Crazy "Amp in a box" idea: need help...

Recording Techniques, People Skills, Gear, Recording Spaces, Computers, and DIY

Moderators: drumsound, tomb

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Crazy "Amp in a box" idea: need help...

Post by greatmagnet » Tue Aug 04, 2009 9:13 am

Hey Folks...semi-newbie circuit-builder here....thanks in advance for listening. It's kind of a loooong explanation but I think this might be a really cool idea if I could get some help, so please read on if you can stomach it...

I was just curious: I have this craaazy idea of basically using a low-wattage amp AS a stomp box...kind of...because I've tried every single guitar overdrive and distortion pedal on the market and frankly I think every single one sucks by like 200% compared to an overdriven tube amp. And in that statement I'm including so-called "high-voltage rails preamp pedals" such as the English Muffin and the V-Twin. I have tried them all. I hate them all. Yes, I am picky.

By contrast I m absolutely in love with what a Weber Mass attenuator (recommended above all others IMHO) can do to bring a classic overdriven amp down to line-level without sacrificing tone for the most part. Gotta love the way Ted Weber uses speaker motors to suck out the voltage rather than resistors. It works. And in particular I think that the tone of something as rudimentary as a tiny little overdriven 5-watt amp like the Blackheart one or the Z-Vex one through a Weber MicroMass (15 watts or less attenuator) is still way, way nicer than any distortion pedal on the market bar none.

So the thought occurred to me that if I could "bundle" those two items (such as the Z-Vex amp and the micro-mass) together into a single enclosure, you'd have a line-level distortion circuit with a really small combined footprint...probably not any bigger than some of the really involved all-tube distortion boxes out there like the Matchless. And it would be the sound of an entire overdriven amp...preamp and power section.

The only thing missing from that picture (for my feeble brain) is how to then step that output all the way back down to "pedal level" (there's got to be a better term for that...help me out) so I can plunk this new goodie right down into my pedalboard as the first thing in line before all the other pedals. For my own purposes I would not even need a true bypass stomp switch to be involved because I basically go through a panning pedal first before anything else and rock it back and forth to switch between my overdriven signal chain and my clean signal chain. I personally like that better than an A/B switch because I can get "in-between tones" with my foot in much the same way that some would use their guitar volume knob...but hands-free. Putting the panning pedal first before any of the other stuff means that as you "pan" the pedal towards the overdrive box (even if it's just a Tube Screamer), it gives that box increasingly more input and therefore gradually more overdrive in a very natural fashion. Plus with that rig I can have different pedals in the "clean chain" than in the "overdrive chain". I bring both chains back together just before the amp with a simple 2>1 summing circuit box followed finally by a reverb pedal that thusly services both clean and dirty chains.

So, the question is: is there a simple circuit I could build, or even some "out-of-the-box" gizmo solution for bringing the (relatively) high line level output of my amp/attenuator combo down to the aforementioned "pedal level" or whatever you call it so I can put it first in line and then feed all my stompers with it?

The beauty of a rig like this is that you could take that pedalboard anywhere and plug it into the shittiest of solid-state practice amps, and the sweet, expressive, full-bodied, crunchy tube-y-ness of your overdrive tone would still be pretty big-league all the way...only limited by whatever speaker you're coming out of.

THANKS!
Adam
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

User avatar
A.David.MacKinnon
ghost haunting audio students
Posts: 3268
Joined: Wed May 07, 2003 5:57 am
Location: Toronto
Contact:

Post by A.David.MacKinnon » Tue Aug 04, 2009 9:35 am

Google the Garnet Herzog. It sounds like what your looking for - a tube amp you can plug into a tube amp without things catching fire.

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Tue Aug 04, 2009 11:45 am

Wow that is some buttloads of amazing info on a brilliant amp designer I'd never even heard of! Great...now I have to collect GARNET amps, too! Thanks.

This guys sounds like an incredible innovator and the circuits sound as if they are unmatched today is some ways. I want a BTO!!!

It DOES claim on the Garnet site (http://www.garnetamps.com) that this amp can be used "just like a stompbox" in front of the amp, but it also appears to be line level in point-of-fact.

My personal experience is that you CAN put something line-level right in front of an OLD TUBE HEAD and it will totally handle it. HOWEVER, I seem to recall that putting a line-level signal in front of a STOMP BOX doesn't work so hot...it overloads it. In a bad way.

My point being simply that if I stuck a Herzog in front of a series of other pedals (chorus, delay, etc.) before it hit the amp I could have tone issues?
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Tue Aug 04, 2009 12:33 pm

That said, I just found elsewhere what I think is the more DIRECT answer to my question...if I had properly worded it to begin with: I need to build a simple attenuator circuit that brings a line-level signal (either +4 or -10 depending) down to "mic level". Which is similar to what I was calling "guitar level" or "stomp box level" and is a much lower level.

Anyhow it's a really simple circuit and here's the link...
http://www.epanorama.net/circuits/line_to_mic.html

...to quote that fellow, Mr. Tomi Engdahl, "Sometimes there is need to convert line level signals to such signal that it can be connected to microphone input. Because the line level signals are typically in range of 0.5..2V and the microphone signals are in millivolt range, quite much attenuation is needed to match the signal levels. This means that typically you will need 40-50 dB of attenuation. "

If you're doing consumer level instead of pro you'd just swap out the first resistor for 10k rather than 33k.
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

User avatar
A.David.MacKinnon
ghost haunting audio students
Posts: 3268
Joined: Wed May 07, 2003 5:57 am
Location: Toronto
Contact:

Post by A.David.MacKinnon » Tue Aug 04, 2009 4:33 pm

Caldo71 wrote:Wow that is some buttloads of amazing info on a brilliant amp designer I'd never even heard of! Great...now I have to collect GARNET amps, too!
Gar was the man. I have a few of his amps and they're pretty great. Right up untill he died he was still repairing and building amps out of his TV repair shop in Winnipeg. I'd put him up there with Leo Fender and Pete Traynor.
If you want to know what the Herzog sounds like go dig up American Woman by the Guess Who. That's a Herzog on the solo.

User avatar
HeavyHand
takin' a dinner break
Posts: 157
Joined: Mon Apr 07, 2008 11:49 pm
Location: Philadelphia, PA
Contact:

Post by HeavyHand » Tue Aug 04, 2009 6:02 pm

hey man. i think you want to bring you line level signal down to instrument level. mic level is a bit weaker signal than instrument level. such is the need to use a d.i. to bring the signal down enough to use a mic pre. also, the input impedence of a mic input can be around 1.5K ohms and instrument input impedence can be around 1M ohms. it all depends. input voltage of a mic is about .002V to 1V. instrument input voltage is around .1V to 1V for passive pickups and 1.75V for active pickups. i hope this helps. i dont really know enough about circuits to be talking about this stuff but im learning.
Ok, who brought the dog? - Louis Tully
www.facebook.com/BigTerribleMusic

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Wed Aug 05, 2009 10:11 am

junkshop wrote:I'd put him up there with Leo Fender and Pete Traynor.
If you want to know what the Herzog sounds like go dig up American Woman by the Guess Who. That's a Herzog on the solo.
Yeah what's up with those amazing unheard of Canadian amp makers? I have a Traynor YBA-1 and it RULES! I did the Plexi mod to it, too. Every piece of info on the Herzog I dug up on the interwebz references that "American Woman" solo...but I doubt that does the amp justice. Iconic perhaps, but probably not exactly the pinnacle of what most people would consider good useful guitar tone for rythm playing, wouldn't you say? I mean, you know, I can do that with a Big Muff!
HeavyHand wrote:hey man. i think you want to bring you line level signal down to instrument level. mic level is a bit weaker signal than instrument level.
Actually that is GREAT info so thank you. I ASSUMED that mic level and instrument level were the SAME. I think that's totally no biggie though...it looks from that page I posted like you just change the aggressiveness of the attenuation by swapping out resistor values in the first position.
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

The Scum
resurrected
Posts: 2428
Joined: Thu Jul 03, 2003 11:26 pm
Location: Denver, CO
Contact:

Post by The Scum » Wed Aug 05, 2009 10:44 am

Or make the thing adjustable. Grab a 100K audio taper pot.

Signal goes into the clockwise end, comes out the wiper. Ground the counterclockwise end. Tada - variable L-pad.

The 100K pot will be large enough to present a minuscule load on the output stage, and you'll probably run it about 1/4 open, so it'll also act as a sizeable source impedance, much like a guitar.

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Wed Aug 05, 2009 11:41 am

The Scum wrote:Or make the thing adjustable. Grab a 100K audio taper pot.
Yeah I've seen schematics for this approach too. Question: does the potentiometer compromise the sound in any way versus a hard-wired resistor?

I ask this out of ignorance...not because i've actually heard anything of the sort either way. More because I know that when people are talking about designing really high-end stuff that the preferred way to attenuate signal is with stepped pots that have a dedicated resistor for each increment.

no idea if this applies to such a rudimentary circuit at all but thought I'd ask...
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

User avatar
A.David.MacKinnon
ghost haunting audio students
Posts: 3268
Joined: Wed May 07, 2003 5:57 am
Location: Toronto
Contact:

Post by A.David.MacKinnon » Wed Aug 05, 2009 11:55 am

Caldo71 wrote:
junkshop wrote: Every piece of info on the Herzog I dug up on the interwebz references that "American Woman" solo...but I doubt that does the amp justice. Iconic perhaps, but probably not exactly the pinnacle of what most people would consider good useful guitar tone for rythm playing, wouldn't you say? I mean, you know, I can do that with a Big Muff!
Ahha. If you're looking for a rhythm type thing the herzog might not be the ticket. It's pretty over the top (more than the Big Muff even). If you want the sound of the apocalypse (with tubes) the herzog is the thing. If you want clean or mildly distorted you might do better with something else.

ashcat_lt
tinnitus
Posts: 1079
Joined: Thu Jan 04, 2007 1:54 pm
Location: Duluth, MN
Contact:

Post by ashcat_lt » Wed Aug 05, 2009 2:07 pm

I'm pretty sure the stepped attenuator thing is just for precision. You can carefully choose and match resistor values to give you, for example, exactly 3db difference between each step. This can be important, especially for things like stereo or balanced situations, where you want both "sides" attenuated by exactly the same amount. It's not really a concern for what you're trying to do. A good quality pot would be fine.

Wired as described above, this pot would go from off (silence) all the way up to whatever the full line level out is. You probably won't actually need it to go to either of these extremes. You could do some fiddling, find a more acceptable min/max level, and choose resistors for both the "bottom" (ground side) and "top" (input side) of the pot to limit its effective range. This would get you more usable resolution to the pot sweep.

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Wed Aug 05, 2009 2:26 pm

Awesome, awesome info...I totally get it. Thank you.

Gods I love TapeOp. I posted this question on several forums: this one, gearslutz, and a couple of other forums that are more specifically focused on guitar electronics. This thread and the gearslutz one have given me some great on-target advice.

The other two sites by comparison were peopled entirely with douchebags who couldn't give you a straight answer if they tried. Just a bunch of witless boilerplate cliches. Real shiny-ponytail-Santana-fan tripe.
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

The Scum
resurrected
Posts: 2428
Joined: Thu Jul 03, 2003 11:26 pm
Location: Denver, CO
Contact:

Post by The Scum » Wed Aug 05, 2009 3:53 pm

Stepped attenuators are for precision and repeatability. You can make it so every step is properly graduated. Mastering engineers like it because you can get the exact same setting on the left and right channels, and recalls actually get the original processing back.

A decent quality pot (even the Alpha 1" ones from Mouser) shouldn't be much less fidelity...but the stepped attenuator game can get pretty fancy...$100 rotary switches with laser trimmed precision resistors.

But you're effectively building a distortion box, so extreme attention to fidelity is probably overkill.

segaface
steve albini likes it
Posts: 320
Joined: Thu Aug 26, 2004 4:50 pm
Location: STL, MO
Contact:

Post by segaface » Thu Aug 06, 2009 9:22 am

You could always try this thing:

Tech21 American Woman pedal.
Tech 21?s American Woman overdrive pedal celebrates the tone of one of the most recognized guitar solos in the history of rock. With just the right balance of odd and even harmonics, the American Woman recreates the cascading effect of two different amplifiers, including pre-amp and power amp stages. This effect is typically only achieved by running two guitar amplifiers into each other. American Woman, she gonna mess your mind?

CONTROLS INCLUDE
? Drive for the amount of overdrive.
? Gate to reduce hiss and noise when not playing.
? Tone shifts the high cut from 10kH to 1kH, which removes the high end without losing mids or turning muddy.
? Level, which is capable of extremely high output - up to 10dB.
Never tried it, but if it's as good as their other stuff, it might be worth a look.
fossiltooth wrote: That's like saying you hate Fenders because of Yngwie Malmsteen.
My musics.

User avatar
greatmagnet
buyin' a studio
Posts: 913
Joined: Thu Oct 16, 2003 2:10 pm
Location: Santa Rosa, CA
Contact:

Post by greatmagnet » Tue Aug 11, 2009 12:14 pm

The Scum wrote:Or make the thing adjustable. Grab a 100K audio taper pot.

Signal goes into the clockwise end, comes out the wiper. Ground the counterclockwise end. Tada - variable L-pad.

The 100K pot will be large enough to present a minuscule load on the output stage, and you'll probably run it about 1/4 open, so it'll also act as a sizeable source impedance, much like a guitar.
Okay, so if I do this "variable L-Pad" version, is THIS what my circuit would look like?

Image

I'm a total noob dummy on all this so I'm getting the placement of R2 as well as it's VALUES from a schematic I just found on the web that I THINK was intended for unbalanced line-level signal.

Actually that schematic did not include wattage or tolerances so I'm totally guessing there.
"All energy flows in accordance with the whims of the great Magnet"
?Raoul Duke
www.greatmagnetrecording.com

Post Reply

Who is online

Users browsing this forum: Recycled_Brains and 9 guests