My main system sounds overbright - way too much trebble and not nearly enough bass. It definitely hasn't always been like this but for various reasons it has had very little use over the last few years so I don't know when the problem might have occurred. During that time I've moved house twice. After the first move I had no bass at all which turned out to be because the surrounds for the bass cones on my JPW AP2s had disintegrated. I replaced and repaired them myself (there's a thread on that here somewhere but the forum search doesn't seem to be working at the moment) after which I could hear bass again and was very pleased with myself but it's possible that the balance was all wrong due to a botch on my part and some confirmation bias was stopping me from realising it.
It's also possible that the problem lies elsewhere entirely. Worn out components in the cross-overs for example or a problem with the amplifier.
I measured the impedance across the woofer input on the speaker (I have them biwired) and it read pretty much exactly 7ohms but when I did the same across the tweeter input I couldn't get a reading. I don't really know why. I was able to get a reading directly across the tweeter (bypassing the crossover components) but that's fairly meaningless because I was interested in finding out what impedance the amplifier was seeing.
Yesterday I needed to test a new stylus I had bought for my record deck and the only amp I have with a phono stage is the one in my main system. Knowing this was very top heavy I took the tape out from my main amp via a very long interconnect to an input on my second system and listened there. This sounded fine. My second system, like my main one, has a Marantz amp and JPW speakers (see my signature for full details). Unlike my main system however, the second one has tone controls and I did notice that I had the bass set at +4db and the trebble set at -2db which is something I had obviously done when I set it up and then completely forgotten about. I swapped the amp from my second system into my main system and listened both with the EQ settings I normally use on my second system and with it flat. It still sounded too bright with the EQ flat but didn't sound too bad with my normal settings. I'm still not completely convinced that it was right though and these kinds of changes take too long for really meaningful AB comparisons anyway.
Right now I'm just completely confused. None of this seems to make any sense and I don't know what to do next. I could move my speakers from the second system (JPW gold monitors) into my main one and listen to that but the gold monitors are so much smaller than the AP2s that there's no way I could expect as much bass from them anyway so I'm not sure what I would learn.
I'm willing to spend money on the right thing to fix this problem but I'm reluctant to chuck money at it blindly. Replacement woofers for the AP2s are still available (made in the original factory with the original tooling despite these being 30 year old speakers!) but at £150 a pair it's an expensive thing to try if I can't be sure that's the problem.
I would really appreciate any advice on how to figure out what on earth is going on. I don't have a background in electronics but I do have a little knowledge from my degree in Physics and I have a decent multi-meter which I'm not afraid to use if there's anything that needs measuring.
Many thanks in anticipation,
Simon.