Re: Just in: 67/68 Pro Reverb
Ah, first thanks for the info on pulling the preamp tube on the other channel, as I think I see what you are referring to here. Concerning the NFB loop, well the traditional presence controls are actually variable NFB loops through a capacitor of selected value, part of the idea of that loop being to increase or decrease the amps reproduction of higher frequencies ... it also effects how the overall amp responds and compresses. A much cooler circuit than the later pure EQ based presence controls found in some modern amps.
Again, I don't know if i'd go totally with out it, but the tech could put in a switch to select a pot ... if you weren't going to use the first channel you could use one of the pots there, which could easily be resoldered back as it was to original condition if need be later wished. Again just an idea.
Falstaff said:Kent, I am interested in making the NFB loop variable as well, that might be fun for dialing in different sounds for different situations. The tech I took it to suggested that I just install a (removable) switch to either put it in or out, but maybe a three way switch could find some medium in there as well.
Rock on!
Ah, first thanks for the info on pulling the preamp tube on the other channel, as I think I see what you are referring to here. Concerning the NFB loop, well the traditional presence controls are actually variable NFB loops through a capacitor of selected value, part of the idea of that loop being to increase or decrease the amps reproduction of higher frequencies ... it also effects how the overall amp responds and compresses. A much cooler circuit than the later pure EQ based presence controls found in some modern amps.
Again, I don't know if i'd go totally with out it, but the tech could put in a switch to select a pot ... if you weren't going to use the first channel you could use one of the pots there, which could easily be resoldered back as it was to original condition if need be later wished. Again just an idea.
