WEREWOLF - 6205 SUBMINI PENTODE OVERDRIVE

[Renegadrian]

As I reported in the main TUBE topic here I found googling that schematic from jon anderson, called the LONEWOLF, using a 6AU6 - simple enough to build, I tried it on the breadboard and yes I like it so much!

I played with some values and bits, so my little changes, the biggest being the use of a 6205 submini pentode, take to this schematic I want to share with you...Still you can use a 6AU6 if you want...
I used my voltage multiplier to give +50V.

Here it is...The WEREWOLF!



PS pins 2 and 8 are both tied to the cathode - you can use one of the two and just leave the other unconnected.

[tranceracer]

That's another sweet little ckt! 

Do you notice the same, more or less gain / boost than the 12AU7 valvy?

[Renegadrian]

It has more gain - it acts more like an overdrive than a booster, while a Valvy can be both with the right settings.
If you follow the link to the other topic and follow the link in that topic (to reach JA site) you will be able to listen to a sound sample of his 6AU6 version, which is not so different from this.

[tranceracer]

Ahh, Yes I've heard that ckt on his site!  Thanks!

[frequencycentral]

Cool Adriano, I'll try this circuit out with my 5840. I wonder it the resistor at pin 7 could be a 470K pot plus a small resistor value to prevent direct coupling to DC, it could yield some interesting tones.

[Renegadrian]

Rick, I suggest that you try some values on the breadboard, as I did. A 47K is a good choice, it gives a "round" bluesy tone, if more gain is needed just lower its value - I had good results with a 4.7K going as low as a 470R. So I believe a 50K pot could be mounted instead of the res. 470K seems too high to me...

[frequencycentral]

Ah, Ok, I read your '470' on the schematic as '470K' for some reason - need to find my specs! Might also be worth trying the 'squish mod' on this one for a bit of compression.

[biggy boy]

Nice work Adriano You guys are great!
I like the distortion it produced in the sound clip!
I have no submimi's thou , but I do have full size Pentodes EL84/6BQ5 got 6 of them.

[Renegadrian]

Rick, what is the 'squish mod'?

Glen, Have you got a 6AU6 around?! You can easily use one, obviously following the different pinout.

[biggy boy]

Rick, what is the 'squish mod'?

Glen, Have you got a 6AU6 around?! You can easily use one, obviously following the different pinout.

No Just the ones I mentioned.
But I may be able to get one in town at the guitar shop.

[frequencycentral]

Rick, what is the 'squish mod'?

Have a look at the first preamp stage: http://dl.getdropbox.com/u/967492/AX84_Blues_Preamp_Schematic.pdf

[Renegadrian]

looks interesting - what does it do?!

[frequencycentral]

looks interesting - what does it do?!

From: http://www.diystompboxes.com/smfforum/index.php?topic=71350.20

You forgot one thing! 

Add a pot(100k-500k) between the 1µf cap and ground.  That way you can dial in compression from the pentode.  I didn't have the idea.  It's ripped off of the Blues Preamp from ax84.com.  It's usually a linear pot, but I've found that a reverse audio generally works better.

Matt

That sounds interesting......what does it do, how does it sound, and do you think it would work at low voltage? Do I need to breadboard this idea?

I've got a couple of amps that use the pentode side of a 6U8 or 6GH8 as the first gain stage that has the 'squish' control in them.  It very much changes the feel of the amp and adds quite a bit of compression when it's dialed in all the way.  I ended up wiring my pots backwards on both amps so the knob is labeled 'dynamics'. 

The summary on what it does is vary the stiffness of the screen voltage.   With just the cap from screen to ground, the screen voltages is very stiff which allows the pentode to have it's full range of dynamics.   If you remove the cap totally, the screen voltage varies with the signal.  The larger the signal, more current the screen pulls which drops voltage through the resistor feeding the screen, the 100k in your schematic.   The pot varies the screen stiffness between these to extremes. 

'Zoe N Iain' over at ax84 are the ones that originated it over there, so they'll probably give you a much better description than me.

And yes, I think it would work at low voltage. And yes, you need to breadboard it.  You may need to drop the value of the cap to get the full range though. 

And yes, I need to order me some submini tubes.  You've come up with some seriously cool stuff.

Matt

[Jered]

  The sub-minis sound so good at the higher voltage. Great work Adriano.

[German]

And why you use it in triode mode? 

[Renegadrian]

  The sub-minis sound so good at the higher voltage. Great work Adriano.

Yes, I agree...My Pentaboost has a lot more "air", more "open sound" running it at 50V. Thank you