New at runoffgroove.com: Eighteen

[B Tremblay]

Sorry, just to add to my last post,
http://www1.korksoft.com/~schem/ampegamps/j12b_jet.pdf  Do the suppressor grids (or screen grids, cant tell which) of the 6v6's have signal passing through them, or is it carrying DC to the 270K in the tremolo circuit?

Here's what I'd try first for emulating the final stage:

from the .02uF cap connected to pin 2 of V2...

1k series resistor to the gate
250 ohm / 20uF from source to ground
100k trimmer to drain
output cap from drain followed by speaker response filtering and master volume

I'd omit the 270k resistor, at least in my first attempt on the breadboard.  Start with another .02uF for the output cap and adjust to taste.

[javacody]

Where would that 270k resistor go if you included it? To ground?

[B Tremblay]

Mr B, you gonna be putting a soundclip up on the Eighteen?

Two sound clips of Eighteen are now available!

http://runoffgroove.com/salvo.html#eighteen

[Lonestarjohnny]

Mr B, I just listened to the the Mp3's, I got a Clone and if You were to ask me the difference between the sound of my amp and your pedal, As Bad as I hate to say this after playin tube amps for 30 somethin yr's, I'd have to say , If you were'nt pullin my leg, Pretty Damn Close, I'm amazed at how close the clean tone was, the dirt has it's moment's also,
Thank's guy's, great wrk,
JD

[B Tremblay]

Wow, that's great to hear!  Thanks!

[aaronkessman]

yes, those clips are awesome. I've got a clone too, and it's definitely there.

a couple questions though...

how does this circuit respond to playin dynamics? on the real 18W, there's a sweet area about halfway up the volume dial in which you can get pretty much the whole range of grit - from clean single notes to raunchy distorted chords. is that there in this SS version?

also, just a curiosity, but the tube 18 has a weird gain hump on the tone adjustment. at about 1:00 on the dial, there's a sweet spot in which the tone is just about right for any guitar and there is also a little gain boost. is that present on this one too?

thanks, and man, im very impressed with this and all the other pedal circuits you guys have come up with.

Aaron

[Gary]

how does this circuit respond to playin dynamics? on the real 18W, there's a sweet area about halfway up the volume dial in which you can get pretty much the whole range of grit - from clean single notes to raunchy distorted chords. is that there in this SS version?

I think so.  The clip I recorded was with the Vol wide open.  You can back it down and get some very subtle shades.

also, just a curiosity, but the tube 18 has a weird gain hump on the tone adjustment. At about 1:00 on the dial, there's a sweet spot in which the tone is just about right for any guitar and there is also a little gain boost. is that present on this one too?

This is a definite yes.  The tone control is exactly the same as the amp.  It's not your typical tone control.  With the tone at 12:00, there is a slight mid dip.  It's cool.

thanks, and man, im very impressed with this and all the other pedal circuits you guys have come up with.

Thanks for the compliments!  It's not tube distortion, but if you've ever used a distortion pedal, these types of circuits will blow them away.  They sound and feel so much more like a turned-up amp than anything I've played so far.  There are a lot of little details you can hear in your sound that diode clippers just can't do.  Also, no matter how high the gain is set, you still hear the guitar and all the flaws in your playing.  You can't hide behind these circuits.  They seem to magnify all your errors, much like a good amp.  I'm not saying to build these.  I don't have anything to gain if you do.  I'm saying you need to atleast breadboard and try something like these circuits.  You may be surprised.

[Lonestarjohnny]

Gary or Mr. B,
I had been playin with the circuit on the breadboard, now I've got it in a pedal and hooked to a filtered 9 V. power supply, I'm getting a slight 60 cycle hum from the pedal when it's cranked WFO, I'm getting a great tone out of it and the J201's are all baised correct, what I was wondering, I've also built the English, Professor Tweed,Super, and a 440 Magnatone, these pedal's do not have this problem but all have a filter cap on the B+, the Eighteen does not, do you think this may be why I hear a slight whining noise when this pedal is turned up all the way ?
Thank's,
JD

[Gary]

Yep!  Add a 100uF or so cap from +9V to ground.  I forgot to add that to the preliminary schem when we started work on the circuit.  It's all my fault!  Please add that filter cap in there and the whine will go away.

Thanks for the report.

[Lonestarjohnny]

Thank's Gary, I already did it and it sounds just Awesom, I played the thing for over an hour last night, the more I played the better the tone got, it for sure won't hide sloppy playing habit's like fuzz will, and once you start to realize that it has a feel like the real amp I killed off the reverb and delay and just played it dry, all the old tone's my plexi gave me were coming out of the front of my old Peavey Classic 50,
AMAZING !
'Will soon post a Drawing for my Magnatone Troubador and next will be the 440 with Maggy vibrato, I Hope !  :?  :?
JD

[Fernando Aguirre]

Yesterday i finished this pedal and...wow!
I play trough a Fender twin (which is not a friend of distortion pedals) and it sounds really nice, i am very happy with it. It is not noisy and it sounds great.

I have read you guys breadboarded the SLO. Are the converted schematics available? if not, i beg you to make this the next runoffgroove project.
Many thanks for such a great job!!

[krister]

I just built the Eighteen. Plugged it in front of my Fender Pro Junior and I was SHOCKED. My Pro Junior sounds just like the clips on 18Watt.com. I still can't believe it. Truly amazing. I think it would fool a lot of discerning ears.

[Rafa]

Cool
Have you notice ROG guys update the page during a 7 months period I think (from January to July).??
Cheers
Rafa