deltafred wrote:Ken Baker wrote:
I do have a question. What effect does this have on the timbre of the instrument in series mode? Does it still have that characteristic bite & boom?
Ken...
It certainly does not seem to affect the tone when played normally, I spent quite some time going back and forth to see if there was a drop in treble due to any capacitive loading of the preamp. I could not detect any and (later) looking at the G&L schematic it does not present any capacitive load so should not suffer any loss of treble (as the pre Ernie Ball MusicMan EQ did). I deliberately did not check the schematic first as it may have biased my perception.
Aftermarket preamps may be different but I would have thought that they should be pretty well behaved so should not be a problem.
I am pretty sure the bite and boom is still there when you dig in, it sounds pretty similar to what it did before. Plenty of bass and aggressive middle without too much top in series. Switch to parallel and it looses some bass and gains quite a bit of top and so clarity.
I have just had another testing session, this time specifically for boom and bite and all seems well both active and passive.
Overall I am happy with it, I would have removed it if I were in any doubt.
I have had this circuit running on my project bass (MM clone - with treble compensation) for some months and played it to a few minor gigs and lots of rehearsals and have been very happy with it.
mgward is using it on his passive Yamaha Jazz copy and he reported that the treble was fine on that without compensation, the last thing an amplifier would do is present a capacitive load.
What I should have done was record a before and after. Isn't hindsight wonderful. If I get chance I will do some recording with and without.
fred
Interesting that there is not a perceived change in treble response. There is a 1000pF capacitor between the pickups and the preamp that would place a single pole filter at 3.4kHz. And in passive mode this capacitance would double with a 20' instrument cable adding an additional 1000pF resulting in single pole roll off at 1.7kHz.
I recently did a mod at the output of the preamp with a 33K resistor what would be working against a 1000pF cable capacitance (4.8kHz roll off). And to my ears I did not hear it as a significant roll off at low volumes for 5 minutes of playing around. And I was using round wound strings as I recall.
I think we are in the area of the stack knob jazz basses that placed resistors between the two pickups and "dual" tone controls as an attempt to isolate the two tone controls. I have read about old timers who love the stack knob jazz bass sound. I have never wired one up as I have always seen it as introducing a significant low pass filter that modern bass circuits, preamps, tweeters, and strings are all trying to overcome. That said the older I get, the less I use the tweeter and the more I roll off the tone control.
Anyone ever measure the inductance of the G&L MFD coils? One thought is that the high inductance of the pickup along with the outside world capacitance is already rolling off much of the frequencies above 2kHz. I would anticipate the MFD coil inductance to be in the 2-5H range. Jazz bass pickups are around 3H if memory serves correct.
This discussion makes me want to capture the raw signals coming off the G&L pickups and do a frequency analysis. Given that I just put flats on my L2000, it probably would not be the best test sample for measuring frequency spectrum.