RAW switch revisited

jhundt · March 23rd, 2003, 12:22 PM

I read the thread below about the Allen Amp RAW control. I have done a similar thing with my Fender Princetons. The ground from the tone stack is lifted and run through a pot, in my case the footswitch can enable this pot or return the tone stack to ground (thus stock). As the resistance of the pot setting increases the sound gets back to the normal Fender sound. With the pot at zero resistance, the sound is more tweed Deluxe sounding. am curious about the Allen setup, if it is as simple as what I did, and mostly what is the value of the pot he uses? Anyone got an idea about this?

Tom P. · March 23rd, 2003, 12:35 PM

I'd e-mail David Allen. He is a very friendly guy and gets back to you pronto.
http://www.allenamps.com[/url]

Smokey · March 23rd, 2003, 01:47 PM

Oh so this "Raw" control is basically a way to bypass the tone stack it seems, since less signal is being shunted to ground. I guess that would make it more "raw". Heh. :D

Big Cookie · March 23rd, 2003, 01:50 PM

Davids raw switch is a push button, not a pot.

Smokey · March 23rd, 2003, 01:52 PM

Push button? So odds are it's a tone stack bypass then. Anyone have a schematic? I'll check it out.

smokes-~

Jim Collins · March 23rd, 2003, 08:44 PM

It used to be a push button, now it is a pot. He was using A250K, but he may have changed that.

KBR · March 23rd, 2003, 10:56 PM

8)
Big Cookie,
I have 2 Allen Old Flames, a Vibroclone w CA 15 & 4x10
and the New OF's have a Pot for the raw, you can dial it in, Dude.

KBR

Spanky · March 24th, 2003, 08:53 AM

On the Encore model it is most definitely a pot NOT a switch--------

JDO · March 24th, 2003, 11:07 AM

i emailed david allen last night. here's what i wrote.

hello david,

there has recently been some discussion going on over at the tdpri amp board about your raw control. we're wondering what exactly it does. i know that it takes out the tone stack but how?

is it a pot that lets you dial in as much as you want of the tone stack, or is it a switch that bypasses the tone stack?

also, do you mind if we know how it's done? yours' are the only amps i've seen it on so i don't know if it's an issue or ownership or anythign like that. if so i understand. if not do you mind if some of us over there know about it. what i'm learning from the discussion it sounds like a really cool/useful option to have. it would be a great thing to have in a homebrew.

thanks for reading. and thanks for the help you give freely over at the webervst board. if i ever get the money i'll defenetly buy one of your kits.

clean as a whistle,
dean

here's his response.

The Fender blackface tone stack is a “subtractive” type of tone control network. It bleeds off the frequencies you don’t want and lets the rest go to the next gain stage. It is also very inefficient and robs the next gain stage of quite a lot of the signal. The RAW control gradually increases the impedance of these “thrown away signals” trying to go to ground thus forcing them to go on to the next gain stage. There is a dip in the tone stack about 300-400hz where the curve of the bass control overlaps the curve of the treble control. At first the RAW control brings this dip back to unity for a flatter response and then from there, it raises the entire curve which is perceived as gain.

Due to its popularity and time spent tweaking it, I really don’t want to hand over the design at this time. I hope you understand.

Sincerely,
David

don't know if that helps any of you in this discussion. i was slightly disappointed when he said that it's something he wants to keep for now but completely understandable. this might also be something that some of you want to keep in mind if you have a schematic from one of his kits.

Tim Swartz · March 24th, 2003, 11:13 AM

FWIW, putting a pot on the ground of the tone stack is simply adding a midrange control. If it is a 250k pot, I doubt the tone stack is involved. Just guessing that it may be a feedback loop attenuator on one of the gain stages or even more likely on the output section.

March 23rd, 2003, 12:22 PM	#1 (permalink)
jhundt Friend of Leo's Join Date: Mar 2003 Location: Netherlands Age: 54 Posts: 2,735 9 Photos	RAW switch revisited I read the thread below about the Allen Amp RAW control. I have done a similar thing with my Fender Princetons. The ground from the tone stack is lifted and run through a pot, in my case the footswitch can enable this pot or return the tone stack to ground (thus stock). As the resistance of the pot setting increases the sound gets back to the normal Fender sound. With the pot at zero resistance, the sound is more tweed Deluxe sounding. am curious about the Allen setup, if it is as simple as what I did, and mostly what is the value of the pot he uses? Anyone got an idea about this?

March 23rd, 2003, 12:35 PM	#2 (permalink)
Tom P. Tele-Holic Join Date: Mar 2003 Location: Eastern Ct. Posts: 909	I can't tell ya but... I'd e-mail David Allen. He is a very friendly guy and gets back to you pronto. http://www.allenamps.com[/url] __________________ Just Pickin'

March 23rd, 2003, 01:50 PM	#4 (permalink)
Big Cookie Banned Tele-Holic Join Date: Mar 2003 Location: Ennis, Texas Posts: 693	David's Raw Switch Davids raw switch is a push button, not a pot.

March 23rd, 2003, 10:56 PM	#7 (permalink)
KBR Tele-Holic Join Date: Mar 2003 Posts: 649 5 Photos	Allen Amps (Raw switch) is a Pot, I like it on 2 8) Big Cookie, I have 2 Allen Old Flames, a Vibroclone w CA 15 & 4x10 and the New OF's have a Pot for the raw, you can dial it in, Dude. KBR __________________ KBR http://home.earthlink.net/~blueray/

March 24th, 2003, 08:53 AM	#8 (permalink)
Spanky Tele-Meister Join Date: Mar 2003 Location: Baldwin,(Long Island) NY Posts: 117	On the Encore model it is most definitely a pot NOT a switch-------- __________________ Rev. Spanky************************** God plays a 52ri--He's really GOOD TOO ! *************************************

March 23rd, 2003, 01:47 PM	#3 (permalink)
Smokey TDPRI Member Join Date: Mar 2003 Posts: 78	Oh so this "Raw" control is basically a way to bypass the tone stack it seems, since less signal is being shunted to ground. I guess that would make it more "raw". Heh. :D

March 23rd, 2003, 01:52 PM	#5 (permalink)
Smokey TDPRI Member Join Date: Mar 2003 Posts: 78	Push button? So odds are it's a tone stack bypass then. Anyone have a schematic? I'll check it out. smokes-~

March 23rd, 2003, 08:44 PM	#6 (permalink)
Jim Collins Tele-Meister Join Date: Mar 2003 Posts: 309	It used to be a push button, now it is a pot. He was using A250K, but he may have changed that.

March 24th, 2003, 11:07 AM	#9 (permalink)
JDO Tele-Holic Join Date: Mar 2003 Location: Pittsboro, NC Posts: 597	i emailed david allen last night. here's what i wrote. hello david, there has recently been some discussion going on over at the tdpri amp board about your raw control. we're wondering what exactly it does. i know that it takes out the tone stack but how? is it a pot that lets you dial in as much as you want of the tone stack, or is it a switch that bypasses the tone stack? also, do you mind if we know how it's done? yours' are the only amps i've seen it on so i don't know if it's an issue or ownership or anythign like that. if so i understand. if not do you mind if some of us over there know about it. what i'm learning from the discussion it sounds like a really cool/useful option to have. it would be a great thing to have in a homebrew. thanks for reading. and thanks for the help you give freely over at the webervst board. if i ever get the money i'll defenetly buy one of your kits. clean as a whistle, dean here's his response. The Fender blackface tone stack is a “subtractive” type of tone control network. It bleeds off the frequencies you don’t want and lets the rest go to the next gain stage. It is also very inefficient and robs the next gain stage of quite a lot of the signal. The RAW control gradually increases the impedance of these “thrown away signals” trying to go to ground thus forcing them to go on to the next gain stage. There is a dip in the tone stack about 300-400hz where the curve of the bass control overlaps the curve of the treble control. At first the RAW control brings this dip back to unity for a flatter response and then from there, it raises the entire curve which is perceived as gain. Due to its popularity and time spent tweaking it, I really don’t want to hand over the design at this time. I hope you understand. Sincerely, David don't know if that helps any of you in this discussion. i was slightly disappointed when he said that it's something he wants to keep for now but completely understandable. this might also be something that some of you want to keep in mind if you have a schematic from one of his kits. __________________ clean as a whistle

March 24th, 2003, 11:13 AM	#10 (permalink)
Tim Swartz Tele-Afflicted Join Date: Mar 2003 Location: Michigan - Tweenst the Great Lakes Posts: 1,774	FWIW, putting a pot on the ground of the tone stack is simply adding a midrange control. If it is a 250k pot, I doubt the tone stack is involved. Just guessing that it may be a feedback loop attenuator on one of the gain stages or even more likely on the output section.