Ola amigos; I have a Lab Series L7 which I am pretty sure is the same amp with 4 ten inch spkrs instead of 2 twelves. I can only get normal volume using one low gain input. The other three inputs are much lower volume than it must have come from the factory. A fellow amp dude from another forum suggested checking the input op amps. That sounds to me like there may be a weak link in those input chips because you say your L5 works good after correcting that problem. Any thoughts ??

thanks

do you think that adding something as simple as a small audio transformer to change the input Z would be a real fix so it would "pickup" a small transducer signal?

thanks, jack

Mr Phatt; I use a transducer pickup in my big body acoustic guitar. These do not use any active components and the signal strength is minimal. Most preamps do not work because the input sensitivity is too poor. Could you make a suggestion on whether the Phabbtone could be modified to amplify such a small signal?

thanks, jack

thanks gents. I like the discussion about frequency and I made a copy of Roly's adj CR schemo. I generally set the tone and volume when playing and leave it there. I switch pickup positions often but not the basic tone and vol. I have several different types of buffers already built so maybe I will try some combinations with the Phabbtone and see what sounds good.

adios for now,   :tu:

senor phatt; thanks. question; have you used other pedals to specifically boost the signal ?  or, maybe what I would really like to know is, have you done any mods like adding another IC or mosfet to boost the signal more without changing the basic sound/tone?

thanks, jack

hi; I just built one of these Phabbtone pre's from the 3.5 ver. schemo. absolutely love it. I have only tried it with my mahogany body franken-strat but strat tone is my measuring stick for new builds. I don't play much humbucker stuff these days. This pre gives a sweet, transparent sound and a nice natural compression. I did not use the full size pots, I used trim pots for my initial build. I ran out of real estate so I used a fixed 39k resistor instead of the 100k trim pot shown on the schemo by the output. here are a couple pics.

I have not tried it with any other pedals/effects.

I second the scrap and build a better outhouse suggestion. Those amps don't seem to make good tone for guitar so I think other ideas would be time better spent. Just one man's opinion mind you.

:loco

Ajax; I wouldn't replace the blue coupling caps until after I had the amp up and running. Then you can see if you like the tone. Changing those caps to other varieties will mildly change the tone and one of the reasons for wanting a silver faced fender amp is that sought after tone. I would definitely do the startup of this amp using a current limiter. It's not a bad idea to then bring the amp up slowly on a variac to allow the older caps to get used to having current through them again.

Yes, you need polarized electrolyic caps to replace the main filter caps and the bias cap. Be careful to ensure you replace them with correct polarity observed.

I like Sprague Atom electolytic caps and I also like F&T which are made in Germany. Spragues are more expensive than the F&T. 

smacko  jack