU6's, I ran some off 45V, used a 12V transformer and a voltage multiplier. Made a low voltage Plexi-sort-of. Sort of worked, I did not play around with it too much. Really need more voltage for the power tubes, made a 1/4 of a watt.

[vigilante397]

The schematic and other Dropbox links seem to be dead. Can you repost the schematic, or (better) a vero layout?

This thread has been inavtive almost 5 years, and iccaros has been inactive on the forum over 3 years...

[Renegadrian]

As long as Icaros may have a notification, or other members can help someway, your post is freckin' useless...