A friend recommended I take the Lpads out of the signal path and replace them with fixed resistors. Basically I removed them and measure the resistance of them at the setting I had chosen previously. Then replaced them for fixed resistors at that resistance. I didn't use an fancy resistors. I has previously cleaned the lpads with deoxit and didn't think much of them as a source of signal degradation. When I popped a couple of then open they didn't appear to be in such bad shape. But anyway I proceeded with the job.
So the result has been actually quite amazing. Much livelier, clearer and more sensitive for all drivers the Lpads were connected to. A lot more sparkle inthe uhf, more startling clarity form the hf horns, and more punch from the MF. I'd actually say this was a bigger improvement that getting rid of that awful biamp rotary switch.
Next step I'll try some fancier metal oxide etc resistors. Also I'll take some freq response measurments to check if the response is flat, but sounds pretty flat to my ears.
Highly recommend trying this for any older Studio monitors with Lpads. Obviously you lose the ability to tweak values on the fly. I do wonder if high quality new lpads would be the answer or simple if all those sliding contacts are just a bad idea even with fresh ones. It was a little bit of work, but well worth it, definetley not going back.
So here's where I'm up to with the tweaking of my 4343s
- Biamp switch removed: Say a 10% improvement. Better clarity.
- Baimping with a First Watt F4, again a 10% improvement over not biamping or biamping with a poor crossover. Better bass definition
- Getting really solid stands that put the monitors to a height such that the bottom of the hf lens is at ear level. 5% Better Bass.
- Getting rid of Lpads: 20% improvement. Better clarity, liveliness
Next Steps:
- measuring Freq response, tweaking resistance values to get flattest response, and replacing resitors with good ones.
- Rebuild whole network.