Peavey Hisys 115 Bass bin question

midiman1962

Hi all
I know this is "old tech" and potentially a bit uncool but i'm trying to fix a bass bin speaker.
There is sound but no bass - i've cleaned out the "coil groove".
Yet to test , but my question is ...does this coil look in reasonable condition ?
Thanks in advance
https://drive.google.com/file/d/1inj_MEwFGEMUfJyEQYJwNm0OygVAVtTG/view?usp=sharing

https://drive.google.com/file/d/1G8QqFiJdL_SeDGSBAYRskrJp-hd3zd6W/view?usp=sharing

ICBM

Yes, it does. It would be brown and obviously 'cooked' looking if it had been overheated, although it's possible that it has simply broken, usually at one of its solder connections - but that would give no sound at all.

When the speaker is assembled, does the cone move freely and silently when you push gently on it? Lay the speaker on its back and press on it with several fingers spread around the dust cap.

If it does, do these cabs have a crossover? I can't remember. If they do it's likely that one of the components has failed. Try connecting a cable directly to the speaker and test it separately.

midiman1962

thanks for the response ICBM - i swapped both 15 inch speakers over and i think i managed to prove that the built in crossovers are ok. the other speaker gives proper bass but has a little rattle and distortion - this could also be the same issue so plan to have a look at the basket/coil in that one

ICBM

Now that I'm looking on a computer screen instead of a phone - it may be an optical illusion caused by the photo angle, but in your first pic it looks like the coil gap is much smaller on the far side of the magnet than the near side. This can happen if the cabinet is dropped heavily and the magnet core shifts on the plate it's attached to. If that is the case, it will definitely cause the coil to bind - you may see evidence of scraping on the sides of the coil. Unless you can get it centred correctly and stuck back, it's probably easier to replace the speaker.

midiman1962

been through both of the 15 inch speakers - the other one had a big lump of black foam and associated detritus which i had to remove. all working fairly well now (rattle has disappeared in no 2) though one seems to be running near full range so maybe the cross over in that one is suspect - though if i replug into the biamp socket it sounds different again - even more full range !

ICBM

I think the biamp input connects directly to the driver, so it should be pretty full-range if you don’t feed it with a pre-crossovered signal.