Tech21 VT-Bass - where's the magic ?

[OldogNewTrick]

After reading the predominantly glowing reviews and post in 2 megathreads plus JimmyM's challenges, I knew I wanted one.

It's now partnering my Carl Martin para EQ (clean channel) as tube preamp channel, feeding directly into a poweramp.

I wanted to find out, what it does to a waveform to shape sound / to perform its magic.

The actual EQing capabilities are nothing special.... worth nting is that flat ist B=12 M=12 T=9 (o'clock)

In these plots, the respective control is turned 7-9-10-11-12-13-14-15-17 o'clock, all others at 12, except for Drive set at 7 o'clock.

Bass sweep

Mid sweep

Treble sweep

Character sweep - covers the same range as the mid control.

So no magic yet....

 

[rodl2005]

MUST be REAL Magic then!!!!! ;-)

 

[grifff]

You have to believe....

 

[OldogNewTrick]

lets now have a look at the Character control... how does it add / shape character.

For all plots:
Sine wave at 500 Hz, amplitude to match the "Bypass"

Bypass and Ch=9 o'clock

Bypass and Ch=11 o'clock

Bypass and Ch=12 o'clock

Cool, the Character control does not only shape Mids, but adds Harmonics...

Bit of magic here...

 

[OldogNewTrick]

But what about the Drive control ?

Again, all plots sine wave 500 Hz, all controls 12 o'clock


Bypass and Drive at 9 o'clock

Bypass and Drive at 11 o'clock

Bypass and Drive at 12 o'clock

Bypass and Drive at 14 o'clock

Cool, look at the varying emphasis of even and odd harmonics....

 

[OldogNewTrick]

Anything else the Drive control can do ?

Let's have a look what it does to a 500 Hz sine wave...


Drive at 9 o'clock

Drive at 10 o'clock

Drive at 11 o'clock

Drive at 12 o'clock

Drive at 15 o'clock

Well, that explains the distortion and compression effects

 

[OldogNewTrick]

And how do the recommended settings in the manual shape out?

All controls set as per manual
Plots with frequency sweep and 500Hz sine wave and generated harmonics


SVT

Fat Tube

Flip Top

here some more...

T9-M12-B12_Ch10-Dr9

T9-M12-B12_Ch11-Dr10

 

[OldogNewTrick]

now, that is magic....

















Enjoy...

 

[bassophil]

Thanks a lot man!!

 

[bongomania]

Good stuff! I also valued very much your similar plots for the Carl Martin pre.

 

[rpsands]

Great thread. +10

 

[rodl2005]

Excellent stuff Old Dog NT. VERY interesting!!!!!!!!

 

[koobie]

Thanks for the plots, cool to see some of what it's doing to the frequency response. Did I miss something, or did you not say whether or not you liked it? Does it seem to change the feel? Does it make you want to bust out a groove?

 

[boing]

Again, all plots sine wave 500 Hz

I know it's a bass pedal and all, but is there a digestable layman's explanation for why 500 Hz is a relevant test frequency, and shows the behavior of the processing throughout the frequency range? I would have guessed...hell, I dunno...pink noise or some such thing would be needed...?

Concur.

 

[Rick Auricchio]

Rather than pink noise, which would be a huge mess with the harmonics, why not 250Hz and 125Hz?

With one gig under my belt using the VT, I'm liking the thick low end.

 

[Jim C]

Thank you; great job

 

[JimmyM]

That is some world class pedal sleuthin' right there! Finally, the mysteries of the character knob revealed! I always thought it was centered much higher, like in the 800 hz range. But it just seems to have a longer and more shelved Q. Those pics took about 10 minutes to download on this lousy hotel internet, but it was worth the wait. This is gold to me! Thanks, ODNT!

 

[Jjango]

Thanks for the great thread – but shouldn't it be in Effects?

 

[JimmyM]

Thanks for the great thread – but shouldn't it be in Effects?

It should be in both. Not only clears up a lot about the pedal but gives you an idea about the tones of Ampeg tube amps and how they behave as well.

 

[riker1384]

I'm guessing the difference between Character and the mid are that one is pre and one is post some gain stage (and possibly other stuff).

There's probably more to it than is shown on these graphs. In this interview: http://www.soundonsound.com/sos/1996_articles/jun96/andrewbarta.html he mentions the harmonics changing with the input level, the decay of the note. He also mentions using an inductor to simulate Xformer saturation. He doesn't get into many specifics beyond that.