KVR Audio

annode · Post by **annode** » Fri Oct 21, 2005 6:12 pm

Don`t know if this plug applys as in tube modeling...but it`s worth a peak and a demo trial;
http://www.starplugs.com/sess/utn;jsess ... shopscript

You may find this useful.
There is a demo availible.

fritzman · Post by **fritzman** » Fri Oct 21, 2005 6:35 pm

Ah yes,

I have to become a "member" to download a demo plugin. Very clever.

Best wishes, FRitz

annode · Post by **annode** » Fri Oct 21, 2005 6:59 pm

I`ve done it..was very painless.
You can op out of the newsletter.

fritzman · Post by **fritzman** » Fri Oct 21, 2005 7:24 pm

Hm,

a cheap looking site with a cheesy name which offers SynthEdit plugins wants me to register to become a member to be able to download demo plugins. Sorry, no. I wasn't even told by anybody what they sound like. No audio demoes as far as I could see. No thank you.

Best wishes, FRitz

kylen · Post by **kylen** » Fri Oct 21, 2005 7:45 pm

RogerPerrin wrote:...I'd just remind, that while we all talk about the magic of tubes and tube amps, there is more happening than just the tubes. There are the tubes, yes, but which tubes, the 12ax7's in preamp or the bigger power tubes. Also, the rectifier sag of the power supply, the audio output transformer, the speaker type and age, and the cabinet - large or small, open or closed back, plywood or particleboard. The speakers sound best if they are the older alnico magnet type instead of the newer ceramic magnets.

Yes indeed - this brings back fond memories of playing thru some nice tweeds and blackfaces where one can feel the nuances of an electric guitar. Tone and touch heaven! I'm reminded by one particularly "greasy" sounding Ameg amp that was just so sweet.

What I'm more into these days in my remastering and restoration is leveraging some of the audiophile features of amplifiers for rebalancing and EQing per this Steve Hoffman interview (renowned Mastering Engineer):
http://www.stevehoffman.tv/forums/showt ... 070&page=1

In there he mentions some tape decks that on occasion he would simply pop on the master, select a few tubes (for EQ) and print a digital master thru a A/D converter. Some of his weapons of choice are Ampex ATR-100, 350 or 351.

On this site is a 351 manual with a schematic of the playback amp:
http://www.ampexdata.com/Support/Legacy ... nuals.html

It uses 3 stages of 12AX7/ECC83, an inverter (of course!) and a push/pull output section with 12AU7. I don't see any feedback circuits in that design (unless I'm mistaken!).

I'm thinking that in that application power supply sag has a small percentage to do with the sound if anything and that the harmonic distortion of the amplifier system is the interesting thing to Mr. Hoffman. If there is no feedback circuit, and minimal consideration of power sag (?) then maybe it's possible to focus on the harmonic distortion of a triple stage/push-pull tube amp. Still considering the power sag whether or not it's significant - I know in a guitar amp it is, you can even feel it. I just don't have the experience of power sag in an audiophile amplification system...

kylen · Post by **kylen** » Fri Oct 21, 2005 7:48 pm

annode wrote:Don`t know if this plug applys as in tube modeling...but it`s worth a peak and a demo trial;
http://www.starplugs.com/sess/utn;jsess ... shopscript

You may find this useful.
There is a demo availible.

What did you think of that one annode? Did you sweeten up some mixes with it? Thanks!

fritzman · Post by **fritzman** » Fri Oct 21, 2005 8:30 pm

kylen wrote: In there he mentions some tape decks that on occasion he would simply pop on the master, select a few tubes (for EQ) and print a digital master thru a A/D converter. Some of his weapons of choice are Ampex ATR-100, 350 or 351.

On this site is a 351 manual with a schematic of the playback amp:
http://www.ampexdata.com/Support/Legacy ... nuals.html

It uses 3 stages of 12AX7/ECC83, an inverter (of course!) and a push/pull output section with 12AU7. I don't see any feedback circuits in that design (unless I'm mistaken!).

I'm thinking that in that application power supply sag has a small percentage to do with the sound if anything and that the harmonic distortion of the amplifier system is the interesting thing to Mr. Hoffman. If there is no feedback circuit, and minimal consideration of power sag (?) then maybe it's possible to focus on the harmonic distortion of a triple stage/push-pull tube amp. Still considering the power sag whether or not it's significant - I know in a guitar amp it is, you can even feel it. I just don't have the experience of power sag in an audiophile amplification system...

Hi kylen,

in this circuit are several feedback paths. E.g. look at the first 12AX7 of the playback head circuit. Between the anode of the second half and the cathode of the first half there's some eq stuff going on.
For sure the input transformer does something to the sound.
About the PSU sag: The PSU is very important to the sound. The inner resistance is not the same for all frequencies. This changes the dynamic response and that dependant on the frequency. In a heavily working guitar amp this is easily heard and in amps like this tape amp it's more subtle. But it does it's part to the sound. Change the PSU and you change the sound.

Best wishes, FRitz

kylen · Post by **kylen** » Fri Oct 21, 2005 8:34 pm

Thanks FRitz - your comments are much appreciated...more thinking & learning!

johnnypig · Post by **johnnypig** » Fri Oct 21, 2005 9:18 pm

The playback head circuit is a hi/lo bias, selecting a cathode resistance.

Waveshaper for a tube? For a diode maybe.

Since your basic 12ax7 triode has 3 main elements, and 4 tiny capacitances, a few resistances, transconductance, and overall amplification factor, sometimes a person might get a little silly and figure that's the end of the line re: harmonic generation.

Not quite! Capacitors (cathode bypass and coupling cap) are pretty good at causing distortion/harmonics, as would under-rated resistors. B+ power, the DC supply for the circuit, is usually full of ripple noise/harmonics one attempts to filter with caps and chokes.

Those are just a few examples of many in a DRIVEN tube stage... please note that at normal volumes in a vanilla circuit like the 351, there would not be much more distortion or harmonic generation than a solid state device.

I'll post a few links:
Steve Bench on Capacitor sound: http://members.aol.com/sbench102/caps.html

Radiotron Designers Handbook (don't even pretend to know what a tube is without it!): http://geek.scorpiorising.ca/RDH4.html

Simulanalog's Tubestage model paper: http://www.simulanalog.org/tubestage.pdf

www.duncanamps.com for really cool spice models and links to great ideas for modelling tubes.

see ya - robot

annode · Post by **annode** » Fri Oct 21, 2005 9:21 pm

Ive been using the starplugs "resonators"for adding specific resonant tones to single synths so far...and they both work great !
I`ll see what they do with a complete song mix and get back to you.

annode · Post by **annode** » Fri Oct 21, 2005 9:47 pm

ok..gave them a try with "seal`s-crazy" and can see no real application for them as a master plugin.

kylen · Post by **kylen** » Fri Oct 21, 2005 9:51 pm

johnnypig wrote: Those are just a few examples of many in a DRIVEN tube stage... please note that at normal volumes in a vanilla circuit like the 351, there would not be much more distortion or harmonic generation than a solid state device.

Nice first post johnnypig & interesting observation!

Thanks for the comments and links. After listening to many folks like yourself and researching I think I'm more inclined to try and "mimic" (a mo' better word than "simulate" in my case!) the harmonic distortion of the system more than any one element or tube or PS or passive element. I don't know if it's possible to ignore the individual contributions of elements and their combined synergy and just shoot for the big picture but my tools are limited in the DAW. All I've got are the same basic software EQ, Compressors, and distortion devices everyone else has.

While I'm at it I'll post a couple of links I'm currently reading and find interesting concerning the negative feedback was mentioned:
http://www.normankoren.com/Audio/FeedbackFidelity.html
http://w3.mit.edu/cheever/www/colloms.htm

I really appreciate everyon's comments and links - I'm just trying to cure my ignorance in this area with a little education - and fun experiments! Maybe something will shake loose

kylen · Post by **kylen** » Fri Oct 21, 2005 9:52 pm

annode wrote:ok..gave them a try with "seal`s-crazy" and can see no real application for them as a master plugin.

Thanks for trying annode! I like that seal song too - hope it didn't ruin it for you...

johnnypig · Post by **johnnypig** » Sat Oct 22, 2005 10:42 pm

"Modelling" is fun stuff to play with. I happen to use spice alot (check out www.duncanamps.com spice section), which allows you to enter a schematic and run tests on it. But I enjoy designing amps and stuff which alot of people probably wouldn't.

LTspice www.linear.com simulator lets you run wav files through your circuits which yields really fun results but it takes forever to render.

Better yet for the system-wide approach would be to use MAX/MSP or maybe PD and try to create a single tube stage using Norman Koren's really cool spice tube theory.

Or try building a real amp, guitar or hifi. It's not so complex if you can use a soldering iron and read a $20 multimeter. It's also pretty cheap if you buy a kit. You really learn the most about tubes by using them in my experience. Check out www.ax84.com that's where I started and many other people into amps today did too.

see ya! - robot

Why is waveshaping bad for simulating tube harmonics?