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Plexi PI input level?
Posted: Thu May 02, 2013 6:55 am
by jof006
Could someone tell me what a typical peak-to-peak signal level is going into the PI of a brown sounding Plexi?
I've got a 6101LM that does its channel switching with op-amps just before the PI using +/- 15V rails, so obviously I'll never get more than 30V peak-to-peak. Is that enough?
Cheers.
Re: Plexi PI input level?
Posted: Sun May 12, 2013 9:59 am
by VelvetGeorge
You can see 90V P-P in a plexi.
Steve's loop, for example, uses FETs and is called "zero loss" specifically because it can deliver full signal into the PI, overcoming that limitation of op amps.
George
Re: Plexi PI input level?
Posted: Fri May 17, 2013 10:37 am
by jof006
Thanks George.
I thought < 30V pk-pk would not give me the cranked Plexi sound, but it's good to know for sure.
It seems like the PI's clipping is quite important in getting a good brown sound.
Cheers.
Re: Plexi PI input level?
Posted: Fri May 17, 2013 10:42 am
by vanhalen5150
What's the voltage FETs can accept? Is there a max?
Re: Plexi PI input level?
Posted: Fri May 17, 2013 2:23 pm
by jof006
vanhalen5150 wrote:What's the voltage FETs can accept? Is there a max?
MOSFETs can be easily obtained with a drain-source voltage of up to 1.5kV.
Re: Plexi PI input level?
Posted: Fri May 17, 2013 4:18 pm
by vh junkie
jof006 wrote:vanhalen5150 wrote:What's the voltage FETs can accept? Is there a max?
MOSFETs can be easily obtained with a drain-source voltage of up to 1.5kV.
I don't think the devices are quite that robust... but they can essentially operate at the same voltages as preamp tubes (up to 500v)... The input signal that they can handle without distortion would increase with the B+ that they are operating at. You can read the installation instruction for the loop to see that target B+ range that is desired.
Re: Plexi PI input level?
Posted: Fri May 17, 2013 4:46 pm
by demonufo
vh junkie wrote:
I don't think the devices are quite that robust... but they can essentially operate at the same voltages as preamp tubes (up to 500v)...
You'd be surprised. There certainly are, but not necessarily designed with audio use in mind. MOSFET's have a multitude of different applications.
Re: Plexi PI input level?
Posted: Fri May 17, 2013 5:58 pm
by vh junkie
demonufo wrote:vh junkie wrote:
I don't think the devices are quite that robust... but they can essentially operate at the same voltages as preamp tubes (up to 500v)...
You'd be surprised. There certainly are, but not necessarily designed with audio use in mind. MOSFET's have a multitude of different applications.
I was talking about the the particular mosfet used in the loop... not mosfets in general...