@Mister Audio I never would have thought of treating those wires with engine oil. It just so happens I was going to grab some today as the car is low. The silica gel suggestion is also something I haven't thought of, but can certainly do 🙂
I was looking at these:
And it seems as though the crossover frequencies for the K2 are 800 and 5000 Hz. I also noticed that the rating for the K is 25 Watt, whereas the K2 is 40 Watt. Interestingly, I also got the woofer spec wrong in my earlier post. The Goodman's literature says both woofers go down to 30 Hz.. I could have swore blind I read somewhere that the K2 woofer was 20Hz. 🤔
This is going to change things if I want to mix up the drivers. Could I ask for your advice on this as you know way more about crossover frequencies than I. I would like to try dropping the K alnico mid in the K2 and also a K2 tweeter in the K. This would seem to give each speaker the best of both worlds.
I was looking at these:
And it seems as though the crossover frequencies for the K2 are 800 and 5000 Hz. I also noticed that the rating for the K is 25 Watt, whereas the K2 is 40 Watt. Interestingly, I also got the woofer spec wrong in my earlier post. The Goodman's literature says both woofers go down to 30 Hz.. I could have swore blind I read somewhere that the K2 woofer was 20Hz. 🤔
This is going to change things if I want to mix up the drivers. Could I ask for your advice on this as you know way more about crossover frequencies than I. I would like to try dropping the K alnico mid in the K2 and also a K2 tweeter in the K. This would seem to give each speaker the best of both worlds.
The quoted bass frequency figures mean little. To compare the K and K2 bass drivers, you would have to measure their resonance frequencies when out of their enclosures and in free air.
The power ratings also require qualification. Note 1 in the second attachment is really stating the maximum recommended amplifier power. The speaker can handle the 'up and down' power variation of music signals from such an amplifier, but would not withstand a full 40W RMS of power applied continuously.
The power ratings also require qualification. Note 1 in the second attachment is really stating the maximum recommended amplifier power. The speaker can handle the 'up and down' power variation of music signals from such an amplifier, but would not withstand a full 40W RMS of power applied continuously.
Well I’ve certainly learned a lot from this little endeavour. Thanks again for chiming in with little nuggets of knowledge Galu
In which case for me, not having anything to measure with, probably the next best way is a good listen to something that canes the bass drivers. I’ve just ordered a load of stuff to seal and repair the cabs because I noticed that some of them are not great. Don’t even get me started on the K… it’s got multiple points of possible failure for air leaks. The K2 cab is clearly superior for an infinity bass driver. The K grille for example secures from the inside by EIGHT points - holes drilled in the baffle.
In which case for me, not having anything to measure with, probably the next best way is a good listen to something that canes the bass drivers. I’ve just ordered a load of stuff to seal and repair the cabs because I noticed that some of them are not great. Don’t even get me started on the K… it’s got multiple points of possible failure for air leaks. The K2 cab is clearly superior for an infinity bass driver. The K grille for example secures from the inside by EIGHT points - holes drilled in the baffle.
I'll add that the Magnum-K leaflet statement that there is "minimal distortion right down to 20 Hz" should not be taken to mean that the bass will have significant amplitude at that frequency, i.e., it should not be regarded as an indication of audibility.
A bass extension figure like the 30 Hz given for the Magnum-K should really be qualified by adding the number of 'decibels down'.
For example, a lab report might quote a bass extension thus: LF extension 30 Hz (-6 dB with reference to 200Hz).
A bass extension figure like the 30 Hz given for the Magnum-K should really be qualified by adding the number of 'decibels down'.
For example, a lab report might quote a bass extension thus: LF extension 30 Hz (-6 dB with reference to 200Hz).
Call me a little confused, but I'm not sure I have yet seen the true-correct-proper K2 crossover circuit? Could someone post it?
(I find it hard to believe that the K2 would have no filtering on the woofer)
With the product pictures you posted > zoomed out I can't read, and zoomed in, too much is missing.
I would hate to give poor/incorrect advise, so I need this extra information to be of help.
Are the K & K2 mids the same size? What are their main differences?
@Mister Audio I was surprised at this also but I think I may be able to offer some insight. One of the things I have been considering is modding one of the K (not K2) speakers using doping on the bass and mid and removing the crossover components. There are lots of threads about this over at Hifi Subjectivist. The process involves drizzling contact adhesive near the dust cap in the centre of the cone to mute higher frequencies, then coating the entire cone in a rubberised spray. I think it's possible that Goodman's may have already done something like this with the K2 bass. It's coated in kevlar, and there is often a lot of glue near the centre caps. Here is a historic post from someone trying to rescue the cap on the Magnum SL speakers, which uses the same bass driver: https://www.diyaudio.com/archive/bl...odmans-magnum-k2-sl-cone-rescue-dsc06847s.jpg there seems to me to be a LOT more glue there than is needed for a little paper cone. I believe this driver may be doped out the factory.
As for the mids, they are both paper 4 inch. You can swap them round and they fit exactly. The obvious difference is the alnico magnet, but as I understand it this is more a sensitivity thing, there are probably other differences you cannot see with the eye if the quality is superior. From the front, they look very similar:
Note the metal frame is present but behind the baffle on the K.
But from the back....
Similar until the magnet begins.
Just in case there is some sort of disparity between batches or even possibly a second revision of the K2, here is another crossover from a different pair. It still looks like the woofer is full range to me (now I know what I am looking for!) but perhaps @chrisng could cast an eye over this one too just in case it's different:
I like how the person assembling it wrote "go" in the corner 😀 This board isn't stamped with a serial so I am guessing it's earlier than the other one I attached.
As for the mids, they are both paper 4 inch. You can swap them round and they fit exactly. The obvious difference is the alnico magnet, but as I understand it this is more a sensitivity thing, there are probably other differences you cannot see with the eye if the quality is superior. From the front, they look very similar:
Note the metal frame is present but behind the baffle on the K.
But from the back....
Similar until the magnet begins.
Just in case there is some sort of disparity between batches or even possibly a second revision of the K2, here is another crossover from a different pair. It still looks like the woofer is full range to me (now I know what I am looking for!) but perhaps @chrisng could cast an eye over this one too just in case it's different:
I like how the person assembling it wrote "go" in the corner 😀 This board isn't stamped with a serial so I am guessing it's earlier than the other one I attached.
@planet10 in the above pics, the crossover was actually mine but the drivers were google images because I was out and didn’t have a pic of them. Mine don’t look too dissimilar, but there is some rippling of the plastic surround.
Here is a pic (that really is mine):
The photo makes it look a LOT worse than it is. Every little ripple in that shiny surround goes white but it’s really not that bad at all. I think the photographer in the google image photo just got lucky. If I compare the above to the shipwreck K2s that I’ve given to my friend, the centre was pushed in, the paper was unglued all around, the paper was looking ropey. Clearly an abused set. I think they’ve been salvaged though. These are quite resilient drivers!
Here is a pic (that really is mine):
The photo makes it look a LOT worse than it is. Every little ripple in that shiny surround goes white but it’s really not that bad at all. I think the photographer in the google image photo just got lucky. If I compare the above to the shipwreck K2s that I’ve given to my friend, the centre was pushed in, the paper was unglued all around, the paper was looking ropey. Clearly an abused set. I think they’ve been salvaged though. These are quite resilient drivers!
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And to me. The red and black wires at the bottom of the crossover are connected directly to the input terminals and presumably also connect directly to the bass driver terminals.
It's not unusual to find bass drivers that have been designed to have a high frequency roll off that requires no additional support from an LC filter.
This one look identical to the first one, but the red leads from mid and high drivers doesn't seem to be connected to the negative post, maybe a picture taken from a different angle would give a better view?
Hey there,
Having done a little more research, it turns out that the K2 circuit diagram in the very first post is correct and YES
the woofer does connect direct to the amplifier without any filtering. It also became apparent that compared to the K,
the K2 is a bigger, more powerful and much 'louder' speaker system, possibly designed with rock music in mind.
The somewhat odd component values in the crossover are obviously tailoring the sound, and also creating a system -
impedance that has dips down to 4 ohms. The product spec's say 4-8 ohms so that's all in order.
It appears that there may be a significant efficiency difference between the K and K2 mids, and with the K mid being
an older and more delicate driver, I wouldn't recommend swapping them over.
In a video I saw, I thought the K2 woofer cones were coated in manufacture, but if not, thin rubber spray could be good.
The positive mid & tweeter terminals go to - ground due to the crossover design.
CHEERS🙂
Having done a little more research, it turns out that the K2 circuit diagram in the very first post is correct and YES
the woofer does connect direct to the amplifier without any filtering. It also became apparent that compared to the K,
the K2 is a bigger, more powerful and much 'louder' speaker system, possibly designed with rock music in mind.
The somewhat odd component values in the crossover are obviously tailoring the sound, and also creating a system -
impedance that has dips down to 4 ohms. The product spec's say 4-8 ohms so that's all in order.
It appears that there may be a significant efficiency difference between the K and K2 mids, and with the K mid being
an older and more delicate driver, I wouldn't recommend swapping them over.
In a video I saw, I thought the K2 woofer cones were coated in manufacture, but if not, thin rubber spray could be good.
The positive mid & tweeter terminals go to - ground due to the crossover design.
CHEERS🙂
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But on the second K2 crossover photo I not sure both high and mid driver red leads are connected to "ground" post, what I see is a single red wire bend to a V shape rest on top of the crossover (please take a closer look of the blue circle on the photo).
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@chrisng that really does look like one continuous red wire in the first photo doesn’t it? But I’ve just opened it back up and:
It’s 2 separate wires connected to ground.
Also, for anyone who’s interested, this cabinet has a good example of the doped bass:
You can see the abundance of glue from approx 1 o’clock to 7 o’clock.
It’s 2 separate wires connected to ground.
Also, for anyone who’s interested, this cabinet has a good example of the doped bass:
You can see the abundance of glue from approx 1 o’clock to 7 o’clock.
Hi, im interested in your findings if you managed to try a different tweeter in the Magnum K.. I love my refurbished and recapped Magnum K’s but the tweeter is getting a little discoloured with an oily substance and I’m sure they can be bettered. I have the option of purchasing a couple of k2 tweeters locally but not sure if to buy them as I don’t know enough to determine if they are a simple drop in replacement or not.. thx
Hi @shaunmaxr the only thing I’ve done with my Ks so far is to recap the pair that are in poor cosmetic condition and remove the LPADs. I did this to see what they sound like when in perfect order. I did plan to try a K2 tweeter in them, but I haven’t so far.
I’ve actually spent more time on the K2s to start. I have a mediocre pair that I’ve altered by removing most of the crossover and I’ve doped the drivers with contact adhesive and rubber spray. They now sound amazing. Truly amazing. Probably closer to Ks in terms of those mids, but with the K2 deep bass and crystal highs.
I know that the tweeters are often swapped out on Ks for non purists, and the K2 tweeter is indeed a much better tweeter. The model number is the DM3, but the DM2 and DM4 are the same with minor differences. Note these drivers aren’t always marked DM2/3/4 but have a distinctive appearance with the later DM4s having a mottled finished.
In terms of dropping a DMx driver in there, you’ll have 3 potential issues if straight swapping:
1. This tweeter may not rear mount in the K cabinets (I haven’t tried) so you may need to front mount it, but it should clear the grill. You may get lucky and find it rear mounts if the holes match up. If I get time over the next few days I’ll size it up for you.
2. You’ll need to make sure that if there are any holes from the previous driver, that they are filled and the cab is sealed. A sealed (or leaky) cabinet really affects infinity (closed box) bass so if you have a leak you’ll find yourself cranking up the bass dial to try and compensate (this is actually one of the reasons why I started on a K2 pair because the Ks have many many points for leaks to happen. Those grilles are one… they’re secured from the inside by 8 nuts.
3. The K2 tweeter has a 0.7mH inductor to just take off the top edge, and a 5uF cap to kill the lows. The K crossover uses a 4uF cap, this will be sufficient for the DM3, but you’ll have to either:
a) fit a 0.7mH inductor
b) dope the driver with Plastidip (a rubber spray)
You can either grab the inductor from your local shop or eBay / Ali. Or buy a can of Plastidip and dope it. If you don’t do either of these, you’ll get distortion on the extreme highs, like female vocals and piano. I know this to be the case because I’ve tried it.
With my modded K2s, I doped the driver but this is because I was doing the whole lot. It might be cheaper to buy an inductor, but depending on your knowledge it would be easier to dope it. Just do a few layers with a kids paint brush.
The final option which could cost less and would definitely be the least fuss is to grab some super tweeters. May I ask how much the DM3s you’ve seen are and what your soldering skills are like?
I’ve actually spent more time on the K2s to start. I have a mediocre pair that I’ve altered by removing most of the crossover and I’ve doped the drivers with contact adhesive and rubber spray. They now sound amazing. Truly amazing. Probably closer to Ks in terms of those mids, but with the K2 deep bass and crystal highs.
I know that the tweeters are often swapped out on Ks for non purists, and the K2 tweeter is indeed a much better tweeter. The model number is the DM3, but the DM2 and DM4 are the same with minor differences. Note these drivers aren’t always marked DM2/3/4 but have a distinctive appearance with the later DM4s having a mottled finished.
In terms of dropping a DMx driver in there, you’ll have 3 potential issues if straight swapping:
1. This tweeter may not rear mount in the K cabinets (I haven’t tried) so you may need to front mount it, but it should clear the grill. You may get lucky and find it rear mounts if the holes match up. If I get time over the next few days I’ll size it up for you.
2. You’ll need to make sure that if there are any holes from the previous driver, that they are filled and the cab is sealed. A sealed (or leaky) cabinet really affects infinity (closed box) bass so if you have a leak you’ll find yourself cranking up the bass dial to try and compensate (this is actually one of the reasons why I started on a K2 pair because the Ks have many many points for leaks to happen. Those grilles are one… they’re secured from the inside by 8 nuts.
3. The K2 tweeter has a 0.7mH inductor to just take off the top edge, and a 5uF cap to kill the lows. The K crossover uses a 4uF cap, this will be sufficient for the DM3, but you’ll have to either:
a) fit a 0.7mH inductor
b) dope the driver with Plastidip (a rubber spray)
You can either grab the inductor from your local shop or eBay / Ali. Or buy a can of Plastidip and dope it. If you don’t do either of these, you’ll get distortion on the extreme highs, like female vocals and piano. I know this to be the case because I’ve tried it.
With my modded K2s, I doped the driver but this is because I was doing the whole lot. It might be cheaper to buy an inductor, but depending on your knowledge it would be easier to dope it. Just do a few layers with a kids paint brush.
The final option which could cost less and would definitely be the least fuss is to grab some super tweeters. May I ask how much the DM3s you’ve seen are and what your soldering skills are like?
Just some info for the thread as well, I have since learned that what I believed to be excess doping material under the PVC as in the above pic, was actually the PVC layer separating from the paper layer. So apologies for the misleading post. If you find this happens to your K2 (and SL or Magister) bass, this is fairly easily fixed:
1. Heat gun, keep it moving, around the outside of the dust cap then as the glue starts to soften, use a small flat screw driver to separate the cone from the PVC and remove. You may need to lift slowly whilst applying heat in stubborn areas. DON’T PULL HARD, if it’s not coming off give it a bit more heat. When pulling pay extra attention and care to the part that’s separated, else it’ll just rip. Never leave the gun in one place. You’ll melt the PVC quicker than you’d think.
2. Apply a small amount of contact adhesive in under the PVC, if you use too much it will ooze out into the voice coil, so use sparingly. Don’t be tempted to dilute with acetone because you’ll risk setting it alight when reintroducing heat. Some may opt for PVA glue here, you could use that also.
3. As the contact adhesive (or PVA) starts to go off, use fingers from the outside pushing gently down towards the centre to stick the PVC back down. If you did use PVA, it’s grip isn’t as good as contact adhesive so you may need to put something light and gentle on top to hold it while it sets.
4. Heat the outside of the dust cap (inside edge where glue is) to soften again and place back.
5. Remember that you can always have a break to let the PVC cool down. Contact adhesive can be softened again and again with heat. PVA cannot and this should be taken into consideration if wanting to use that.
6. If you’re nervous about doing this, check for bass drivers on ebay first so see if any are currently listed…. Or… leave it alone! 🙂 it doesn’t appear to affect the sound measurably.
@shaunmaxr if you are interested in super tweeters….
On eBay:
Basic, cheap and plastic risk it for $10? https://www.ebay.com.au/itm/274527872840
Or on Ali, GHXamp have good stuff:
Nice, still plastic but good reviews and nicer shape/stand: https://a.aliexpress.com/_EwMc95V
Nicest, wood, better spec: https://a.aliexpress.com/_EQBhvTD
The most expensive ones are the nicest finished and go the highest (supposedly if you believe the spec) but I think that’s reflected in the price. Technically on paper the other 2 go no higher than your K drivers but I expect you’ll probably still hear a massive difference.
Edit: Hang on… you said you have an oily substance on your paper cone tweeters…. If you can see them you have the grilles off? Please can you attach a pic of your entire front of speaker?
On eBay:
Basic, cheap and plastic risk it for $10? https://www.ebay.com.au/itm/274527872840
Or on Ali, GHXamp have good stuff:
Nice, still plastic but good reviews and nicer shape/stand: https://a.aliexpress.com/_EwMc95V
Nicest, wood, better spec: https://a.aliexpress.com/_EQBhvTD
The most expensive ones are the nicest finished and go the highest (supposedly if you believe the spec) but I think that’s reflected in the price. Technically on paper the other 2 go no higher than your K drivers but I expect you’ll probably still hear a massive difference.
Edit: Hang on… you said you have an oily substance on your paper cone tweeters…. If you can see them you have the grilles off? Please can you attach a pic of your entire front of speaker?
Thanks for the reply.
I’ve got a pair of Townsend super tweeters and I’ve just dusted them off and installed them. It isn’t night and day but just listening again it does improve matters.
I checked through my photo album and it seems that the oily substance has been there since I refurbished them 10 years ago (I’ve only just noticed it when I put them in a lighter part of the house. It could be something and nothing.., not sure.
Mine don’t suffer from air leaks as I’ve veneered the fronts and sealed the backs and drivers with neoprene. Pics attached.
I’ve got a pair of Townsend super tweeters and I’ve just dusted them off and installed them. It isn’t night and day but just listening again it does improve matters.
I checked through my photo album and it seems that the oily substance has been there since I refurbished them 10 years ago (I’ve only just noticed it when I put them in a lighter part of the house. It could be something and nothing.., not sure.
Mine don’t suffer from air leaks as I’ve veneered the fronts and sealed the backs and drivers with neoprene. Pics attached.
