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Studio Devil Virtual Tube Preamp

StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Thu Nov 22, 2012 10:04 pm

Yes, and no.

I designed VTP as a circuit simulator, which uses a numerical solver to step through a system of non-linear differential equations...

what does this mean in English? Well, it uses the input sampling rate at all times, but it does step through the simulation at more than one spot for each sample...it's not up-sampling, or over-sampling, per se, but it does resemble it.

I'm not sure if this helps answer the question, but if you have other questions, maybe I can help.

BTW, the CPU switch varies the number of steps and precision of the solver, so that's why it affects the CPU so much. However, the DSP is coded very efficiently, and you will get great results from the lower CPU setting...and the CPU is pretty usable, even with multiple instances.

Hope this helps...

Marc
K-Slash
KVRAF
 
1643 posts since 9 Jul, 2006, from Paris, France

Postby K-Slash; Thu Nov 22, 2012 10:24 pm

I'm liking it more and more.

On the Drums bus, I use it just after the compressor, followed by SoundToys LittleRadiator at (50% MIX).

Sounds wonderful. Makes the Drums cut and pop in the mix really nicely.

Can't wait for the next plugins ;).
StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Sat Nov 24, 2012 7:20 am

I find it works great as a kind of leveler...you can push the levels up on a vocal or instrument track and the tube just softly rounds out the clips...brings up volume without sounding like a gnarly saturator...when used in moderation, of course!

also, the bass contour can turn down the bass on lead instrument and vocal tracks to help prevent muddying up the bottom end.

i'm sure there are tons of other uses...i've tried it as a "front-end" to lots of plugins we have here, and it seems to improve every one of them...

try chaining VTP in front of your other "go-to" channel insert plugins...love to hear what you find!
K-Slash
KVRAF
 
1643 posts since 9 Jul, 2006, from Paris, France

Postby K-Slash; Sat Nov 24, 2012 11:54 am

Sure, when used with care, it acts as a "betterizer".

Could be used as the first insert in each channel to add some harmonic content, or as a "colorbox" (the use I prefer) to give impact to Drums or else.
kvaca
KVRian
 
1048 posts since 30 Oct, 2005

Postby kvaca; Sun Nov 25, 2012 12:34 am

Robmobius wrote:I tried it... It's quite nice. But I still prefer the Wavearts (despite its high cpu).


well,I do NOT...becouse TS is CPU hog compared to this preamp and do not sound as smooth at higher drive levels becouse of harsh aliasing that Wave Arts guys "cannot hear" and thus dont care about
but the question is if I will still prefer my TLA Ivory hw preamp...damn :shock:
StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Sun Nov 25, 2012 5:28 pm

kvaca wrote:but the question is if I will still prefer my TLA Ivory hw preamp...damn :shock:

please let us know if you do!

i don't know the 5001 preamp schematic off-hand, but I'm sure you'll get similar results from Studio Devil VTP, especially if the Ivory is a straightforward triode preamplifier without fancy EQ.

VTP emulates a single triode stage...although, that bass cut switch on the Ivory gives me ideas!

Marc
kvaca
KVRian
 
1048 posts since 30 Oct, 2005

Postby kvaca; Mon Nov 26, 2012 6:54 am

StudioDevil wrote:
VTP emulates a single triode stage...

thanks for clearing this up!

from the beginning I got a strong feeling that your preamp sounds closer to my TLA hw than to Wave Arts TS plugin preamp...and now I know why,becouse Wave Arts are modelling DUAL stage triode instead,so TS should not sound similar...and that also explains much bigger CPU load of Tube Saturator

from listening by ear I think that your preamp distorts more easily than TLA,but I need to do some proper measurements before any final conlusions...
StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Mon Nov 26, 2012 1:37 pm

kvaca wrote:
StudioDevil wrote:
VTP emulates a single triode stage...

thanks for clearing this up!

from the beginning I got a strong feeling that your preamp sounds closer to my TLA hw than to Wave Arts TS plugin preamp...and now I know why,becouse Wave Arts are modelling DUAL stage triode instead,so TS should not sound similar...and that also explains much bigger CPU load of Tube Saturator

from listening by ear I think that your preamp distorts more easily than TLA,but I need to do some proper measurements before any final conlusions...

Yes, VTP is a single stage...the reason, is that if you want a dual stage, you can simply put two VTPs in series!!! ;) Which works nicely, BTW.

Gain may not match real hardware due to scaling...I chose to add a multiplier on the input, because if I chose 1.0=1.0V scaling, then the tube wouldn't saturate at all...and that's not fun. So there's a scaling factor of 12.0 on the front end, so that you can get the tube to do fun stuff...it's really meant to be used artistically...so play and listen until it's cool.

Another difference is that Studio Devil VTP does NOT have any EQs in it, nor does it model any analog filters...I think the TS has a built-in analog EQ sim (Baxandall type, three-band). I specifically avoided this to make this plugin more generally useful...VTP does have filtering qualities, but they come only from the inherent properties of the circuit capacitors of the preamp.

If you can get a hold of an Ivory schematic, I can comment further on the differences and similarities!

Marc
onqel
KVRist
 
93 posts since 8 Jan, 2008, from norway

Postby onqel; Mon Nov 26, 2012 2:55 pm

StudioDevil wrote:what does this mean in English? Well, it uses the input sampling rate at all times, but it does step through the simulation at more than one spot for each sample...it's not up-sampling, or over-sampling, per se, but it does resemble it.


Runge-Kutta? :P
StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Mon Nov 26, 2012 3:25 pm

Runge-Kutta is one method that works well...but you must be careful! It is not guaranteed stable for stiff systems, i.e. tubes! Works okay for low drive settings, but when the gain and clipping are very high, or when capacitors are very small...you're skating on thin ice!

But, if you're asking if a step-integration numerical solver is at work here, the answer is: YES! Studio Devil VTP uses a proprietary vector-valued state-variable non-linear dynamical system numerical solver, specifically tailored for everything a musician and tube lover would want: low CPU and valve-like tone :)

when choosing a solver, one needs to balance CPU with precision and accuracy. the art of this lies here...and it's the part that relies so heavily on intuition and trial and error.

I can't tell you more, because if I did, then everyone would be Studio Devil, and right now, I'm rather enjoying that there is only one...besides, what's life without a little mystery?

:)

Marc
kvaca
KVRian
 
1048 posts since 30 Oct, 2005

Postby kvaca; Tue Nov 27, 2012 7:43 am

StudioDevil wrote:i don't know the 5001 preamp schematic off-hand, but I'm sure you'll get similar results from Studio Devil VTP, especially if the Ivory is a straightforward triode preamplifier without fancy EQ.


Ive found it very hard to compare 5001 to VTP directly, becouse it doesnt accept line level signal well...so I have used another TLA tube device /Fatman/ for direct comparison and I have to say that not only the sound by ear but also the resulting waveforms are very similar /but TLA is still less harsh in hi-freq region/...good work!

StudioDevil wrote:Yes, VTP is a single stage...the reason, is that if you want a dual stage, you can simply put two VTPs in series!!! Which works nicely, BTW.


But using 2 VTP in series doesnt result in sound more similar to TS,the waveforms are still very different...assuming that Wave Arts done their modelling well there must be some added magic missing...
Wild Hades
KVRist
 
154 posts since 6 Sep, 2007

Postby Wild Hades; Tue Nov 27, 2012 11:29 am

kvaca wrote:assuming that Wave Arts done their modelling well there must be some added magic missing...

The "magic" missing is the interaction between the two coupled stages in grid current limiting conditions.
When the second triode saturates in the positive region, the load seen by the first stage changes, causing its gain and saturation behaviour to change as well. The decoupling capacitor will also charge faster, modifying the low-frequency response and the transient response when the triode exits the positive saturation region.
Putting two triodes in series that don't interact with each other is (and sounds) quite different (and is also a lot lighter on the CPU) from modeling all the interactions between two coupled triode stages.
K-Slash
KVRAF
 
1643 posts since 9 Jul, 2006, from Paris, France

Postby K-Slash; Tue Nov 27, 2012 2:59 pm

Wild Hades wrote:
kvaca wrote:assuming that Wave Arts done their modelling well there must be some added magic missing...

The "magic" missing is the interaction between the two coupled stages in grid current limiting conditions.
When the second triode saturates in the positive region, the load seen by the first stage changes, causing its gain and saturation behaviour to change as well. The decoupling capacitor will also charge faster, modifying the low-frequency response and the transient response when the triode exits the positive saturation region.
Putting two triodes in series that don't interact with each other is (and sounds) quite different (and is also a lot lighter on the CPU) from modeling all the interactions between two coupled triode stages.

Hey man, sounds like you know lot of things on the subject ;).

Maybe well see a plugin preamp with multiple tubes from you in the future :D...
StudioDevil
KVRist
 
56 posts since 17 Jul, 2007, from New York, NY

Postby StudioDevil; Tue Nov 27, 2012 5:07 pm

Wild Hades wrote:
kvaca wrote:assuming that Wave Arts done their modelling well there must be some added magic missing...

The "magic" missing is the interaction between the two coupled stages in grid current limiting conditions.
When the second triode saturates in the positive region, the load seen by the first stage changes, causing its gain and saturation behaviour to change as well. The decoupling capacitor will also charge faster, modifying the low-frequency response and the transient response when the triode exits the positive saturation region.
Putting two triodes in series that don't interact with each other is (and sounds) quite different (and is also a lot lighter on the CPU) from modeling all the interactions between two coupled triode stages.

100% true...and well said. :tu:

I should add that the asymmetry of the 2nd stage grid causes an effect I call "grid-clamping", which in conjunction with the decoupling interstage cap causes an effect much like a diode clamp circuit...it decays away with the signal, so you get nice, transient/level-dependent bias shifting there. Not really a reduction in gain, just different clipping, and a dynamic effect.

Although, I can't agree so much with the CPU side of things...not here anyway. I've got 4 stages running with full interaction and it's only 4 times CPU of a single stage...due to the approach / solver I'm using...of course it's a guitar preamp...you'll be hearing it sometime next year, if all goes well :)

Well, I guess the point is...do you want a single stage or a dual stage? A dual stage is more complex, but it's not really right for a tube warming front end...certainly not with a built-in EQ...in my book, that's more of a "channel"...but if the general consensus is to add a second stage and/or an EQ, I can certainly add switches that allow these options to the MORE screen?

I'd rather just say that VTP is NOT TS, nor tries to be. If you want a dual stage triode with EQ, get TS...if you want a single stage triode then use VTP...but I'm considering putting both options under the hood now.

yes? no?
what's your vote?
conservative single stage, no eq
OR
agressive dual stage with Eq option?
OR
both?

Marc
K-Slash
KVRAF
 
1643 posts since 9 Jul, 2006, from Paris, France

Postby K-Slash; Tue Nov 27, 2012 5:14 pm

StudioDevil wrote:Although, I can't agree so much with the CPU side of things...not here anyway. I've got 4 stages running with full interaction and it's only 4 times CPU of a single stage...due to the approach / solver I'm using...of course it's a guitar preamp...you'll be hearing it sometime next year, if all goes well :)

Do you mean a guitar amp featuring 4 tubes or 4 stages with multiple tubes in each ?

StudioDevil wrote:I'd rather just say that VTP is NOT TS, nor tries to be. If you want a dual stage triode with EQ, get TS...if you want a single stage triode then use VTP...but I'm considering putting both options under the hood now.

yes? no?
what's your vote?
conservative single stage, no eq
OR
agressive dual stage with Eq option?
OR
both?

Marc

Well, it's always good to have both, like you said, a VTP, and a VTP Deluxe :).

On a side note, with the new modeling technology you built and your recent work on the Clariphonic DSP, I really hope that you'll do more contract work like that, when it comes to modeling a particular unit, because it ended up sounding so good.

Is it true to assume, that you are not only able to model tubes properly now, but also transistors, transformers, op-amp and all the rest that can be inside a hardware gear like a tube equalizer, or tube compressor ?
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