M800 at 18V

[martre]

Hi
I've found the 800 great at 18V. What about bias JFET? I've used the "half voltage rule" but I found more open if on Q1, Q2 and Q3 I set with higher drain voltages (I can't hear many differences by biasing Q5 and Q6).
The only problem is a low end loss...
I'm working around 10V for Q1, 14V for Q2 and 11V for Q3...
Some experiences?
Thanks

 

[cooder]

I have built it with a switchable 9 to 18 V charge pump circuit and found it worked great with readjusting the bias, I just set it for 9V and that sounded still good in 18 V.
I guess if you always want to run it on 18 V you might want to try optimizing the voltage, but for me I like having both sounds available, the more compressed 9V and the higher headroom more punch 18V. Just my two cents.

 

[martre]

I have built it with a switchable 9 to 18 V charge pump circuit and found it worked great with readjusting the bias, I just set it for 9V and that sounded still good in 18 V.
I guess if you always want to run it on 18 V you might want to try optimizing the voltage, but for me I like having both sounds available, the more compressed 9V and the higher headroom more punch 18V. Just my two cents.

mmmmmh, so you not readjust bias at 18V? All JFET values will be out...Without rebiasing I measure some 15-16V !

 

[fig]

I bias as prescribed as a starting point. Where the voltages end up is where the guy who built it thinks it sounds the best.

 

[music6000]

When you think you have dialed it in as best as you can with the 6 Knobs, Adjust the TONE trimmer internally and see how much more you can give or take to make it even better, it is critical to the overall sound.

 

[cooder]

I set it to about 4.5 V bias when running on 9V and then when switched to 18V I think I measured about 12V if I remeber correctly, sounded fine to me.
As mucic6000 stated the internal tone trimmer is critical to get it to sound nice either way, that was an important one for me to get happy with pedal.