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General Discussions => Drawing Board => Topic started by: BackHand on March 25, 2008, 06:48:51 PM

Title: Distortionbox
Post by: BackHand on March 25, 2008, 06:48:51 PM
I want to build something like the thermionik CULture VULTURE box...something I can send a line signal (or a stereo pair) from my sound card into and then distort like Vocals, drums and so forth.

Is this hard? I'm no wizzard..I've built API preamps a SSL clone and three g7's with dale's lovely capsules..but all of those were finished designs...is there anything like that for this distortion box thingy?

I was also thinking of buying a Tl Audio PA-1 tube preamp ( http://www.tlaudio.co.uk/docs_07/product_07/PA-1.shtml ) and try to send line signals into that...but...that would not work very well right since it's a microphonepreamp...it don't work with line signals...

Thanks!
Title: Distortionbox
Post by: Ian MacGregor on March 25, 2008, 11:48:53 PM
I apologize in advance as this is a totally shameless plug, but have you seen this: http://www.standard-audio.com/home.html ??

It is a Level-Loc inspired limiter/distortion box for the 500 series with line in and out. Again, sorry for the self promotion (I started Standard Audio with a producer/friend and designed the unit). I'd be happy to answer any questions about the unit as it pertains to your search for a line level distortion box...

Iab
Title: Distortionbox
Post by: discobloud on March 26, 2008, 02:40:55 AM
Hey Ian.  I just sent you an e-mail about the awesomeminator.  I failed to mention it might be cool to have a scale/special knobs for recall.  

mark
Title: Distortionbox
Post by: BackHand on March 26, 2008, 11:55:12 AM
Quote from: "Ian MacGregor"
I apologize in advance as this is a totally shameless plug, but have you seen this: http://www.standard-audio.com/home.html ??

It is a Level-Loc inspired limiter/distortion box for the 500 series with line in and out. Again, sorry for the self promotion (I started Standard Audio with a producer/friend and designed the unit). I'd be happy to answer any questions about the unit as it pertains to your search for a line level distortion box...

Iab


I listened to the mp3 clips and they sound great! Do you make a stereopair for stereosources?
I still miss the tube sound though...
Title: Distortionbox
Post by: sonicmook56 on March 26, 2008, 01:46:55 PM
Quote from: "Ian MacGregor"

It is a Level-Loc inspired limiter/distortion box for the 500 series with line in and out.


I wanted to build the exact same thing, just never got around to doing it!
Title: Distortionbox
Post by: Ian MacGregor on March 26, 2008, 01:48:00 PM
We don't make a stereo version, but I have used two units on stereo sources before and they work pretty well.

You are right, this box definitely does not have a tube sort of character...

Ian
Title: Distortionbox
Post by: BackHand on March 27, 2008, 05:12:16 PM
So beside the great iron version...any ideas on a tube version of the distortionbox  :twisted:?
Title: Distortionbox
Post by: Ian MacGregor on March 27, 2008, 07:08:25 PM
How about a tube mic pre with a pad on the input? Up the impedance of the pad so as to not load down the stage driving it. I would place the pad in front of the input transformer, they can sound way cool when overloaded. You might also need a pad on the output so you can fine tune the output level to your recorder/console.

To make the mic pre interface with line signals, try a -40dB U-pad with the two series resistors being around 5k. The shunt resistor will be low, try 100 ohms. It will probably be kinda noisy, but it might work for you. You can vary the amount of drive by hitting the mic pre front end harder or softer.

Ian
Title: Distortionbox
Post by: MLM on March 27, 2008, 10:26:09 PM
valve distortion box....you have to check this guy out -


http://www.youtube.com/watch?v=UGZCbX_nUSc
Title: Distortionbox
Post by: lernith on April 07, 2008, 10:29:42 PM
Dosn't the thermionik CULture VULTURE have you adjust the bias of a pentode tube? That's different from overdrive, isn't it?  What else would be going on in an amp like that?
Title: Distortionbox
Post by: MartyMart on April 09, 2008, 03:38:10 AM
I've had good results sending stuff through valve guitar pre-amps, such as
the Hughes and Kettner "Cream Machine" and Marshall "JMP-1" etc.
Even using guitar combo's sometimes, remember Jon Lord and his Hammond - Marshall setup !!

I'm sure that it wouldn't be hard to coax some distortion from a simple valve
mic pre .... thinking in guitar "pre" mode for a few moments right ?

MM.
Title: Distortionbox
Post by: Sorr on April 10, 2008, 07:23:34 PM
The Culture Vulture uses a 6AS6 which is a dual control Pentode.
The suppressor grid can be used as an additional control grid.

You could also try connecting it (suppressor) to a variable external voltage source say -10V to +10V :wink:

Sorr
Title: CULTURE VULTURE
Post by: inputoutput on May 07, 2008, 02:51:58 PM
Yo Sorr,  I've worked a bit on my culture vulture lately with some  simple mods and improvements. Took some pics before putting it back into the rack. Maybe they'll help you out, or inspire you

I've had it for several years, but it has never worked right - until recently.  Been trying to reach the Thermionic guys, but they have never replied on my emails!  So, when I opened it, I found lots of solder mess all over, and several bad poorly connected wires.  And at a closer look, I noticed that two pots  (bias) had different values on each side- plus that the EQ had different caps on each side. :evil: It is obvious that they have sold me a f….ing prototype! (and I have changed the tubes 4 times, thinking that they were  the ones that were messing it up) ...anyway,

First, after putting the 10K Sowters on the input, the sound just blossomed.  Then dual stepped attenuator on the bias helped me stabilize it, plus two new 100K pots on the input (“drive).

I also changed the caps on the EQ filter, bringing it up to 7000Hz and 10000Hz cutoff.  The original 4000Hz is just way to low.  I was planning to install output transformers to (10K) but I’m not sure that it’s necessary anymore. Sounds nice enough to be used on the masterbus now!! This unit finally kicks ass. very inspiring indeed.

inside pic  after cleaning but without mod :
(http://www.kaada.no/DIY/CV/under.jpg)

top - without mod (oh there's two different caps here too):
(http://www.kaada.no/DIY/CV/u-mod.jpg)


top - (with my mod!) with stepped attenuators and input transformers:

(http://www.kaada.no/DIY/CV/attenua.jpg)
Title: Re: Distortionbox
Post by: on May 07, 2008, 03:26:02 PM
Quote from: "BackHand"
I want to build something like the thermionik CULture VULTURE box...something I can send a line signal (or a stereo pair) from my sound card into and then distort like Vocals, drums and so forth.

Is this hard? I'm no wizzard..I've built API preamps a SSL clone and three g7's with dale's lovely capsules..but all of those were finished designs...is there anything like that for this distortion box thingy?

I was also thinking of buying a Tl Audio PA-1 tube preamp ( http://www.tlaudio.co.uk/docs_07/product_07/PA-1.shtml ) and try to send line signals into that...but...that would not work very well right since it's a microphonepreamp...it don't work with line signals...

Thanks!


I don't understand why it is called pentode amplifier, if it uses 12AX7 tubes?



2-Channel Pentode Tube Preamp

TL Audio PA-1 - 2-Channel Pentode Tube Preamp Zoom In: Front Panel Back Panel
   TL Audio PA-1 - 2-Channel Pentode Tube Preamp
TL Audio Valve Signal Processing    TL Audio PA-1 - 2-Channel Pentode Tube Preamp
TL Audio PA-1 - 2-Channel Pentode Tube Preamp    
Overview

The PA-1 Pentode Preamp is TL Audio's top of the range preamp - producing a stunning sound from any source - and offers a significant improvement over the vast majority of console preamps in any price range. The new PA-1 offers several improvements over its best selling forerunner, including a raven blue 6mm CNC milled aluminium front panel, General Electric US military specification ECC83/12AX7A valves, gold plated ceramic valve bases and circular back-lit VU meters which monitor output level. Internal circuitry has been refined too, to offer smoother frequency response around the valve stages and provide extra output gain - thus enabling easier interfacing with digital recorders.
Title: Distortionbox
Post by: Sorr on May 08, 2008, 08:24:27 PM
Inputoutput,                                                                                                      Looks like you have an early version.
The one I saw had a PCB.
I only had in the workshop for a short time, so I didnt have time to trace the circuit.
Did you?

Sorr
Title: Distortionbox
Post by: inputoutput on May 09, 2008, 02:35:19 AM
no,  I just did a quick fix, swapping some parts.
Title: Distortionbox
Post by: dshay on May 13, 2008, 01:29:25 AM
I wonder how an op amp with Rf clipping adjust would sound with a 1176 following it.

Pretty bad ass I imagine.
Title: Distortionbox
Post by: Sorr on May 13, 2008, 03:08:10 AM
Like any other distotion pedal using this approach.
I prefer a discrete design, but it all depends on what sort of distortion sound youre after.
There are a number of valve (tube) distortion/waveform altering circuits that have been lost in the mists of time and using the suppressor grid to introduce
"colour" was around in the sixties.
The orignal Aphex Aural exciter patent is interesting to read.

Sorr