dirt box

[daArry]

y0 butta...

Aint got anything to add, expect a :grin: and a :thumb:...

Really would love to get some lo-fi gritty soundin boxes done soon n all for drums n perc so will be keepin an eye on this one!

Nice1!

 

[tk@halmi]

Butta,

If you have the 10k/600 wire it up as 600/10K. Lows will distort, highs will be mostly gone. That is all you need to soil your mix without anything else added. :thumb:

Tamas

 

[clintrubber]

needs stereo drum samples to be really dirtied up, and i'm looking for a solution.

Sounds like there's a nice box coming up. :thumb:

But just let me add a possible ready-to-go alternative: have a few alike gtr-amps ready ? Push them & mic them. Might be not what you're looking for - or just the ticket and easy for now.

 

[MikoKensington]

Not so foxy lady. :sad:

 

[Gus]

for the real DIYer try old modem transformers

 

[Sleeper]

hey butta, you think filters might be in the realm.
edit: looking at the beginning of the post, I guess you do.

first thing I ever built was a c. anchortoon res. 3 band filter eq. from eclectic pre-jects for moo(sic)uns.. a one chip design with lpf, hpf, and bpf... it still gets alot of use around here for big dirty sounds from little not so dirty drum machines and such. I'll have to look around but i'm sure i have it.

sleeper

this is much much easier than the moog state variable filter BTW...
I'll try and dig this one up too.

 

[Gus]

I built a guitar splitter one side direct one transformer out using a modem transformer (one of the bigger ones) The guitar player that uses it thinks the transformer side is "warmer" sounding.

I am guessing hitting it harder might be very cool

 

[Samuel Groner]

Anybody think that this would give enough DC to dirty things up?

IMO this is not a good idea. First it will reduce headroom of your IC and make it clip asymmetrical (OK, even more dirt!); second it will probably not get you enough shift for most transformers; third, placing the trim far away from the IC might be dangerous for stability due to stray capacitance.

But it's really easy with a coupling cap and a resistor...

Samuel

 

[daArry]

Hey...

Just thought this thread kinda reminded me about my 1st ever post (starting from the other place) made when I aked about a valve saturator box...I saved some of that original thread to a text file for future ref, maybe could prompt further thoughts for this dirtBox - so here's some extracts:

I'd recommend the amplifier section from the pultech clone -
just leave out the eq section for now, and you have a ~20dB
gain tube driver stage with really nice sonic sideeffects.

http://www.gyraf.dk/gyraf2/gy_pd/pultec/pultec.htm

But if you're looking for the sound of these modern
"starved-plate" designs that ate widespread in consumer "pro"
audio, you're better off with distorting by two germanium
diodes..

Jakob Erland
Gyraf Audio

Hey all,

not a tube saturator project, but I had an idea of a
transformer saturator inside my mastering console I will build
in the near future. The input stage would have a rotary switch
where 1 is bypass and the others different gains feeding a
transformer, after which the gain is set back to normal. I
think it could be handy and sometimes could be nearly the only
thing that is needed. The knob could be labelled as "bad-good"
or "less-more".

Does anyone have any idea of the sound of different
transformers - does a Sowter distort more generally than a
Lundahl, for example?

Jaakko

I've kind of had the same idea but I thought it would be a
good experiment to use multiple transformers. From cheap to
expensive for differing charecteristics.

--------------------
Paul Gold
Digi-Rom
www.vinylmastering.net

Hi Paul,

multiple transformers sounds very good to me. And idea I had
was also to put a passive eq behind the transformer - for
example boosting at lows some amount before and then cutting
it back after the transformer to have different
characteristics.

I quess I'll do this around the preamp of the console: thereby
it'd have options of:

1) totally bypassing the whole mess
2) adjusting the gain without feeding transformer
3) adjusting gain feeding transformer
4) saturating through TFX - lowering the gain back to normal
after it.

Jaakko

I´m working on a simple "variable DC current" Xformer output
stage, remembering most of the lovely "soundmakers" like 1176
rev. D, neve 1073 or telefunken V72 have all DC biased output
transformers or inductors (V72) that make most of the sound.
making the DC current adjustable would give the option for
more or less iron sound on any trannie you choose.

steff

:thumb:

 

[clintrubber]

Quote:

I´m working on a simple "variable DC current" Xformer output
stage, remembering most of the lovely "soundmakers" like 1176
rev. D, neve 1073 or telefunken V72 have all DC biased output
transformers or inductors (V72) that make most of the sound.
making the DC current adjustable would give the option for
more or less iron sound on any trannie you choose.

steff

Hey that's cool - the same thing that was discussed here about
the N#v*-output etc.
Didn't remember something alike was discussed at the old place as well, cool.
Steff, please tell, any news from your experiments ?

 

[clintrubber]

from Buttachunk:

so we apply the current to just one side of the windings ?

There are some circuits in the thread below that look related. Haven't put a soldering iron to it, but think of using the Fabio '283 output boards for this.

Thread
with some more in
a preceeding thread

I guess these circuits could be convenient realizations of the idea, nothing beats the already suggested TX+cap+resistor to test it in the most simplest form.

Bye,

Peter

 

[soultek]

I tried this DC thing for almost the same application you are talking about. I used some the ELCF Jensen output transformers and a high voltage high output current class A opamp of my own design. I took it to a friend's studio and we did not find the 'saturated' transformer to be that pleasing of a sound. Puting around 20mA of current seemed to change the distortion characteristics enough to make it an interesting subtle variation, but any more and the sound started to sound anemic rather than fat.

I didn't experiment too much more with this, but I'm sure you may get different results depending on which transformer you use.

To get the 'neve' transformer sound, you would have to use the same neve output transformers, in which case you might as well use the same preamp too. Those were special transformers that are very different form most non-vintage ones available today.

It's a very non-linear thing, so experimentation might be the best way to tackle it. Please post your findings!

 

[Rob Flinn]

I quite liked Eddie Cilettis line input mod to the Altec Valve mic pre.

The gain control is between stages in this, which means that if you overload the input stage you can create some quite coloured tones.

It also has the advantage of that you can use it as a mic pre amp !

 

[surfkat]

I am reviving this old thread because I am wondering if anyone has successfully implemented this concept of DC bias applied to a gaped output transformer to create controlled saturation. I have searched and have found many discussions of the possibilities but no actual implementations. I like the idea of incorporating this into a transformer based line driver box. Can anybody point me in the right direction for further research on this subject? Is this euphonic dream a DIY possibility worth pursuing?

Or would it be just as good to just use a gain stage before the transformer to overdrive it and an attenuator after to tame the output? This is the method I see on many mic pres. I like the idea of building a "dirt box" and I am looking for non-tube ideas. thanks in advance for any help.

 

[Svart]

The point of a gapped tranny is to keep it from saturating in the presence of DC.  So you want an UNgapped transformer.

 

[Gus]

I don't think saturation is the "magic" about transformers.  Read chapter 5 of the big red book and other things about transformers you can find on the web

 

[surfkat]

Read chapter 5 of the big red book...

Please excuse my ignorance. What is the title of this "big red book"?

edit: OK, I found the big red book and i am reading chapter 5. Thanks for the pointer.

 

[flaheu]

hello surfkat,

Can you post the link please ?

 

[surfkat]

It is on this page with many other "vintage" books. A wealth of knowledge here.
I am studying the valve info. Some of the math is more than I want to know.

http://www.pmillett.com/technical_books_online.htm

I am still hoping that someone who has explored this concept of DC bias output transformer saturation will share some of their results. I searched and found several folks who were "working on" ideas but I see no results. Is this a dead end street?
Thanks
Surfkat in Wonderland