Re: mic&amp

[Mike Curtis <wd6ehr@xxxxxxxxxx>]

> 
> Having followed the mic & amp discussions for a long time
> I tried a few experiments that might help newly amplified blues players.
> I play a stock JT-30V thru a '65 blackface Princeton Reverb.
> I AB'd a 10ft. and a 20ft. cord and could not hear a difference.
> I built a voltage follower preamp with one op-amp in a small
> box.  I AB'd the JT-30V with and with out the preamp...no difference.
> I also have a Shure Green Bullet which I tried with and without the preamp.
> No differnce.  Then I tried mounting the Astatic crystal in the
> Green Bullet body.  This is not a quicky AB but the sound was not
> different enough to make me think that the mic body was a major factor
> in tone. (This was like changing guitar strings and then trying to
> remember what the previous ones sounded like 15min. ago.)  I prefer
> quick AB tests that are more objective.  I have also tried my Green Bullet
> wired for low and high impedence (had the wires hanging out so I could
> change them quickly), and my feeling here is that you arrive at the
> same tone and volume in either case if you just turn up the amp volume
> just before feedback.  (Note, the JT-30V volume is max on all tests which means
> the pot is shorted and has no effect.) 

The pots total value is shunted across the element, loading it with
whatever its overall resistance is.  mine has a 500k pot.  the bottom of 
this goes to ground (along withj one lead from the element), the top goes 
to the other element lead, and the wiper goes to the output jack.  When 
set at full volume, you still have 500k across the element.  the JT-30 is 
spec'd to run into 50 megohms (50,000k), so the pot still affects the sound.

Also, because the pot is loading the element, the voltage follower has 
negligible effect.

(BTW, "pot" is short for "potentiometer", the technical name for the part 
used as a volume control.  A potentiometer is not always a volume 
control.  They're also used as tone controls, bias adjusters, and many 
other things.)

> My conclusion, based on what
> I have read here and my own experience, is that, once you have good
> acoustic tone, get a small old tube amp and a new or old bullet mic.
> Crank the amp up to just below feeding back, then spend a lot of time
> experimenting with how you cup the mic and seal your hands to your
> face, and you will love your sound and the rest (different mics, cords
> etc.) will just be fine tuning.
> I hope this helps, because I know what it is like to always be wondering,
> 'can my tone be better if I just spend some more money on the right
> gadget, or should I go back to shed and keep practicing.

yup - there's no substitute for acoustic sound.  A good acoustic sound 
will give you a good electric sound.  There's no box that can do this.

However, proper equipment will help you sound better once you have the 
acoustic sound.  With the Green Bullet, cords aren't much of an issue 
(i.e. cheap, length, etc.)  With a JT-30 terminated into a 500k pot, cord 
quality and length is a little more of an issue.  If you swap the 500k 
out for a 5 meg, or build a voltage follower that goes before the volume 
control, or eliminate the volume control entirely, cable length and 
quality becomes quite important.

I'm going to look into building a voltage follower using a single ended 
op amp and 3 volt lithium cell into my JT-30 and see how well that 
works.  But it might be a while before I actually get it finished.  I 
want to make sure it's totally bulletproof (no pun intended), and will 
work as seamlessly and flawlessly as possible.

 --  mike curtis
wd6ehr@xxxxxxxxxx