Goodman's Magnum K series MEGA collection... Mod advice
Posted: Wed Jun 14, 2023 10:32 am
Hi fellow hifi tinkerers
I have recently been given 5 pairs of Goodmans Magnum speakers (yeah, you did read that correctly!) in what I believe was a house clearance from someone who clearly liked Goodmans and horded them (or worked for them and ended up with stock sitting at home, can't decide which!)
I don't really want to necro old threads despite there being a few of them so here goes...
I've got: 2 pairs of K's and 3 pairs of K2s. Some googling and linking from other forums seems to suggest that this is the place to be if one wants to alter these models. One of the Ks is the original birch ply construction and is in pretty good condition bar a couple of dents, even the Lpads seem to work well, not that I care too much for them. The other is chipboard and smells like an old fish tank inside - but the drivers appear pristine, thankfully!
One pair of K2s have been extremely well looked after and are almost pristine, one pair are in 'ok' condition, and the last ones are working but are very poor cosmetically - they look like they've been dragged down the road behind a car and some toddlers have been let loose on the tweeter domes :-/
Despite not being able to refuse the offer (it was take them all, or not at all!) I do not have the room in my house for 10 K series speakers! I would like to b**** the poorer units over for the best drivers ultimately preserving the nicest pair of K's and K2s. Then replace caps and run through the list of other well known upgrades / mods. As I understand it, the paper tweets that come with the Ks are inferior to the K2 DT-3s but the Alnico mid in the K's is superior to the K2 mid. I'm not worried about the majority of cosmetic stuff for now, it's mostly functionality.... So:
K's: bypass/remove Lpads, swap tweeters for DT-3s, recap, rewire, add decent 4mm posts, remove wadding, line cabs, dope bass / mids, seal cabs properly
K2's: swap mids for K Alnico mids, recap, rewire, add decent 4mm posts, remove wadding, line cabs, dope mids (not sure on bass as it's already covered in a coating), seal cabs properly
The vast majority of this I am able to do, and I've been reading through the many many threads here, but I have a couple of questions for those in the know or who have completed these mods and know what's what:
1. Which Bison compound is used? I can find reference to both the car mirror stuff and the kit stuff in a tin. They seem quite different products!
2. Does anyone have a photo of the Bison compound once 'wormed' round / drizzled down to the cap? (most the tinypic links are shot). It seems to me that there could be quite a variation on amount depending on user [in]experience and I don't want to screw it up.
3. Does anyone have a photo of the cab once steel lined? (again, most pic links are shot). I'm trying to get an idea of how completely edge to edge the coverage is. Are we talking do your best but some gaps are ok, or it MUST be edge to edge?
4. I was toying with the idea of using acrylic to line the K2 cabs just because of ease of cutting, it's not going to be as easy as with the Ks as the back is sealed... I read acrylic can be used - is this a waste of time / should I persevere with steel? That baffle is going to be interesting!
5. Can someone recommend a sealant to run round the inside of the cabs for air tightness? I'm not used to infinity bass and didn't realise the air leak thing was so important - will hot glue / liberal PVA suffice?
6. Does anyone know if the K2 bass cone paper caps be sprayed with the Plastidip? I have read they may need to breathe.. but it would be good if it matched the rest of the cone like the end result of the K bass.
7. On paper, the K2 bass goes lower, but I would welcome some input from those with these models - and I do not know how the doping will affect this - would you guys also swap the K bass to the K2 or is it worth keeping? Apart from the cab design, that will be the only difference between the two. I don't really subscribe to "on paper", I only care what the end result is.
I think that's it for now, I might have to ask other things as issues arise! Sorry if this is yet another Goodmans Magnum thread, but its pointless to necro the others.
I have recently been given 5 pairs of Goodmans Magnum speakers (yeah, you did read that correctly!) in what I believe was a house clearance from someone who clearly liked Goodmans and horded them (or worked for them and ended up with stock sitting at home, can't decide which!)
I don't really want to necro old threads despite there being a few of them so here goes...
I've got: 2 pairs of K's and 3 pairs of K2s. Some googling and linking from other forums seems to suggest that this is the place to be if one wants to alter these models. One of the Ks is the original birch ply construction and is in pretty good condition bar a couple of dents, even the Lpads seem to work well, not that I care too much for them. The other is chipboard and smells like an old fish tank inside - but the drivers appear pristine, thankfully!
One pair of K2s have been extremely well looked after and are almost pristine, one pair are in 'ok' condition, and the last ones are working but are very poor cosmetically - they look like they've been dragged down the road behind a car and some toddlers have been let loose on the tweeter domes :-/
Despite not being able to refuse the offer (it was take them all, or not at all!) I do not have the room in my house for 10 K series speakers! I would like to b**** the poorer units over for the best drivers ultimately preserving the nicest pair of K's and K2s. Then replace caps and run through the list of other well known upgrades / mods. As I understand it, the paper tweets that come with the Ks are inferior to the K2 DT-3s but the Alnico mid in the K's is superior to the K2 mid. I'm not worried about the majority of cosmetic stuff for now, it's mostly functionality.... So:
K's: bypass/remove Lpads, swap tweeters for DT-3s, recap, rewire, add decent 4mm posts, remove wadding, line cabs, dope bass / mids, seal cabs properly
K2's: swap mids for K Alnico mids, recap, rewire, add decent 4mm posts, remove wadding, line cabs, dope mids (not sure on bass as it's already covered in a coating), seal cabs properly
The vast majority of this I am able to do, and I've been reading through the many many threads here, but I have a couple of questions for those in the know or who have completed these mods and know what's what:
1. Which Bison compound is used? I can find reference to both the car mirror stuff and the kit stuff in a tin. They seem quite different products!
2. Does anyone have a photo of the Bison compound once 'wormed' round / drizzled down to the cap? (most the tinypic links are shot). It seems to me that there could be quite a variation on amount depending on user [in]experience and I don't want to screw it up.
3. Does anyone have a photo of the cab once steel lined? (again, most pic links are shot). I'm trying to get an idea of how completely edge to edge the coverage is. Are we talking do your best but some gaps are ok, or it MUST be edge to edge?
4. I was toying with the idea of using acrylic to line the K2 cabs just because of ease of cutting, it's not going to be as easy as with the Ks as the back is sealed... I read acrylic can be used - is this a waste of time / should I persevere with steel? That baffle is going to be interesting!
5. Can someone recommend a sealant to run round the inside of the cabs for air tightness? I'm not used to infinity bass and didn't realise the air leak thing was so important - will hot glue / liberal PVA suffice?
6. Does anyone know if the K2 bass cone paper caps be sprayed with the Plastidip? I have read they may need to breathe.. but it would be good if it matched the rest of the cone like the end result of the K bass.
7. On paper, the K2 bass goes lower, but I would welcome some input from those with these models - and I do not know how the doping will affect this - would you guys also swap the K bass to the K2 or is it worth keeping? Apart from the cab design, that will be the only difference between the two. I don't really subscribe to "on paper", I only care what the end result is.
I think that's it for now, I might have to ask other things as issues arise! Sorry if this is yet another Goodmans Magnum thread, but its pointless to necro the others.