Vulcan Issues

[CodeMonk]

Recently build Joe Davidson's Vulcan (BJT version).
Really like the sound of it.
I added and extra diode along side D2 (but reversed). Lost some gain but got a nice volume increase, which for me was perfect.
I then went about adding a tone control. Used BMP tone control. Worked fine but lost alot of volume, then added the BMP gain recovery stage. Back up to decent volume, but still below unity even at max volume.
So I',m thinking, add a second gain recovery stage.

I also tried, as a gain recovery stage, the Vulcan circuit, 3rd stage. Worked alright, but not as much of a volume recovery as the BMP recovery.

I have 4 amps. some no name 10 watt amp (which I loaned to a friend), and 3 Vox amps. AD30VT, AD50VT and an AC30CCH (the head only, I built my own cabinets, 1x12, 2x12, and put some Celestion G12K-85's in them).

I generally use one of my ADxxVT amps for pedal testing. When I like what I get, I hook it up to my AC30 and see how that sounds since it the amp I usually gig with.

Well, herein another problem lies.
The Vulcan with the BMP additions sounded fine through my AC30, but still lacked enough volume.
So, for the hell of it, I bypassed the BMP circuits. Nice volume through the ADxxVT amps, but when I hooked it up to my AC30, I was damn near blasted out of my chair. I mean it was REALLY REALLY loud. Thought I was gonna blow a speaker. Even turning the Level control all the way down I still got a VERY loud output. Amp is fine and works great with all my bought pedals and the several I have built.

Just a guess here, but my thought is that the standard Vulcan has the wrong output impedance for the AC30 and that the added BMP circuitry took care of that. Not sure how to check for output impedance. I'm guessing just check the output jack for resistance between the tip and the sleeve connection?.
I can search for that and am sure I will find the answer, but I'm more curious as to if my thoughts on the output impedance being incorrect are valid.
And what should correct impedance be?

So what are your thoughts on my thoughts with the output impedance being incorrect and adding a second BMP recovery stage to bring the volume up past unity?

Thanks

[Steben]

Normally, a recovery stage would bring the level at least back to original guitar level. So that should be ok. Are you sure you had decoupling caps in every situation?

[CodeMonk]

This is the layout I used  for the Vulcan.
And as per the original schematic, R4, R9, and R13, as well as the one I added were changed to bias the voltage to 4.5v.


For the Vulcan recovery stage, I went from, after the tone control, I C7 on. Maybe I should have skipped R16 there and put it after the recovery stage?

For the BMP version, I used the highlighted section here (I used the boxed values):


I also tried a few AMZ tone controls as well. But my issue is acceptable gain recovery.

[Derringer]

making the emitter resistor larger will increase your output volume

Try a 5k pot wired as a variable resistor in its place and see if you can get the gain where you want it. If you do .... pull the pot, measure it's value and replace with a resistor of approximate value

see this thread
http://www.diystompboxes.com/smfforum/index.php?topic=70717.0

[CodeMonk]

Actually, that thread was the first one I saw when looking for info on making a gain recovery stage.
My mind must have went blank though

Thanks

[CodeMonk]

One thing I noticed, didn't really notice it before but I'm sure it was still there...
After I engage the effect (via stomp switch, or actually a toggle in this case), the first note or 2 that I play, the volume isn't that bad (still a tad low, but not bad). But after that, the volume drops off drastically.
From what I have read here, I am led the believe that this is a capacitor issue.
Is that correct?

For all my prototype/breadboard building, I generally use used components. I have loads of boards from used/busted TV's radios. etc. that I use for prototyping.


Thanks