Hi guys, I have a question about TDA chip in Vupyr-15 power amp section:
http://music-electronics-forum.com/attachments/5037d1239065731-pv-vypyr-15-pa.pdf
What is the purpose of the current sense circuit in the speaker feedback loop? I read somewhere that it's there to raise amp's output impedance to mimic  tube amps; is that true? and how does it affect the sound?
Another question is how does it affect the amp's gain?

Thanks
Sajad

Hi guys, I'm planning on building a tube preamp/SS power amp style hybrid guitar amp.

The preamp section is basically from ax84 High-octane with tone stack:
http://www.ax84.com/hioctane/AX84_Hi-Octane_101004.pdf

After the preamp and tone stack I'm planning to use a fixed resistor divider in the place of MV to attenuate the signal level to around 3.5V p-p and feed it into an opamp buffer; something like this:
http://www.tremolo.pl/Przedwzmacniacze/JCM%20900%20Marshal.gif
I'm assuming the HV doesn't damage the opamp at start up, does it?

My main issue is the power amp; At first I was going to simply use a TDA20X0 chip, but it seems with a 12V+12V supply and 8 ohm speaker the input signal must be under 0.40V to avoid clipping.
So maybe I should build a discrete power amp section...
What's your opinion on this project?
Any help would be appreciated...

Thanks
Sajad

Hi guys, I'm new here, I was trying to build a FET-based practice amp and I found this:http://www.hawestv.com/amp_projects/amp_solid_tube/art_guitar_amp/2_IRF510adj_Dif_In.GIF
I modeled it with LTSpice with two stages of ROG Fetzer valve and I've got some interesting news:
Input signal of 100 mVhttp://i587.photobucket.com/albums/ss312/sajy_ho/FETInferno100mv-1.jpg?t=1388776143
Input signal of 300 mVhttp://i587.photobucket.com/albums/ss312/sajy_ho/FETInferno300mv-1.jpg?t=1388776150
The distortion characteristics is alot like tubes, but I'm wondering does the output sinal need to be in the same phase as the input signal or not? And what do you say about the circuit? Does have a worth of trying?
Thank you guys and sorry for terrible English :duh