New at runoffgroove.com: Thor

[B Tremblay]

Happy Holidays from runoffgroove.com!

Thor is a redesigned and improved version of the Thunderchief circuit.  It much more accurately resembles the character of the legendary Marshall Super Lead sound.  Check it out: http://runoffgroove.com/thor.html

Also, we are holding a contest for the best Thor sound clip. Submissions must be an mp3, with a maximum file size of 1MB. Please e-mail your sound clips and all the recording setup information to the address at the bottom of the page linked above. Results will be announced by February 1, 2007.  The winning sound clip will be posted as the official sound clip for Thor and the winner will also get a sneak peek at the next runoffgroove.com project.

[trevize]

Thank you for the christmas gift! great new ideas in your new creation. Thank you!

[MikeH]

1)  Awesome! 

2)  Dammit!  I just etched and started building a Thunderchief 2 days ago.   

[jrc4558]

  YEAH!!!

[tommy.genes]

Did your research happen to identify how the Super Bass differed from the Super Lead? Could a "Bass Thor" be just a matter of substituting components?

Yes, I am thinking of emulating a Chris Squire sound...

Thanks,
-- T. G. --

[tungngruv]

Hey B Tremblay, thanks yet again for another Amp sim. circuit! 

[petemoore]

Did your research happen to identify how the Super Bass differed from the Super Lead? Could a "Bass Thor" be just a matter of substituting components?
  I believe the Super Bass Schematic would be available, it is simply a matter of printing one or both, then noting...what is probably mostly value differences in components, most often larger cap values to let more bass through. Not that Chris hasn't had his SB modded, or that every SB has exactly the same values, this could probably be researched...
  @@R@te, my estimation is that an emulation is a good bet at trying to gett a Bass Sounding a certain way..then just tune the circuit...like someone would an amp for certain bass guitar, I haven't read "Thor" text....next, there's probably a tweek or two in there you could pass over to the Jfet SB emu, for bass, possibly shooting for lower gain ... I dunno!...build some fairly easy to get to gain mods [like start with source resistors longlegged so you can piggyback parallel R for the smaller R value testing there] trimpot drains, try hi/lower gain Q's, make accomodations for voicing series SP Caps, LP filters which tap signal and shunt to ground are generally very easily accomodated as afterthoughts.

[JHS]

For a "Super Bass" change the 1n to 10n drop the 470p and decrease the 100n at the output to 220n or bigger, maybe a additional samll bypasscap on the 1st FET is needed (if the Thor sound somewhat like a SLP from the the first years, it's all you must do).

Stephan Möller has spent alot of time comparing the reaction and distortion of Fets and preamp tubes, he published the results somewhere on the www. Interesting article and he decided to use ICs and diodeclippers for the AC30 sim instead of Fets.

BTW:
Marshall changed the SLP and SB circuit in details quite often from '66 to '70, used different tubes and brands, trannies, changed the anode voltage ....  All SLPs I've played sound quite different, so mod the Thor to your personal liking.

JHS

[jimbob]

Looks  great! Thanks guys! I think Ill givr a try this week end.

[Xavier]

Bump for another great addition at ROG. Will try a perf layout as my own little present for Xmas.

[MartyMart]

Thanks guy's nice xmas pressie 

MM.

[mydementia]

Music to my ears... 'new at runoffgroove.com'... 
Can't wait to build this one!!
Thanks, as always, to ROG for their excellent contributions...

Mike

[Doug_H]

Nice work.

The active filter idea is a good one- Coincidentally, I came up with a very similar idea for a design I've been working on for a few weeks.

[Gary]

Did your research happen to identify how the Super Bass differed from the Super Lead? Could a "Bass Thor" be just a matter of substituting components?

Yes to the first question.  And yes to the second.

The Super Bass is essentially the same as the JTM45.  The shared cathode design of the early leads also were very similar.  You won't be able to work out the cathode resistor for the first stage without jumping through some hoops, but you can simply change the source bypass caps to a larger value like you'll see on the Super Bass schematic.  You'll also need to increase the sizes of the coupling caps as seen on the Super Bass schematic.

If you aren't sure what to do, shoot an e-mail to the RoG contact address.  I'll help you out.

Doug, I love your sig line!  That's funny stuff!

Happy Holidays!

[WGTP]

Great Stuff.   

[B Tremblay]

It's great to see such enthusiasm from everyone.  Thanks!

I should point out that for a sound clip to be eligible in the contest, it must be recorded using the circuit exactly as shown on the schematic.  If you ABSOLUTELY must deviate, please explicitly indicate the changes that were made when you e-mail the clip.

[stm]

We do not want to limit creativity by imposing audio samples using the exact version of the circuit, but it is quite obvious that a clip of a modded circuit will not be totally representative of the circuit itself.  Nevertheless, we are open (and eager) to receive the suggestions/improvements/mods that you find when building your own THOR.

Also, it is very important to accurately indicate your recording setup for each audio clip, as different gear has different sonic characteristics.  Please consider including information such as:

1) Type and location of the pickup(s) used
2) Knob and switch settings for THOR
3) If any other effect is active in the chain
4) Which amplifier & speaker type you are using, or if a cabsim was used
5) Postprocessing effects used (such as reverb)
6) Any other relevant information that might apply

[stm]

Just to remember everybody that there is great variation in parameters when it comes to FETs in general (JFETs and MOSFETs).

As we wanted to make sure the circuit would be reproducible by other builders (one of the shortcomings that had the Thunderchief), we specifically chose "average" J201's and 2N5457's.  The J201's had a Vp between -0.8 and -0.9V, while the 2N5457's had a Vp around -1.6V, both quite representative of the devices we've seen so far.  It is not mandatory to measure your devices, but if in doubt or if you feel like it, the Fetzer Valve article provides additional information on how to do this.

Perhaps the main difficulty some builders will face is having a single type of JFET available.  This will of course affect the sound of your build, not necessarily in a negative way, so just consider these guidelines:

1) When using a J201 in the first stage, use the drain and source components as indicated for the second stage. You will have more overall gain.
2) When using a 2N5457 in the second stage, use the drain and source components as indicated for the first stage.  Install a 10u capacitor in parallel with the source resistor so as to compensate the lower gain of this stage.
3) When you replace the 2N5457's by J201's in the third stage the clipping will be somewhat harder.
4) Tune bias for the first and second stages as indicated in the schem first and then fine tune by ear as desired.

To MikeH: The light side of having a Thunderchief nearly done is that you can compare it side by side with Thor and see which you like best, and of course, tell us back!

[tommy.genes]

Thanks for the Super Bass replies. It will surely be into next year before I get to play with this, but I will report what I find.

-- T. G. --

[markm]

Nice job fellas!
I always look forward to new offerings from ROG with great interest.
Thanks for sharing!