madbeanpedals::forum

General => Open Discussion => Topic started by: PhiloB on October 02, 2014, 05:35:28 PM

Title: Favorite Jfet Overdrive?
Post by: PhiloB on October 02, 2014, 05:35:28 PM
Have a friend that is set on a Jfet overdrive.  What would you recommend?  All he can say is that he likes the 'Liquid sunshine' OD but can't get any more specific than that.  What say you?

Thanks


Sent from my iPhone using Tapatalk
Title: Re: Favorite Jfet Overdrive?
Post by: Haberdasher on October 02, 2014, 05:43:19 PM
azabache from rog is highly regarded but i have yet to build one.

i built a liquid sunshine once, it didn't sound half bad iirc.
Title: Re: Favorite Jfet Overdrive?
Post by: PhiloB on October 02, 2014, 05:51:06 PM
Thanks, would Josh's (1776) Brittania be a good option? 
I'll have to have a good look at the Azabache.


Sent from my iPhone using Tapatalk
Title: Re: Favorite Jfet Overdrive?
Post by: Haberdasher on October 02, 2014, 06:07:51 PM
i guess it just depends what sound he wants.  the 1776 brit emulates something vox-y, and i understand the azabache is very fender-y :)
Title: Re: Favorite Jfet Overdrive?
Post by: mmlee on October 02, 2014, 06:09:41 PM
I'm a big fan of  the azabache, been using it ever since I built it.
Title: Re: Favorite Jfet Overdrive?
Post by: pietro_moog on October 02, 2014, 06:11:01 PM
plexi drive. very nice.
Title: Re: Favorite Jfet Overdrive?
Post by: midwayfair on October 02, 2014, 07:37:13 PM
I heart FETs.

The Britannia is absolutely amazing. I like the Azabache better but mainly because I prefer the tone shaping in it over that of the Britannia.





The Britannia is a little better direct to a console and as an all-purpose OD. The scoop on the Azabache is better for more midrange heavy amps, though, and you can't get that out of the Brit. One thing I highly recommend is socketting at least the last set of diodes in the Azabache -- I ended up with an asymmetrical arrangement there, and a slightly lower gain FET, to get a bit more headroom.

Ultimately, I'm pretty partial to the Snow Day, though. ;)

Title: Re: Favorite Jfet Overdrive?
Post by: jubal81 on October 02, 2014, 07:47:13 PM
I think it'd be good to know what kind of amp he's playing through. That seems to make a bit of a difference with these.


My favorites are the CB30/Galileo, Black 65, SVT and Plexi Drive. A 2-in-1 with a boost for pushing it would be a  great idea, too, because these respond VERY well to that. I've been using a Silver Pony specced Klone lately as a boost and it's really great for that.


I thought the Azabache sounded pretty good, the Britannia was not my cup of tea, but I think the Britannia is designed to go with a solid state amp. They both had that diode noise in the decay, which seems ironic to me because avoiding that should be one of the benefits of a JFET design and I don't really understand why ROG put those diodes in there.
Title: Re: Favorite Jfet Overdrive?
Post by: midwayfair on October 02, 2014, 10:21:32 PM
Quote from: jubal81 on October 02, 2014, 07:47:13 PMwhich seems ironic to me because avoiding that should be one of the benefits of a JFET design and I don't really understand why ROG put those diodes in there.

It's complicated. Diodes aren't hard clipping when they are connected directly to the gate of a JFET, but they do prevent the signal from hard clipping the JFET's input (remember, once the signal exceeds |Vp|, the JFET hard clips). Someone explained it on DIYSB, either in the Azabache or Britannia thread. The clipping waveform looks very different, too, with a much slower turn-on and the front of the wave significantly more compressed than the next couple milliseconds.

There's another way of doing it with a single diode connected to the negative feedback of the emitter (it goes Emitter > resistor > bypass cap + /resistor/base diode  > ground). I don't have a link handy.

But notice I didn't use them in the Snow Day, even though I actually think they sounded good that way (I'm not sure what the "diode sound" is on the decay, but I assume it's the slightly swirly/cold sound) and made for good tube emulation. The thing is, it matters which type of tube distortion you want to emulate. Power tubes and preamp tubes have different harmonic profiles, and push-pull circuits have far less odd order harmonics than single ended. So building a FET drive that sounds like a cranked power amp is different from one that emulates an overdriven preamp.

I should say too that I don't really like any JFET drive at high levels of distortion, so I think we are on opposite sides of the taste fence on most of these. :)
Title: Re: Favorite Jfet Overdrive?
Post by: PhiloB on October 03, 2014, 02:45:08 AM
After talking with him further, sounds like he would like the Azabache.  Is there an etchable project somewhere?


Sent from my iPhone using Tapatalk
Title: Re: Favorite Jfet Overdrive?
Post by: ggarms on October 03, 2014, 03:57:13 AM
Here's the link to the etch mask:

http://runoffgroove.com/azabache-pcb.pdf
Title: Re: Favorite Jfet Overdrive?
Post by: mmlee on October 03, 2014, 07:33:44 AM
TH Customs also has a fabbed board.  I did the cap change that's mentioned in the ROG article about the highs.
Title: Re: Favorite Jfet Overdrive?
Post by: PhiloB on October 03, 2014, 01:18:54 PM
Thanks guys


Sent from my iPhone using Tapatalk
Title: Re: Favorite Jfet Overdrive?
Post by: Muadzin on October 03, 2014, 03:19:58 PM
I've tried many overdrives, way too many, but once it got on my board NOTHING has managed to kick off my Dirty Little Secret. One of Madbean's old Grapevine boards.
Title: Re: Favorite Jfet Overdrive?
Post by: PhiloB on October 03, 2014, 04:57:56 PM
I've been wanting to build the DLS for myself for a while.  My buddy is set on a Fender Amp OD sound.  Seems like the Azabache fits the bill.



Sent from my iPhone using Tapatalk
Title: Re: Favorite Jfet Overdrive?
Post by: ggarms on October 03, 2014, 07:58:48 PM
I am with Muadzin. The grapevine and the swamprat (plexi) are staples on my rig.
Title: Re: Favorite Jfet Overdrive?
Post by: Blues Healer on October 04, 2014, 01:18:59 AM
another vote for the DLS
Title: Re: Favorite Jfet Overdrive?
Post by: lincolnic on October 04, 2014, 05:01:02 AM
Quote from: PhiloB on October 03, 2014, 04:57:56 PM
I've been wanting to build the DLS for myself for a while.  My buddy is set on a Fender Amp OD sound.  Seems like the Azabache fits the bill.



Sent from my iPhone using Tapatalk

You might also want to look into the Formula No. 5, which is a Tweed Deluxe sound. Jubal81 did some PCBs for it not long ago, he may still have some. There's also a very nice vero layout over at Tagboard Effects.
Title: Re: Favorite Jfet Overdrive?
Post by: lars on October 04, 2014, 08:22:14 PM
My personal experience has not made me a fan of J201-based Jfet overdrives. I've built both the Azabache and the Umble from ROG, and although both had great tube-like overdrive tone, the amount of background solid-state hiss was unacceptable to me. The Grapevine/Dirty Little Secret option people have recommended looks good. The demo I heard of this pedal sounds great, and the build does not use J201s, it uses 2N5457s, which I built a boost from one of these and had no hiss whatsoever.
Title: Re: Favorite Jfet Overdrive?
Post by: gordo on October 05, 2014, 03:18:17 AM
Jon:

Ummm, do we have access to any info on the Snow Drive?  Unless I missed something :-)

This is one of those eagerly anticipated circuits so don't go teasing us mere mortals...
Title: Re: Favorite Jfet Overdrive?
Post by: Shrtyska9 on October 05, 2014, 03:25:07 AM
Quote from: gordo on October 05, 2014, 03:18:17 AM
Jon:

Ummm, do we have access to any info on the Snow Drive?  Unless I missed something :-)

This is one of those eagerly anticipated circuits so don't go teasing us mere mortals...


The video has most of the info. Brian has the board on the project page with an October date so sometime this month we should be able to order and build. Sounds great. Nice work Jon.

Richard